1964 corvair monza Spyder when I shut the engine off it will sometimes backfire. What are the possible causes?

No one seems to be responding so I'll start out with something lame.
Backfiring out the exhaust? In a broad sense that is sometimes air being introduced into the exhaust system by a leak somewhere, although that may be more like when coasting rather than shutting it off. Inlet or outlet becomes the question, is it making any boost?
Same with ignition timing issue, I would think more likely when running than when shutting off but what do I know?.
My buddy had a 95 that backfired out the exhaust all the time. The muffler is all bulged out which makes me LOL and LMAO when I see it.

Jim Brandberg
Isanti, MN
CorvairRepair.com

2nd on Jim's question - Is it making boost? How often do you drive it while making boost (helps keep turbo/exhaust clean)?

Did you do any work on it recently (potential cause)?
Rich? If it's running rich, it could backfire. Check the plugs to determine if rich condition exists. Heck, change the plugs if they are old.
Carb? Check if there is a slight leak/drip from carb.
Timing? Timing being off can cause "run on" which sounds alot like backfire. Make sure dwell is in spec for points or replace.
Carbon? Also could be carbon buildup on pistons. Start using Techron Fuel System Cleaner

Ken
'62 Spyder
Florida





Edited 1 time(s). Last edit at 03/17/2023 08:56AM by kmart356.

Sometimes unburnt fuel will do this. What about when you’re driving, especially in boost?

Cam or crank gear slipping can do this too, as it causes your timing to go way off. If the easy suggestions don’t work, your next move would be to drop the pan and check to see if the timing mark on the cam gear lines up with the center bolt on the gear end of the oil pan with #1 cylinder at top dead center.

Is the engine freshly rebuilt? New cam gears are commonly one tooth off, and sometimes more. Try the easy stuff first. Keep us posted.

Rocco
65 EFI Turbo Corsa
YS113
Barboursville, Va



Edited 1 time(s). Last edit at 03/17/2023 02:01PM by zarfnober.

Thanks for all of your answers.But now I have a bigger problem, l wrecked it 2 nights ago. Major damage to left rear fender enter fender and rear of the car.
Does anyone have a lead on a solid parts car.

Location...Location...Location...

Friends Don't Let Friends Drive Stock
Been Aircooled Since 1973
Northwest Ohio 45840

Wagon Master Wrote:
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> Location...Location...Location...

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From a previous post he lives in LaGrange,GA
(near the border 1/2 way between Montgomery AL & Atlanta, GA)

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Dan Davis ~ Pierce County, WA ~ CCF admin ~
CORSA +Corvairs NW + North Cascades Corvairs + Corvanatics
1966 Corsa Turbo coupe ~ ~ 1966 Corsa 140 Coupe ~ ~ 1965 Monza 140/4 Convertible Sierra Tan/Fawn ~ 1964 Monza Spyder Convertible ~ 1960 Monza Ermine White/Red PG ++ ~ 1965 Monza 140/4 CoupeEvening Orchid w/ ivory/black interior ~ 1962 Monza Wagon 102/4 ~ 1963 Rampside/Scamper ~ 1963 Red/Greenbrier ~ 1969 Ultra Van #468