Hi guys, we are getting our bracket car back out after sitting for a few years since my dads passing. We installed a vacuum pump(moroso 22640) on the engine and have discovered that the pump works and is pulling vacuum but it appears the engine is not sealed up as well as it should be for pulling vacuum. My question is where are the typical problem areas that you guys have run into where BBM's struggle to seal most. We want address these issues so we can get the engine sealed up. We plan to pressurize the crankcase and check for leaks but haven't quite gotten that done yet. Any help is appreciated. Thanks

Obviously the biggest gasket areas will need the most attention. The oil pan should have a thick and true rail and have all the windage tray stuff built into it instead of a sandwich type. The valley pan area is probably the hardest thing because with aluminum heads you are entirely dependent on the beads of silicone down the sides. Using a Jesel belt or a Milodon gear will help the front area big time. The distributor hole is also a challenge. Pull as much as you can and hopefully you can get north of 10 inches. High quality silicone like "The Right Stuff" will seal well but I've read here that it is a challenge to remove. You should be able to see anything that needs attention with 10 psi max. of pressure. Don't over do the air pressure in the crankcase. Post up your results! FWIW, I have seen 8-10 inches at the finish line (72-7,600 rpm) with my little 493 with the above mentioned stuff on it.

Here you go. Billet valve covers seal up that area. Billet valley cover seals that up. Jesel belt drive seals up the front. Billet rail on the oil pan seals that up. Belt drive distributor allows the distributor hole to be tightly sealed. You get the idea.

Oil dipstick is an obvious leak. Have to plug it. Any caps or breathers in the valve covers as well. Leak test the engine to determine the condition of the ring package.

I use a late model dipstick with the o-ring. Biggest leak area I found was at the head gasket/valley tray corners. Mine needed a little RTV at the very top corners of the head gasket. Air it up with some soapy water.
Doug

The biggest area of leakage I found on my engine has always been rings. Having an alloy block doesn't help as it passes more oil when it's cold compared to when hot. But once warm I have 5" of vac when idling so that's reassuring the system has sealed up well.

When my Dad's engine was on the Dyno the shop used a smoke machine to fill the crankcase and spot the leaks it really highlighted the areas that needed attention.

I use a vacuum pump and a air flow meter to measure leakage. The biggest that I have found are the crankshaft seals. In fact if you pressurize the engine with a smoke machine the rear seal doesn't seem to leak, pull 10 inches of vacuum and it's a different story.


Joe

Biggest leak we found was at the valley pan corners. We will re-seal that, let the silicone cure and check for leaks again to make sure we have no issues.

Seems to me that the crank seals can be expected to be big leakers simply by design. They're made to seal under pressure one way only.The solution in those areas would be something like an o-ring but you'd have to figure a way to keep them lubed. If you're running a vacuum pump, maybe install those seals backwards ?!?!?

I ended up buying a cheap, rather crude, but effective smoke machine from Amazon that helped me a lot.

Biggest problems on my small block were the pan seals and the corners of the valley cover (R3/W9).

Are you running with mufflers?

They're made to seal under pressure one way only
40 years ago, Bill Jenkins put the rear main seal in his pro stock SBC engines backward for that reason.

I know a little about running a pump but , not going to bother posting cause I hate to argue