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RE: [T3] Carbs popping


It's only under acceleration, and it only occurs when the engine is under
load. It doesn't occur when I rev the motor as the car is standing still,
just under load. 

I do believe you are right about the exhaust leak. I will check this
tonight.

Thanks Steven. 

By the way, do you guys get 85 octane gas in Northern Arizona? We have it
all over Colorado, and I've only ever seen it in higher altitude locations.
How does this gas affect our cars as compared to 87 octane at lower
elevations?

Doug


-----Original Message-----
From: Steven Ayres [mailto:comwest@att.net] 
Sent: Wednesday, August 31, 2005 9:36 AM
To: type3@vwtype3.org
Subject: Re: [T3] Carbs popping

DougG=> popping thru the carbs under acceleration.
=> ... anyone have suggestions? I'm suspecting an intake leak?

Actual backfire -- fire up through a carb -- is when an intake valve is 
open as the cylinder is firing. You may be right about the intake leak, 
but not, I suspect, the sort of leak you imagine. This is a timing or 
valve-train problem. Very not good, it can cause carb damage and 
possibly engine fire.

OTOH: To clarify, are you testing and seeing this while standing over 
the motor, or while driving? if the latter, it's more likely 
postignition -- fire in the exhaust system -- which is often related to 
an exhaust leak.

Steven Ayres, Prescott AZ
'66 343

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