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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 1979ChevyMorgan on August 14, 2014, 10:36:55 pm

Title: Popping sounds from carb maybe?
Post by: 1979ChevyMorgan on August 14, 2014, 10:36:55 pm

So im driving down the interstate and my truck start to makes this popping noise and I loose all power. Ive got a 454 big block so there should be lots of power. Anyways, i put her back home and she makes this popping sound when i accelerate and/or rev the engine in nuetral. I fiddled with the timing and no luck there. Havent taken a look at the plugs and wires yet cause it got dark on me. Weird thing was when i would down shift to 2nd, it would not make the popping noise only when i push on the gas. idel is a bit rough too.

Also she is VERY hot too, new thermostat and plenty of fluid so im not sure why she still runs so hot. I will open the hood and its like a heat wave coming out. Well id appriciate any help you guys can give me.

1976 Chevy with 1979 454 with 750 Edelbrock carb.

Title: Re: Popping sounds from carb maybe?
Post by: bake74 on August 14, 2014, 11:36:22 pm

     First question that needs to be answered, is it popping up through the carb, or from the exhaust ?  Makes a difference.

Title: Re: Popping sounds from carb maybe?
Post by: emod20 on August 15, 2014, 12:07:50 am

could be many things but one possible one is when an exhaust valve stops opening it will cause a rapid popping or backfire usually just when you crack the throttle. cause by one of the following worn cam lobe . pushrod broke or bent. rocker arm loose or broke.  other causes lean condition such as accell pump. fuel delivery problem ....just some ideas

Title: Re: Popping sounds from carb maybe?
Post by: Captkaos on August 17, 2014, 12:32:28 pm

By very hot have you verified the temperature?
as said it could be a number of things.  By chance did you fill up prior to this happening?

Title: Re: Popping sounds from carb maybe?
Post by: 1979ChevyMorgan on August 18, 2014, 04:56:08 pm

The popping noise is from the carb, and no I havent verified the temp but i know that it is way too hot. It has never been this hot. I did fill up prior to my road trip. Ill take a look at those valves see if theres anything unusual there. Thanks for the imput, ill let you guys know with more details when I figure it out.

Title: Re: Popping sounds from carb maybe?
Post by: bobcooter on August 21, 2014, 10:59:53 am

Popping trough carb could be a flat cam lobe. I had a big block with a flat lobe and you would only hear it popping at certain speeds. As for the heat, is your timing too far advanced?

Title: Re: Popping sounds from carb maybe?
Post by: Captkaos on August 21, 2014, 08:00:47 pm

If you filled up before the trip, and everything else is ok, I would suspect bad gas.  Do you buy there often?

Title: Re: Popping sounds from carb maybe?
Post by: 1979ChevyMorgan on August 21, 2014, 08:59:37 pm

Well found the problem, not a good one either. Camshaft is rounded.

Title: Re: Popping sounds from carb maybe?
Post by: emod20 on August 22, 2014, 09:18:32 am

exhaust lobe ?