Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2410282
11/28/17 08:19 PM
11/28/17 08:19 PM
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Cab_Burge
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The motor is talking to you about it not liking something at that RPM, understanding what is saying Is the hard part AKA aside, I would try reversing what you did with the mechanical advance and have it all in by 2000 instead of 3400 RPM. If that doesn't fix it try replacing # 7 spark plug with the next hotter range plug and see if that helps it or not Maybe you have a intake gasket sealing problem on # 7 Is that plug shiny or dull looking?
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2410297
11/28/17 08:44 PM
11/28/17 08:44 PM
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RapidRobert
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at 2500 does it stay rough from then on as high as you rev it? is that part or WOT or cruise. I would measure the vac & fuel psi & timing at that exact point when it starts to act up. Yes do a compression test & maybe a leakdown & try the new plug first & see if the new plug straightens it out for awhile. Describe the roughness (shakeing/missing). EDIT if it dont continue to be rough from 2500 on up, how much more RPM does it continue to run rough?
Last edited by RapidRobert; 11/28/17 09:21 PM.
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Re: Back with rough spot around 2500 rpm
[Re: RapidRobert]
#2410420
11/28/17 11:46 PM
11/28/17 11:46 PM
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at 2500 does it stay rough from then on as high as you rev it? is that part or WOT or cruise. I would measure the vac & fuel psi & timing at that exact point when it starts to act up. Yes do a compression test & maybe a leakdown & try the new plug first & see if the new plug straightens it out for awhile. Describe the roughness (shakeing/missing). EDIT if it dont continue to be rough from 2500 on up, how much more RPM does it continue to run rough? It’s hard to describe the rough spot, I just know it happens in every gear at the same rpm. Starts around 2500 and continues on up as far as I can tell. It almost feels like a driveshaft vibration and sounds like one in the cab specially when I get the rpms up higher around 3500-4000 rpm. Seems like it takes a little longer to cycle once im at a higher rpm around 3500-4000 rpm if that makes sense. At 2500-3000 it seems like its cycling pretty quick and the higher the rpm goes up the slower it gets but it’s still there. You can feel it in the floor boards in the steering wheel, in the seat. I know this isn’t a drivetrain issue becuause it’s rpm dependent not speed dependent. I have a 1350 series cv shaft for a rear driveshaft, pinion angle is set perfectly at -2 to -3 so that the pinion is inline with the shaft while driving. For the longest time I thought this was drivetrain related but now I’m convinced it’s not. My converter is correct I’ve verified that, flex plate is correct. Balancer is correct. And like I said since it’s rpm dependent the drivetrain theory kind of goes out the window. I’m convinced it’s in the engine somewhere, ether ignition or there is an issue with one of the cylinders. Its just strange cause the last time I did a compression test all cylinders were dead even at 150 psi. Below is a pic of the spark plug that came from cylinder 8. The plug on the left cane from cylinder 6 plug on the right is cylinder 8. All the other plugs looked just like cylinder 6’s plug. Cylinder 8 was the only one that didn’t look right and smelled like fuel a little bit. I’m heading out right now to pull cylinder 8’s plug and do a compression test. The engine is still warm from driving it home from work. I’ll report back with what it puts out, last time it was 150 and that was only like 6-8 thousand miles ago and I never abuse this engine. I baby it big time. So I don’t see how compression could have just dropped in one cylinder all a sudden.
Last edited by pjc360; 11/28/17 11:53 PM.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2410469
11/29/17 01:09 AM
11/29/17 01:09 AM
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RapidRobert
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Can you bump the original post back up so we can reread/refresh our info?. A balanceing issue? just crossed my mind.
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Re: Back with rough spot around 2500 rpm
[Re: RapidRobert]
#2410480
11/29/17 01:21 AM
11/29/17 01:21 AM
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Can you bump the original post back up so we can reread/refresh our info?. A balanceing issue? just crossed my mind. I’ve verified the torque converter and the flex plate, they are correct. I have the magnum weighted converter and a standard la style flex plate. I just pulled number 8’s plug with the engine warm and the brand new plug I just put in it a couple of days ago is already looking like it isn’t firing right just as before. Did a compression test on that cylinder with engine warm and carb wide open cranked on it that way for about 5-6 seconds and it’s reading 155 psi. I’m at a loss with what’s going on with cylinder 8. I suspect cylinder 8 is causing the rough spot. Should I pull the valve cover and inspect rocker arms and valve springs?
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2410490
11/29/17 01:37 AM
11/29/17 01:37 AM
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I’m leaning towards a bad valve spring on cylinder 8. But what I don’t understand is why I’m not seeing something obvious with the vacuum gauge hooked up. But it makes sense, only cylinder 8’s plug isn’t firing correctly all the others look pretty good. It idles fine and drives perfectly fine below 2500 rpm. Once you get up to 2500 or higher it just gets rough. I’m seriously thinking valve spring on cylinder 8 but the only thing that has me wondering if that’s really the case is the vacuum reading at idle appears fine. Maybe I should hook up the vacuum gauge and sling it up to 2500 rpm and watch it and see what it does then. Cause from what I’ve read online about bad valve springs and the symptoms I’m having it sure makes sense at this point. Specially with cylinder 8 pumping out good compression.
Last edited by pjc360; 11/29/17 01:39 AM.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2410501
11/29/17 01:53 AM
11/29/17 01:53 AM
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RapidRobert
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Just thinking out loud, I'm wondering if a badly worn guide/valve stem/seal is letting the plug, oil foul almost immediately, the compression would still be good as would the valve spring. when you put the new plug in there is it still running rough IMMEDIATELY? (before the plug has time to foul) If so I might be wrong but I keep thinking a "balancing issue".
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Re: Back with rough spot around 2500 rpm
[Re: RapidRobert]
#2410517
11/29/17 02:14 AM
11/29/17 02:14 AM
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Just thinking out loud, I'm wondering if a badly worn guide/valve stem/seal is letting the plug, oil foul almost immediately, the compression would still be good as would the valve spring. when you put the new plug in there is it still running rough IMMEDIATELY? (before the plug has time to foul) If so I might be wrong but I keep thinking a "balancing issue". I’m just not seeing where the balancing could be off and why that would be affecting the number 8 plug? Like I said i have crawled under the truck and removed the converter inspection plate and verified that it is a weighted Magnum converter. And a La style flex plate. The engine still has the balancer on the front that came with the engine from Mopar. And the number 8 plug isn’t oil foiled, it’s fuel. This just doesn’t make sense to me, but I have a strong feeling the rough spot I’m feeling is connected to what’s going on with cylinder 8. Would it be a good idea to have the engine hooked up to some kind of monitor to watch the spark events to see exactly what’s going on? There has to be way to determine whatever is going on here.
Last edited by pjc360; 11/29/17 02:20 AM.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2410683
11/29/17 01:45 PM
11/29/17 01:45 PM
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So I talked to a mechanic friend of mine and he said that if there was a weak valve spring the compression test doesn’t always reveal that. He let me barrow a leak down tester and said to make sure the valves are closed on cylinder 8 and test it. He said something is allowing more fuel into cylinder 8 and that he agrees with me that it does sound like a weak valve spring. And he said that could most definitely be causing the rough spot im feeling. He said it sounds like the spring is ok at idle and lower rpms but it starts revealing its self around 2500 rpm where the rough spot comes on and it could be allowing the valve to stay open to long drowning the number 8 plug in fuel.
Last edited by pjc360; 11/29/17 01:46 PM.
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Re: Back with rough spot around 2500 rpm
[Re: krautrock]
#2410806
11/29/17 05:26 PM
11/29/17 05:26 PM
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in that other post you said you got rid of the vibration by swapping in a new distributor. is that correct?
now the vibration is back? i see you posted a thread about fouled plugs and the #8 plug being darker. did you make adjustments to your carb to clean your plugs up?
Well what’s throwing me off is why are the other 7 plugs looking perfectly fine but cylinder 8’s plug is looking like it’s struggling to fire. This rough spot has been there for a long time and I’ve just kept throwing parts at it trying to figure out what’s going on. Everything I have done has made it a tiny bit better each time but it’s never been eliminated all together. New plugs, new wires, new distributor, new coil. Timing is set at 18 initial and 32 total. I’ve verified it with two different lights, both dial back lights I have show 1/2 of a degree of each other. When I un-plug the vacuum advance it gets better. That’s what led me to believe it was possibly a rotor phasing issue at first. But I’ve verified rotor phasing on my new distributor and it’s fine with and without vacuum advance. The only area I haven’t really checked out is the heads. Compression test revealed 155psi on cylinder 8 with engine warm and carb wide open cranking on it for about 5 seconds. I’m going to remove the valve cover and do a leak down test on cylinder 8 and hopefully that reveals something cause this is driving me insane.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2410833
11/29/17 06:22 PM
11/29/17 06:22 PM
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Everything I have done has made it a tiny bit better each time but it’s never been eliminated all together.
When I un-plug the vacuum advance it gets better.
Compression test revealed 155psi on cylinder 8 with engine warm and carb wide open cranking on it for about 5 seconds. I’m going to remove the valve cover and do a leak down test on cylinder 8 and hopefully that reveals something cause this is driving me insane. I reread back thru the old thread. with these changes/adjustments makeing it better it would not be the balancing. unplugging the can changes (4) things: reluctor gap/Rotor Phasing/timing/rotor tip to cap terminal air gap (related to RP) but the RP is corrected which gets the best rotor radial air gap & iirc you bumped the timing up to make up for what the can took out correct? there might be a ring issue causing the fouling but iirc you said it was fuel not oil? How the can capped is helping things & getting #8 to fire is on my mind.
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Re: Back with rough spot around 2500 rpm
[Re: RapidRobert]
#2410868
11/29/17 07:11 PM
11/29/17 07:11 PM
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Everything I have done has made it a tiny bit better each time but it’s never been eliminated all together.
When I un-plug the vacuum advance it gets better.
Compression test revealed 155psi on cylinder 8 with engine warm and carb wide open cranking on it for about 5 seconds. I’m going to remove the valve cover and do a leak down test on cylinder 8 and hopefully that reveals something cause this is driving me insane. I reread back thru the old thread. with these changes/adjustments makeing it better it would not be the balancing. unplugging the can changes (4) things: reluctor gap/Rotor Phasing/timing/rotor tip to cap terminal air gap (related to RP) but the RP is corrected which gets the best rotor radial air gap & iirc you bumped the timing up to make up for what the can took out correct? there might be a ring issue causing the fouling but iirc you said it was fuel not oil? How the can capped is helping things & getting #8 to fire is on my mind. That’s whats on my mind as well. I’m just going to do a compression test on all 8 cylinders and a leak down test and go from there for right now. Everyone else I have chatted with about this seems to agree that something is causing number 8 to get more fuel. And they all seem to think it’s a valve or valve spring problem. I’m also going to remove the valve cover and see if I can see anything out of the ordinary. I have a feeling whatever is causing this is something that’s not so obvious but will make sense once it’s found. It’s just finding it that sucks.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2410975
11/29/17 10:08 PM
11/29/17 10:08 PM
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I have a feeling whatever is causing this is something that’s not so obvious but will make sense once it’s found. It’s just finding it that sucks. We're gonna have a good laugh when we find it, as in THAT was it!.
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Re: Back with rough spot around 2500 rpm
[Re: RapidRobert]
#2411020
11/29/17 11:34 PM
11/29/17 11:34 PM
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I have a feeling whatever is causing this is something that’s not so obvious but will make sense once it’s found. It’s just finding it that sucks. We're gonna have a good laugh when we find it, as in THAT was it!. Check out this article, this guy was having the same issue I was having except he was having problems with cylinder 6 and he had his computer throwing a miss fire code. It ended up being a broken valve spring on cylinder 6 and the tech said historically it’s cylinder 8 that has issues with the valve springs. https://www.justanswer.com/dodge/192b9-2001-dodge-ram-1500-truck-5-9l-v8-my-problem.html
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2411233
11/30/17 01:00 PM
11/30/17 01:00 PM
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I'm thinking I would toss in a regular MP dist/ECU for a quick test to see if that makes it dissappear. Wouldn't be hard to do with some jumpers. I keep coming back to capping/plugging the vac can hose makes it much better. We've checked that the can/hose ain't leaking & we've added back in the timing the can was providing & we've corrected the rotor phaseing.
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Re: Back with rough spot around 2500 rpm
[Re: RapidRobert]
#2411391
11/30/17 06:06 PM
11/30/17 06:06 PM
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I'm thinking I would toss in a regular MP dist/ECU for a quick test to see if that makes it dissappear. Wouldn't be hard to do with some jumpers. I keep coming back to capping/plugging the vac can hose makes it much better. We've checked that the can/hose ain't leaking & we've added back in the timing the can was providing & we've corrected the rotor phaseing. Well isn’t possible that a broken valve spring would work better with less timing? Take away the 10-12 degrees fromvacuum advance and your making it easier on it, Seems logical to me. Idk though I’ll pull the valve cover tonight and have a look at it.
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Re: Back with rough spot around 2500 rpm
[Re: 360view]
#2412829
12/03/17 09:45 PM
12/03/17 09:45 PM
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Did you re route the ignition wires exactly like the TSB shows?
Have you replaced #8 ignition wire and spark plug with "known good" substitutes?
Like i wrote in your previous post looking at all 8 spark traces on an old Sun machine display could eliminate doubts about ignition. Those old Sun machines could also do a "cylinder power balance" test at 2500 rpm.
Looking at the valve springs, rocker arms and hyd lifter bleed downs is quite reasonable, as Magnums have been known to have problems in all 3. A video boroscope makes this inspection quicker and easier but removing valve covers is also worth the time and gasket costs. Looking inside all 8 cylinders with the video boroscope through the spark plug hole is worthwhile. Are there deposits on intake valve stems?
Having down the static compression test on #8 is good. Your 155 is typical. A "running compression test" also called a dynamic compression test would also be instructive in spoting a bad valve spring or lifter, and could even give a hint about intake manifold runner air distribution variation cylinder to cylinder.
Have all the previous worries about the Carb set ups been eliminated?
I removed the valve cover this afternoon and took a close look at both valve springs on cylinder 8 and I’m not seeing anything out of the ordinary compared to the rest of the springs. I have a leak down tester that I have barrowed from a friend but I haven’t had time to perform the test. I was told cylinder 8s valves need to be closed while performing the leak down test. How do I determine when the valves are closed on that cylinder? The plug gaps are set at .40 cause I am running a crane cams hi-6 cd ignition and a crane cans ps92 e-core coil. I did another compression test on cylinder 8 while the engine is cold and it revealed 147-148 psi this time. Is it normal for it to drop a few psi when it’s cold? I haven’t ran the truck in a few days cause I’ve just been so frustrated with whatever the hell is going on with it. So you reccomend I call a few shops and find out who has the equiptment to monitor ignition while it’s running and have them bring the throttle to 2500 where the rough spot starts and go from there? Cause I’m throwing in the towel I have no idea what’s causing this issue. Number 8s plug looking darker then the rest has me thinking it’s all connected some how. One thing I can do is turn my chokes fast idle down a little bit more; throw a new plug in cylinder 8 and see what happens. All plugs are brand new and my plug wires are also brand new. Coil is brand new, distributor is brand new, timing has been verified with two different lights. Timing mark on balancer has been verified with piston stop. This is just strange and I have no idea why this rough spot is a lot more prominent when vacuum advance is connected. With no vacuum advance it’s much better.
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Re: Back with rough spot around 2500 rpm
[Re: Dave Hall]
#2412845
12/03/17 10:28 PM
12/03/17 10:28 PM
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Just try a tighter gap. .040 to .025 isn't going to hurt anything. With high output ignitions the gap will only get wider over time. Start a little tighter. I’m running all 8 plugs at .040. The cd ignition should have no problem firing that. Most company’s reccoemnd .045 to .060 with cd ignition boxes and coils. I’m turning the choke down a little bit and turning the fast idle down a little bit as well and I’m going to try and route number 6 and number 8 plug wires as far away from each other as possible. I just don’t know how I’m going to accomplish that cause I only have the plug wire looms that bolt to the valve covers. I know plug wire 6 and plug wire 8 cross each other but where the do cross is up near the distributor cap.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2412858
12/03/17 11:13 PM
12/03/17 11:13 PM
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RapidRobert
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.040" ain't an issue nor is 6/8 crossing each other (& crossing at a good angle as opposed to running parallel for a good length is the best). the problem is elsewhere.
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Re: Back with rough spot around 2500 rpm
[Re: RapidRobert]
#2412886
12/04/17 12:16 AM
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.040" ain't an issue nor is 6/8 crossing each other (& crossing at a good angle as opposed to running parallel for a good length is the best). the problem is elsewhere. Well tonight I turned down the electric choke a little bit and turned down the fast idle a little bit and installed a brand new plug in cylinder 8. I’ll drive it to work tomorrow and check the plug when I get home from work tomorrow night and see if that made a difference. Cause every morning when I fire it up it is running off the choke and fast idle, its possible the choke being a little on the rich side and the fast idle being a little too high was causing the rich condition on cylinder 8’s plug. And maybe the rough spot around 2500 is still rotor phasing or maybe it’s just my crane ignition box. I’m going to call around to a few shops tomorrow and hopefully find someone with a sun machine or a spark analyzer that can hook up to my ignition and bring the Rpm up to 2500 and watch the ignition to get a better idea of what’s going on.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2417549
12/12/17 08:14 PM
12/12/17 08:14 PM
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can you jet it up (richer) 4 or 6 sizes and see if it gets any better?
Last edited by krautrock; 12/12/17 08:14 PM.
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Re: Back with rough spot around 2500 rpm
[Re: krautrock]
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12/12/17 09:36 PM
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can you jet it up (richer) 4 or 6 sizes and see if it gets any better? I’ve already increased the idle feed restrictors up 3 sizes, I’ve increased the main jet 1 size, and I’ve decreased idle air bleeds 5 sizes. There is no way this thing is lean. I even took the carburetornoff thenither day tire it all down and cleaned it very well used 3 cans of carb cleaner and blew out every orfice in the carb main body and the metering blocks and put it back together with new gaskets. I have a strong feeling it’s strictly cylinder 8 that’s the issue. Another reason I believe this is cause of all the things I’ve read online with people having issues with cylinder 8 in particular. But the compression test on cylinder 8 checks out. So I’m kind of stuck not knowing what to do next to pin point what the issue is. Tonight I’m going to hook my timing light up to number 8’s plug wire and bring it up to 2500 where it gets rough and see if the flash from the timing light is erratic.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2417664
12/12/17 11:18 PM
12/12/17 11:18 PM
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So what are your guesses? I wondering if the oil rings are fubared on #8. A quick visual would confirm the spring ain't broken & did we check the seal? I was thinking we did. but if #8 blinks differently than the rest of em, plug wire or check the underside of the cap, the # 8 brass terminal. didn't we replace the plug wires?
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Re: Back with rough spot around 2500 rpm
[Re: RapidRobert]
#2417667
12/12/17 11:24 PM
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So what are your guesses? I wondering if the oil rings are fubared on #8. A quick visual would confirm the spring ain't broken & did we check the seal? I was thinking we did. but if #8 blinks differently than the rest of em, plug wire or check the underside of the cap, the # 8 brass terminal. didn't we replace the plug wires? Yep brand new plug wires, brand new plugs, brand new cap and rotor. And number 8’s plug is never oil fouled it’s always fuel and it even smells like fuel. I’m seriously thinking valve spring. Something is letting more fuel into cylinder 8 which is causing the plug to semi fuel foul.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2417673
12/12/17 11:34 PM
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I would think, but the compression rings could be adequate & the oil rings can still be bad. First we gotta resolve the blinking light potential.
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Re: Back with rough spot around 2500 rpm
[Re: RapidRobert]
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12/13/17 12:01 AM
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I would think, but the compression rings could be adequate & the oil rings can still be bad. First we gotta resolve the blinking light potential. So where do I go from here? Should I buy a couple valve springs and put them inn on cylinder 8!and see if that fixes it?
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2417708
12/13/17 12:41 AM
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Circle Track
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I would put a clean plug in #8 & see if the light blinks differently on #8 than on the rest of em & if so we might swap some plug wires & see if the intermittent blinking follows the wire (that is on #8 now). I wouldn't buy a valve spring right now.
live every 24 hour block of time like it's your last day on earth
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Re: Back with rough spot around 2500 rpm
[Re: RapidRobert]
#2417720
12/13/17 01:12 AM
12/13/17 01:12 AM
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Joined: Nov 2011
Posts: 653 montana
pjc360
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I would put a clean plug in #8 & see if the light blinks differently on #8 than on the rest of em & if so we might swap some plug wires & see if the intermittent blinking follows the wire (that is on #8 now). I wouldn't buy a valve spring right now. Ok the only issue is I don’t have a shop and my truck is on the side of the road and it would enrage the entire neighborhood if I sat out there Reving the engine. My neighbor already hates my truck says it’s too loud. My main thought on that is I have tried multiple plugs on cylinder 8 and the result is always the same the number 8 plug always ends up semi fuel fouled and smelling like fuel. These are brand new plug wires with less then 100 miles on them, same with the coil and same with the distributor. The only part of the ignition that hasn’t been replaced and isn’t brand new is the crane cd ignition box. This issue has been present for a long time and at first I thought it was a vibration from drivetrain then realized that wasn’t the case because of how it’s rpm dependent. Then I buy new plugs and wires and a new distributor and a new coil all at once and that doesn’t make a difference. I’m just so annoyed with running in circles with this thing and never pin pointing exactly what the issue is. It’s been driving me insane.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2417766
12/13/17 02:22 AM
12/13/17 02:22 AM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
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Lincoln Nebraska
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I will go back thru everything & see if anything jumps out at me.
live every 24 hour block of time like it's your last day on earth
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2418092
12/13/17 06:44 PM
12/13/17 06:44 PM
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Joined: Jan 2003
Posts: 74,969 U.S.S.A.
JohnRR
I Win
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I would think, but the compression rings could be adequate & the oil rings can still be bad. First we gotta resolve the blinking light potential. So where do I go from here? Should I buy a couple valve springs and put them inn on cylinder 8!and see if that fixes it? Change the springs, they aren't that expensive. What is the timing at 2500 rpm?
running up my post count some more .
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2419796
12/17/17 12:32 PM
12/17/17 12:32 PM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
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I wish you were nearby as we could put a spare OE MP ign on it & see if it straightens out. The box IS beginning to look guilty.
live every 24 hour block of time like it's your last day on earth
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Re: Back with rough spot around 2500 rpm
[Re: RapidRobert]
#2419903
12/17/17 04:18 PM
12/17/17 04:18 PM
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Joined: Nov 2011
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pjc360
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I wish you were nearby as we could put a spare OE MP ign on it & see if it straightens out. The box IS beginning to look guilty. Well I used to have a the factory Mopar wiring harness and a chrome Mopar ignition box and a canister oil filled coil. But now the harness is all hacked up, I still have the chrome box, and I don’t have a coil or a ballast anymore, I don’t know what happened to them. I moved a couple years back and I suspect it’s probly all buried in my storage unit somewhere. I could just go buy an msd digital 6 box for a couple hundred bucks at my local Oreilly auto parts store, it would be super easy to wire inn since I already have a cd ignition box wired inn and all the wiring is there for a cd ignition. I just hate spending money on things without knowing without a doubht that what I’m replacing is the cause of the problem. But everything at this point seems to be point at the crane box. Specially when you consider I went through an un-usual amount of pick up coils in my previous Mopar distributor. I always thought that was strange, I went through 3 pick up coils in about 10k miles and I think whatever issue this crane box has is what was wiping those pick up coils out. And when you also consider the box gets kind of warm to the touch when you hold the throttle at 2500 and it starts missing and the red led light on the box starts flickering while the throttle is held at 2500 and it’s missing.
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Re: Back with rough spot around 2500 rpm
[Re: Tom Fox]
#2420080
12/17/17 11:28 PM
12/17/17 11:28 PM
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Posts: 653 montana
pjc360
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you can disable the rev limiter all together by setting your rotary switches to 00. also if you want to disable the multi spark & rev limiter, you set them to 01 I thought if you set the rev limiter to 0 the engine won’t start?
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2420357
12/18/17 03:16 PM
12/18/17 03:16 PM
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Joined: Jan 2003
Posts: 2,094 central texas
krautrock
top fuel
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top fuel
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central texas
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you can disable the rev limiter all together by setting your rotary switches to 00. also if you want to disable the multi spark & rev limiter, you set them to 01 I thought if you set the rev limiter to 0 the engine won’t start? is this for your ignition box? http://www.cranecams.com/uploads/instructions/9000-6000c.pdf00 disables rev limiter, 01 disables multispark AND rev limiter...
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Re: Back with rough spot around 2500 rpm
[Re: krautrock]
#2420418
12/18/17 05:10 PM
12/18/17 05:10 PM
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Joined: Nov 2011
Posts: 653 montana
pjc360
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you can disable the rev limiter all together by setting your rotary switches to 00. also if you want to disable the multi spark & rev limiter, you set them to 01 I thought if you set the rev limiter to 0 the engine won’t start? is this for your ignition box? http://www.cranecams.com/uploads/instructions/9000-6000c.pdf00 disables rev limiter, 01 disables multispark AND rev limiter... Yes I still have the instructions and I have went over the wiring multiple times. Pick up coil wires are wired correctly, the purple crane wire goes to orange positive on distributor and green crane wire goes to black negative wire on pick up coil. The yellow rev limiter wire is wired directly to battery positive. The main power wire on crane box is 10 gauge wire going straight to battery positive and the negative main wire on crane box goes directly to negative battery terminal. Coil wires are correct. Thin red wire is going to it’s own switched 12v toggle switch to power the box on and off. I have pick up coil wires routed as far away from the other wires as I can. Rev limiter is set at 6k rpm on both dials.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2420776
12/19/17 02:21 AM
12/19/17 02:21 AM
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Joined: Aug 2003
Posts: 954 garnett kansas
rhad
super stock
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have you tried bypassing the toggle switch and going direct for a test?
my ladder of success is missing some rungs
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Re: Back with rough spot around 2500 rpm
[Re: rhad]
#2421149
12/19/17 10:04 PM
12/19/17 10:04 PM
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Joined: Nov 2011
Posts: 653 montana
pjc360
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have you tried bypassing the toggle switch and going direct for a test? Going direct to what? Since this truck was efi before I got it and I put a carbed engine in it I’ve always used a toggle switch to power my ignitions, first with the factory Mopar electronic ignition and now with this crane ignition box. Could powering the cd box off of a toggle switch be an issue or cause an issue? It’s a 50 amp toggle switch that turns the box on and off. I didn’t know what else to use to power the box on and off.
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Re: Back with rough spot around 2500 rpm
[Re: krautrock]
#2421258
12/20/17 01:10 AM
12/20/17 01:10 AM
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Posts: 653 montana
pjc360
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if it's like an MSD it should have a low current turn on lead that should be a switched 12v source. the thicker red wire should be wired through a fuse to basically the battery.
still doubt any of that is going to give you a miss only after 2500rpm. and especially be worse when it's colder...
Ya it’s exactly like an msd, the thin red wire is a switched 12v wire. I have that going to a 50 amp toggle switch. The big main power wire is going directly to positive terminal on battery and the big ground is going directly too negative battery terminal. Coil wires are correct, pick up coil wires are correct. It’s just strange whatever it is, I would be confident it was the ignition box at this point except for the fact that the issue seems to get better when I take away the vacuum advance. That’s what led me to rotor phasing a few months back. But I have checked rotor phasing with my current firecore distributor with and without vacuum advance and it looks good. So that’s the only thing that has me a little baffled. I’m still leaning towards the ignition box, I just wish there was a quick and easy way to test the box before spending the money on another one.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2421286
12/20/17 02:01 AM
12/20/17 02:01 AM
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Joined: Aug 2003
Posts: 954 garnett kansas
rhad
super stock
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super stock
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garnett kansas
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my thinking on the toggle switch is that it may be causing resistance thereby lowering the voltage/amperage draw run a jumper from the battery directly to the box that the toggle switch controls
my ladder of success is missing some rungs
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Re: Back with rough spot around 2500 rpm
[Re: krautrock]
#2422159
12/22/17 01:26 AM
12/22/17 01:26 AM
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Joined: Nov 2011
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pjc360
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the turn on lead doesn't need to be high current, it should work all way down to 10v or so. all it does is tell the ignition box to turn on. the bigger voltage wire that he has running to the battery is what provides the ign the real power.
seems you have good ignition and timing. you have good compression. the only other thing needed is fuel right?
what is the baseline tune on the carb you have and how is the carb setup now??? Carburetor is a quickfuel super street series 680cfm vacuum secondary carb. I’m running 65 main jets and 75 secondary jets. .031 idle feed restrictors, .065 idle air bleeds, .033 high speed air bleeds. A 9.5hg power valve with .049 pvcr’s. Floats are set half way up the sight glasses. Idle mixture screws are about 3/4 to 1 turn out. This isn’t a fuel issue I know it’s ignition. I keep thinking it’s the crane box but what’s throwing me off is how this missfiring clears up once I take away the vacuum advance. So that leads me back to rotor phasing. But I have checked rotor phasing and it’s good. So this is very strange I just don’t know what’s causing this.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2422188
12/22/17 02:52 AM
12/22/17 02:52 AM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
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This isn’t a fuel issue I know it’s ignition. I keep thinking it’s the crane box but what’s throwing me off is how this missfiring clears up once I take away the vacuum advance. the vac can does three things, adds timing/shifts RF/increases reluctor gap. Are you saying the problem completely dissappears when the can is capped? something might be loose inside the dist that is being moved when the can shifts. I would cap the can & bump the timing up to where it is when the can is operational & see if it straightens out (grab your dialback). You're sure the RF is close enough when the can is deployed? iirc you said the reluctor gap does not change when the can is pumped up (it changes-gets wider on a regular dist) not sure how this dist is getting around that but it is a good thing). if you duplicate the timing & that ain't it then it has to be something in the dist functioning. (& this is a steady 2500+ miss correct?) EDIT & the can has no vac leak?
Last edited by RapidRobert; 12/23/17 03:26 PM.
live every 24 hour block of time like it's your last day on earth
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Re: Back with rough spot around 2500 rpm
[Re: RapidRobert]
#2422726
12/23/17 06:02 PM
12/23/17 06:02 PM
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Joined: Nov 2011
Posts: 653 montana
pjc360
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This isn’t a fuel issue I know it’s ignition. I keep thinking it’s the crane box but what’s throwing me off is how this missfiring clears up once I take away the vacuum advance. the vac can does three things, adds timing/shifts RF/increases reluctor gap. Are you saying the problem completely dissappears when the can is capped? something might be loose inside the dist that is being moved when the can shifts. I would cap the can & bump the timing up to where it is when the can is operational & see if it straightens out (grab your dialback). You're sure the RF is close enough when the can is deployed? iirc you said the reluctor gap does not change when the can is pumped up (it changes-gets wider on a regular dist) not sure how this dist is getting around that but it is a good thing). if you duplicate the timing & that ain't it then it has to be something in the dist functioning. (& this is a steady 2500+ miss correct?) EDIT & the can has no vac leak? Can does not have a vac leak, I have checked the air-gap with and without vacuum advance while holding the distributor in my hand and applying vacuum to the vacuum advance with a mighty vac. But when it’s in the engine and spinning at 2500 rpm it’s possible it looks a little different then how it looks in my hand. Someone had mentioned that maybe the oil pump drive bushing could be wiped out causing the inconsistency in timing at 2500. And it is a steady miss at 2500 that’s affecting every cylinder. I will cap the vacuum and bring the distributor timing up to 43-44 degrees where it is when vacuum advance is hooked up at 2500 rpm and I’ll bring the rpm up and check every cylinder with the light and report back. Since it’s chiristmas weekend I’m not sure when I’ll get to it but I’m gonna try ether today or tomorrow or Monday.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2423486
12/25/17 12:08 PM
12/25/17 12:08 PM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
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I’m not sure if rotor phasing can cause a missfire on all 8 cylinders or not. Maybe at 2500 rpm the rotor is being pulled back a little bit further then what the picture shows when it’s idling and that’s whats causing the missfiring. The most interesting part of this issue to me is how taking the vacuum advance away seems to clean it up. RP is the same on all cyls (the spatial distance gap) but if the "gap" is borderline it can be random missing as different cyls have different charateristics but to KISS, the ans is yes. some of these Q's are redundant but you say capping the hose completely elims the issue? What Dave said, shine your light in there while IDLING & see where RP is at in relation to the cap terminal "bulge with (A) the can capped & (B) with it plumbed into manifold & the can will shift it CCW (SB). I'm assuming you have a dialback, get it running at 2500 & note the (total) timing then plug the hose & twist the dist to get the timing degrees back up to where it was with the can operational. NAPA has a rotor (# MO-3000 iirc) that has a .060" longer blade that helps with phasing ($8.xx out the door iirc) cuz it is the total gap that is in question, the circumferential gap (that you see with the light) & the radial gap (longer rotor helps with that) & if the total gap makes the "required" voltage greater than the "available" voltage from your particular ign setup then it will misfire & the required voltage is greatest at WOT at which point the can is non op (but this is a steady cruise from 2500 on up correct?. Short version: circumferential & radial distance is too great/reluctor gap issue (but we covered that potential)/too much timing (way less likely) but do get a number/cracked cap/bad plug wire(s).
live every 24 hour block of time like it's your last day on earth
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Re: Back with rough spot around 2500 rpm
[Re: RapidRobert]
#2423668
12/25/17 05:34 PM
12/25/17 05:34 PM
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Joined: Nov 2011
Posts: 653 montana
pjc360
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I’m not sure if rotor phasing can cause a missfire on all 8 cylinders or not. Maybe at 2500 rpm the rotor is being pulled back a little bit further then what the picture shows when it’s idling and that’s whats causing the missfiring. The most interesting part of this issue to me is how taking the vacuum advance away seems to clean it up. RP is the same on all cyls (the spatial distance gap) but if the "gap" is borderline it can be random missing as different cyls have different charateristics but to KISS, the ans is yes. some of these Q's are redundant but you say capping the hose completely elims the issue? What Dave said, shine your light in there while IDLING & see where RP is at in relation to the cap terminal "bulge with (A) the can capped & (B) with it plumbed into manifold & the can will shift it CCW (SB). I'm assuming you have a dialback, get it running at 2500 & note the (total) timing then plug the hose & twist the dist to get the timing degrees back up to where it was with the can operational. NAPA has a rotor (# MO-3000 iirc) that has a .060" longer blade that helps with phasing ($8.xx out the door iirc) cuz it is the total gap that is in question, the circumferential gap (that you see with the light) & the radial gap (longer rotor helps with that) & if the total gap makes the "required" voltage greater than the "available" voltage from your particular ign setup then it will misfire & the required voltage is greatest at WOT at which point the can is non op (but this is a steady cruise from 2500 on up correct?. Short version: circumferential & radial distance is too great/reluctor gap issue (but we covered that potential)/too much timing (way less likely) but do get a number/cracked cap/bad plug wire(s). Ive checked timing with and without vacuum advance at 2500 . With vacuum where it starts missfiring is 42-43 degrees. Without vacuum it’s 32-33 degrees. The rotor I am running does have a longer blade. All of the electronic vacuum advance firecore distributors come with a longer blade rotor. The length of the blade on the firecore rotor is the same length as the napa M03000 rotor. I have a napa M03000 rotor in my tool box and I have compared it to the rotornthat cane with my firecore distributor they are the same length on the rotor blade. Awhile back I had done a gear swap on the 8 3/4 that I put in that truck, went from 3.55s to 4.56s and I never got around to re-gearing the front Dana 44 axle to match. So now the truck is at a shop waiting to have the front Dana 44 axle geared to match the rear axle. We have over a foot of snow on the ground this morning otherwise I would have ran over and grabbed it today to do a couple more quick tests on the issue and then brought it back. But without 4wd I’m not sure I could even drive it back to the house from the shop.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2423673
12/25/17 05:45 PM
12/25/17 05:45 PM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
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Ive checked timing with and without vacuum advance at 2500 . With vacuum where it starts missfiring is 42-43 degrees. Without vacuum it’s 32-33 degrees. And with the timing giving 32-33 degrees at 2500 RPM with the hose capped, it is NOT missing? EDIT If NOT missing, can you plug the can in & twist the dist CW to get the total back down to 32/33.
Last edited by RapidRobert; 12/25/17 05:48 PM.
live every 24 hour block of time like it's your last day on earth
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Re: Back with rough spot around 2500 rpm
[Re: RapidRobert]
#2423689
12/25/17 06:37 PM
12/25/17 06:37 PM
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Joined: Nov 2011
Posts: 653 montana
pjc360
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Ive checked timing with and without vacuum advance at 2500 . With vacuum where it starts missfiring is 42-43 degrees. Without vacuum it’s 32-33 degrees. And with the timing giving 32-33 degrees at 2500 RPM with the hose capped, it is NOT missing? EDIT If NOT missing, can you plug the can in & twist the dist CW to get the total back down to 32/33. Yes once I get the truck back from the shop I will perform all the tests you are suggesting. I will verify where timing is for a second time with vacuum advance connected at 2500 where the missing occurs. Then I’ll plug the vacuum advance and verify that the missfiring is gone when the vacuum is capped off. Then I’ll bring distributor timing only up to the same amount of timing when vacuum advance is connected and it’s missfiring and bring rpms up and see if it misses without vacuum advance but at the same timing setting at 2500. Then I’ll turn the distributor down and plug vacuum advance back inn to get the timing around 32-33 degrees where it is without vacuum advance at 2500. I’ll report back what I find. My truck is at the shop waiting to get the front axle grated to 4.56s to match the rear axle. It is near by but with over a foot of snow on the ground I don’t want to try and drive it with no 4wd, not to mention I don’t have a shop or garage at the moment. I am moving into a new house at the beginning of January that does have a small garage. So I’ll be able to mess around with it and not be out in the elements. I’ve got a lot going on in the next week, we’re moving on the 29th and 30th of the month. I’m starting a new job on January 2nd. Just had to get Christmas out of the way with the wife and 3 kids. And the truck is in the shop waiting to be re-geared up front. And I still have to figure out this strange missfiring bull crap. So it’s been pretty stressful to say the least. Plus I had to give notice to my current job which I do like a lot but this new job opportunity pays 3 dollars more an hour with better benefits and paid holidays and more paid vacation. So it’s just been a hectic month and I really haven’t had much time to mess with the truck and specially now since it’s sitting at a shop without 4wd.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2423737
12/25/17 09:47 PM
12/25/17 09:47 PM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
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You got a lot on your plate, If we cant get this dizzy straightened out I will blueprint a regular one (if it will work with your setup/I will read back thru all the posts to ans that Q) & send it to you.
live every 24 hour block of time like it's your last day on earth
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Re: Back with rough spot around 2500 rpm
[Re: RapidRobert]
#2423790
12/26/17 12:16 AM
12/26/17 12:16 AM
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Joined: Nov 2011
Posts: 653 montana
pjc360
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You got a lot on your plate, If we cant get this dizzy straightened out I will blueprint a regular one (if it will work with your setup/I will read back thru all the posts to ans that Q) & send it to you. I just need to get the truck back and get in the new garage and have some time to perform a couple more tests. I’m going to start by bringing distributor timing only up to 42-43 degrees at 2500 and see if it’s still missing. Then I’m going to retard the distributor timing down to around 22-23 degrees at 2500 and plug the vacuum advance back in to bring it up around 32-33 at 2500 and see what happens. That should be able to pin point wether it’s soley a vacuum advance problem or if it’s a problem without vacuum advance. Then I should have a better idea on what direction to go inn from there. It’s just gonna take a week or two before I’m in the position to have the time to play around with it some more. But I will report back on this thread after I perform the foloweing tests.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2426993
01/01/18 11:55 AM
01/01/18 11:55 AM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
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I'm assuming the rev limiter is in the Crane box, otherwise it could be disconnected (we gotta add/run one this season). it is sure looking highly likely.
live every 24 hour block of time like it's your last day on earth
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Re: Back with rough spot around 2500 rpm
[Re: RapidRobert]
#2427220
01/01/18 04:40 PM
01/01/18 04:40 PM
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Posts: 653 montana
pjc360
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I'm assuming the rev limiter is in the Crane box, otherwise it could be disconnected (we gotta add/run one this season). it is sure looking highly likely. Yes the rev limiter is inside the box but I can dis-connect the 12v source to the rev limiter. Which I may very well try today. I’m going to try a few other things first and I’ll post the results. I need to pull the plug in cylinder 8 since it seems to be the one missing the worst at the moment. And put a new plug inn and start some more testing with and without vacuum advance. And with the rev liimter set at different rpm’s and with it dis connected.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2427431
01/01/18 10:26 PM
01/01/18 10:26 PM
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Joined: Jan 2003
Posts: 2,094 central texas
krautrock
top fuel
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top fuel
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Posts: 2,094
central texas
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pjc360 i thought of you the other day. i thought my msd streetfire died on me. it was just a funny mistake though. i haven't driven my truck in a month or so, i needed to move it, so i moved my coronet first, the battery ran down so i had to get jumper cables out. i was in a bit of a rush too.
got it moved then went to start my truck, turned the key in the ignition and i could tell it wasn't firing. checked some stuff and then gave up. later i checked resistance on the pickup coil in my dist, seemed fine. i was thinking i would just swap out the dist real quick. then i got back in my truck and turned the key, got one turn out of it and it fired off once and then nothing with the key. then i remembered the ignition switch in my truck is bad and it wasn't supposed to be turning over with the key, there is a button to bypass it. ign. switch doesn't give the ign 12v in the start position, only in run. LOL. i just forgot how to start my own truck...
also, it's wayyyy cold here now and i still have the summer tune on the carb which is actually just a box stock quick fuel HR650 with the transition leaned out. it's just a bit lean in the summer but totally driveable after it gets about 5 mins of heat in the motor. with it in the low 30's to 20's right now it's misses real bad until it's fully warm. it's mostly in the transition circuit. because i have the jets at stock baseline tune. i thought about bumping the IFR's up to .029 from .028 but i just gave the idle mix screws the smallest turn i could give them (setting is about half turn from closed) and it smoothed it out a bit, driving better now. will prob drill the .028 IFR's to .029 when it warms up.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2427472
01/01/18 11:41 PM
01/01/18 11:41 PM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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Maybe your issue is that number 8's injector is leaking not that the ignition is the problem?
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: Back with rough spot around 2500 rpm
[Re: Supercuda]
#2427496
01/02/18 12:24 AM
01/02/18 12:24 AM
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Joined: Nov 2011
Posts: 653 montana
pjc360
OP
mopar
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OP
mopar
Joined: Nov 2011
Posts: 653
montana
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Maybe your issue is that number 8's injector is leaking not that the ignition is the problem? It’s carbureted not efi. Floats are half way up sight glasses, idle feed restrictors are .031’s, idle air bleeds are .065’s. Main jets are 65s and secondary jets are 75s, high speed air bleeds are .033’s. Timing is 18 initial 32 total, 10 degrees of vacuum advance @ 20hg of vacuum. I have played with the carburetor settings a million different times, I’ve tried smaller ifr’s bigger ifr’s smaller and bigger main jets, I’ve tried raising and lowering the floats. Nothing works the missing is still there regaurdless of carburetor tube and settings. I’m convinced there is a specific issue with cylinder 8 most likely a broken valve spring or the crane cd ignition box is causing the issues. I’m just not sure which one. Normally I’d be blaming the crane ignition box but the fact that cylinder 8s plug always seems to be struggling to fire compared to the other 7 cylinders has me thinking that there is a chance that cylinder 8 has a specific issue that’s isolated to just cylinder 8. But then again I hooked up my timing light to all cylinders and brought the rpm up to 2500 and I could see every cylinder missing at 2500 rpm with my timing light. Then I decide to increase the rev limiter from 6k rpm to 9k rpm and now I’m no longer seeing the missfire on every cylinder at 2500 rpm. But I am still having an issue with cylinder 8s plug becoming fuel fouled. I pulled the passenger side valve cover and looked at the valve springs on cylinder 8 and didn’t see anything un-usual with them or anything un-usual with the rockers. So I’m just confused and frustrated cause I have no idea what’s going on with this thing.
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Re: Back with rough spot around 2500 rpm
[Re: pjc360]
#2427520
01/02/18 12:58 AM
01/02/18 12:58 AM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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Could it be oil fouled? & I'm assuming the valve stem seal is looking good (pliable not stiff). might be a ring issue on that cyl
live every 24 hour block of time like it's your last day on earth
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