Well this is pissing me off. Backdrop - recent (1 year ago) engine rebuild by Tangerine. 2056 with Webers. Tangerine wire line linkage. Car was running great, a thing of beauty, for the first 500 miles after the rebuild. Now I cannot get rid of the backfiring on the down rev. Pulls great on acceleration. After discussion with Chris at Tangerine I cleaned out the fuel bowls, tightened the heat exchangers, and balanced the carbs. Better but still lots of popping.

Could it be a cracked header/heat exchanger. The heat exchangers are stainless steel and probably were put on back in the late 70s. They have around 100+k miles on them.

They are one of the last untouched parts on the car. I know this because my wife constantly reminds me that I replaced every part on the car.

Any help would be greatly appreciated.

Too rich?

I have been driving aircooled vw my whole life

Buy i think its easy to determine if the pop is from carbs or too rich or


If its the exausht side ...exausght manifold gasket (most times)

Yes, it could. There's a thread on here showing that the SS can crack at the pipes under the sheet metal covers.

Might be time to take them off and do a pressure test.

Did the weather change? You're more likely to get pops out of the exhaust on hotter days.

Also has the sound of the muffler changed? if you lose the baffles / packing in the muffler you'll hear it more also. (think of it like close to straight pipe)

I cracked my exhaust. It backfired on downshifts. I thought I was rich too.
Fixed the exhaust = no more backfires.

Have someone follow you at night and if it's an over-rich situation, they might be able to see it pop fire. If it just started from nowhere, my money is on a cracked heat exchanger, and there's a slight chance that could be visible too.

Use a shop vac in blow mode and connect it to the tail pipe, it can help find an exhaust leak

Now that’s a good idea!

I will give it a shot. So if cracked, who makes the best heat exchangers?

Also, forgot to add that the backfiring is out the exhaust pipe.

Try a smoke machine Ralph, when I used one it showed a leak at the exchanger/head interface that was pretty substantial and causing the popping, apparently...

I have one of those from holloween days. I will give it a try. Thanks buddy