I am currently going through a frame-up on my '69 TR6. This includes
balancing, porting, camshaft upgrade, & compression to about 9.6:1. Staying
with stock ZS carbs but working through an upgrade of the distributor. Memory
has it that my stock exhaust is a cast iron to a single exhaust system.
On talking to the people overhauling the engine, they said I should either
upgrade the exhaust manifold to the twin-pipe exhaust used on later year TR6's
or go to a S/S exhaust header. The negative on the S/S exhaust header is that
about every 20K miles I will need to replace the exhaust manifold gasket.
They say that this is due to the different metals - cast iron for the block
and head vs. S/S for the header. They expand and contract at different rates
and therefore create problems for the exhaust gasket.
Any thoughts or recommendations on this? I have to replace the single (Stock)
manifold anyway due to a crack in its flange.
Doug Fraser
69 TR6
Sammamish, WA
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