Quote:
Originally Posted by Glenn Sedig
Leak down before the inserts were installed, and with 15 runs on the old gaskets, on cyl 3 & 5 was 15%. On cyl 4 & 6 was 8%. The heads were installed with new gaskets. The cylinders heads were flat with no bad areas except between the center cylinders. I got more than 15 runs (more like 30 runs) when the heads were new and no deformation had occurred in the center area.
The inserts where installed to sit .001 above the head surface. The heads have not been surfaced since new. The leak down after the 8 runs - 3 & 5 is 2% 4 & 6 is 3%
Engine is 473 Cu in, 14.5:1 comp. N/A
I need to clarify the engine consitency. Along with the inserts and new head gaskets, I changed my valve lash from .026 cold to .010 cold. Hoped to achieve .018 when hot. I believe the lash change and the fact that the track was prepped before each Q - 8 session also helped with the consitency.
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Those leak down numbers are really good, do you normally re-torque the head once it's been on a running engine for a number of heat cycles?
I really believe, due to the nature of this insert material, this will solve many of the head gaskets woes our tied together, Pontiac siamese exhaust engines can have. Once the exhaust temps get so hot, the small amount of mating surface will not cool properly and weakens.
In today's bigger bore engines, our larger bore spaced cousins (BBC) have other issues when the chambers begin to collapse due to the lack of surface real estate.
Increased power will always come with a cost.
Calvin Hill
Hill Performance
708-250-7420