I have a stock 1970 455 intake and a 74 800 QJet that had done by Ken at Everyday performance. This carb has not been on my engine before had a different 800 on it. Before I had the thick black gasket with the metal inserts around bolt holes.. But this time have thinner grey gasket no metal and the seems like can hear the hiss of vacuum and will not stay idling. Is this a problem somebody has seen prior with these gaskets ? I have torqued bolts only to 10-12 ft/lbs and still leaking pretty good. Have not done any testing for leaks, just switched carbs only. Unfortunately turfed the ole gasket out. I am sure there is no issue with carb since was done by Ken. Thanx Dave
Make sure the gasket is installed correctly. If it is flipped over right-left, it can do this. Squirt a little carb cleaner around the base of the carb. If it changes the idle a lot (maybe have it on fast idle to keep it running) when you spritz in the back, that's probably it.
It almost sounds like you have an open vacuum port that you're not seeing. If you can hear a hiss, I doubt it's leaking from the base gasket.
Really !! I never even knew there was a left right to these!!! I will tryt a few squirts and see if around base. I triple checked and just to be sure capped all vacuum sources. I hope just the gasket is backwards. Question...like most gaskets would this not be a one time use only now that it is crushed ??
just use the one with the 4 round holes then it wont matter had the same thing happen on the same setup
Hard to say. If this is indeed the case, and it's only been on a few days, you may be able to flip it over. It'll be obvious- if material tears off, it's a goner.
You know what !!! I had the 4 hole one on there before with the last carb which worked poorly ( Was just 180 miles). This time it is the open one and never dreamed it would be a problem. So I ordered the 4 hole today from NAPA. Last time guy parts guy did not have have it and said take the open one same thing no different. Ah Yep. So the 4 hole one is best used for a Q-Jet on stock iron 455 intake ?? And by the way thanks so much guys for taking the few moments to type back, sincerely appreciated !!! Thanx Dave
There are compatibility issues in and after 1971 with base gaskets. Make sure the gasket you use seals off the "U" channel in the front, and the vacuum port on the choke side if using a 71-74 Buick baseplate. Many 1970 and earlier gaskets woln't seal off the "U" channel on 1971 and later carburetors, and some gaskets will leak on 71-74 Buick carburetors in the rear on the passengers side where they pull vacuum for the rear choke pull-off......Cliff
