OS GT33

You say both engines have approx the same run-time, does this mean that the Pepsi's engine went flaky recently? Can't think why they want to see both engines, after all they know exactly how a GT33 performs, so sending back the good engine is a waste of time. Have you explored every possible glitch in the carburettor?

Based on your description (2 identical setups) It is highly probable that one of your engines has a fault and as Ripmax are offering to bench test the suspect unit, its got to be worth the postage to let them deal with it. If you investigate yourself and subsequently decide to send it to Ripmax they may say you've messed with it and deny warranty.

3 screws hold the inlet manifold onto the cylinder head. Why not just swap them over?

Hi Phil - In my opinion I would take up Ripmax's offer & return BOTH engines so they can undertake
the comparison suggested.
Colin.A

JRI wrote: 3 screws hold the inlet manifold onto the cylinder head. Why not just swap them over?

That's what I'd do first.

i would rather not tamper with the engines other than the normal jet adjustments. Why both? I Don't understand why? Pennzoil's engine is just fine but the later Pepsi engine is the one with the issue. As it does not perform as would be expected then that shoud be reason enough to send it back for testing. Thanks for all your inputs Guys.

I will email Peter and suggest that the only engine needing checking is the Pepsi and see what he says.