MGD72Monte Posted May 5, 2013 Share Posted May 5, 2013 I noticed at the end of last season the Monte was hard to start when warm, thought it was because of the colder weather. Since I have taken her back out I have the same problem even though weather is warm, seemed to be flooding once warm, and noticed hesitaion, sort of like running rich when driving, getting worse. Well I think I found the problem when I shut her down tonight but I don't understand it. After turning the engine off I was hearing a coffee maker type percolating sound so took the aircleaner off and found the carb flooding itself after shut down, pooling on the throttle plates of both primaries and secondaries then it started leaking out the throttle shafts onto the intake manifold and continuing to do so many minutes after shut down? I had to use towels to soak up the pooling gas. What is going on? Stuck float? Set up is 350SB with a Holley 600CFM Vac secondaries, manual choke. Help Quote Link to comment Share on other sites More sharing options...
montefrazer Posted May 5, 2013 Share Posted May 5, 2013 Carb heat soak problem. Here are a few sites to look at for ideas. http://www.edelblog.com/tech-tips/resolving-heat-soak http://www.camaros.net/forums/showthread.php?t=132115 Also, do you have stock exhaust with a heat riser? If it doesn't open all the way, or is stuck closed, your right bank exhaust will be running under the carb in the intake cross over and could be the problem. It should be closed when the engine is cold and open when it's warmed up. Quote Link to comment Share on other sites More sharing options...
Guest 1970 James Byers Posted May 5, 2013 Share Posted May 5, 2013 I had same problem with mine. Your carb has got a piece of dirt or trash under needle valve need to take it apart clean make sure all dirt is out of it put back together &also chheck or replace fue filter and also would recomend useing sea-foam it is a cleaner that cleans fuel system even in lawnmowers weedeaters diesel trucks anything that has motor it is good to use to keep ethenal cleaned out of carbs and fuel injectors run in everthing i own. You can get it any auto parts store or walmart good luck.. Quote Link to comment Share on other sites More sharing options...
footballubet Posted May 5, 2013 Share Posted May 5, 2013 Sounds like a needle and seat issue or possibly a float sunk. I'd be pulling it down to see what is going on in there. Quote Link to comment Share on other sites More sharing options...
overdrive Posted May 5, 2013 Share Posted May 5, 2013 Quote: I was hearing a coffee maker type percolating sound This statement indicates heat soak, as posted earlier. The fuel is boiling, causing the sound you heard. I've had to use an extra thick gasket to cure this.Thick gasket Dan Quote Link to comment Share on other sites More sharing options...
MGD72Monte Posted May 5, 2013 Author Share Posted May 5, 2013 Thanks for the great input guys. As this problem seems to have come out of nowhere when weather was cold and the car does not have a heat riser, I'm leaning on the contamination in the needle/seat assembly but I will check the fuel line routing to see if anything has happened which could have caused a fuel heat issue. Quote Link to comment Share on other sites More sharing options...
MGD72Monte Posted June 2, 2013 Author Share Posted June 2, 2013 As a follow-up to this I rebuilt the carb and the percolating/leaking and hot start problem went away. Thanks to everyone for their input. I still have a hesitation issue - see spark plug post. Quote Link to comment Share on other sites More sharing options...
71BLACK_MC Posted July 23, 2013 Share Posted July 23, 2013 I just bought my 71 MC w/ 350 about 2 months ago and was told by the old owner that it needed a carb. Long story short...I went out and recently purchased a replacement carb (Rochester 2 barrel) to replace the old carb (not knowing at the time that it was a Holley at the time until i took it off). Replaced it with the Rochester. Turned in the Holley core and now have more problems adjusting and tuning it. I know...rookie mistake, right?. Was looking to see if there was a standard Holley used on these motors. Can some one help me find what model the Holley carb was? Thanks. Quote Link to comment Share on other sites More sharing options...
monte70car Posted July 23, 2013 Share Posted July 23, 2013 Thomas welcome to the site. The basic carb that came out on the motors was a q-jet Holley's were used on the high performance motors like the ls-6, l-88 motors. I take it your car still sports the original 2 barrel carb since that is what you brought. One think you can so is turn the mixture screws out about 3.5 turns and adjust the idle screw in about 3 turns this should get you in the ball park. Another item would be to change over to a 4 barrel intake and stay with the q-jet carb or a Eddy carb. Where about in Virginia are you at also make a post in the new member forum and tell us more about your car. Quote Link to comment Share on other sites More sharing options...
rsorg Posted July 24, 2013 Share Posted July 24, 2013 hi, also had a carb issue with my original rochester quad , big block, had a vacuum leak , that I could not find , my mechanic used a propane bottle ( unlit)and waved the propane along the carb base , the engine went up in rpm , found out the brass throttle plate bushings were worn out enough to let the car idle rough , found an experienced rochester rebuild outfit to do a proper rebuild , runs like a champ now. Quote Link to comment Share on other sites More sharing options...
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