Backfire all the way home

[corvette8n]

I drove my ‘41 from the storage unit to home about 4 miles, once warmed up it backfired all the rest of the way. It also backfires while it idles. I had Skip rebuild the coil and Charlie NY do the carb two years ago, Tubman condenser, helmet has not been touched. Previous owner put new plug wires. I suspect a valve hanging up as the Reds headers have the paint burning off the driver side but not the passenger side. I have a vacuum gauge and a pressure gauge to check fuel. It has an electric pump and mechanical pump.
As soon as it stops snowing I’ll get it out into the driveway to trouble shoot).
Is there a checklist of where to start?

[Ron Pilger]

Faulty condensor if I was a betting man.

[Jack E/NJ]

>>>I suspect a valve hanging up as the Reds headers have the paint burning off the driver side but not the passenger side.>>>


Do you mean a backfire sound or pop from raw gas igniting in the exhaust system, not back up thru the carb? Jack E/NJ

[corvette8n]

Originally Posted by Jack E/NJ

>>>I suspect a valve hanging up as the Reds headers have the paint burning off the driver side but not the passenger side.>>>


Do you mean a backfire sound or pop from raw gas igniting in the exhaust system, not back up thru the carb? Jack E/NJ

Sounds like thru exhaust.

[tubman]

Originally Posted by Ron Pilger

Faulty condensor if I was a betting man.

I'll take that bet!

[JWL]

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First step--CHECK COMPRESSION all cylinders.

[Charlie ny]

8n,
Keep me posted here or at [email protected]
Charlie ny

[Angledrive]

Originally Posted by tubman

I'll take that bet!

Me too!

[B-O-B]

Run a QT of MMO or AT fluid thru it before you try anything. KISS

[rotorwrench]

A back fire is where the fire comes back through the intake plenum and carburetor. An after fire is where fuel gets past an exhaust valve and ignites in the exhaust with a loud report. A sticky valve or more is generally the cause. Engines don't like to set for too long. MMO down the carb with some in the fuel might do the trick.

Back fire is generally caused by a lean condition in the carburetor. Occasionally a carbon tracked or cracked distributor cap can cause a cross fire to the wrong cylinder at the wrong time. A bad condenser generally causes a miss fire of one or more cylinders with poor or no idle.

[Old Redneck]

Clean and check points for gap. Run Carb Cleaner through carb also.

[corvette8n]

Originally Posted by JWL

First step--CHECK COMPRESSION all cylinders.

So I did a compression test
Drivers side 75,80,80,80
Pass side 75,95,85,75

It was as the car sat since I drove it home, I did not oil the cylinders ahead of time.

[corvette8n]

Here’s what my plugs look like.

[Jack E/NJ]

Mixture rich. Clean plugs and it'll prolly run fine again. Jack E/NJ

[JWL]

Basic mechanicals seem adequate. Missing is likely ignition related problem. Plugs are indicating miss firing or over rich condition.

[petehoovie]

Originally Posted by corvette8n

Here’s what my plugs look like.