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TR4/4A tr4a exhaust manifold

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grant tr4a

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Hi, I just registered, have been reading and doing site searches for a few months. I found some very useful ideas and tips to help me on fixing up my 1966 tr4a. All has been going good until i started to here an exhaust manifold leak, after some close inspection i found the ex manifold pipe from cyl #4 to be cracked all the way around where it y's. It seems to me that it is not fixable. I have started a search for a replacement. No luck yet. If anyone can help me along the path to finding a ex manifold it would be greatly appreciated. Thanks Grant
 
I think you are right that they are NLA. I bought a replacement many years ago, before they became unobtanium, because I had the same problem. I'd suggest buying a header. I have often considered doing that just so I could box up the good manifold and save it from eventual failure...
 
They show up on e-bay from time to time. Search all of the specialty bone yard guys too, they are out there but like me I am hording the extra one I have. Since 1969 I've gone through 3 of them. I should be good for my lifetime with the spare that I have. Also put a note on the other Triumph lists asking for help.
 
Mine came with one that had been repaired by brazing. I reckon it had covered many thousands of miles like this.
However I scounged up a replacement eventually.

It also had a defective clamp between the gearbox and the exhaust pipe. I have always believed these two things to be related faults.

The exhaust was only supported at the extreme rear and by the manifold. I'd guess it wangs up and down if you do this.

al.
 
Yes the 4A is a 2 into two downpipe while the 4 is a 4 into 1 downpipe. They can be interchanged if you also change the downpipes to the first connection.
 
I believe the exhaust manifold changed right at the TR4/4A transition, but there might be a few cars on either side. The later version has two outlets instead of just one.

In theory it can be welded, but it takes a lot of prep work and special techniques that not all welders can do. I've known lots of welders that claim they can, but I've never seen a repaired car manifold that held for very long in service.

Probably have a better chance with brazing, as the braze material is relatively soft and will deform before the cast iron breaks.
 
Mine looks like it has been welded, but I have owned the car since 1980 so it would have had to have been done before that. Also I have a spare engine (parts) that I think has the TR4 manifold on it. I will check it out the next chance I have.
 
Is there any reproduction exhaust header that makes a 2 into two downpipes so it could tie in with my existing exhaust two pipe flange? I don't want to mess with my exhaust because it is stainless from the manifold all the way back. Grant
 
grant tr4a said:
Is there any reproduction exhaust header that makes a 2 into two downpipes so it could tie in with my existing exhaust two pipe flange? I don't want to mess with my exhaust because it is stainless from the manifold all the way back. Grant
Click to expand...

Generally, the headers replace the manifold and the down pipe, the two header outlets will either join up to your y-connector or front muffler, depending on what system you have. There are 4-1 headers, but the 4-2-1 is is more common.

https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=112370
 
grant tr4a said:
Is there any reproduction exhaust header that makes a 2 into two downpipes so it could tie in with my existing exhaust two pipe flange? I don't want to mess with my exhaust because it is stainless from the manifold all the way back. Grant
Click to expand...
Not that I know of. However, I see where Neil Revington has used original manifolds listed for sale. Probably close to $300 by the time you pay shipping from the UK, though.
 
I found a tr4a ex manifold in very good shape & it is on the way. I have a couple of related questions. 1. are better gaskets available (better seal?) 2. what torque for manifold bolts 3. where the vacuum line connects to the front su hs6 carb it goes into a 90* rubber connector---how do i get this disconnected? thanks Grant
 
Mine came with a brazed up manifold. It had probably done quite a lot of miles like that.

It also had a broken clamp between the gear-box and exhaust pipe. I have always believed these two things were related.

The pipe was hanging between the mounts right at the end and the mainfold. It probably wangs up and down if you do this.

Al.
 
Just out of curiosity, what is a fair price for a TR4A exhaust manifold and where do they usually crack? I have a friend that may have one for sale. Berry
 
Al, thanks for your post about the hanger bracket on the trans bolt. I checked to see if that bracket was not doing it's job. Found that there was no bracket at all in that location. The first bracket I found was behind the rear tires. So it was maybe 8 feet to the first bracket. (maybe that had something to do with it breaking) Checked out the parts book and found the bracket that I am missing. I will get one and install it when it goes back together. Grant
 
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