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Q & A: XPAG Head Studs

I have a 1954 Lotus Mark VI fitted with a 1466cc XPAG factory-racing-block, Laystall-Lucas aluminum head, and TC gearbox.

1. The head studs and nuts seem to be 10-1.5 mm. Can I chase the threads with 10-1.5 mm die and tap?

2. What torque would you recommend I use for the head nuts with my aluminum head?
(I'm using a .110" solid copper head gasket to drop its racing days compression of about 12:1 to a more
reasonable 9:1.)

3. Is it true that the XPAG (my engine) and the 1466 XPEG had different bore spacings?

Thank you,

Walter

Walter,


The studs are, in fact, 10mm x 1.5 so you can use a 10x1.5 tap and die to clean the threads on the studs and the nuts.

I would use a torque of 50#, then retorque to 50# when the engine is hot.read more