I'm starting on my 303 Olds engine assembly and I need to decide which type of rear main seal to use. I have both the rope and rubber seals from Best Gaskets. Some people have mentioned that the rubber seal leaks, I really want to avoid having to deal with a leaky rear main seal. Which seal are you guys using, and how good do they work. Any tricks or tips on a leak free install would be appreciated.
The only seals that don’t leak are a single piece. If you install a rope properly and have a PCV system you should not have a leak. It must be packed TIGHT. I get them so tight you need to use a breaker bar to turn over the engine with no rod/pistons. I also “peak” either the cap or block side. I never very little to cut off. If you can’t get an original asbestos the Best is the best.
What do you mean by "peak" the cap or block. The rope seal kit comes with a spacer that sets on the cap and block and guides the knife to cut the seal slightly above the mating surfaces I guess allowing for a little bit of a crush factor. Is this what you mean by "peaking". If I use the rope seal, I plan on making a mandrel slug to match the crank journal diameter at the seal and use it to seat the rope section into the groove in the block and cap.
Since they removed the asbestos from the rope seals they leak. Try to find a NOS gasket set with an asbestos rope seal and use that.
I’ve used both from best gasket (the best) with good results. If the engine is out I would use the rope, if you’re crawling around underneath the car I would use rubber. If you want to use the rope seal which engine in the car ,dropping the crank a little makes the job easier.
Haven't done a Olds since the early 60s did they have Knurling on the seal aera if so don't go rubber
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