[TR] long TR4 inlet manifold in a TR3A/B ?

Rick chandler.rick at comcast.net
Wed Mar 17 11:00:51 MST 2010



The use of the superior TR4A intake manifold will bring performance benefits
to your TR3A. However, the mod is a bit more complicated than it appears; I
did it two years ago during my TR3A rebuild. Firstly, the TR4A intake AND
exhaust manifold must be mounted together, as they are interlaced. The TR4A
exhaust manifold is a superior design and is worth mounting on your Tr3A. I
can absolutely confirm that the TR3A intake is NOT compatible with the TR4A
exhaust manifold, and I believe that the converse is also true, but I
decided at the time to retain the TR4A exhaust and found a TR4A intake to
mount. If you go this route, you will need the Y-connector on the exhaust
pipes. Secondly, you will need to use HS6 carburetors. The throats of these
carbs were designed with the TR4A intake manifold in mind, and the ensemble
fits nicely in the TR3A engine compartment. I used thin air cleaners, but I
believe that the truncated-cone K&N cleaners will work as well. You will
also have to change the throttle linkage, as the HS6 carbs use a center-pull
arrangement. Jeff at PalTech can set up the linkage for you. Expect to pay
just south of a grand to get the whole system on your car. 


Rick in Seattle

1960 Triumph TR3A

1970 BSA 441 Vistor

1972 Norton 750 Commando Combat

1975 Norton 850 Commando Mk3

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