That pesky O-ring...
 

One thing about Pontiac engines that to me is a problem area is the O ring that seals the intake to the timing cover. It seems to me that it should have been made a little thicker to seal better. Anyone know of one that seems to work better? Thanks in advance!

I had the same issue recently and wound up at a gasket making company in Fort Worth. They made me a few out of .250 thick viton for $30. Not cheap, but sealed perfectly and that made it worthwhile. The company supplies custom aircraft gaskets to nearby General Dynamics and the American Airlines maintenance center so they had a wide variety of sealing materials. They were able to make these out of leftover scrap, so cost was really for the thirty minutes it took. You might look for the same type of firm where you're at.

Butler sells a thicker seal, about .030" thicker. Also made of a better material than the leaky Fel-pro ones. They work just great. I have had 100% success with them.

I've used the Butler ones as well and they seal nicely - keep extras on hand. Here is the link:

https://butlerperformance.com/i-2445....html?q=o+ring

I havent had a problem with the felpro ones, but Im pretty sure I used a Molyote product we used to use on fuel pump O-rings from my aircraft days.

I think its Molykote 55, but I wont quite swear to that. But it swells the orings rings slightly after install.

I have never had an issue , but here’s a few cures.

You can sand down the lip of the seating area in the crossover to get more compression.

You can put on a bead of gasket maker and let it set up overnight.

You can make a wire O ring from thick copper wire and lay it in there, just be sure to over lap the ends by a 1/8”.

You put a oil plug drain plug gasket in there to give more compression as I did on a drag strip race day once in a pinch.

Never had a issue. A little silicone on both sides and dry overnight. Done it plenty of times without letting it dry too.

I always use the one Ames sells. It is slightly thicker than original and it works great. Part number N539AL

Thank you for that info!

A lot of these old 50-60 year old original timing covers are badly corroded and heavily pitted at the sealing surface.

Yes, that pitting is reason enough for some sealer to be applied.

Go to you local hardware store plumbing depargment and check out their selection of seals and Orings. I didn’t trust that crappy “foam” one that Felpro supplies now either and found a viton “donut” that fit in the recess and didn’t restrict the opening.

I always separate the water Log: allows for best ability to preload that donut seal. No issues on variety of builds since late 80's.

Thermostat HSG is more of the worry since a bolt flange can micro-fracture and seep through the aluminum crack. Makes a want for an iron T-stat Hsg.

Never had a problem with the OEM felpro type O-ring, important to tighten the cover to intake bolt first before torquing the intake bolts. On the last few Pontiacs I built I use a thin coat of ultra black on both sides of the O ring and a little if there is any pitting on the timing cover area, been bone dry for 10-15 years on them.

O-rings are sold under a million different part numbers. However, the sizing is standardized. If you find an O-ring sizing chart, you can pick any diameter you want within reason, along with a variety of wall-thicknesses. Then you can choose the material--Viton, neoprene, silicone, etc., and then the hardness/firmness of the rubber.

For most automotive applications, it's hard to go wrong with Viton, as long as it doesn't catch fire.