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Grommets and Rubber Caps
Pontiac V8 Grommets and Rubber Caps
Small Rubber, Big Difference — Grommets and Rubber Caps for Pontiac V8s
Grommets and rubber caps are the small rubber parts that finish a Pontiac V8: the grommet that holds a PCV valve in the valley pan, the one that seats a breather or vent pipe in a valve cover, and the caps that block off a heater nipple you are not using.
Butler stocks valve cover grommets and PCV grommets in the sizes that actually fit Pontiac valley pans, factory vent pipes and fabricated aluminum covers, a baffled valve cover grommet, a Super Duty PCV block-off grommet, and heater nipple block-off caps in 5/8" and 3/4".
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1. Valve cover grommets — measure the hole and the pipe
A grommet has two dimensions that both have to be right: the outside diameter has to match the hole in the cover, and the inside diameter has to match whatever goes through it.
| 1" ID x 1.200" OD | the size used with fabricated aluminum valve covers. |
| 1" ID x 1.25" OD | the same inside diameter in a larger hole, for covers punched to 1.25". |
| Baffled | Butler stocks a Moroso baffled valve cover grommet for a 1.22" hole — the baffle keeps oil out of the breather or the PCV line, which matters on a high-rpm Pontiac. |
| Factory vent pipe | the 1967-79 Pontiac valve cover vent pipe grommet is 3/4" ID by 1" OD and requires a 1" hole in the cover. |
2. PCV grommets for the valley pan
On a Pontiac the PCV usually lives in the valley pan, not the valve cover, and the grommet is matched to the PCV valve.
| Push-in PCV grommet, .75" ID x 1.2" OD | for Pontiac valley pans running the 774 PCV valve, and also the right part for installing a factory 3/4" vent pipe in a valve cover with a 1.2" hole. |
| Tomahawk valley pan grommet | Butler stocks the PCV valve grommet for the Pontiac valley pan and the Tomahawk TPP-TP-041S pan used with the 1226 PCV valve. |
| 1973-74 Super Duty 455 | a PCV block-off grommet for the valley pan. On those engines the original PCV is in the oil fill cap, so the pan location gets blocked rather than plumbed. |
| Buy the kit if you are doing the pan | Butler's valley pan installation kits include the pan gasket, the grommet, the PCV valve and a bolt kit with sealing washers, which saves matching the parts individually. |
3. Heater nipple block-off caps
If the car is not running a heater, or the engine is on a stand or in a race car, the heater ports still have to be closed.
| 5/8" and 3/4" | Butler stocks the block-off caps in both common heater hose sizes, sold individually. |
| Do not rely on a cap alone at pressure | a cap plus a clamp is the right way to do it. Under a pressurized cooling system a push-on cap will find its way off. |
| The other end | if you are deleting the heater entirely, the rear of the passenger side head still needs a fitting or a plug — Butler carries both the press-in heater hose fitting and the brass head plugs. |
4. Getting them in without tearing them
These are the cheapest parts on the engine and the easiest to ruin at installation.
| Deburr the hole | a punched valve cover hole has a sharp edge that will cut a grommet the first time the engine shakes. Knock it down before the grommet goes in. |
| Lubricate with water, not oil | a little water or soapy water lets the grommet roll into the groove. Petroleum products swell rubber over time. |
| Grommet first, pipe second | seat the grommet in the cover, then push the breather or PCV through it. Trying to install the assembly as a unit is how the lip gets rolled under. |
Order these at the same time as your valve cover gaskets and valley pan gasket. A perfect gasket job still leaks oil through a torn grommet, and nobody wants to pull a cover back off for a two-dollar part.
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.