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BJ-8 Exhaust Installation

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fwtexasbj8

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I have apparently been a good boy this year and Santa Clause is bringing me a new Trophy SS exhaust system for my BJ-8! I have not touched an exhaust system since I tried to make it louder on my BJ-7 I had in high school 35 years ago! I have read about checking the threads, using new brass nuts and high temp silicon to seal the joint at the manifold but am wondering if I need to do anything special to seal the other joints as I assemble it. Santa bought new hangers and SS clamps plus the Moss skid plate. My plan was to start at the front and just work aft but not tighten anything down until all was installed.

Any installation tips are much appreciated!
 
yea let someone else do it ,if you don't have access to a lift its tough to do it on the ground ,i installed a nos ansa and still have leaks
 
First, get the car up as high as possible on jackstands (prudent safety precautions apply).

Make sure the downpipe flanges are smooth and flat--flatfile (or mill) if not. Some/all have a very slight bevel by the holes; I assume these are to allow the steel to bend a little, applying a bit of spring load against the manifold flanges--don't file/mill this away. If you happen to have the manifold out do same to it.

Make sure the studs are in good shape; if not, replace them. In my experience the SS ones are no stronger than the mild steel, but are probably less prone to corrosion.

Install the downpipes. I've seen two types of gaskets: copper and silver, perforated metal. In my experience neither work better than the other; one person I know had some solid copper ones made--presumably, that is best. Use new brass nuts; however, I've had best results using anti-seize on the studs and double-nutting steel nuts after torquing (nickel anti-seize is best for high-temp applications). Coat both sides of the gaskets with Permatex High-Temp Silicone (the copper-colored stuff). Install the front downpipe first. Torque carefully--you do not want to break a stud--and double-nut if you choose.

Then, work back from the front. The flattish, stock British-style clamps aren't great, but the American-style, bent rod type put a crimp in exhaust tubes that make removal difficult. Sealing these joints has been a long-term problem--note the modern way is flanges with a doughnut-shaped gasket. A muffler shop will usually weld most joints when fabbing an exhaust; you'll have your exhaust off again someday (trust me) so I wouldn't advise that.

Put some of the silicone on the 'male' part of the tube and insert; torque the clamps appropriately and hope for the best. Good idea to keep everything loose, then do final tightening when everything is in place and aligned.

Short of welding the joints, I don't know if it's possible to get perfect seals on every joint. If you do get them, consider yourself lucky; if not, you won't hear leaks over the usual din of a Healey (though large leaks can cause the 'popping' you sometimes get on deceleration).
 
I have been meaning to post to this thread as a suggestion to those installing the stainless exhaust. I just installed the stainless one on the BN-4 and this is what I did. I used header wrap on the down pipes prior to putting them on. I also used a large muffler blanket and wrapped it over the muffler followed up with a layer of the matching header wrap. This gives the muffler two layers of heat insulation. With all the talk of heat intrusion into the interior I thought this would help some of the exhaust heat to go out the tailpipe instead of radiating up to the floor boards. I also put a layer of the dynamat extreme to the underside of the floor board before putting on the cement boards (which hides the dynamat). One main argument against using header wraps is their possibility of trapping moisture and rusting out the exhaust system, but with a stainless system that is not a concern. I also like the clean looks it gives.

Jim
 

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I found the kit I bought that was SS, (not Trophy) fit well but still had two spots where a bender would have been nice to tweek the pipes away from a hard point so there was not a rattle. Also, the joints were sealed using a SS flange which had two sizes, MOSS has them. One bolted tight, they seal around the joint. Pretty good seal.

Jerry
 
That is a good idea and it looks great. I finally got an unexpected project finished on my son's Mustang so am about to tackle my Healey exhaust. One concern I have is how the guy that installed my steel system 25+ years ago mounted it. I am not sure he used the correct mounting hardware or if he just cobbled some together. Does anyone have a set of pictures of the correct mounts? AS always on this forum, much appreciate the help!
 
richberman said:
I was told header wrap is ill advised and may negate warranty.
Click to expand...

The only reason I have ever heard why is it would hold moisture and rust the pipes prematurely. This usually applies to the actual tubular headers which are almost always made from steel. I only used them on the stainless sections of pipes and the muffler which is also stainless. If you have heard of other reasons please advise. Also most manufacturers are just looking for ways to avoid honoring a warranty, and this just gives them an excuse.
Jim
 
I did some research on this--OK, I googled it--before wrapping my mild steel downpipes. The claim is the wrap works to retain heat in the pipes, which can accelerate erosion of the pipes (or something like that--I'm too lazy to 'research' it again). I disregarded any claim that the wrap 'retains water' or anything similar because, well, the pipes get pistol hot and any moisture would get vaporized. Plus, I coated the wrap with the silicone coating and it seems to repel water pretty well. I pulled the downpipes for other reasons a couple years--and 10K miles or so--after wrapping them. As far as I could tell they looked completely normal--i.e. carboned-up a little--but with no other visible issues.

Like others, I've dealt with many exhaust issues over the years. I'm on my fourth 'solution,' which is a cobbled together system of Ansa piping with JC Whitney glasspack mufflers. It's loud and raspy--some people swear I must have a V8 under the hood--but, curiously, seems very quiet at higher speeds. The main issue I have found with all systems is that the muffler sections are usually some type of fiberglass or steel wool pack. Typically, the packing will be gone before the pipes corrode through. I assume this will be the case with the SS systems as well. I wish someone would build a good-fitting mild steel system that didn't use glasspack mufflers; i.e. what the hotrodders call a 'turbo' muffler.
 
Jim- could I make a suggestion that you wind stainless lockwire over the insulation to stop it all unwrapping if any one bit is damaged. I V8-ed a car some years back and it had headers with two 3" header collectors under the floor which made things rather hot inside so I did as you have done and wrapped them in insulation. This worked well until I just scraped a speed hump. The slight graze marks weakened the insulation and it unwound itself and disappeared within a few weeks. The wrap feels quite strong when it initially goes on but after a few months of exhaust heat it becomes very brittle.

Keep an eye on it anyway because it comes off real fast once any single bit is damaged. You'll see bits of fuzz flying up in the rear view mirror.

Andy.
 
Andy good suggestion. I will probably have to drop down the muffler portion to bolt the seats in and I will lace some stainless tie wire around at that point. On good thing is if the wrap comes off the muffler I still have the heat blanket layer next and it is one large piece not a wrap. I will also probably use the spray coating too to help resist staining. Thanks for all the tips guys.
JIM
 
I have to agree with some of the comments made here. Why can't someone offer a one peice exhaust pipe and muffler system that would just bolt up to the flanges in front and extend all the way back. I've always felt with the proper hangers this type of sealed system would work on AH.
 
Exhaust wrap is unsightly but now that ceramic coating costs more than the exhaust there's not much choice.

Has anyone tried heatproof paint laced with ceramic vacuum microcapsules to limit engine bay heat?
 
Project update! I was able to remove the old system in about 15 minutes! Nothing was frozen and all of the bolts came out easily:smile:. I learned two things though, first, the flange to the manifold had hex bolts instead of studs and nuts. While I realize this isn't the correct arrangement, is there any reason replacing the old bolts with new stainless ones would not work as well? The old system never leaked with bolts. Second, when I compared my mounts with the Moss catalog, I do not have the set of mounts that appear to go just aft of the mufflers under the seat. I have searched the frame and cannot see anywhere that the mount would go and my frame does not appear to have ever been patched that would cover the mounting holes. Can anyone describe if they have this mid-mount and where the rubber mount bolts into the frame?

Thanks again for the help!
 
For the most part, in non-critical applications, the difference between bolts and studs is inconsequential. Studs make it a bit easier to line things up. I've used both steel and stainless steel studs, and can't say there's a big difference in strength (the SS studs may even be a bit more brittle). I think grade 8 bolts would be best; just don't torque so much you strip the threads in the flanges. Use grade 8 flatwashers under the bolt heads.
 
I should also add to use anti-seize grease--nickel is best for high-temp applications--on the bolt threads. Shouldn't be any trouble getting the bolts out if you do that.

I've had a lot of trouble getting a good, long-lasting seal here. Though I usually prefer to stay original, if there's room to use slightly long bolts then locking them down with nuts on the backside of the flange this may be a way to get a good clamp on the flanges.
 
healeyblue said:
I have been meaning to post to this thread as a suggestion to those installing the stainless exhaust. I just installed the stainless one on the BN-4 and this is what I did. I used header wrap on the down pipes prior to putting them on. I also used a large muffler blanket and wrapped it over the muffler followed up with a layer of the matching header wrap. This gives the muffler two layers of heat insulation. With all the talk of heat intrusion into the interior I thought this would help some of the exhaust heat to go out the tailpipe instead of radiating up to the floor boards. I also put a layer of the dynamat extreme to the underside of the floor board before putting on the cement boards (which hides the dynamat). One main argument against using header wraps is their possibility of trapping moisture and rusting out the exhaust system, but with a stainless system that is not a concern. I also like the clean looks it gives.

Jim
Click to expand...

Jim, the finish on the underside of your Healey is exquisite!

Jeff
 
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