What you use for a boosted app. I have always used the rubber felpro in back and a stock timing cover seal but always had blow by at 30PSI of boost. Need a better seal.

Sounds like you need better crankcase ventilation, bigger and or more breathers
There should no pressure in the crankcase or the rest of the motor
How about a vacuum pump
IHTHs

Not a lot of choices for a BB Mopar. You can upgrade to a Jesel belt drive in front since that would give you access to better seals. In the rear you can try the one piece setup from Fast Fish.

I used an aluminum cover, and fabricated a thin ring out of aluminum as a retainer to hold the seal in. Two small allen head screws sealed with rtv, plenty of room to fit behind balancer, did it on several Chevy engines as well.

Pics?

Don't have any pics, but just used two hole saws and clamped a piece of 1/8 aluminum to the drill press. first for the inner diameter and then a bigger one for the outer, its got to be clamped tight, then die grinder to smooth up. Got some stainless allen head bolts smallest ones they had and drilled and tapped the cover sealed the bolt treads with rtv.

Not trying to steal the thread but my question is relevant to the OP..
I run a 8:71 on my BBM. I also run a vacuum pump. I use the Fast Fish rear seal, no leak there. But I'm trying to stop any vacuum leaks at the front seal. I have packed the backside with RTV but I'm not happy with it. I know the chebby crowd has a double lip seal they use on their builds.
Anyone have a part number for a double lip seal or a better way to go for a BBM?

Thanks
Dave

The NASCAR guys developed a super high vacuum front cover seal. I bought a couple of them years ago when I was developing the billet timing cover for SB Mopars. The seals are expensive and not widely available. I bought mine from some shop in NC, don't recall the name.

Tritec seals, before they were bought by a bigger company i bought three upper and lower double lip jesel seals as well as well as 3 double lip rear main high vacuum seals. i recently looked up and found the company that acquired them,im sure they still make the same seals...

Have you filled the rear main seal holder edges to the block with adhesive silicone gasket maker yet on the rear main? if not try that, I've seen a lot of rear main seal leaks there, which made the owners, racers, mechanics, think it was the crank seals instead of the side seals leaking: work:: scope: wrench:

I use a mopar chrome front cover but might upgrade. Seems like it's time lol.

Thanks gents.
Is a hemi seal the same size as a big block. ?

Yes

Tritec's website is down, but I think these guys sell their seal for a BBM.

https://www.fastfishautoparts.com/store/p_1203721/big-block-mopar-performance-rear-main-seal-

So I dug this out but I need the crank gear. And prolly some shims or a setup kit. Never messed with this stuff before.

Can I order just the crank gear and setup kit.

no those seals are not tri tec seals https://www.fh-group.com/work/tritec-motorsports/

tritec seals https://www.raceenginesuppliers.com/Suppliers/tri-tec-seals

I need some parts too. I'll make some calls in the morning and see if parts are still available for these.

For the OP: I think that gear drive is for a raised cam block. Do you have a raised cam block?

No I don't. Neither of my aluminum blocks are raised cam