first off heres my setup: 355 w/ stock bottom end, crane 272H cam (.484", 218*, 112* lb sep), trick flow heads w/ 1.47 springs, Edelbrock RPM AIR GAP, Speed Demon 750 DP.

The problem:
I'm sitting at a stop light, and i rev it a couple times in nuetral. From there on out, the car runs terrible. I can give it just a tiny bit of throttle, and it will run fine, but as soon as i give it a little more, it bogs and tries to die until i get into the secondaries. Once i'm in the secondaries it will accelerate, but the A/f shoots off the guage lean. When the car first starts it has about 8 psi FP. When it take it for a spin and check it again, it's down to 4-6 psi. occasionally i get backfire through when free-revving from the linkage. It almost feels like the valves arent opening and closing or something??? I'm totally lost.

Things i've checked and Ruled out:
Fuel pump, put stocker back in and problem remaines unchanged

Rocker arms, didn't check lash, but looked for any that were real loose, and found none.

Regulator, thought maybe the regulator had been clogged somehow so i bypassed it, no change

Filter, has about 25 miles on it so i doubt it's dirty

Float level is perfect

idle air screws are adjusted.

no fuel leaks that i can see.

No kinked lines that i can see

Ignition, it would run really rich if it were an ignition prob wouldn't it?


Things i Haven't ruled out:

Timing, don't think its related but i'll check tomorow anyhow

some kind of internal blockage in the front fuel bowl.

damaged cam, don't think this is the prob, cause it was sudden

TIMING CHAIN WALK the more i'm thinking about it, the more this making sense to me. If anyone thinks this might be the cause, tell me and i'll tear it apart

valve damage somewhere, again it's a long shot

Bad gas. I had filled up about two minutes before this happend (sunoco 94). the car could have been running off the fuel in the bowls, and started acting up when it got the new gas...



Just a little more info, the car ran fine for about two weeks. It had a little stumble when brought to WOT, which i attempted to correct with a jet change, and an orange accel. pump cam. It seemed to be helping until this happened. I broke the gasket on the fuel bowl and had to replace it with a non- nontear one. (thats all the store had). I dont' think i scraped any of the old gasket into the fuel bowl, but i haven't ruled out the possibility. The car revs more or less perfect in nuetral, but it just falls on it's face when under load. Can somone please help me out here, i'm out of ideas, and almost out of patience...

thanks....., A LOT
Eric

 

sure you have a good tune up? checked push rods? run the valves, again.

 

I had similar symptoms and couldn't figure it out. I went as far as to swap out the cam because I figured I must've done some damange during break in....... I rechecked the timing gears and chain, rods, rockers, timing, carb, plugs (3 times because they would always end up fouling badly), wires, cap, rotor, coil, check for an intake leak, you name it.....

Turned out to be nothing more than the ignition module.

For some reason, every ignition module I could find at CarQuest, Pepboys, NAPA and Autozone just wouldn't cut it. At first the car would start, and idle fine, until I drove it. Then it would stumble, grumble, gripe and moan at me, sometimes even die.

I slapped an Accel module in there and haven't had a problem since.

Certain $30 well spent. I'd give it a shot.

 

<b>Timing, don't think its related but i'll check tomorow anyhow

some kind of internal blockage in the front fuel bowl. </b>

I would say front fuel bowl related. or timing related.
Fuel bowl because you say lean which makes sense and bog/backfire which makes sense. You also say it revs fine in neutral? makes sense.

Timing I say because a retarded condition will do that. rev fine in neutral then backfire under load...

But Im leaning towards front fuel bowl. Or bad gas. Water in the fuel will cause that too.

my opinions... hope it helps...
Spray some carb cleaner down the 2 small holes in the throttle body of the carb. the fuel should shoot out of the venturies when you do, if not, theres a block. if it does, the block may have just been removed. the 2 small holes are right after the fuel bowl on the top of the carb... you will see 4 on both sides of the carb, but only 2 of them (2 front 2 back) are going to be the culprit.

 

yeah, i had the same problem. When i put my cam in almost a year ago, the car would be fine in the morning when i choked it, and after a minute or two o fdriving i had to keep my foot on the gas even when stopped or the car would stall. Turned out I need a new fuel pump and ignition module. The car would stutter under WOT too, and wouldn't catch until i let off about half way. Try the module.

~Matt

 

i just took the front fuel bowl and low and behold, there is a small piece of gasket in each of the jets. It's not blocking it completely, but enough to where under load i can see it being a problem. i'm going out to put it all back together right now and find out. Keep the suggestions coming though....

thanks a lot for your help guys...

Eric

 

no problem zupman. Doubt I did much though. I hope that is the problem and now it is fixed. Good luck.

~Matt

 

Is the accelerator pump giving a good strong squirt when the throttle moved quickly to WOT?