Hey,

I just rebuilt my 350 and have been having a bit of a problem with the acceleration due to a hesitation. I have the timing set to just about as perfect as I"m going to get but when I try to get her some gas the car hesitates and almost dies. This doesn't happen if I slowly accelerate from idle but if I try to get up and go from a stop she has this problem. I heard that something the carb may have messed up which is could cause this problem. When we started her up the she back-fired through the carb. I have a holley double pumper which was rebuilt. I'm looking for some sort of help here... No point in having a such a rebuilt engine if I can hardly get her off the line....

Thanks'
-G.

 

mine did the same thing until i got the power valve to the right size. mine being a stock 305 i had to go with a 95 power valve.

 

I'm thinking that that is what i'm going to have to do but how would I know exactly what power valve I should look into? Is there any way of measuring in order to get the right valve. I'm looking on Holley's website right now and as i'm sure you know there are a whole punch of different valves....

 

what ii did was hook a vacuum gauge up and would rap the throttle real quick a few times. it ended up averaging out at 9.2 to 10.0 when i did it. so i went to a 95 and it seems to have cured it.

 

Nice... thanks for the help. I'm gunna have to look into that in the next week or so. This may be a dumb question but would a double pumper still only have one power valve?

 

Sounds like your problem is in the primary(front) side power valve. Get a vac. reading at idle in gear.divide that number in half. That will give you a ballpark figure. A lot of times the power valve number will actually need to be a little higher than half.

 

Typically just in the primaries. The secondaries PV is blocked and the secondaries jetted up to compensate.

 

Probably not the power valve at all, as it does it from a dead stop. I'd be looking at the accelerator pump. Unless the backfire blew the power valve completely.