engine backfiring

[jkeinert]

RE: Lark V-8----What would cause the engine to backfire, after it has been idling for 4-5 minutes?? I did spray some ether into the carb to help it start initially after it sat in storage all winter. Dont know if it needed that, as the engine has been rebuilt. IT was a pretty loud backfire, and then we shut it off. Don't know if we have a serious problem on our hands or not(not real mechanically savvy)---appreciate those of you who are!!!
Thanks

[studegary]

Does it backfire occasionally/randomly or with each second revolution of the engine. The second case may be a stuck or burnt/damaged intake valve. The first case may be a vacuum leak. Do you have a brake power booster? Also, it could be as simple as a timing issue. I just re-read your post. Now, rather than a backfiring problem, it seems as though your engine just backfired once, you shut it down and haven't proceded. My guess is that an intake valve hung open as the cylinder fired.

Gary L.
1954 Commander Starliner (restomod)
1959 DeLuxe pickup (restomod)

[jcarmichael]

Or was it just one backfire which could be caused by the ether exploding in the muffler as it got hot.

1961 Lark

[CHAMP]

It could have just been a cold engine back-fire. Has it back-fired anymore?

[studegary]

The two posts following mine raise an interesting point. Did the car backfire through the carb. or out the exhaust?

Gary L.
1954 Commander Starliner (restomod)
1959 DeLuxe pickup (restomod)

[Dwain G.]

Was it idling smoothly, or maybe a little rough? Could have been a fouled plug that decided to come to life and ignited an overrich mixture.

Dwain G.

[jkeinert]

quote:Originally posted by studegary

Does it backfire occasionally/randomly or with each second revolution of the engine. The second case may be a stuck or burnt/damaged intake valve. The first case may be a vacuum leak. Do you have a brake power booster? Also, it could be as simple as a timing issue. I just re-read your post. Now, rather than a backfiring problem, it seems as though your engine just backfired once, you shut it down and haven't proceded. My guess is that an intake valve hung open as the cylinder fired.

Gary L.
1954 Commander Starliner (restomod)
1959 DeLuxe pickup (restomod)

[jkeinert]

Now that I recall, it backfired once after idling for a few minutes, and it did not keep running. I started it again, and after a few minutes it backfired again. I shut it off and left it as I was out of time and did not want to risk any damage. Cant recall where it backfired--I was at the front of the car and it was a Very Loud "crack". I did not see any flame, but was not at the rear/exhaust. Is it safe to restart and run it??
Thanks--JK

quote:Originally posted by studegary

Does it backfire occasionally/randomly or with each second revolution of the engine. The second case may be a stuck or burnt/damaged intake valve. The first case may be a vacuum leak. Do you have a brake power booster? Also, it could be as simple as a timing issue. I just re-read your post. Now, rather than a backfiring problem, it seems as though your engine just backfired once, you shut it down and haven't proceded. My guess is that an intake valve hung open as the cylinder fired.

Gary L.
1954 Commander Starliner (restomod)
1959 DeLuxe pickup (restomod)

[jkeinert]

It was actually idling fairly smooth once it started. I am wondering if it was the ether I used, although it idled for quite awhile before it backfired?

quote:Originally posted by Dwain G.

Was it idling smoothly, or maybe a little rough? Could have been a fouled plug that decided to come to life and ignited an overrich mixture.

Dwain G.

[showbizkid]

Have you checked the distributor cap? I've seen caps with carbon traces randomly arc two plugs at a time. If it's the "right" plug, it could cause a backfire.

---------------------------
Clark in San Diego:

Proud new owner of a '63 Lark!

[jkeinert]

After backfiring--Is it safe to fire it up and run it?? I am not sure how to trouble shoot--and dont want to damage anything!
JK

[Dick Steinkamp]

quote:Originally posted by jkeinert

After backfiring--Is it safe to fire it up and run it?? I am not sure how to trouble shoot--and dont want to damage anything!
JK

JK,
If you are unsure of your mechanical skills, I'd get it to a garage you trust or bring a mechanic you trust to the car. There are lots of things that could happen with an engine backfiring. If it is backfiting through the carb, it could easily start an engine fire. Through the exhaust could blow out the exhaust system. You could have a stuck valve or two and if you run it, it can break the guides, or damage a piston or valve head. I would say the ether is not the cause. It would have been burned up by the first revolution or two of the engine.

Just my 2 cents.