help with new 383 stroker issue

[mattfranklin]

You say you've tried less timing.
Have you experimented with 5 deg. more?
It's something very easy to try.
When I have had crappy running engines a little more timing sometimes helps smooth things out and gives you a chance to work on the other things.

Also, was your 600cfm carb a known good carb?

BTW, I agree on the accelerator pump cam.
I think the Holley "yellow" one is the most aggressive.
I have an Excel spreadsheet from Holley that lists the curves for all of them.

[88Stanger]

Originally Posted by HO455

Before removing the heads I would pull the timing cover and verify your cam timing. At the same time check your push rod lengths. At this point it certainly sounds as if you have checked the basics. Did your camshaft get degreed when installed? It could be a mismachined keyway in the cam or the timing chain set.
Good luck

I was afraid of what you mentioned, so I did a full degree on the cam, checking everything i.e. Intake opening and closing values along with exhaust and compared those numbers to th cam card and they are on.
This is why I'm so frustrated at this point.
I am thinking about removing the heads, install an old iron set and try it on my buddies run on stand at this point. The only thing Howard's suggested s that the cam is really small and with my compression (static) being 190 lbs yet doing a compression calf it should be 10.0 to 1 and static compression #s closer to 170 to 180. So they suggest a larger duration cam to lower the static pressures to the 170 to 180 which should help.

[88Stanger]

I really appreciate any and all ideas and comments! Thanks for taking time out to help. I know eventually we will figure it out.

[AussieinNC]

Before you go ripping it apart, please drop the pipes off of the exhaust manifolds or headers...

Even new mufflers can have bad baffle welds...

If the engine will idle, what happens if you slowly increase the revs...slowly...does the engine seem to load up and finally stop, usually then pushing unburnt gas out the carb...aka Puke...

With cylinder pressures in the 190's, the vales are closing ok, pushrods are not too long....but !!!!

I have seen a bad lifter pump up and hold a valve open, then bleed down and compression test out ok...

If it was me, drop the pipes at end of headers or manifolds...if still no good, I would look at a bad lifter...even new stuff can be bad...

Question...is this a roller cam engine or flat lifter?

keep smilin mate...we will get it going...

[KQQL IT]

5 and 7 swapped? Easy to do has got me once or twice

[KQQL IT]

Or is it AFR meter time and see if it is going rich or lean when it coughs

[HO455]

Have you checked the timing while reving the motor. Maybe your mechanical advance has gone wrong. I don't remember if you tried a different distributor cap or coil.
In the carb your primary butterflies may be open too far at idle and the off idle transfer circuit is not able to work. When you open them there is no fuel shot to keep the engine running until the accelerator pump shot arrives. So the engine stumbles then receives a big glob of fuel and basically chokes on it. If you pull the carb you can check this on the bottom of the carb. The butterflies should be in somewhere in the bottom 2/3 of the transfer slot. Definitely not above it.

I just reread the thread and most of the above is not valid as you already have swapped those components. A leak down test may reveal the problem. Leaky valve or bad head gasket are possibilities.

[AussieinNC]

OK...your cam specs out as a HOWARDS CAMS CL111145-10...good cam, little chat about failures...so you should be good

190 PSI gives you roughly 9.5 to 1 compression...not too high...

A 600 HP power adder is overkill for this engine, but that is another story

I know this is silly, but you did check firing order 18436572
Drivers side front to back 1357
Passengers side front to back 2468

I have also seen cams boxed wrong and you end up with a 4/7 swapped firing order cam...so the firing order becomes 18736542...but I really doubt that would happen...??? grasping at straws here...do you have the tube the cam arrived in ?

How smooth does it fire when at idle? Does it want to shake itself all over the place?

[Marine-58]

This may be the dumbest post of the year and certainly do not intend to insult your intelligence, but did you verify the firing order for the plug wires going on the distributor?

1-8-4-3-6-5-7-2

Driver side 1-3-5-7 Passenger side 2-4-6-8

Are you sure that when you stabbed the distributor that it isn't 180 out?

Have you tried another carb?

When I get lost in a nonsensical trouble, going back to the very basic beginning usually helps. Interesting trouble, looking forward to seeing what the fix is.

[Marine-58]

Originally Posted by AussieinNC

OK...your cam specs out as a HOWARDS CAMS CL111145-10...good cam, little chat about failures...so you should be good

190 PSI gives you roughly 9.5 to 1 compression...not too high...

A 600 HP power adder is overkill for this engine, but that is another story

I know this is silly, but you did check firing order 18436572
Drivers side front to back 1357
Passengers side front to back 2468

I have also seen cams boxed wrong and you end up with a 4/7 swapped firing order cam...so the firing order becomes 18736542...but I really doubt that would happen...??? grasping at straws here...do you have the tube the cam arrived in ?

How smooth does it fire when at idle? Does it want to shake itself all over the place?

Aussie, either you have to slow down pushing send or I have to speed up. It feels like I'm generally a couple minutes behind your posts with a similar idea...

[Marine-58]

Another idea just popped in... You said that it is a full roller set up. Was that hydraulic lifters? Used to with hydraulic, you take it to zero lash and then another 3/4 turn down. When doing my 383 which is hydraulic, they are adjusted 1/8 turn from zero lash. IF you did the old 3/4 turn, it could match up with an earlier idea about intake being open too long....

Oops I delayed 30 seconds, bet Aussie (or someone else) sends this before I do...

[AussieinNC]

Thanks Marine...

I am more concerned about a bad lifter pumping up...then bleeding down and comp testing ok...

I need to go beat on some of my bedsides for a while...

Am replacing the inner edges with Mar K bits...good stuff

or maybe he ended up with a 4/7 swap cam...???

[AussieinNC]

Hey Marine...GREAT MINDS THINK ALIKE !!!!!!!!

[Mike C]

Having messed with multi-carb setups on 240z and motorcycles, usually a backfire out the carb is a lean condition. Needs more accelerator pump shot, faster pump cam timing or just to be enriched. A 600 cfm carb is probably set up WAY lean for a cammed 383. See if moving the stock pump cam to a the second position makes a difference (I'm assuming a Holley carb but if not check how to adjust accelerator pump voluem/timing on the Edelbrock.) Go up several sizes in the shooter and see if that doesn't improve things.

If it runs fine at idle and at cruise speed, it seems to be a transition thing which is either idle circuit too lean or pump shot too small etc. Increase your idle mixture richness as well. Sometimes that improves the transition between part throttle and full throttle and will cover the "hole" or backfire that's created when you stomp on it.

On Webers of Del'Ortos, the "idle" circuit controls mixture until around 3000 rpm when the mains come in. So it's imperative that you get that right or you have all sorts of driveability issues.

[toolboxchev]

I have seen a 454 with a distributor put in wrong then adjusted by moving the cap around until it ran. Did the same thing except it came out the exhaust blowing both mufflers off it.

Scared the @#$! out of the technician.

Small block distributors can shift off one tooth when installing them and still mate up the oil pump shaft. Throwing the timing out.

I think you have a timing/ignition problem also.

[88Stanger]

Originally Posted by mikecaddy500

are the pushrods the right length? if valves aren't closing all the way this will happen.

Correct length pushrods
Posted via Mobile Device

[88Stanger]

Originally Posted by AussieinNC

Before you go ripping it apart, please drop the pipes off of the exhaust manifolds or headers...

Even new mufflers can have bad baffle welds...

If the engine will idle, what happens if you slowly increase the revs...slowly...does the engine seem to load up and finally stop, usually then pushing unburnt gas out the carb...aka Puke...

With cylinder pressures in the 190's, the vales are closing ok, pushrods are not too long....but !!!!

I have seen a bad lifter pump up and hold a valve open, then bleed down and compression test out ok...

If it was me, drop the pipes at end of headers or manifolds...if still no good, I would look at a bad lifter...even new stuff can be bad...

Question...is this a roller cam engine or flat lifter?

keep smilin mate...we will get it going...

If I slowly raise the idle it revs up, but you can tell it's just not right.
You have a great idea on the lifters.
Hydrologic roller cam and lifters
Posted via Mobile Device

[88Stanger]

Originally Posted by KQQL IT

5 and 7 swapped? Easy to do has got me once or twice

Checked a few times
Posted via Mobile Device

[88Stanger]

Originally Posted by HO455

Have you checked the timing while reving the motor. Maybe your mechanical advance has gone wrong. I don't remember if you tried a different distributor cap or coil.
In the carb your primary butterflies may be open too far at idle and the off idle transfer circuit is not able to work. When you open them there is no fuel shot to keep the engine running until the accelerator pump shot arrives. So the engine stumbles then receives a big glob of fuel and basically chokes on it. If you pull the carb you can check this on the bottom of the carb. The butterflies should be in somewhere in the bottom 2/3 of the transfer slot. Definitely not above it.

I just reread the thread and most of the above is not valid as you already have swapped those components. A leak down test may reveal the problem. Leaky valve or bad head gasket are possibilities.

Leak down test is actually what I was planning to do first just to check
Posted via Mobile Device

[geezer#99]

What's your idle rpm?

[randy500]

Did you check with vacuume gauge yet? Quicker and easier test than leakdown and more informative at this point.
If smooth gauge reading then find the vacuum leak which is causing the lean condition.

[88Stanger]

Originally Posted by AussieinNC

OK...your cam specs out as a HOWARDS CAMS CL111145-10...good cam, little chat about failures...so you should be good

190 PSI gives you roughly 9.5 to 1 compression...not too high...

A 600 HP power adder is overkill for this engine, but that is another story

I know this is silly, but you did check firing order 18436572
Drivers side front to back 1357
Passengers side front to back 2468

I have also seen cams boxed wrong and you end up with a 4/7 swapped firing order cam...so the firing order becomes 18736542...but I really doubt that would happen...??? grasping at straws here...do you have the tube the cam arrived in ?

How smooth does it fire when at idle? Does it want to shake itself all over the place?

The Fi-Tech is up to 600 hp. I understand what you are getting at though. Cam came in plastic tube. Idles fairly smoothly and fires right off. I fully understand the "grasping at Straws". I have been told a few times that 190lbs static pressure is very high, maybe for this cam to high, pushing past the open intake valve at the very end before it closes, back to the grasping thing...
I do plan to remove the heads and dismantle them to check for sticking valve or ...
Posted via Mobile Device

[88Stanger]

Originally Posted by Marine-58

Another idea just popped in... You said that it is a full roller set up. Was that hydraulic lifters? Used to with hydraulic, you take it to zero lash and then another 3/4 turn down. When doing my 383 which is hydraulic, they are adjusted 1/8 turn from zero lash. IF you did the old 3/4 turn, it could match up with an earlier idea about intake being open too long....

Oops I delayed 30 seconds, bet Aussie (or someone else) sends this before I do...

i have even tried zero lash, even tried the let it run, loosen till you hear the clacking and take it just to where it stops and lock them down. still had issue.

[88Stanger]

Originally Posted by AussieinNC

Thanks Marine...

I am more concerned about a bad lifter pumping up...then bleeding down and comp testing ok...

I need to go beat on some of my bedsides for a while...

Am replacing the inner edges with Mar K bits...good stuff

or maybe he ended up with a 4/7 swap cam...???

i will say this. when i am working on adjusting the rockers by twisting the pushrods back and forth i find that a couple of them the rocker can be tightened way down before any real Resistance. I was told that this is common, that it does not mean a lifter is bad or soft. not sure on that idea, but that is what i was told.

[88Stanger]

Originally Posted by Mike C

Having messed with multi-carb setups on 240z and motorcycles, usually a backfire out the carb is a lean condition. Needs more accelerator pump shot, faster pump cam timing or just to be enriched. A 600 cfm carb is probably set up WAY lean for a cammed 383. See if moving the stock pump cam to a the second position makes a difference (I'm assuming a Holley carb but if not check how to adjust accelerator pump voluem/timing on the Edelbrock.) Go up several sizes in the shooter and see if that doesn't improve things.

If it runs fine at idle and at cruise speed, it seems to be a transition thing which is either idle circuit too lean or pump shot too small etc. Increase your idle mixture richness as well. Sometimes that improves the transition between part throttle and full throttle and will cover the "hole" or backfire that's created when you stomp on it.

On Webers of Del'Ortos, the "idle" circuit controls mixture until around 3000 rpm when the mains come in. So it's imperative that you get that right or you have all sorts of driveability issues.

i hear ya on this, and you make a good point. I have tried Fitech fuel inj system, even increased the pump setting alot, and then tried the carb that i know is good.