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Grommets
Pontiac V8 Grommets
Measure the Hole First — Grommets for Pontiac V8s
A valve cover grommet is a two-dollar rubber part that decides whether a breather seals or leaks, and it is the single most returned item in this whole section because people buy it to match the breather instead of the hole. Measure the hole in the cover, then buy the grommet.
Butler stocks the common Pontiac sizes — 1" ID by 1.25" OD, 1" ID by 1.200" OD for fab aluminum covers, a baffled grommet for a 1.22" hole, and the 1967-79 vent pipe grommet at 3/4" ID by 1" OD — plus the Butler breather tube kit for plumbing the crankcase.
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1. The grommet follows the cover, not the breather
The OD of the grommet has to match the hole in your valve cover. The ID has to match the neck of whatever is going into it. Get those two numbers and the choice makes itself.
| 1" ID / 1.25" OD | the common aftermarket size. This is the grommet for a 1.25" hole taking a 1" neck, which covers the 6001-style billet push-in breathers and the chrome oil separators. |
| 1" ID / 1.200" OD | the slightly tighter OD used with fabricated aluminum valve covers, and the one the billet push-in oil fill cap calls for. |
| 1.22" hole, baffled | a Moroso grommet with a baffle built into it, for covers drilled at 1.22". It gives you some oil control at the hole without adding a separate plate inside the cover. |
| 3/4" ID / 1" OD | the 1967-79 Pontiac valve cover vent pipe grommet, and the one you need for a factory 1" hole. This is the small-neck route, not the 6001 route. |
2. Stock 1" hole versus aftermarket 1.25"
This is where most of the trouble starts. A stock Pontiac valve cover is drilled for a 1" hole and an aftermarket aluminum cover is almost always 1.25", and the parts are not interchangeable between them.
| Stock cover, 1" hole | takes the 3/4" ID by 1" OD vent pipe grommet and a small-OD-neck push-in breather. A 6001-style billet breather will not fit it, no matter how hard you push. |
| Aftermarket cover, 1.25" hole | takes the 1" ID by 1.25" OD grommet and a 1" neck breather. Some filtered and hooded breathers seat straight into a 1.25" hole and need no grommet at all. |
| Count your holes | grommets here are sold as singles, so order one for every hole you are filling, including the oil fill if it is a push-in cap. |
3. Plumbing the crankcase
If the crankcase is being routed somewhere instead of vented to atmosphere, the grommet is only the first piece.
| Butler Pontiac Breather Tube Kit | the full kit to plumb an air filter housing to an oil separator on aftermarket valve covers. It needs a 1.25" hole for its grommet, so check the covers before you order. |
| Smog tube fitting | the air cleaner side of that plumbing, for connecting the tube into the housing. |
Pull a breather out, put a tape on the hole, and write the number down before you order. It takes thirty seconds and it saves a return.
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.