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Exhaust down pipes

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stinky60

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I'm ready to install the down pipes on my BT7,I have some copper gaskets which seem to be very thin, .016 thick is this good? The other gaskets I have are thicker and are made of some kind of sandwiched fiber, this is my first attempt at this. Any suggestions ? Thanks Bob
 
Hoo boy ... this is a known PITA. There are two kinds of gaskets generally available: one type has two copper sheets with some white fibrous material in between, and one has perforated silver metal with black fibrous material in between. I've tried both--repeatedly--and it's a wash IMO. Solid copper gaskets should be best, if you find any please let us all know.

It's difficult to get a good, lasting seal at this joint. The 4-cyl cars had a bracket and clamp anchored by one of the pan bolts that stabilized the (single) downpipe. The 6-cyl cars don't have this, and I think part of the problem is the downpipes vibrate and work the studs, nuts and gasket so eventually you get leaks. I've gotten best results by:

- make sure the studs are in good shape (threads clean, not stretched)
- flat-file (or mill, if you can) the downpipe flanges as flat and smooth as possible (if you have the manifold out do same to it)
- apply high-temp silicone to both sides of the gasket (looks like Rich did this)
- either use new brass nuts or apply anti-seize to the stud threads and double-nut with steel nuts (my preference)
- check the nuts regularly for tightness
 
I had a lot of backfiring on coast down. Found out it was caused by air getting in the joint. I also had problems with loosening nuts at the flange. Cured both problems with the copper sandwich gasket and brass nuts at the flange.
 
Rich, those are some nice looking pipes, off hand do you know roughly how thick those gaskets were, I can get various thickness sheets of copper, they were not hard to make,Bob I'm going to follow the new brass nuts, and dbl nut them. Tim were those composite with outer copper on both sides? Thanks guys :thankyousign:
 
013.jpg


Two thin sheets of copper with two thicker fiber gaskets between.
 
Moss includes SS clamps with the pip set. If you look at the other pictures you'll see them. It's a really nice setup! I highly recommend it.
rich
 
Hi,
I have a blowout at the flange on my BT7, so I will replace the down pipes using the SS-pipes, copper sandwich gaskets and brass nuts. The link you indicated no longer exists,
so I think the FRONT PIPE-(front)S.S is partnumber EXS125: https://www.ahspares.co.uk/austin-healey/performance-parts/Exhaust/FRONT-PIPE-frontSS.aspx
and the FRONT PIPE-(rear)S.S is EXS126: https://www.ahspares.co.uk/austin-healey/performance-parts/Exhaust/FRONT-PIPE-rearSS.aspx
My car is a BT7 but I have a BJ8 engine on board with a tricarb. Can anyone explain me the difference between the downpipes for bn4-bj7 and bj8?
many thkx and regards
Pascal
 
The spacing down below is different, so it depends on what exhaust you are using. The early single muffler(2 in- 2 out) or the BJ8 system that requires the wider spacing. Order according to the exhaust system.
Bob
 
Hey Stinky, I used the perforated silver ones and sprayed them with Copper Coat. (made by Prematex).
 
AH3000_DS5 said:
Hi,
I have a blowout at the flange on my BT7, so I will replace the down pipes using the SS-pipes, copper sandwich gaskets and brass nuts. The link you indicated no longer exists,
so I think the FRONT PIPE-(front)S.S is partnumber EXS125: https://www.ahspares.co.uk/austin-healey/performance-parts/Exhaust/FRONT-PIPE-frontSS.aspx
and the FRONT PIPE-(rear)S.S is EXS126: https://www.ahspares.co.uk/austin-healey/performance-parts/Exhaust/FRONT-PIPE-rearSS.aspx
My car is a BT7 but I have a BJ8 engine on board with a tricarb. Can anyone explain me the difference between the downpipes for bn4-bj7 and bj8?
many thkx and regards
Pascal
Click to expand...

If you have a blowout, wouldn't that mean either the flange connection is loose - for instance one of the nuts missing, or that you need new gaskets, rather than replacing the downpipes?

Moss catalog shows the same gaskets for all 6-cylinder cars.

BJ8 downpipes are different because of different BJ8 exhaust system, not anything on the engine or exhaust manifold.
 
Vette, I did use the perforated silver ones, but didn't use any copper coat , so far haven't had any problems,, that's a good idea, will do that if any problems arise
 
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