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Re: [T3] Backfiring...


On 21 Oct 2003 at 13:28, William Kunz wrote:

> Sorry to bring this up again, but it looks like I'm
> getting a backfire thru the carb. When I go to start
> the car, the engine will kick over with a couple of
> pumps to the accelerator. While the engine is trying
> to maintain an idle there is "popping" from the
> engine, not thru the exhaust. My friend confirmed this
> as he saw a flash come out of the right hand carb when
> we took the air cooler off and restarted. I have dual
> 32 PDSIT carbs. After the car is idling, the popping
> stops and the car runs normally. Any suggestions?

Is there any chance that you have the idle ignition timing set extremely 
advanced? It makes me wonder if the mechanical advance on your distributor 
might be frozen and someone has dialed in a lot of static advance to make it 
seem to work better at speed. I really don't know if this would cause your 
problem, but I can't think of any other reason other than an intake valve that 
is not sealing, but that's pretty unusual.  

I suppose it's possible that you have an intake valve stem which is varnished  
up and is sticking until it gets warm. This might explain why ignition within 
the chamber is able to flash back to the carbs. You might find the culprit by 
doing a compression test with the engine cold.  

-- 
*******************************
Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA
*******************************

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