Re: 440 struggles past 4,000 rpm
[Re: TonyS451]
#2671031
06/28/19 10:00 AM
06/28/19 10:00 AM
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Torquemonster440
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I know you found some metal flakes in the carb bowl, did you check your fuel filter as well? I know you said it holds steady fuel pressure, but worth a check. It's a fairly large "high flow" filter.. but, yes.. I should check it..
1966 Satellie.. 12.55 @107.75. 906 heads. 3780 lbs.
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Re: 440 struggles past 4,000 rpm
[Re: lewtot184]
#2671033
06/28/19 10:01 AM
06/28/19 10:01 AM
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Torquemonster440
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[quote=lewtot184]going up "4 steps" on jetting could be a bunch; especially if your not figuring jet area; and using a carb with a sensitive booster. too fat kills power/rpm. [/quote
I jetted up 4 sizes anticipating much more airflow with the new heads. Even after going up those four steps, the plugs still look lean.
1966 Satellie.. 12.55 @107.75. 906 heads. 3780 lbs.
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Re: 440 struggles past 4,000 rpm
[Re: Torquemonster440]
#2671040
06/28/19 10:10 AM
06/28/19 10:10 AM
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Joined: Jun 2006
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GTX MATT
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Which 850 Annular carb is it? 9380? Yes, it's the 9380. And yeah I did follow up on Holley's website.. looks like it should of had 78's all the way around when new. They came with 78s, and 78s are RICH in my experience. I'm surprised your plugs look lean, but the air bleeds may have been modified.
Now I need to pin those needles, got to feel that heat Hear my motor screamin while I'm tearin up the street
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Re: 440 struggles past 4,000 rpm
[Re: GTX MATT]
#2671053
06/28/19 10:37 AM
06/28/19 10:37 AM
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Torquemonster440
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Which 850 Annular carb is it? 9380? Yes, it's the 9380. And yeah I did follow up on Holley's website.. looks like it should of had 78's all the way around when new. They came with 78s, and 78s are RICH in my experience. I'm surprised your plugs look lean, but the air bleeds may have been modified. Supposedly the carb was new.. "never installed" when I bought it, but obviously someone fooled with it at some point.. because it had 82's on the primary side when I brought it home.
1966 Satellie.. 12.55 @107.75. 906 heads. 3780 lbs.
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Re: 440 struggles past 4,000 rpm
[Re: Torquemonster440]
#2671090
06/28/19 11:42 AM
06/28/19 11:42 AM
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lewtot184
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[quote=lewtot184]going up "4 steps" on jetting could be a bunch; especially if your not figuring jet area; and using a carb with a sensitive booster. too fat kills power/rpm. [/quote
I jetted up 4 sizes anticipating much more airflow with the new heads. Even after going up those four steps, the plugs still look lean. airflow increase doesn't always mean more jet area. airflow increase will up the vacuum signal to those boosters and it may at times dictate more control on the fuel side. i'd put the carb back to factory specs and then make "as needed" changes.
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Re: 440 struggles past 4,000 rpm
[Re: Torquemonster440]
#2671097
06/28/19 11:56 AM
06/28/19 11:56 AM
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Joined: Jan 2003
Posts: 2,094 central texas
krautrock
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Which 850 Annular carb is it? 9380? Yes, it's the 9380. And yeah I did follow up on Holley's website.. looks like it should of had 78's all the way around when new. They came with 78s, and 78s are RICH in my experience. I'm surprised your plugs look lean, but the air bleeds may have been modified. Supposedly the carb was new.. "never installed" when I bought it, but obviously someone fooled with it at some point.. because it had 82's on the primary side when I brought it home. you should put the carb to baseline, it probably needs to go down on the prim jets. once you get the miss sorted maybe you can play with removing the secondary side power valve and upping the jets 6-8 steps... also, i've seen pics of those carbs new or NOS without air bleeds in some positions, you should check that.
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Re: 440 struggles past 4,000 rpm
[Re: krautrock]
#2671102
06/28/19 12:04 PM
06/28/19 12:04 PM
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Torquemonster440
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you should put the carb to baseline, it probably needs to go down on the prim jets. once you get the miss sorted maybe you can play with removing the secondary side power valve and upping the jets 6-8 steps...
also, i've seen pics of those carbs new or NOS without air bleeds in some positions, you should check that. [/quote]
All good advice, I will take it back to base line and and work from there.. also, what has me stumped is, there is no noticable "miss".. surge or even a loss in power, it's just that it doesn't RPM easily past 4k in high gear.
Last edited by Torquemonster440; 06/28/19 12:32 PM.
1966 Satellie.. 12.55 @107.75. 906 heads. 3780 lbs.
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Re: 440 struggles past 4,000 rpm
[Re: Torquemonster440]
#2671116
06/28/19 12:39 PM
06/28/19 12:39 PM
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GTX MATT
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I have the same carb, mine did not come with any restrictions on the IABs on the primary side. Square jetted at 78 out of the box it pinned my wideband at 10:1 (lowest it reads) at WOT. If you've got more jet I would suspect you are way rich at WOT if yours is of a similar vintage to mine and has the same calibrations. 74s or 75s square was a much closer starting point for me with the stock passage calibrations, still way rich everywhere except WOT though.
I would go to 78 square and see what that gets you. With 78 square this carb will cruise with an AFR of less than 12.0. What is you current jetting? If you are at 86/82 I'd suspect you could be on the verge of a rich missfire.
Last edited by GTX MATT; 06/28/19 12:45 PM.
Now I need to pin those needles, got to feel that heat Hear my motor screamin while I'm tearin up the street
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Re: 440 struggles past 4,000 rpm
[Re: GTX MATT]
#2671128
06/28/19 01:16 PM
06/28/19 01:16 PM
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ChrgrCuda
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All due respect you have more of a mechanical (fuel pump, pushrod, restriction, valve springs etc.) than you do a "Jetting" problem. Changing jets are not going to solve your problem.Something mechanical is causing it to run out of fuel at 4000 RPM's.
68 Cuda Notchback [Email]10.86@120[/Email]
69 Charger R/T 440/505
2009 Challenger SRT8
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Re: 440 struggles past 4,000 rpm
[Re: ChrgrCuda]
#2671132
06/28/19 01:21 PM
06/28/19 01:21 PM
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lewtot184
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All due respect you have more of a mechanical (fuel pump, pushrod, restriction, valve springs etc.) than you do a "Jetting" problem. Changing jets are not going to solve your problem.Something mechanical is causing it to run out of fuel at 4000 RPM's. this could be true, but I believe baselining the carb could eliminate it as a problem.
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Re: 440 struggles past 4,000 rpm
[Re: krautrock]
#2671141
06/28/19 01:41 PM
06/28/19 01:41 PM
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Joined: Jan 2003
Posts: 14,506 So. Burlington, Vt.
fast68plymouth
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If you have a friend with a “known good” carb you can borrow....... you could try it and see if the problem went away or not.
If it acts the same, it’s unlikely a carb issue(and I don’t think it is).
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: 440 struggles past 4,000 rpm
[Re: fast68plymouth]
#2671200
06/28/19 03:59 PM
06/28/19 03:59 PM
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Torquemonster440
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If you have a friend with a “known good” carb you can borrow....... you could try it and see if the problem went away or not.
If it acts the same, it’s unlikely a carb issue(and I don’t think it is). Yeah, unfortunately I don't think it's the carb either, although taking it back to base line won't hurt. Dwayne, you suspect the springs ? Even with my mild cam and rockers? And only at 4,000, rpm ? I' m gonna dig into the cap and rotor first and see if that helps. Thanks for all the input and ideas everyone.👍
1966 Satellie.. 12.55 @107.75. 906 heads. 3780 lbs.
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Re: 440 struggles past 4,000 rpm
[Re: Torquemonster440]
#2671213
06/28/19 04:18 PM
06/28/19 04:18 PM
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Joined: Jan 2003
Posts: 14,506 So. Burlington, Vt.
fast68plymouth
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If it noses over at 4K in every gear, it’s not fuel related.
Which is why I asked if the recovery was instant after a gear change.
If the recovery after the shift is instant...... it’s ignition or mechanical.
I had a very similar situation many years ago after a cam swap, but at about 5k instead of 4K.
Old cam revved over 6k easily....... new cam was totally flat at 5k. Not a bunch of drama....... no popping, didn’t really surge or carry on....... just ran into a wall. You could pretty much just hold your foot on it in 2nd...... it would just maintain 5k. The instant you pulled 3rd....... it just took off again...... til 5k.
This was in like 1986, and I was pretty puzzled by it. Thought it was fuel..... hooked up a gauge I could see while driving...... never dropped below 4psi........ and the gauge never changed when you went from flat at 5k in 2nd to pulling hard in 3rd.
I was buying speed parts from one of the local engine shops...... took the owner for a ride. He agreed it didn’t really feel or act like float........ but since I found nothing else wrong he suggested adding a shim under the springs and see if it changed. So, I added a .060 under each spring.
Totally cured it........ it would rev as high as I wanted after that(63-6500).
At one point I also had an issue with the rev limiter on a MSD digital 6 box coming in at 5k. It tested perfect with an msd ign tester, but with the motor running, any setting over 5k...... still engaged the limiter at 5k....... even in neutral. Rolled the knobs back to zero....... motor revved fine.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: 440 struggles past 4,000 rpm
[Re: fast68plymouth]
#2671235
06/28/19 05:18 PM
06/28/19 05:18 PM
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madscientist
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If it noses over at 4K in every gear, it’s not fuel related.
Which is why I asked if the recovery was instant after a gear change.
If the recovery after the shift is instant...... it’s ignition or mechanical.
I had a very similar situation many years ago after a cam swap, but at about 5k instead of 4K.
Old cam revved over 6k easily....... new cam was totally flat at 5k. Not a bunch of drama....... no popping, didn’t really surge or carry on....... just ran into a wall. You could pretty much just hold your foot on it in 2nd...... it would just maintain 5k. The instant you pulled 3rd....... it just took off again...... til 5k.
This was in like 1986, and I was pretty puzzled by it. Thought it was fuel..... hooked up a gauge I could see while driving...... never dropped below 4psi........ and the gauge never changed when you went from flat at 5k in 2nd to pulling hard in 3rd.
I was buying speed parts from one of the local engine shops...... took the owner for a ride. He agreed it didn’t really feel or act like float........ but since I found nothing else wrong he suggested adding a shim under the springs and see if it changed. So, I added a .060 under each spring.
Totally cured it........ it would rev as high as I wanted after that(63-6500).
At one point I also had an issue with the rev limiter on a MSD digital 6 box coming in at 5k. It tested perfect with an msd ign tester, but with the motor running, any setting over 5k...... still engaged the limiter at 5k....... even in neutral. Rolled the knobs back to zero....... motor revved fine. LOL. I had a cheap customer who just didn't want to change anything, or even check most any thing. He brought in a 6 cylinder ford head and said, kiss the seats with a stone and slam it back together. Don't check it for cracks, don't check the surface, just do it. A week later he drives the ruck over and it's barely running. The springs were so weak anything more than idle speed or slightly higher RPM and the lifter would pump up and open some valves! He wanted me to "shim" it. I said get bent. It either comes off and gets done right or take your garbage somewhere else. After that, I never let him dictate what i did whether he was paying or not.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: 440 struggles past 4,000 rpm
[Re: sgcuda]
#2671281
06/28/19 07:02 PM
06/28/19 07:02 PM
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Joined: May 2014
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Torquemonster440
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What ignition box and coil are you using? Are you running a ballast resistor? Orange box with a ballast resistor. An Accell 80410-C ignition coil.. the coil is showing higher than spec resistance 1.8 ohms vs spec: 1.4 ohms on the primary side. And 10,200 ohms vs spec:9,200 ohms on the secondary side. Not sure if that's enough's to cause this issue though?
1966 Satellie.. 12.55 @107.75. 906 heads. 3780 lbs.
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