Need some idears!

Cant remember, back fire through the carb under quick acceleration means fat or lean?

Could this be a timming issue? I am running 10 initial and 30 total all in by 3400 rpm. small block chevy. edelbrock carb, msd ignition.

runs smooth everywhere but under quick acceleration...dangit!

 

Not a Chevy guy, but I don't think 30 is enough total, so I would bump it to 36 and see what happens....

 

Check your intake manifold for a vacuum leak, had exactly the same problem once and that was the cause.

 

Thanks guys...Keep em coming!!!


wouldnt total timming not even come off into play. The issue is going from idle to wot, quickly. Total timmin would be power loss up top. just my thoughts, but I do think your right...36 sounds better as memory serves...

 

Paul Senior at Orange County Choppers has lots of Idears. Let us know what you find out when you get it goin.

 

Sounds lean to me.

 

i would look at the accelerator pump and power valve.

 

any more details? New engine? Old engine? Miles on engine?

 

Soundl like a lean condition, is there a little stumble when you transithion from an idle? remember more advance needs more fuel so if you raise your advance you will lean out your top end. Are you running a Holly twice pumper? I traced a problem like yours to the accellerator link, no clearance, the clearance between the screw and the pump arm should be .010 elsewise it sits there and vibrates pumping the accellerator half dry so you don't get a full squirt when you mash the throttle. my $.02

 

I agree with looking at the accelerator pump.

 

One backfire(tuning) or several(possible flat exhaust cam lobe)?
You ask if it's timing. Bump it up and see if it likes it would be an easy answer. But, if I had to guess, weak accelerator pump shot

 

took some intial timming out of it. messed with the accelator pump. fattened up a bit....I think Im close. Need more total timing I think though. When I hook up the vac*** advance the timing shoots way up, idle picks up too.

Wish I knew wtf I was doin...anyway

Took it for a spin, ran the piss out of it...

now I got cooolant everywere....more issues!


Wouldnt know about Paul SR.

 

Stumbling or backfire on rapid acceleration is sometimes a sign of accelerator pump malfunction. Check to see if you get a strong discharge out of the pump squirters when you open the throttle rapidly.

Frank

 

Sounds like you're trying more than one thing at a time. You'll not know which helped, or if the 2 things counteract eachother. The vacuum advance should be hooked to "ported" vacuum. A source that supplies vacuum at the crack of the throttle, NOT at idle. It's NOT more total, but initial timing that'll affect your off-idle response. Take it to a shop

 

HAHAHA I think he was making a comment on your addition of the r to the word ideas. Something Paul senior does as well.

 

I watch American Chopper all the time. Paul Senior Says he has Idears all the time. I think its a Cool Word. Thought maybe you were speaking Paul Senior. Good Luck with the Car, sounds like your making headway.

 

could be a bad power valve or accelorator pump. had a holly 442 that backfired like a sone of a ***** on accelorationon a 390, it was the accel. pump.

 

**4412

 

Threw a belt when I was drivin the hell out of it....that made my coolant issues. I will swap the vac*** port, Hell I dont even know if an edelbrock carb has a power valve...lol

Its just quick initial, right from dead idle. When I was driving it I didnt even have it pop once. Anyway, The carb has been sitting, (but looks new and unused) so I could have some issues with it.

After I get another belt I will keep messin with it...thanks for all the suggestions...