SBC surges?

Hey guys,
Any thoughts on what would cause a carburated SBC to surge intermittenly?
It doesn't do it all the time, sometimes it's slight, and sometimes it's fairly noticeable.
She also refuses to idle at a stop while in gear but that is also intermittend. Sometimes she'll idle just fine in gear.

thanks

 

Sounds like a vacuum leak.

 

or trash in the carb. water in the tank

 

I second the vacuum leak or possibly a bad float. Spray some starting fluid around the base of the carb, the edges of the intake and on all the vacuum lines. If the car revs up, you've found your leak. When you stomp on the gas at idle, does it take a while to get back to idle RPMs? That would indicate a vacuum leak as well. As stated above, it could also be crap in your gas. Good luck.

 

You guys were right. It's a vacuum leak.
The starting fluid around the intake told the tale.
I guess I know what my next project is. New gasket and strip down the top of that rascal.

thanks for the help

 

You could try re-torquing the intake before tearing it a part...May work......

 

Squeeze a little high temp RTV where the leak is and let it dry overnight. I've done that years ago and it works great

 

From experiance, best to just pull and re-set/re-seal the intake. Do the job once and do it right.

 

also, you could have a leak in the valley that the outside fix, doesn't fix.

 

Should burn oil then, atleast i'd assume

 

another place to look is the vaccume canister on your distributor, it'll leak there without showing on a spray down of the manifold either