carb stumble???
 

I recently changed the carb and intake on my sbc (350 .60 over .510 lift cam 292 duration,edelbrock rpm heads 10.5-1 comp. victor jr intake 750 dp) now when I feather the accelerator to take off (4 spd) it has a slight dead spot and it has a low speed miss?? But as soon as I get past that spot in the accelerator pedal it clears right up. I was planing on going to the track sat. for test and tune, and was wondering what I should be looking for to cure this problem, I already played with the accelerator pump adjustment and checked the floats, and low speed mixers. thanks in advance.

stumble
 

Have you read your plugs. Sounds like you need to rejet the carb.

no I have not read the plugs. I havent had it to the track yet or any place I could wind it up and shut it down . any other suggestions.

any idea what size jets I should be running with this combination?? I havent pulled the bowls off to see yet.

jeys
 

I'd pull the bowls and see what it has. Then, I'd jump the size a couple and retry it.

the fronts are 66 the rear is 72H does this sound right??

What is the model number? That looks too lean for a 750.

4779 came with 75/76 and 8.5 PV
4779-1 came with 70/80 and 8.5 PV
4779-2 came with 70/80 and 6.5 PV
4779-3 came with 70/73 and 6.5 PV
4779-4 came with 70/80 and 6.5 PV
4779-5 came with 70/80 and 6.5 PV (same as the dash 4)
4779-6 came with 71/80 and 6.5 PV
84779 came with 70/73 and 6.5 PV

There are also some other OEM and marine part numbers.

Dave

I drove to the (local)speed shop today and talked to a guy that teaches a hi-po class at the local college. he told me I needed a 45 power valve I had a 65 and told me to jet it 72 in the fronts and 80 in the rears. I put it together and now its raining :cry: it does seem to have better throttle response now :roll: I guess I'll see sat.

That's a pretty big jet spread. Rear cylinders are going to get more fuel than the front.

Last I heard (haven't run carbs in a long time), 4 jets were the biggest spread you want to do from front to rear.

Maybe someone with better carb knowledge can comment on that.

Jets
 

I always tried to run mine square. All four the same. I guess there is no real reason except that it was race only.