I was going through my spare parts, and found two Mopar Performance rear main seal kits for a 440 big block.
P4271961, They have the regular black rubber lip seals, and red rubber side seals. Just like this kit on Mancini
Mancini rear main seal kit (LINK)


Do these hollow red rubber side seals work well?

They work fine. I glued them to the retainer with 3m adhesive, smeared a film of silicone sealer on the seals. Retainer slid right in.

don't you have to push a pin in the side seals once assembled to spread them?

YES... install the pin ... its needed to expand the rubber side seals/

I only use the Fel-Pro Vito rear main seals, part number 2947 and cost $25-$30.

Taken from 440Source "They have a much greater resistance to high temperatures than standard rubber. It also doesn't have a tendency to dry out and shrink over time."

I also do not use the side seals, I use black RTV, either Permatex Ultra Black or Right Stuff. I clean the surfaces, fill in the sides and then installed the seal and then fill in the back cavity with RTV.

I dont use any side seals. Ultra grey by itself. Zero leakage.
Doug

I fill in the sides with RTV and then slide in a piece of copper rod to expand the RTV. Trim flush.

Permatex aviation gasket sealant on the back sides of the seals and between the retainer and block.

I have done it both ways with big block mopars, but my last few I've been using Permatex Ultra Black on the sides with success. It does depend on the RMS retainer you're using. Some aftermarket units use two thin rubber seals. Those channels would be too hard to fill with RTV from the top. My most recent build was a Ford FE Big Block which has the same type of side seal / pin system (as the topic starter pictured) and I again filled the void with the Ultra Black. It works very well.

The trick is using the supplied screw on applicator that comes with the Permatex. You get the nose of the applicator in side the void and squeeze hard filling the void completely. I use one of the intended rubber side seals to push the Ultra Black down and pack it in the void. Then I top it off until it's oozing out the top and wipe flush.

Ultra Black takes a while to dry when thick, so I recommend letting it set up for a few days before adding oil / starting the engine.

Anyone have a picture of the pin mentioned here?

X2, never seen the mentioned pin. Sounds like a good idea though....

I have never had issues with the Indy Billet retainer leaking . Yes always used RTV sealer . Gary

A water-dampened pipe cleaner to expand the RTV works better. RTV sets up by exposure to moisture.

A water-dampened pipe cleaner to expand the RTV works better. RTV sets up by exposure to moisture.

This is exactly correct!!! RTV must have humidity to cure.

I did not know that, I thought it needed exposed to air
I've never sprayed water on the back, crank flange side, of the main seals after sealing them with adhesive silicone on any of the motors I've built

adhesive silicone is different than RTV, correct ?
so no moisture needed to cure, correct ?

Unless you live in an environmental chamber where the humidity is 0%, there is alway some moisture in the air
So you're right (it needs exposure to air) but for the wrong reason (it's not the air, it's the water in the air)

Water and pipe cleaners work good!

Great info on the pipe cleaner. I'll do this on the next build. FWIW, RTV=Room Temperature Vulcanizing.

how does adhesive silicone cure ? internally out/absent of air and humidity, or externally in/exposure to air and humidity ?

Humidity and temperature, normally 24 hr cure time.