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Wisconsin has Backfire in carb

Denny63

Registered
57 AENDL new coil, points and condenser. Check ed timing TDC and x Mark spot on. Great spark hard to start. Will backfire through carb. Tried multiple carb adj. Will only start (when it starts)only run for a few seconds. Like its fuel starved. Pull plug it's slightly damp. Compression 80psi and I put air in the cylinder at DTC no leaks in intake or exhaust. There plenty of gas in the carb the air cleaner housing leaking a little and it's premium. Could an intake valve be sticking on this? Driving me nuts! Any ideas? Thanks.
 

K-Tron

Registered
Welcome to smokstak. Your engine will certainly run on 80psi of compression. If it is backfiring, either the valve seats are corroded, the valves are dirty, the valve lash is way out, or the timing is off. The X might be aligned when looking through the timing plug, but if the impulse of the magneto was not just ready to snap when the gears were lined up, the timing is still off. I make sure to clean, lap and adjust the valve lash on every new old Wisconsin engine I pick up before attempting to run it. I also take this opportunity to pull the oil pan and flush out fifty plus years of sludge and test the oil pump, before running the engine.

Chris
 

Gene Williams

Subscriber
Last Subscription Date
12/15/2019
Sometimes on tractor engines the valve springs can become weak and not allow the valve to close fast enough when running causing back firing. I am not really sure this is your engines trouble because it doesn't start and stay running too well. K-Tron has some good thoughts also.

Gene williams
 

Denny63

Registered
Thanks guys. I'll double check the mag snap to make sure it correct. I've owned this for 20 years. It just been sitting because of the starting issue.
 

John Campbell

Registered
Could someone have crossed a couple of wires. I have found, it doesn't take much out of time for an engine not to run. Most likely something simple. Good luck. John
 

tew45

Registered
usually if the backfire is through the carburetor it is running too lean and through the exhaust too rich. Just a thought!
 

CharlieB

Registered
Fuel mixture too lean.
Check the throttle shaft for wear. If it wobbles, air is getting in and fouling up the air/fuel ratio. A bad carb to intake gasket will do the same thing. (If the carb hasn't been rebuilt since "57, maybe now would be a good time ??)
 

Denny63

Registered
Took mag off after checking spark with a gap jump tester instead of electronic light type. Weak spark. Cleaned every connection in the mag. Starts right up 1st pull. Thanks guys!
 
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