engine surges...

patman

patman

Club Member
Got a stock 1971 350 chevy with a edelbrock performer and carb on it. I bought the car with this installed. The engine is supposed to have been rebuilt and the intake and carb new. The car did sit for about 4 months before I bought it. The engine runs good, no smoke etc. the problem I'm having is that the motor surges. It moves a hundred or so RPM in park and 2-300 in drive. I've done everything I can think of with the carb short of rebuilding it. I've adjusted the floats, messed with the mixture screws, etc but I can't get this thing to smooth out. any ideas?
 
lol what kinda cam does it have in it. get rid of that edelbrock and get ya a holley. sounds like its real lean base gasket leak maybe get out the spray can and find the leak thats my guess.
 
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dave89iroc said:
check for vacuum leaks?
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I tried the spray can test on the manifold and couldn't find any.

some times that thing will loose about 300 RPM and stay there. I have to basically readjust everything to get it to come around again. :confused:
No if I cover the top of the carb with my hands while its running it settles right down and runs better.

could it be anything else than vacuum?
 
If you cover the top of the carb it runs better ? So adding choke to the carb makes it run better if I am reading this correctly ? Sounds like the idle circut is not feeding enough fuel to the engine.
 
Sean said:
If you cover the top of the carb it runs better ? So adding choke to the carb makes it run better if I am reading this correctly ? Sounds like the idle circut is not feeding enough fuel to the engine.
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so what do I do to fix that?
 
normally you would just adjust it however if its erratic and can't be set I would still say vacuum, had this problem on my challenger and the carb base was warped. but Im not really a carb expert so there may be something else wrong internally with the carb.
 
I think I got it! I shot some carb cleaner down a couple of tiny tubes that come out the top right next to the horn. one side immediately effected the engine, the other took a few squirts before it effected the engine. Once that was cleared it tuned out nice and runs good.

Sean, I'm guessing that the mystery tubes I'm talking about might be something to do with the idle circuit?
 
Could be the idle circut air bleeds.



patman said:
I think I got it! I shot some carb cleaner down a couple of tiny tubes that come out the top right next to the horn. one side immediately effected the engine, the other took a few squirts before it effected the engine. Once that was cleared it tuned out nice and runs good.

Sean, I'm guessing that the mystery tubes I'm talking about might be something to do with the idle circuit?
Click to expand...
 
Sounds like the idle circut air bleeds. If they are clogged the carb will have a hard time moving fuel through that circut IIRC.
 
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