Neal with an a Posted March 31, 2022 Share Posted March 31, 2022 I have a 41 Buick Special with the compound carburetor 248 engine. I’ve been having trouble with the engine racing at very high rpm after it has been running for a few minutes. It runs great on initial start up but after a few minutes it races. After shutting it off and letting it sit for a few minutes it starts and idles fine again but only for a few minutes and then it starts racing again. Any ideas on what I should look for. Link to comment Share on other sites More sharing options...
EmTee Posted March 31, 2022 Share Posted March 31, 2022 I'd first look for a vacuum leak. After that, I'd take a look at the throttle linkage to determine whether there's any chance it may be binding or running close to the exhaust somewhere that could explain the temperature dependency... When I saw the title of this thread I was hoping to see a picture of the time slip from your local dragstrip! 1 1 Link to comment Share on other sites More sharing options...
dibarlaw Posted April 1, 2022 Share Posted April 1, 2022 I know the throttle linkages on my 1937 248 were very worn and would hang up. Also, there was a throttle stop on the side of the carb attached to the butterfly and was somewhat touchy to remain seated causing high idle. I had to make sleeves and ream out the holes in the linkage blocks to fit. 3 Link to comment Share on other sites More sharing options...
Daves1940Buick56S Posted April 1, 2022 Share Posted April 1, 2022 Compound carb? Maybe the weighted butterfly on the rear carb is opening for some reason? Link to comment Share on other sites More sharing options...
Neal with an a Posted April 1, 2022 Author Share Posted April 1, 2022 It only has one steel vacuum line from distributor to primary carb. It’s in good condition and not leaking. The throttle linkage is in good condition also with no apparent wear that would cause binding. I have not looked at the weighted butterfly on the secondary carb. I will check that out tomorrow to see if it is the problem. I really appreciate the thoughts you guys have given. Thanks Link to comment Share on other sites More sharing options...
EmTee Posted April 1, 2022 Share Posted April 1, 2022 Also check the area around the carb gaskets where they mount to the manifold. Link to comment Share on other sites More sharing options...
Marty Roth Posted April 5, 2022 Share Posted April 5, 2022 Any chance the automatic choke spring is upside down? this would open the throttle so that your fast idle setting is reversed- odd chance, but not impossible. Link to comment Share on other sites More sharing options...
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