Thread: back fireing through the carb

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Ive got a 74 Nova with a 350 in it. Holley Carb. When ever i try to "push" the car a little bit it backfires through the carb. I already replaced the power valve. Any suggestions!?!?

Thanks
-Chris

Got good plug wires? New doen't always mean good. Had it happen to me before.

your distributor might have jumped, the timming chain might be the problem, make sure the pulg wires are routed right. When was the last time you timed the motor.

flat cam, weak valve springs,broken valve spring, intake valve not seating,valves adjusted too tight????????????

Back fire through the carb could also be a lean condition...
check acc pump, float level,fuel pump pressure

MM64

Gee guys cstud87's not gonna sleep tonight if we get too worried. Start by checkin out the simple stuff like ignition parts and timing before diggin too deep. Nothing like goin overkill..we all binderdundat!

Did you just have any valve problems? Happened to me when one of my hydraulic lifters in the olds failed. I just cracked the valve covers and looked for anything out of the ordinary. Found the intake valve opening waaaaay to early, so i removed the pushrods to that cylinder, drove uptown, got new lifters, drove home, and put them in. no problems, no damage.

Cstud, backfiring thur the carb means you have a lean condition. Either install a larger squirter nozzle ( from 25 to a 28, 35 etc) or bigger jets in the front bowl.

If while driving in the crusing mode,.... and say you want to accelerate just a little, ...and if there seems to be a stumble,.... as in the nose of the car dipping slightly before going, you need bigger jets in the front bowl (primary circuit). Go up in size from,... say a 68,.. to a 70 or 72.

When you have that part tuned real good, then replace the secondary jets in the rear float bowl to 6- 8 sizes larger than the front ones. So if you end up with 72s in the front, go to 80s in the rear.

You might also try installing a power valve with a smaller numerical value. So say you have a 65 in the front bowl, change to a 45. This will richen the mixture a little earlier upon acceleration and prevent the back fire condition that you are currently experiencing.

As always, good luck.

Not to be rude, but I got a headache trying to comprehend Typhoon's message.

..CarFreak...Ya need to read more of the other good book..AKA.....for example....Motors Repair Manual 5<43..How to re-jet carburetors....

Originally posted by CarFreak
Not to be rude, but I got a headache trying to comprehend Typhoon's message.

Hahha, I hear you! Sometimes when I re-read my own posts, I say, "WHAT"? Anyways, I went back and tried making the former post a little more user friendly! Thanks for pointing it out!

Cstud, I am just wondering....
1) Did this problem just start happening?
2) Has it been going on for a while?
3) Why did you replace the power valve?
4) Was that your first attempt to solve the "problem"?
5) What else was done to the engine before it started?
6) Have you done a compression check?

Lots of good advice here, but I gotta ask............. In ten responses nobody has asked some preliminary questions.

Did this problem just start happening? Has it been going on for a while? Why did he replace the power valve? Was that his first attempt to solve the "problem"? If it just started, what else was done to the engine before it started, even if stud doesn't think it's related? Has he done a compression check? Maybe some of those answers will help the helpful and knowledgeble here zero in instead of "shotgunning".

Originally posted by Bob Parmenter
[B].. nobody has asked some preliminary questions./B]

Ha hah, you are a funny man, Bob.

'Stud's probably fixed it and cruisin' and everybody else is still trying to figure out what's wrong with his car!!!

Originally posted by TyphoonZR
Ha hah, you are a funny man, Bob.

Well Typhoon, the edit time tag let's me know at least YOU'RE reading the thread. Now let's see if stud still is, or maybe Dan's got it!!