Fast idle

[427TJ]

Well I couldn't find any obvious vacuum leaks--all the vacuum caps and hoses seem fine. The throttle shaft seems tight as well. The carb may very well need a total rebuild as it's been on there since 1967 and logged over 105,000 miles. I was just wondering--would the avgas have anything to do with it? It idled normally until my second or third tank with the 100LL mixed in, then this 1300 rpm thing started. Oh, and it's also slow to fire after shutting it off warm. During a hot re-start at a gas station, etc., it cranks for several seconds and then stutters to life and then runs fine--at 1300 rpm.

I know they're kinda' pricey but I was looking at the bolt-on Edelbrock Q-jet replacement carb as a possible fix rather than go through the potential agony of getting the Rochester unit rebuilt properly. Any advice on that?

Thanks again guys.

Bill

[Seattle Sam]

Bill,

My guess is, the high level of detergents in the avgas removed all the varnish from inside your carb, and something inside has more clearance than it should. I would recommend you just buy the Quadrajet book and a rebuild kit at your local NAPA store, and rebuild it yourself. But with that high mileage, you might have issues you can't fix with a rebuild kit, such as worn throttle plate bushings.

Where are you in WA? There is a good shop in Kirkland (Totem Lake) that can rebuild your original, no agony involved. They have worked on Denis' Z/28 carbs, Alex really knows what he's doing..
Carburetor and Fuel Injection Connection, http://www.carbconn.com/

Good Luck!
-Sam

[427TJ]

Thanks for the info Sam---I was wondering if the avgas had "cleaned out" the crud in my carb. I'll look into the local Q-jet guy you recommended since I'm not confident I could get the thing back together if I did it myself! Actually, I probably could but I'd rather have a competent person do it. BTW, I'm down in Federal Way.