Afterfire- Real bad

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Oct 25, 2011 | 08:43 PM

hardhat273

Thread Starter

Heel & Toe

Joined: Oct 2011

Posts: 16

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From: NJ

Afterfire- Real bad

My C2 1966 427 is after-firing through the exhaust something horrible. It starts to buck like when a car slows down and you don't throw in the clutch. Even when I have enough speed or am accelerating, it after-fires through the side pipes like a machine gun especially when I let off the accelerator. I rebuilt the carb and set the timing and the after-fire went away. I only drove it a few miles after I timed it and then put it away. The very next time I took it out it started doing it again.

This one has me and my friends baffled. We feel it is Fuel, air or vacuum. Anyone out there with suggestions?

Thanks

Oct 25, 2011 | 09:53 PM

Roco71

Melting Slicks

Joined: Jul 2009

Posts: 3,264

Likes: 3

From: Vero Beach FL

I went through this last month. Vacuum leaks or leaks in the exhaust are often the problem. Mine was a bad plug not burning the fuel in the cylinder and igniting it in the exhaust.

Oct 25, 2011 | 09:54 PM

kf4cln

Advanced

Joined: Apr 2011

Posts: 84

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From: Mobile Alabama

I thought I was going to see( God forbid ) a burnt up corvette after pix

Oct 26, 2011 | 12:43 AM

hardhat273

Thread Starter

Heel & Toe

Joined: Oct 2011

Posts: 16

Likes: 0

From: NJ

Thanks for the help.

I have been reading a lot of posts on this site. Looks like I came to the right place. I will put her on the lift tomorrow and check the exhaust. I will let you know how I make out. Thanks for the replies.

Oct 26, 2011 | 01:43 AM

Peterbuilt

Le Mans Master

Joined: Aug 2006

Posts: 7,426

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From: mount holly NC

2025 c3 ('74-'82) of the Year Finalist - Unmodified

2019 C3 of Year Finalist (appearance mods)

Welcome!

I might try a new set of points, check the dwell and timing and go from there.

A little more history like: what carb, any other mods and such will help.

And by the way you posted on the C-3 Tech Forum, but thats OK!
You'll get help on this question here too!

Oct 26, 2011 | 09:02 AM

njfl

Pro

Joined: Nov 2010

Posts: 602

Likes: 32

From: Old Bridge, NJ

You mentioned that you rebuilt the carb and set the timing and the problem went away...then came back.

You didn't mention if you checked the timing after the problem returned.

Consider that your distributor hold-down could be faulty, causing it to rotate and mess up timing or your points could be moving.