im ahving soem problems with what is like a pop or msifre comming through the exhaust. the car will idle great but when u put it in gear it was to bog down and pop through the carb. if u give it a little gas tho it's fine. and then when i driving every once ina while it will pop a few times out the exhaust. i don;t knowwhats going on.

the engine has a holley 750 carb on it. its got 68 jest and a 3.5 powervalve so you think it could be too lean or what. im totally stumped and i can;t figure this out. im thinking maybe its something in the carb but the fact that it backfires and pops makes me think otherwise

 

Have you checked the ignition timing, accelerator pump adjustment, float levels and idle mixture and idle speed first? Why are you using a 3.5 powervalve? Check your sparkplugs and distributor and distributor cap, it mght be something else and not the carb

Did it just start doing this when you put this carb on?

 

actually this is the only carb thats been on this motor. i went with a 3.5 power valve because i only have 8 inches of vacuum. so they say take half of that and go down to the next one. if its an even number. the dist. wires and everything are all brand new

 

Whats the background on the motor? Start from the beginning, it sounds like it has always ran this way. Right? Or did it just start this all of a sudden?

 

the history of the engine is real short its has 22 miles on it and i just put it in. at first it didnt pop it was just way too rich and now it does. the only things i have done it rejet it and put the 3.5 power valve in it. i also put a different base gasket in it.

 

If you just blindly changed jets then yes thats probably your problem. You need a kit and just change one size at a time

 

i didn;t blindly change jets. it was running so rich that it kept fouling plugs out. i then talked to a guy that had about the same engine and he said start out at 68's and go from there.

 

Thats not how it's done, just go one size at a time

 

Sounds too lean. Idle is too lean also.

 

That or it has a vacuum leak.

Did you ever get it running right?

 

yep runnin great now. dont know what i did but it works good