DRILL EXTRA HEAD BOLT HOLES
TA Performance Buick Stage 1 heads have the capability to incorporate four additional head bolts or studs for increased head gasket clamping. This option is advisable on applications that will produce alot of cylinder pressure, as these application have the tendency to leak combustion pressure by lifting the head down towards the exhaust ports. These extra mounting bolts are not needed on milder street applications. The extra bolts also require that the block be drilled and tapped to accept these extra bolts as the Buick block did not originally come with these holes. The extra head bolt holes are only partially drilled by TA on the head gasket surface side. The last inch or so is not drilled from TA for several reasons.
- Extra bolt holes intersect with the exhaust manifold/header mounting bolt holes, which can weaken them.
- Aesthetically the heads look nicer without extra holes drilled if they are not being used.
What we do:
- 8 extra head bolt holes are drilled completely thru and edges chamfered.
- Header mounting bolt holes that are compromised have stainless steel Heli-Coils installed.
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The cylinder head is securely attached to the milling machine. Bolt holes are drilled true to the head deck surface.
Stainless Steel Heli-Coils are installed in header bolt holes.
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