Backfire out carburetor
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New User
Joined: Feb 2011
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Backfire out carburetor
We recently installed an 8010 weiand manifold and a1406 edelbrock carb onto a 351m. We got it all adjusted and it worked ok but now after the motor gets warmed up it begins to backfire and make a popping noise out of the carb and the pickup loses power. However when the engine is cold it runs fine. It has only began doing this after 2bbl carb was replaced with 4bbl. Any help would be greatly appreciated.
Hotshot
Joined: Jan 2011
Posts: 13,129
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From: THIS IS SPARTA!, ...Mo.
Cramming more gas and air into an engine not designed to take it is never a good idea. Four barrels make more power, IF THE REST OF YOUR COMBINATION SUPPORTS IT. Until you change the cam, do some head work and put headers with dual exhaust on it, it won't run as good as it did with the two barrel. A cold engine needs more fuel than a hot engine. It sounds like you're flooding the poor truck.
Put the 2 barrel back on or do the rest of the mods to make the four barrel work properly. There's no short cuts in performance.
Put the 2 barrel back on or do the rest of the mods to make the four barrel work properly. There's no short cuts in performance.
Lead Driver
Joined: Mar 2004
Posts: 8,922
Likes: 153
What do the plugs look like ? Sounds like a vacuum leak. Check it all over for a leak then I'd try another intake gasket. You need to retorque a few times till it relaxes or you could loose the gasket. I'm no fan of Edelbrock-Carter carbs so I can't help you there. If there is no leak & the gasket was ok, bolts tight, then something is up with the carb. It's running too lean.
Senior User
Joined: Feb 2011
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From: Grand Junction, Colo.
sometimes you can look and listen all day for a vacum leak however a mechanic taught me years ago how to narrow down the areas in which to look with the engine at an idle take a propane torch turn it on without lighting it and point the nozzle toward all of the areas that vacum lines attach and if you hear the idle pick up speed then you will know what area you need to concentrate on. Yes it does work i have done it many times just be careful when around plug wires and the coil as well as the battery. Best of luck to you.
Senior User
Joined: Mar 2010
Posts: 222
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From: western ks
starting fluid works for leak check also if you dont have propane ..Also check your vac advance to the distributer if its not getting vac or the advance inside the dist is not working can cause similar problems
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