installed new holley 600 car stuters and back fires when you first give it gas.this came with 64 jets i took jets out of old carb which were 68s.wondering what others were using for jets?i have stock a4 intake and i believe comp 268 cam.i just recently recieved this car back i owned it 15 years ago i had holley on it then it ran great.tried adjusting accelerator pump cam still nothing.runs great wide open.also checked timing set to 10 degrees.also dont remember does vacum advance need full vacum at idle or hook it to advance fitting on carb?runs bad on low throttle
thanks for any info

 

Was the car running better before the new carb went on? I would run the advance can to a ported source rather than a full source. Timing was done without full vacuum hooked up right? Sounds like a timing issue when it backfires thru the carb. Hopefully someone with more brains will weigh in.

 

it ran the same with new and old carb.actually ran worst when i first put new one on until i changed jets from old one.i set timing with vacum advance line off.i am using port on carb that is supposed to be for timing advance.also i have a hei distributor from about 75 on car.first thing i did in 1985 when i purchased car.first car i bought in hs.i sold car to sister when i first got married needed money of course then two years ago i got back she needed newer car had olds achieva to trade her anyways she had someone put different holley 600 on it never has ran right since so i put new one on.do not know what the jets were in the original 600 i had on car 20 years ago when it ran great.so thats full story.always stuters a little when you first take off if you punch it usiually it will pop and kill,once rpms up really goes.