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Stock, Bored, and Aftermarket Blocks- includes Butler Spec Head Gaskets
Pontiac V8 Stock, Bored, and Aftermarket Blocks- includes Butler Spec Head Gaskets
The Everyday Answer — Stock, Bored, and Aftermarket Blocks- includes Butler Spec Head Gaskets for Pontiac V8s
These are the composite head gaskets for the majority of Pontiac V8s — a stock rebuild, a .030" or .060" over block, or a naturally aspirated pump gas build that does not need the expense of multi-layer steel.
Butler's own Butler Spec head gaskets are manufactured exclusively for BP from the original Fitzgerald dies used for GM in the 1960s and 1970s, with improved water hole dimensions that leave more material between the water hole and the cylinder. Butler also stocks Best Gasket GraphTite sets with steel fire rings for the early engines and for 4.200" and 4.250" bores.
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1. Which Butler gasket your block takes
Butler's three composite gaskets are separated by bore limit and by what the block's valve notches look like. Get both right.
| 350-400-428-455, up to 4.191" bore | the standard Butler gasket. It works on blocks with no valve notches at all (full round bore) or with the later-style notches at the 9 o'clock and 3 o'clock positions. |
| Universal, 1964 and later 326-455, up to 4.191" bore | this one also carries the chambers for the 326, 389 and 421. If the block has the offset type or location of valve notch, this is the gasket it requires — and it also works on a block with the later-style notches or with no notches. It is the universal choice. |
| Early 1967 400 | those blocks may have the deep 389-style chamfer. They need the universal gasket, not the 400-455 gasket. |
| Aftermarket blocks, up to 4.380" bore | a separate gasket with some water holes moved to accommodate the larger bore. Butler states plainly that it will not work on stock blocks. It is recommended for naturally aspirated pump gas engines; high compression engines and engines with power adders should step up to Cometic. |
2. Best Gasket GraphTite, and the oil-through-stud question
The Best Gasket sets cover positions the Butler gaskets do not, particularly on early engines.
| 1960-63 326, 389 and 421 | a GraphTite set with steel fire rings that can be used with or without oil-through rocker stud applications — the key detail on an early Pontiac. |
| 4.200" bore, .040" thick | a GraphTite set for 350 through 455. Two limits from Butler's own data: it does not work in a pre-1964 389 or 421 oiling through the rocker studs, and 4.200" is not large enough for a .060" over 455. |
| 4.250" bore, .040" thick | the 455 version, also with steel fire rings. |
3. Install them the way Butler does
Composite head gaskets are sensitive to how they go on, and the two families want different treatment.
| Butler gaskets | spray the metal side lightly with copper coat and let it dry about five minutes, then spray lightly again and let it dry. The metal side goes toward the block and the composition side toward the head. Do not spray the composition side. |
| Crush | Butler's gaskets crush to approximately .045". Use that number when you work out your quench and compression, not the uncompressed thickness. |
| GraphTite | install with a spray-on sealant such as a copper spray, and always re-torque. Best Gasket's own instruction is explicit about it — no short cuts. |
If the build is naturally aspirated and on pump gas, these gaskets are what Butler puts in its own engines. Once cylinder pressure climbs, move to Cometic MLS.
Not sure what your Pontiac needs?
Call our tech team at 866-762-7527. Tell us your engine, heads, car, and power goal, and we will put the parts together as one combination that works.