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Carb Gaskets
Pontiac V8 Carb Gaskets
Get the Flange Right — Carb Gaskets for Pontiac V8s
A carburetor base gasket is a two-dollar part that decides whether your Pontiac idles clean or hunts for a vacuum leak you will chase for a month. The right one matches the carb's flange pattern, the manifold's opening, and the thickness you actually want under the baseplate.
Butler stocks carb gaskets for square bore and Q-Jet flanges, open-center and four-hole patterns for standard Holley and 4500 Dominator carbs, thick 1/4" gaskets, an early AFB base gasket, and the correct Tri-Power center and outer mount gaskets for 1959-66 three-deuce setups.
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1. Match the flange, not the brand
Every carb gasket question comes down to three things: the bolt pattern, whether the center is open or divided into four holes, and how thick you want it. Get those right and the brand on the package barely matters.
| Standard Holley (4150/4160) | the common square bore four barrel flange. Butler stocks open-center gaskets in 1/16" thickness from Mr. Gasket and SCE, and Holley's own open flange base gasket with a 1 13/16" bore. |
| 4500 Dominator | a completely different and larger flange. Butler carries both the open-center and the four-hole Dominator gasket in 1/16" thickness — do not try to make a standard Holley gasket work here. |
| Q-Jet | the spread bore flange on most factory Pontiac four barrels. Butler stocks a 1/16" cellulose/nitrile Q-Jet gasket and a 1/4" thick version. |
| Early AFB | a fiber four barrel base gasket for the early Carter AFB carbs found on older Pontiacs. |
2. Open center or four hole, and how thick
This is the choice most people guess at. It is worth a minute of thought.
| Open center | one large opening under all four throttle bores. Use it when the manifold plenum is open underneath and you want nothing in the way of flow. |
| Four hole | keeps the four bores separated down to the manifold. Use it when the manifold has a divided or four-hole opening — an open gasket over a divided manifold defeats the division. |
| 1/16" standard | the normal sealing thickness. Enough to conform to a slightly imperfect flange, thin enough not to change hood clearance. |
| 1/4" thick | Butler stocks 1/4" gaskets in square bore four-hole (1 5/8" bore, rated up to 600 CFM carburetors) and Q-Jet. The extra thickness buys a little insulation from manifold heat and a little height — check your air cleaner and hood clearance before you commit. |
3. Tri-Power: count the gaskets before you order
Three-deuce Pontiacs use two different two-barrel mount gaskets, and the quantity changes by year. This is the single most common Tri-Power gasket mistake.
| 1959-65 | one center gasket plus two outer gaskets. The center and the outers are not the same part. |
| 1966 | three outer gaskets, no center gasket. |
| Butler part | both the center and the outer Tri-Power two-barrel carb mount gaskets are stocked individually, so you can buy the exact count your year calls for. |
4. Installing them so they stay sealed
Carb gaskets are one of the few places where less is more.
| Do not glue it down | a base gasket is meant to come apart. Silicone squeezed into the throttle bores is a real risk with a carburetor. |
| Check the baseplate | an over-torqued carb warps the baseplate, and no gasket fixes a warped flange. Snug and even, then re-check after a heat cycle. |
| Trim if you have to | composite gaskets can be trimmed to clear a secondary linkage or a manifold that is not quite stock, and Butler stocks cellulose/nitrile material that takes a knife cleanly. |
Buy a couple of spares while you are at it. Carb gaskets get torn on removal more often than they get worn out in service, and having the right one on the shelf beats a Saturday afternoon with the manifold open.
Not sure what your Pontiac needs?
Email our tech team at tech@butlerperformance.com. Tell us your engine, heads, car, and power goal, and we will put the parts together as one combination that works.