I am back again. After world class help from you all on a backfire on decel problem--I decided to buy some stainless steel heat exchangers (used on e-bay). My thought was that I had a leak somewhere and that replacing the original exhaust system might help. Right before I started the job, I tried the trick of plugging the exhaust pipe to see if the engine would still run. It slowed right down and quit--so no leak?? Anyway, I pulled them off anyway and now can't decide if the originals (30 yrs old) are better than the replacements. The stainless steel aren't as heavy duty. Also, they looked a bit warped where they connect to the muffler. What are your thoughts??

The only other thing I have trouble shot on the backfire problem is the cold start valve. Disconnecting it didn't change the problem.


Here are a couple of photos...

Another one. The originals are pretty solid and seem to be in good shape.

Here is a picture of the "patient". Please help her.

Nice looking silver car! You might as well put the stainless on since you've got everything a part. I think the tubes on the stainless HEs have a larger diameter and will flow a little better and free up a few HP. (Maybe someone can verify that.)

Run the SSI's.

It will be a lot more peppy and you will have heat in about 3 nano seconds compared to 15 minutes with the old ones (which have been repaired..looking at your pics)

People over tighten the muffler to the HE.. this warps the flange. take a flat file to it and see where the high spots are... try to flatten them before you bolt the muffler on.

True: the SSI's used the same size tubing on the 2.0/1.7/1.8's Porsche used a much smaller tubing on the 1.7's stock HE's. It really wakes the 1.7 up (by putting 2.0 exhaust size tubing on it)

B

Thank you very much. I will go with the stainless steel. Sound like good advice. If this thing still backfires on decel though, I am going to scream.

I scream daily. You own a 914.. get used to it..LOL

Make sure you take a flat file to the tubes that bolt to the heads also.

Install new copper gaskets in the heads... and make sure you remove the old ones. People have been known to double up on the copper gaskets and cause the ears to break off the SSI's.


B

Will do. Those copper rings were tough to get out.

I was told by someone that the new copper rings need to be heated and cooled before installation. Is this true? Or can I just pop the new ones in?

Just install the new ones.

If you want to try re-using the old ones, you heat them up to cherry-red and then let them cool. Using new ones is easier, no heat required.

--DD

Oh.. just for extra measure.. use Orange high temp silicon to hold the gaskets in place. I use it on both sides of the copper.


B

Nemo,

Correct me if I'm wrong Dave, but heating the new ones helps soften them so that they mate better during install. At least the ones I get seem to be annealed, perhaps not all of them are.