Stumble off idle -

[patrickt]

Originally Posted by Grubby

Best vac was about 7 at 550 rpm idle. Screws are pretty close to 1 turn out. My vac gauge is old and beat up - it may not be accurate.

John, I think you should really double check this with a new vacuum gauge before you start doing any more monkeying with your carb. With your build, if you're down in the single digits with your vacuum, at a normal idle, then I'm going to call "foul" and point to something like an intake manifold leak. You said you double checked your timing and adjusted your valves, those are two other typical causes for low vacuum.... Brent & Bobcat, you don't think his vac is a little low?

[Bobcat]

Patrick .... depending on the cam and idle speed , 7" of vacuum may not be too low . My 482 has a long cam ( 250 @ .050" ) and has about 7" to 8" at 1000 rpm . Having said that , if the vacuum is really that low , then the PV should be in the 3.5 " range ..... and a check for vacuum leaks should definitely be done .
Grubby , you said the timing was ok , but what is your initial and max ? I run 22 degrees initial and 35 degrees max . Ignition/timing should always be checked out before working on the carb .... eliminates one variable . Most carb/ignition people recommend something in the 14 to 18 degree range for initial advance .
550 rpm , for me , is way too low an idle ... I like between 900 to 1000 on my engine .
BTW , as Brent and others have pointed out .... only change one thing at a time or you may have one change cancel out the other . Yes , it`s time consuming , but it`s the best way .

[patrickt]

Originally Posted by Bobcat

Patrick .... depending on the cam and idle speed , 7" of vacuum may not be too low . My 482 has a long cam ( 250 @ .050" ) and has about 7" to 8" at 1000 rpm . Having said that , if the vacuum is really that low , then the PV should be in the 3.5 " range ..... and a check for vacuum leaks should definitely be done .

I vaguely remember his build specs -- and his cam is smaller than mine (mine is 245 @ .050, but with a 114 LSA) and I'm over 12" at idle. If he really is at 7", and I bet he still has the stock PV of 6.5, then it might be easing open and causing problemos. Brent's just spending too much time with that new bratty bundle of joy... he should be on here chasing the important things in life, like carbs.