[TR] TR4A manifold

[carlsereda]

Gary,
I believe fitting the stock TR4-A cast iron exhaust manifold to a TR3 frame requires using the 2-piece; 'Y collector' with the seperately available 'extension pipe' (Moss has them), VERSUS the standard 1-piece stock TR4A Y collector with already welded-on extension pipe. The separated version lets you get the piping through the more restrictive TR3/4 frame easier. 
The TR4-A exhaust manifold COMBINED with the late TR4 'gas-flowed' intake manifold, plus the stock TR4-A camshaft and carburettors, gives you that extra 4 horsepower that the Triumph factory boasted about around 1965. 
So, if you're keeping the original restrictive TR3 intake, and the original TR3 cam and carbs, the improved TR4-A exhaust manifold, or even headers, may not make noticeable improvement in power.
Regards,
Carl
'63 TR4 since '74

Anyway I'd like the later tr-4 manifold with the two separate pipes if 
possible. Are there any used ones available. Another possibility is going with 
headers although cost is a strong consideration here. I'd go with an earlier 
header (i have the high port head) also if available.