Ever install rope type rear seals?

The Cadillac 346 engine I just bought runs but leaks.  Right now the transmission is off and it's on a stand; this scares the hell outta me because a SBC is ~550 lbs, this thing weighs 887 lbs.  

The 3/8-16 bolts appear strained so I propped it up from below, but I still have to flip it over and it may not be centered.  So, ever done one of these gaskets?  Tips, tricks not seen on Youtube, any suggestions etc appreciated.

I called three shops, one is a big hot roddy guy, big NFW all around.  I think I can do it, problem is I won't know if I can until it's realigned to the trans, painted and in the car.

I do not miss big rope rear mains.  I recommend checking if Fel Pro made a more modern retrofit.  

Yup.  Not a big deal.  I'll do a write up when I'm back in front of a real computer on Monday.  Feel free to IM me a reminder if I forget.

Edit:  here's a good writeup that one of ours already wrote.  GRM thread. Scroll to the bottom.

Very good, thank you!

"Rear main seal" is three four letter words together. I had someone recommend a Lisle Auto Parts tool called a "Sneaky Pete" to get the old one out and that works great. No idea on installation since I used a two piece rubber seal to replace it.

Well, if you see a one piece for a Caddy 346 flat head, shoot me a PM, email, smoke signal, whatever it takes.

=~ )

I found these in the oil pan.  Rubber bumper things for a small door?  No matter, what are they doing in there?

I'm guessing you've seen this but figured I'd share just in case you haven't:

Mercedes rear main (still rope, but 1 piece)

How I feel this project is going.

In reply to 914Driver :

Look on the plus side, you're spinning in circles but your head's above water. 

Similar to packing a valve stem.

In reply to 914Driver :

Picture of the rear main area with the transmission off?  I'm with Preach, I've packed my share of old school pumps and valves, it's not rocket science.  Buy a couple of the rope kits in case you make a mistake.  I'd think you should do it with the transmission off and just before you're planning on re-installing the transmission.  The engine bearings are handling the crankshaft alignment for you, might as well have as much access as you can.

So I was the one who asked the question last time. I never did change out that rear seal, because I discovered shortly after that at least one of the pistons didn't have any compression. I think it wasn't a seal problem, it was a crankcase pressure problem.

I just fixed a leaky front seal on my Cummins at 90k miles by changing the crankcase ventilation filter, too.

The trans is off the car, engine is upside down on a stand.

OK.  I'm at  a computer with a real keyboard.

I'm old enough to have been a tech at a dealership when GM was still building engines with rope seals (early '80s) so I've messed with a bunch of them.

I think you've got four options.

1. Replace the bottom and drive in the top
   1. This is quick and pretty easy
2. Replace both with the crank in place
   1. I like this option the least.  It's very difficult to get the top seal in and in my experience has a lower success rate than option 1
3. Pull the crank and replace both along with the front seal and any front end gaskets that you have to in order to pull the crank
   1.  This is obviously more work but it give you the opportunity to replace some other seals and gaskets, inspect the bearings and take some accurate measurements to see if there's a lip seal that will work
4. Pull the motor apart and freshen it and modify the block and rear main cap to accommodate a lip seal
   1. Option 3 might lead you here

If it were me I'd go with either 1 or 4 depending on how much confidence I have in the engine and what I want to do with the car.

A quick note on your engine stand dilemma.  I stopped using engine stands decades ago.  Instead I run some long bolts in the bellhousing mounting holes and stand the engine on those.

Good tip on the stand!  I've never had an issue until this one that wighs almost 900 lbs all up.