Better Breathing Means More Power

John fits up Triumph manifolds

John matches the fit of this TR3 intake manifold

We have been working steadily to coax more reliable power out of this Triumph TR3.  Currently, it’s running a fully balanced  89 mm bore engine on a set of Omega pistons (not the chancy Asian ones), big valves, and a Revington 1058 Sprint cam with an aluminum flywheel.

Carburetors are the standard SU H6’s, but I’d been eyeing a spare TR4A four into two exhaust manifold which has been beckoning to me from an untidy corner of the shop

John massages the TR4A exhaust manifold for fit

John massages the fit of the TR4A exhaust manifold

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While it might be a straightforward idea, some modification was required.  In this picture you can see John grinding the #’s 2 & 3 exhaust runners for clearance around the balance pipe on the TR3 intake manifold, which was retained here.

Final clearance check: manifolds fitted up on the TR3

manifolds fitted up on the TR3

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Here’s how it came out.  John worked methodically taking small cuts, checking his clearance initially with a .004″ feeler gauge, until he was satisfied that he was in the zone.

carbs & manifolds installed

Final Fit Up: Carbs & Manifolds Installed

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The final result:  Now it looks like this.

John also made up a heat shield for the generator out of stainless steel and fabbed a bracket to move the brake pipe union an additional critical inch away from the outer collector on the exhaust manifold which was now much closer.  Sharp eyed observers will also take note of how we manage fuel filtration.

New Two Branch Collector Pipe

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Here’s the view from underneath The new two branch collector pipe with the overdrive sump plug in the immediate foreground.

one off 2"exhaust

"One Off" Two Inch Exhaust

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In order to take maximum advantage of the improved exhaust flow, John and Butch collaborated on this custom two inch NAPA exhaust system featuring a Thrush muffler which lets the power out without shattering the neighbor’s windows.

Readers’ with long memories will no doubt recall that the old muffler quite literally blew up on the New England 1000 this past summer, and a Midas Mufler shop in Newport, Rhode Island fashioned an emergency replacement out of N.O.S. ’56 Cadillac Coupe deVille resonator.

John road tests his work

John Road Tests His Work

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What’s our Mantra ?   John road tests his work Friday afternoon.  He pronounced it “Most Satisfactory”.

David and an MG TD distributor

What was your scribe doing Tuesday afternoon ?

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We’re letting the question about the Mad River run for another week, there wern’t any takers. So here’s another.

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