Author Topic: Popping through carb  (Read 325 times)

Offline Joec123able

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Popping through carb
« on: November 26, 2018, 04:49:34 PM »
Just posted a thread on coolant leaking, well changed the intake gaskets and after tons of hassle with the distibuter I finally got it running again. I put a timing light on got the timing anywhere between 0 degrees And 10 degrees advanced . Either way I adjust it between, the engine seems to be idling fine but will randomly pop through the carb, especially if I get on the throttle. Also seems to be straining the starter and starting weird. I canít figure out what it would be. 73 Chevy 350, th350
« Last Edit: November 26, 2018, 04:51:20 PM by Joec123able »

Offline bd

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Re: Popping through carb
« Reply #1 on: November 26, 2018, 05:59:10 PM »
It sounds a little like the timing may be over-advanced.  Nonetheless, did you change any valve adjustments while the intake was off?  Is it a random backfire or does it pop-pop-pop-pop with rapid throttle opening?

Check the firing order of the spark plug wires.  Make sure you are checking the ignition timing off of cylinder #1.  Spray for vacuum leaks.  If the foregoing steps don't expose a definite cause, remove and inspect the spark plugs for fouling and cracks and look up inside the boots at both ends of each spark plug wire for black soot or greenish discoloration.
Rich
It's difficult to know just how much you don't know, until you know it....
In other words... if people learn by making mistakes, by now I should know just about everything!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Joec123able

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Re: Popping through carb
« Reply #2 on: November 26, 2018, 06:35:01 PM »
It sounds a little like the timing may be over-advanced.  Nonetheless, did you change any valve adjustments while the intake was off?  Is it a random backfire or does it pop-pop-pop-pop with rapid throttle opening?

Check the firing order of the spark plug wires.  Make sure you are checking the ignition timing off of cylinder #1.  Spray for vacuum leaks.  If the foregoing steps don't expose a definite cause, remove and inspect the spark plugs for fouling and cracks and look up inside the boots at both ends of each spark plug wire for black soot or greenish discoloration.

Okay thank you very much for your reply. I went over my firing order and sure enough, two cylinders were swapped around hahaha feel like an absolute idiot but maybe someone else will learn from it so Iíll leave the post up.

Offline Joec123able

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Re: Popping through carb
« Reply #3 on: November 26, 2018, 06:59:23 PM »
Got whole other problem now. Starter grinding and chunk broke off the edge ear where the outter bolt goes. Just one thing after another

Offline bd

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Re: Popping through carb
« Reply #4 on: November 26, 2018, 11:18:13 PM »
Be sure to set the ignition timing correctly once you get it started.  And, check the flexplate and ring gear for damage.
Rich
It's difficult to know just how much you don't know, until you know it....
In other words... if people learn by making mistakes, by now I should know just about everything!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline fiddler

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Re: Popping through carb
« Reply #5 on: November 29, 2018, 12:31:32 AM »
OK, I am 67 now and rebuilt my first 283 when I was 17.  All I can say is ....been there...done that.  Thank God we don't tinker with people!!
Ricky