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440 struggles past 4,000 rpm

Posted By: Torquemonster440

440 struggles past 4,000 rpm - 06/27/19 07:29 PM

Hey all,

I recently upgraded from my big valve 906's to some Promaxx big block aluminum heads. I upgraded to a set of Comp beehive springs and the appropriate locks and retainers. I also upgraded my Distributor cap to a HEI style terminal type. Along with new plug wires and rotor. I also made the distributor shaft "collar" mod to help stabilize my timing. I jetted my carb (Holley850dp annular booster) up 4 sizes on both sides anticipating the better airflow.

Now, to my issue, when I take it out to romp on it, it pulls hard to about 4k and kinda just holds there.. no misfire, so surging, it does not fall on its face like its fuel starvation, I've already crossed that bridge (while running my 906's) and upgraded to 3/8" line from the pickup forward and I run a QFT 120 GPH mechanical pump.

I verified my fuel pressure does not drop below 6 psi at any time, I ran a gauge up to my windshield. Cranking pressure is 155-160 psi on all cylinders. My timing is set at 37° all in by 1600 rpm. No vacuum advance. I tried 34° first ,but 37° feels better. I am getting full throttle, both sets of butterflies open completely with the pedal depressed. The plugs do look pretty lean, I may need to step up another 4 sizes. Also, that annular carb had 82's on the primary side and 78's on the secondary side when I bought it. Does that sound right? Either way, it ran great with my 906's on there. There is still a power valve on the secondary side. I did adjust the secondary float level too while I had the intake and carb off, because it used to flood from time to time. When I drained the secondary float bowl to remove the intake I noticed some small flecks of aluminum in the fuel, I suspect from cutting the new hard lines I had Installed. I checked the float adjustment after taking it for the first test drive and it looks ok.. just a tiny dribble out the sight hole while the car is idiling.

I took two different people with me for test drives, both say it pulls like a "freight train".. but it should definitely RPM better in my opinion.
Any ideas or input is appreciated. I'm pretty stumped..
Posted By: pittsburghracer

Re: 440 struggles past 4,000 rpm - 06/27/19 07:55 PM

Do you still have the old cap and rotor sitting there. If so throw it on but just for the heck of it check to make sure the wires are on right
Posted By: fast68plymouth

Re: 440 struggles past 4,000 rpm - 06/27/19 08:12 PM

What cam, springs, rockers, pushrods?

Spring installed height?

Verified the pushrods aren’t rubbing on the heads?

If it does the same thing in all gears....... I doubt it’s fuel related.
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 06/27/19 08:23 PM


The wires are on correct, I have fire in all 8 holes. I might give the old cap and rotor a shot for the heck of it tho.
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 06/27/19 08:45 PM


The cam is the .528 solid purple shaft. 1.5 ratio Crane ductile rockers. 5/16" Crower push rods. The pushrods did rub slightly, I used one .015 " spacer shim on each side to achieve clearance next to the intake runners.The springs are Comp 26918-16 , recomended by Comp. 1.8" installed height. Where I exercised some judgement on my part, was to use two .030" shims under each spring to increase my seat pressure from 125 lbs closed to 147 lbs closed. I now know this is not the correct way to achieve more seat pressure. But,by my math of 1.8" installed height -.502 net valve lift, -.060 shim height and a coil bind height of 1.10" I'm still left with .138" clearance from coil bind. I'm really hoping those shims are not my problem. I have visually confirmed that the springs are not close to binding as well.
Posted By: Cab_Burge

Re: 440 struggles past 4,000 rpm - 06/27/19 09:15 PM

If it does the same thing in every gear it is ignition caused twocents scope
Why did you change the jetting?
Posted By: fast68plymouth

Re: 440 struggles past 4,000 rpm - 06/27/19 10:18 PM

My .02.......
I suspect it’s the wrong springs for the app.

Beehive springs rely on being run close to coil bind to reduce the onset of surge/harmonics........ you’re still .120 away.

Granted I would have expected it to go quite a bit higher than 4000 before the unhappiness started.

If you’re in 2nd gear, foot on the floor...... 4000-ish..... it’s doing what it’s doing...... does it recover instantly as soon as you shift to the next gear?

Does the ignition box have a rev limiter?
If so........ turn it all the way down to zero (off).

If you bring the motor up to like 3800 in neutral........ hold it there, and then increase the throttle.... will it go above 4000 cleanly?

What’s the carb part number?
Posted By: 68LAR

Re: 440 struggles past 4,000 rpm - 06/27/19 10:26 PM

Originally Posted by Cab_Burge
If it does the same thing in every gear it is ignition caused twocents scope
Why did you change the jetting?


I agree. Plus the jetting is backwards. Larger jets should be in the secondary, not primary. My book says that an 850 AN should have 74's in the front and 86 in the back with no power valve in the back. I'd address this first. Then move on to the electrical part.
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 06/28/19 12:04 AM

Originally Posted by 68LAR
Originally Posted by Cab_Burge
If it does the same thing in every gear it is ignition caused twocents scope
Why did you change the jetting?


I agree. Plus the jetting is backwards. Larger jets should be in the secondary, not primary. My book says that an 850 AN should have 74's in the front and 86 in the back with no power valve in the back. I'd address this first. Then move on to the electrical part.


Great info, I'll do that.. thank you.
Posted By: krautrock

Re: 440 struggles past 4,000 rpm - 06/28/19 12:57 AM

you changed alot of things at once.

i believe some holley 850 annular carbs were baseline with a secondary PV, if so the jets should be the same all around...

maybe you have a problem with rotor phasing on the new dist cap you are using??

i would try the old ignition stuff. Also, what fast68plym said up there^^ but of course try the easier stuff first...
Posted By: lewtot184

Re: 440 struggles past 4,000 rpm - 06/28/19 02:14 AM

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.
Posted By: RapidRobert

Re: 440 struggles past 4,000 rpm - 06/28/19 11:44 AM

Quote
it ran great with my 906's on there. but it should definitely RPM better in my opinion.
The carb did fine with the 906's? what exactly does it do at 4K?
Posted By: ChrgrCuda

Re: 440 struggles past 4,000 rpm - 06/28/19 12:18 PM

What diameter is the tube coming from the fuel tank sending unit? Is it 3/8 or 5/16 diameter? Also, check your fuel pump pushrod. Just had same issue on customers 440 GTX. The pushrod was wearing down.....
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 06/28/19 12:19 PM

Originally Posted by RapidRobert
Quote
it ran great with my 906's on there. but it should definitely RPM better in my opinion.
The carb did fine with the 906's? what exactly does it do at 4K?


In high gear, it will climb to 4k easily.. then just kind of hold there.. it still feels like its pulling, but by that time I'm out of real esate and I have to get off the throttle. I do need to test some more.. rev it in neutral etc.. but, I'm busy till Saturday evening, I'll report back after I have more time to tinker with it. Thanks for the Input all.👍
Posted By: GTX MATT

Re: 440 struggles past 4,000 rpm - 06/28/19 01:17 PM

Which 850 Annular carb is it? 9380?
Posted By: TonyS451

Re: 440 struggles past 4,000 rpm - 06/28/19 01:19 PM

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.
Posted By: oldiron

Re: 440 struggles past 4,000 rpm - 06/28/19 01:36 PM

You might try opening the exhaust. A baffle in muffler that came loose, or partially collapsed inner wrap on exhaust pipe will cause exactly that
Posted By: cgall

Re: 440 struggles past 4,000 rpm - 06/28/19 01:38 PM

You could temporarily rig an electric fuel pump to see if it's a fuel starvation/vapor lock issue.
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 06/28/19 01:55 PM

Originally Posted by ChrgrCuda
What diameter is the tube coming from the fuel tank sending unit? Is it 3/8 or 5/16 diameter? Also, check your fuel pump pushrod. Just had same issue on customers 440 GTX. The pushrod was wearing down.....
mp

The pickup was upgraded to 3/8" inlet. The pushrod deal crossed my mind, but I have not checked yet. I also doubt it would maintain fuel pressure like it does with the push rod wearing down, but it's a fairly easy check.
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 06/28/19 01:58 PM

Originally Posted by GTX MATT
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.
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 06/28/19 02:00 PM

Originally Posted by TonyS451
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..
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 06/28/19 02:01 PM

[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.
Posted By: GTX MATT

Re: 440 struggles past 4,000 rpm - 06/28/19 02:10 PM

Originally Posted by Torquemonster440
Originally Posted by GTX MATT
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.
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 06/28/19 02:37 PM

Originally Posted by GTX MATT
Originally Posted by Torquemonster440
Originally Posted by GTX MATT
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.
Posted By: lewtot184

Re: 440 struggles past 4,000 rpm - 06/28/19 03:42 PM

Originally Posted by Torquemonster440
[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.
Posted By: MoonshineMattK

Re: 440 struggles past 4,000 rpm - 06/28/19 03:53 PM

I personally will never try to tune a carburetor without an air fuel ratio sensor again. My advice would be to get one. Even if it doesn't help with this particular problem you will have a much easier time jetting the carb with the gauge.

Hope you get it solved
Posted By: krautrock

Re: 440 struggles past 4,000 rpm - 06/28/19 03:56 PM

Originally Posted by Torquemonster440
Originally Posted by GTX MATT
Originally Posted by Torquemonster440
Originally Posted by GTX MATT
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.
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 06/28/19 04:04 PM


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.
Posted By: GTX MATT

Re: 440 struggles past 4,000 rpm - 06/28/19 04:39 PM

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.
Posted By: ChrgrCuda

Re: 440 struggles past 4,000 rpm - 06/28/19 05:16 PM

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.
Posted By: lewtot184

Re: 440 struggles past 4,000 rpm - 06/28/19 05:21 PM

Originally Posted by ChrgrCuda
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.
Posted By: fast68plymouth

Re: 440 struggles past 4,000 rpm - 06/28/19 05:41 PM

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).
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 06/28/19 07:59 PM

Originally Posted by fast68plymouth
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.👍
Posted By: MR_P_BODY

Re: 440 struggles past 4,000 rpm - 06/28/19 08:15 PM

From what your saying and the plugs show it(if your reading right) it running
lean.. now that can be a short pump rod.. that would only allow X amount
of fuel to enter and run lean
Posted By: fast68plymouth

Re: 440 struggles past 4,000 rpm - 06/28/19 08:18 PM

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.
Posted By: Exit1965

Re: 440 struggles past 4,000 rpm - 06/28/19 08:49 PM

I put an engine together long ago that wouldn't go past 3000. Turns out it was pistons hitting valve that I didn't check after installing a bigger cam. I don't know if your new heads change how close the pistons come to the valves, or if you checked that. My little engine had an unfortunate demise as I was trying to figure out why it wouldn't go past 3k.
Posted By: johnnmo

Re: 440 struggles past 4,000 rpm - 06/28/19 09:03 PM

Early 70,s, I had a 427 chevy that did that. about 4500 and it was done. Any gear, everytime.

Valve springs were weak.
That motor had a lot of miles and overheated a few times.
Posted By: madscientist

Re: 440 struggles past 4,000 rpm - 06/28/19 09:18 PM

Originally Posted by fast68plymouth
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.
Posted By: sgcuda

Re: 440 struggles past 4,000 rpm - 06/28/19 10:26 PM

What ignition box and coil are you using? Are you running a ballast resistor?
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 06/28/19 11:02 PM

Originally Posted by sgcuda
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?
Posted By: fast68plymouth

Re: 440 struggles past 4,000 rpm - 06/28/19 11:07 PM

Swap the box, that’s easy enough.

No love for the orange box from me.
Posted By: viperblue72

Re: 440 struggles past 4,000 rpm - 06/29/19 12:13 AM

Originally Posted by fast68plymouth
Swap the box, that’s easy enough.

No love for the orange box from me.


I agree except get rid of all of the mopar ignition and install an msd box
And I bet your problem will be gone. I had a 408 stroker that wouldn’t pull past 5k no matter wht box i added.
Installed a msd 6al and problem solved. Ran a lot better all around.
Posted By: Brian Hafliger

Re: 440 struggles past 4,000 rpm - 06/29/19 04:09 AM

The 26918 spring are the WRONG spring to have on there...swap them out for a nice double spring and it will eat. The valve's need to be really light for those springs to work properly, especially with a solid FT cam. Beehive's don't like the jerk motion that solid FT's have.
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 06/29/19 09:01 PM

Originally Posted by ou812
The 26918 spring are the WRONG spring to have on there...swap them out for a nice double spring and it will eat. The valve's need to be really light for those springs to work properly, especially with a solid FT cam. Beehive's don't like the jerk motion that solid FT's have.


Boy, if that's the case, it really sucks that Comp would recommend them to me.In their defense I did say I was interested in using a beehive style spring, but why would they recommend a part that's completely wrong for the application?
Posted By: fast68plymouth

Re: 440 struggles past 4,000 rpm - 06/29/19 11:17 PM

Swapping the carb and ign box are easier tests than swapping the springs....... but if they make no difference at all, and it still runs into the wall at 4K......... It’s going to be tough to not start taking a harder look at the springs.

Obviously I’m not seeing or experiencing it first hand........ but from the description........ it acts just like it would if the springs wer giving up.

Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 06/29/19 11:43 PM

Originally Posted by fast68plymouth
Swapping the carb and ign box are easier tests than swapping the springs....... but if they make no difference at all, and it still runs into the wall at 4K......... It’s going to be tough to not start taking a harder look at the springs.

Obviously I’m not seeing or experiencing it first hand........ but from the description........ it acts just like it would if the springs wer giving up.



Yes, I agree.. it's just disappointing if the springs are in fact the culprit. I'll do some more testing and report back.
Posted By: sgcuda

Re: 440 struggles past 4,000 rpm - 06/30/19 01:16 AM

Find a chrome box. Orange box isn't much better than stock. Chrome box will go over 6k. Quicker than springs or carb. I can't see either of those causing the motor to just "Stop" at 4k. Acts more like a rev limit than anything else, to me.
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 06/30/19 06:29 PM

Update :

I checked a few things last night,
#1. Fuel pump pushrod looks brand new
#2: verified no obstructions in the fuel filter
#3: baselined the carb back to 78's all around ,per factory

Fired it up this morning, did as Fast68 instructed, revved up to 3,800 then pushed past, it climbed about 5,200 then I let off. It felt good.
Took it for a romp,.. pulls clean to about 5k in second then manually shifted to third.. not a hiccup. I'm not sure if re baselining the carb helped, or if I was just being hyper critical (paranoid) on the first few test drives after the new head install, but it seems to be running just how it should, just with some more "umph"..

Thanks to all for your input and suggestions, I appreciate it. So, next step will be some track time to quantify my improvements, hopefully move forward past my previous 12.55 best et.
Posted By: fast68plymouth

Re: 440 struggles past 4,000 rpm - 06/30/19 06:51 PM

Have you tried going higher than 5k?

I’d expect with those heads and cam it’ll need about another 1000 rpm(or maybe more) to see the best track times.
Posted By: lewtot184

Re: 440 struggles past 4,000 rpm - 06/30/19 08:32 PM

Originally Posted by Torquemonster440

The cam is the .528 solid purple shaft. 1.5 ratio Crane ductile rockers. 5/16" Crower push rods. The pushrods did rub slightly, I used one .015 " spacer shim on each side to achieve clearance next to the intake runners.The springs are Comp 26918-16 , recomended by Comp. 1.8" installed height. Where I exercised some judgement on my part, was to use two .030" shims under each spring to increase my seat pressure from 125 lbs closed to 147 lbs closed. I now know this is not the correct way to achieve more seat pressure. But,by my math of 1.8" installed height -.502 net valve lift, -.060 shim height and a coil bind height of 1.10" I'm still left with .138" clearance from coil bind. I'm really hoping those shims are not my problem. I have visually confirmed that the springs are not close to binding as well.
those crane ductile rockers will check somewhere between 1.57-1.6 true ratio. your actual lift at the valve will be .530-.540. the .028"-.032" recommended lash is somewhat loose; i'd try .022".
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 06/30/19 08:50 PM

Originally Posted by fast68plymouth
Have you tried going higher than 5k?

I’d expect with those heads and cam it’ll need about another 1000 rpm(or maybe more) to see the best track times.


No, I haven't tried much past 5k. Yes, I probably will need to get to 5,500- 5,800 to see the best e.t. maybe kinda hard with a 28" tire and 3.91's .. I'd probably need more gear.. but I like driving it on the street easy too.
Posted By: fast68plymouth

Re: 440 struggles past 4,000 rpm - 06/30/19 09:31 PM

I was mostly referring to the best shift point.
With the bigger heads and 112lsa cam I can easily imagine where it would want to be shifted at 6000-ish for the best ET.
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 06/30/19 10:04 PM

Originally Posted by fast68plymouth
I was mostly referring to the best shift point.
With the bigger heads and 112lsa cam I can easily imagine where it would want to be shifted at 6000-ish for the best ET.


Ok, gotcha... yeah on that 12.55 pass I was thru the traps around 5k.. and just left the trans in Drive. It was probably shifting around 4,200. I plan on upgrading to full manual valve body down the road to better control my shift points. I know I'm leaving a lot on the table just making passes in drive, but I'm not a very experienced track guy. I still need a LOT of practice... lol.
Posted By: krautrock

Re: 440 struggles past 4,000 rpm - 06/30/19 10:54 PM

what car is this in? what torque converter?
a 12.55 seems pretty respectable for short shifting...and it feels alot stronger with the promaxx heads now?
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 07/01/19 12:57 AM

Originally Posted by krautrock
what car is this in? what torque converter?
a 12.55 seems pretty respectable for short shifting...and it feels alot stronger with the promaxx heads now?


Its in a 66 Satellite.. weighs 3,760 with me in it. It's a 9.5" FTI brand converter with a 3,600 stall. Yeah, 12.55 was better than I expected and that was even with a dismal 1.88 60'. I have a lot of room for improvement. I'm hooked now !
Posted By: GTX MATT

Re: 440 struggles past 4,000 rpm - 07/01/19 04:26 PM

Work your way down more on the jetting as long as the plugs look OK. This is where it helps to have a wideband
Posted By: lewtot184

Re: 440 struggles past 4,000 rpm - 07/01/19 06:15 PM

going up 4 steps is about a 16% increase in main jet area (a bunch!) without prior testing. I don't think the current valve spring is good but about anything will go 4000rpm.
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 07/03/19 04:17 PM

Originally Posted by lewtot184
Originally Posted by Torquemonster440

The cam is the .528 solid purple shaft. 1.5 ratio Crane ductile rockers. 5/16" Crower push rods. The pushrods did rub slightly, I used one .015 " spacer shim on each side to achieve clearance next to the intake runners.The springs are Comp 26918-16 , recomended by Comp. 1.8" installed height. Where I exercised some judgement on my part, was to use two .030" shims under each spring to increase my seat pressure from 125 lbs closed to 147 lbs closed. I now know this is not the correct way to achieve more seat pressure. But,by my math of 1.8" installed height -.502 net valve lift, -.060 shim height and a coil bind height of 1.10" I'm still left with .138" clearance from coil bind. I'm really hoping those shims are not my problem. I have visually confirmed that the springs are not close to binding as well.
those crane ductile rockers will check somewhere between 1.57-1.6 true ratio. your actual lift at the valve will be .530-.540. the .028"-.032" recommended lash is somewhat loose; i'd try .022".


Good info, I've never verified actual valve lift at the rocker tip. I have them lashed at .026. A little clackity, but better than the factory spec. I think the solid lifter "sewing machine" sound is cool anyway.
Posted By: Torquemonster440

Re: 440 struggles past 4,000 rpm - 07/28/20 01:36 PM

UPDATE :

Just wanted to wrap this thread up. I know it's over a year later, but better late than never.What was happening after the head upgrade with the new beehive valve springs installed , the engine revved so much faster I was actually hitting the flash stall on my converter very easily. I wasn't used to it because of my old valve train, it revved much slower. So on the first couple of shakedown runs it kinda spooked me. I just wasn't used to feeling the engine flash that fast. So now, yes it flashes to about 3,800/4k rpm very quickly, then begins to pull. It pulls clean to 6k. Thanks for everyone's input. Just wanted to cap it off for anyone reading this thread in the future.
Posted By: moparx

Re: 440 struggles past 4,000 rpm - 07/28/20 05:10 PM

it's always good to hear about results after a problem has been solved. up
beer
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