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Exhaust Header Gaskets
Pontiac V8 Exhaust Header Gaskets
Hold the Heat — Exhaust Header Gaskets for Pontiac V8s
Exhaust header gaskets take the worst of it on a Pontiac V8 — full exhaust heat, constant thermal cycling and a flange that may not be perfectly flat. The first question is always the same one: D-port or round port, and how big is the port.
Butler stocks steel reinforced composite gaskets, graphite, multi-layer steel, reusable dead soft aluminum and solid copper header gaskets for Pontiac D-port and round port heads, plus Ram Air IV and Super Duty sizes for Edelbrock round port heads, collector gaskets and aluminum exhaust port covers.
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1. D-port or round port, and how big
Almost every wrong exhaust gasket starts here. Look at the port shape in the head, then measure it.
| D-port | the shape on the vast majority of Pontiac 326-455 heads. Butler stocks D-port gaskets in several sizes, from the stock opening up to a large 2.120" x 1.540" port. |
| Round port | Ram Air IV, Super Duty and Edelbrock round port heads. Butler carries round port gaskets in 1.785", 1.880" and 1.920", and a 2.00" port copper gasket for HO and Ram Air IV applications. |
| Measure, do not guess | round port sizes are close enough together that a tape measure beats a part number off a forum. A gasket smaller than the port chokes flow; larger than the port and the edge burns away. |
2. Material: composite, graphite, MLS, aluminum or copper
Each material has a job. This is where the stock rebuild and the race engine part ways.
| Steel reinforced composite | the everyday answer. Butler's own D-port header gasket is steel reinforced in a large 2.120" x 1.540" port and is designed to clear the dipstick tube. Its listed fitment covers factory cast iron D-port manifolds, Ram Air Restorations cast iron D-port manifolds, Doug's D-port headers in raw, coated and stainless, Hedman D-port short and long tube, Hooker Competition D-port short and long tube, and Flowtech D-port headers. |
| Composite with relief bends | for stock-type exhaust manifolds, Butler stocks a steel reinforced composite D-port gasket with relief bends formed in to clear the dipstick tube and battery cable. |
| Graphite | a high-density, high-temperature graphite D-port gasket in a 1.900" x 1.900" port at .120" thick — thick and compliant, good on a flange that is not perfectly true. |
| Multi-layer steel | Cometic MLS exhaust gaskets for 1964-79 D-port heads, for builders who want a thin, hard-sealing gasket. |
| Reusable aluminum | the Seal-4-Good multi-layer dead soft aluminum gaskets conform to the flange again and again and can be precisely port matched for uninterrupted flow, in D-port 1.5" x 2.0" and round 1.88". |
| Solid copper | dead soft copper, reusable, and Butler's go-to when heat is extreme. The Mr. Gasket CopperSEAL D-port gasket for 1963-1979 326-455 uses .043" dead soft copper with a .051" embossment around each port for a total thickness of .094", and is recommended for high performance street, drag race, oval track and turbocharged applications. SCE Pro Copper is stocked in D-port, round port and 2.00" HO/RA IV. |
3. Beyond the flange: collectors and port covers
Two things that get forgotten until the car is on the lift.
| Collector gaskets | Butler stocks three-bolt collector gaskets in 3" and 3.5", sold in pairs. Order them with the headers, not after the first leak. |
| Exhaust port covers | aluminum port covers are stocked for Ram Air V race applications — the right part for a long-term storage engine or a mock-up that is not going to have headers on it. |
4. Making a header gasket live
Header gaskets fail from movement and from heat, in that order.
| Flatten the flange | a header flange warps around the bolt holes after a few heat cycles. Surface it or at least check it with a straightedge — no gasket seals a flange that rocks. |
| Re-torque warm | bolt the headers up, run the engine to temperature, let it cool and re-torque. Do it again after the first few heat cycles. |
| Use locking hardware | header bolts back out. Bolt locks, lock washers or safety wire earn their keep here. |
| Dipstick clearance | on a Pontiac the dipstick tube runs right at the number-seven area. Gaskets designed with relief bends or a large port outline exist specifically because of it — use one rather than grinding on a stock gasket. |
For a stock rebuild with cast iron manifolds, a steel reinforced composite gasket with the relief bends is the straightforward choice. For a headed, high-compression or power-adder Pontiac that sees real exhaust temperature, step up to copper or reusable aluminum and plan on re-torquing.
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.