good luck. Let me know what you come up with, Bugs like this drive me nuts and I'd like too hear what you find. Thanks.
Martin.

Mine does the same thing. Drives me crazy. Holley 750 vac sec, Thunderbolt V ignition. Springs, linkage ok. If you guys figure it out, I will be sooooooo happy. I have no vacumn leaks around the base. The timing on a T-bolt V is hard to read cause it's all over the place normally at idle. It will return to 700 rpm after a while of idling, but won't reset by shutting it off and turning it back on....

help.! I thought I was the only one.....

we could start a club, Docking would be sooo ugly though.

Ok, here is another potshot at the answer. Engine speed is controlled by how much air is metered into the induction system. When air is heated, it like all fluids becomes less dense. When a fluid becomes less dense (or less viscous) it flows more easily and at a higher velocity through a metered restriction (ie. butterflies), at equal pressure or vacuum. So through a given restriction (butterflies of the carb) hotter, less dense air will flow more cfm than colder air and therefore increase idle speed.

Glad to hear you got it fixed Just Once.

BT

Gas tank vent clogged,creating vacuum = lean condition?

ZZZZZZ:Interesting thought, but wouldn't you experience perf. problems under WOT since the fuel draw is more then.

O.K last night I was heading out to Lake Mich so I put on my cruising prop, 29 pitch marage + , haven't used it in awhile, ran the boat hard ,came to Whitehall channel ,pull the throttle down and idle perfect? thought damn problem gone! worked fine all night. Soooooo got back to the dock and for the hell of it put the 25 pitch chopper back on, ran it hard and it wont idle down till I shut it down then start it back up or wait for about 3 min. then it will also return, still stumped. The marage + wont rev past 4600 @ 5 psi boost but has a very nice 60 mph at 3000 cruise, I can rev the chopper to 5800 rpm, so the problem must be when the engine runs higher than 4600 rpm, just a thought, Buck