How important is it for a tight fit, or not, of the SS heat exchangers at each end where they connect to the exhaust headers and the muffler?

It’s important.

Unless you're immune to carbon-monoxide poisoning Curtis, it's very important. Performance-wise you can also have backflow/freeflow issues with leakage.

It's best to start out with a fresh/new set of gaskets & attachment hardware when doing these, since the gaskets, copper nuts/washers, etc. get mashed & distorted from the prior install, as they're supposed to do to make tight connections. Also IIRC, the factory manual calls for an appropriate exhaust sealant be applied to some of the connections.


Tom
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On mine I had to take a large file to the exchangers to get them flat. seemed to be a bit distorted from the welding. After that all good.

Is the looseness where pipes pass thru the outer casings? If so, it's fairly tipical. The file work you need a light touch where the piping meets the head. Darken the ends with a sharpie and make a light pass contacting both pipes at the same time. A pretty good sized bastard file is needed.

Hi Rhody, yes, it’s the outer casing that seems loose. Does that mean no problem?

Some of your heater air is lost through the loose connection between the heater box sheetmetal and the exhaust tubes but it is not really an issue in most climates, especially California.

Jim

I used high temp silicone for those gaps after they were installed. Be sure to anneal the copper rings !

Ahhh Jim, what copper rings?

The ones between the HEs and the exhaust ports.

The SS HEs have a thinner inlet that attaches to the motor; it’s critical to get a nice even fitting. The annealed Copper rings ( gaskets ?) will help.

Ditto on what Mike said.

The stainless steel “jackets” can be loose. There’s no CO exchange unless the pipes are cracked. There’s enough heat even with some lost around the seams. The fit to the heads and muffler need to be tight as previously noted.

Thanks Mep, that’s what I thought.

How frequent is this? I just inherited a pair of stainless exchangers on an old engine I bought: bright & shiny under all the dirt, the odd evidence of knocks and bangs, but nothing major. On cleaning them up, one of the pipes felt......odd. Putting a borescope down one end revealed a complete break in the pipe about halfway down. So it’s junk, throw it away, don’t even attempt to use it. Bit drastic for what is an expensive item, but the consequences don’t bear thinking about. But how about the other, seemingly undamaged, one?

We have a smoke machine at the shop so it’s easy to test. You can either rig something up or take it to a mechanic. The smoke machine is also a great way to test for vacuum leaks.

An update......the other one is broken too. This is the outside pipe on the driver's side, about 3 or 4" from the rear end of the jacket:

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And this is the inside pipe on the passenger's side, about midway: (the semi-circular arc visible is a complete break around the pipe: it's essentially 2 halves).

Click to view attachment

Wall thickness appears to be a shade under 2mm, I don't know whether this is normal. But from the outside they appear undamaged:

Click to view attachment

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So they are both destined for the bin: fortunately I don't have to use them myself, but............what would be the first warning of failure while in use? Unconsciousness? Seems a bit drastic.

WOW, good catch !
the longitudinal crack is understandable from my experience with SS tubing as it's along the draw lines from producing tubing. The circumferential crack is very odd as thats an area of a very gentle bend and the break looks very clean & not a fracture like surface, looks more like cut with a cut-off tool very odd !!