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73-87 Chevy _ GMC Trucks => Performance => Topic started by: na79 on October 05, 2017, 03:11:44 PM

Title: Kickdown pop
Post by: na79 on October 05, 2017, 03:11:44 PM
Hi All, I live in London, UK, and have a ‘74 SWB stepside pickup. It has a 350 motor and 350 trans. The engine has been modified with summit racing heads, an edelbrock intake manifold, Holley 4 barrel carb, straight through exhausts, high lift cams, etc. It is crazy fast. When I first got it the kickdown cable wasn’t attached on the carb and it was driving pretty great. Just had a load of work done on it, and one thing was to reattach the kickdown. After full service and a bunch of work it drives even better, BUT, if I floor it the engine/exhaust/can’t really tell, makes a popping sound and hesitates slightly. Any ideas why, what is causing it, and what the solution might be?

Thanks, Nick
Title: Re: Kickdown pop
Post by: bd on October 05, 2017, 04:34:59 PM
You need to determine from where the "popping" originates - exhaust or carburetor.  Does it pop-pop-pop-pop with full throttle or just once?  Until you can be more specific, symptoms could originate from ignition breakdown, lean fuel delivery, or low cam lobe, etc.
Title: Re: Kickdown pop
Post by: VileZambonie on October 05, 2017, 05:42:19 PM
and if you aren't running mufflers this is to be expected the way it sounds you are setup
Title: Re: Kickdown pop
Post by: na79 on October 06, 2017, 06:51:16 AM
Update! It’s not kickdown related, disconnected it and still did the same thing. Also, it’s not a regular occurrence, it happens randomly. It’s definitely a pop, coming from the carb, adjusted fuel I to carb and that looks healthy, do you think it could be ignition? And if so, anything in particular to look out for?
Title: Re: Kickdown pop
Post by: VileZambonie on October 06, 2017, 12:06:49 PM
If it's popping through the carb check your ignition system, check for vacuum leaks, check for anything that would cause a lean condition, fuel restrictions etc. Next check valve adjustment and for camshaft/lifter wear.