How well should a muffler fit when installing?

[smpiers]

I am putting on a new muffler and new-used SST heat exchangers. My question is, how easily should the muffler fit when putting in place? With the heat exchangers tightened up they mismatch the muffler about 1/2". I can get the muffer to fit with a little pre-load on the heat exchangers. Is this bad? I think the HE were modified as the "ears" that the nuts tighten up to seem a bit off. I am going to investigate having a custom muffler shop replace them for me.

Thanks,
Shane

[Mark Howard]

Shane - I just put a Bursh muffler on my '75 914 and had a similar issue. I found that it mated to the heat exchangers, but was also slightly off alignment as well. First, I took my time. There is no such thing as a 5 minute Porsche project. Second, loosen everything up (except the manifold that bolts to the head)and fit the HE to the muffler without putting the top bolts through the muffler support bracket. Be careful with this because you don't want any weight pulling down on the manifolds bolted to the head, ensure you support the HE with a floor jack or something (ask me how I got a cracked head). Once the main parts of the muffler, test pipe and HE are together, put the bolts through the muffler support bracket. This will require some prying and pulling, but it will fit. One all together, tighten bold securely.

This worked for me and took about 1.5 hours of head scratching and a long but sharp learning curve.



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Mark Howard
'88 Carrera
'62 356/B
'75 914 1.8 resto

[Dave at Pelican Parts]

I had a similar problem for a while. I'll tell you how I fixed it, but I am not very proud of my methodology. There has got to be a better way than this....

After struggling with my heat exchangers for several years (and bending at least one exhaust stud), one day I got pissed-off at them while trying to re-install them. So I took them off the car again, figured out which way the tubes that mate to the heads needed to move, and then took my favorite BFH (Big Hammer) to them. After a few whacks (felt good, BTW!) they were much more in line with what I wanted. After I called the alignment good, I took a large file to the ends of the tubes to get them flat. They need to be flat with respect to each other so they will fit flat on the gasket in the head. I went over both tubes at the same time with a single motion of the file--that's why I needed a large one.

The filing makes a lot of noise.

They seem to fit pretty decently, and it is a whole lot easier to install them now.

--DD

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Pelican Parts 914 Tech Support

A few pics of my car: http://www.pelicanparts.com/gallery/Dave_Darling

[robby750]

I received my new Mittlemotor Muffler the other day and just got it installed. This thing is BEAUTIFUL! It is about as heavy as the OE muffler. The sound is awesome, absolutley the best sounding 914-4 I have ever heard. Even my wife who normally could care less, just called me while driving it and told me how good it sounds. Total cost including shipping was $390.00 and it took 17 days from Der Fatherland to Kentucky. Highly reccomended!

[ovilla]

Don't worry about a slight mismatch. I swapped out my 75' heat exchangers for a 74' SSI unit and also installed a new 74' Bursch and had the same mismatch problem. First, I made sure that I filed across both HE's evenly with a big "bastard" file (actual name of the Sears file). Then I bolted the HE's to the heads and tightened one end to the new Bursch. I then used a really long threaded bolt and nut to get the "mismatch" to line up temporarily so that I could install the other two bolts and then replace the long threaded bolt. Anyway, you'll find that the HE's will warp after some use as the heat brings them into alignment. Next time you take them off they should line up better. Finally, if you did a retrofit from a 75' or 76' to an earlier exhaust set up (70'-74'), you will need to use the earlier muffler hanging bracket as well.