I know there are a million vacuum leak threads, sorry for posting another. I have been hunting down the cause of my high idle (was around 2500). Yesterday I re-torqued the carb bolts which brought it down to 1700 (the gasket is new, I figured it was just settling in. Re-torquing the intake bolts yielded no help. Using carb cleaner and propane didn't give me any response from the engine. I tried feeding the propane directly down the carb throat, and the engine once again did not respond. If I can't get a noticeable RPM change with propane or carb cleaner, how else can I find this leak? I also re-checked the timing on the engine as well, 8 degrees advanced at TDC. I'm really hoping the leak isn't internal to the manifold, is there any way to differentiate whether the leak is inside or outside the manifold? Thank you in advance.

 

Additional info: I have adjusted the transition slot, idle speed screw (it's all the way closed), fast idle screw, and the mixture screws are at 1.5 turns from bottomed out.

 

It's getting in there from somewhere. Have you blocked off all the vacuum ports?

 

I had tried blocking off all the vacuum ports, with no change to performance. I got a hold of a smoke machine, which showed smoke coming from both my valve cover vents, I didn't realize you should not run both breathers and PCV, there's my vacuum leak!

 

Yeah i was about to say 2500rpm at idle isnt a vacuum "leak"... thats pure unadulterated flow!

 

Sounds like maybe the wrong gasket.

Torquing carb bolts is rarely a good idea.

 

I capped off one of my breathers and got it to idle around 1100, I'm going to retime it and keep adjusting the carb, but for now I can live with 1100. I'll update the thread if I run into any more problems, thanks guys!