Hot Rod Forum banner

rear main seal rope style

15K views 20 replies 6 participants last post by  81camaro1 
#1 ·
hi guys , need some help here, im rebuildin a pontiac 400 , i never installed a rope seal before, i want to know whats the proper way to install it, and steps to install.... the engines that i have rebuild i always used rubber seals,,,, i dont really like rope seals, but my buddy (his engine) wants to use rope seal , soo i need some help here thanks
 
#4 · (Edited)
thanks denny for the detail instructions and the pictures,
at the end of the rope seals, after you have trimed them and seated them in place, and ready to install crank for last time, do you also apply some rtv on the ends of the rope seal?? the ends that chamfered thanks alot for this information ...
sal.... also once the seal is installed is there a slight drag on the crankshaft, reason i ask , is because i tried installing this rope seal and it had a pretty medium drag on the crankshaft,, hence i stopped and asked on this forum lol.. before i brake anything
thanks again denny
 
#6 · (Edited)
The objective is not to have the seal parting lines line-up with the cap and block parting lines. That is does by offsetting the seal in the block about 3/8" - 1/2" and offset the seal in the cap the same amount.

The EPA made car makers replace their asbestos rope seals with nylon rope seals. You cannot clean-cut the nylon rope seals with a razor blade. That is when I started using aftermarket 462 Ford neoprene seals or 472 Cadillac neoprene seals. That was in the time period before aftermarket neoprene seals for Pontiac engines were indroduced.

To install the Ford or Caddy neoprene seals, I would squeeze a large bead of RTV sealant in the seal cavity, let it set for 30 minutes and then install the seals in the cap and block with the parting line offset with the parting lines of the cap and block and then install the crankshaft. The RTV fits the Ford and Caddy neoprene seals in the Pontiac main and block seal cavities and the fits the seal lip to the crankshaft.
 
#7 ·
The objective is not to have the seal parting lines line-up with the cap and block parting lines. That is does by offsetting the seal in the block about 3/8" - 1/2" and offset the seal in the cap the same amount.

The EPA made car makers replace their asbestos rope seals with nylon rope seals. You cannot clean-cut the nylon rope seals with a razor blade. That is when I started using aftermarket 462 Ford neoprene seals or 472 Cadillac neoprene seals. That was in the time period before aftermarket neoprene seals for Pontiac engines were indroduced.

To install the Ford or Caddy neoprene seals, I would squeeze a large bead of RTV sealant in the seal cavity, let it set for 30 minutes and then install the seals in the cap and block with the parting line offset with the parting lines of the cap and block and then install the crankshaft. The RTV fits the Ford and Caddy neoprene seals in the Pontiac main and block seal cavities and the fits the seal lip to the crankshaft.
so what you are saying is i can use a ford or caddi seal on this pontiac engine ? and follow the above installation procedure?
thanks
 
#9 ·
RED FLAG!!!! The seals in the Flepro sets are NOT the GraphTite seal. Best Gasket makes them. Many sources for the Pontiac. We get them from BOP. The Felpro is fiberglass and basically worthless.

The BOP Viton seal is made specifically for the Pontiac. The Caddy seal "works" in the large journal blocks (421, 428, 455) with minor "fitment". It does not fit the 400 (3" main). Installing the "rubber" seal is iffy at best, in stock blocks. The seal "groove" is not machined close-tolerance, as the builders knew they were using a rope. About 1/2 of the reports we get say they leak. In aftermarket blocks, they're excellent. Unless a customer insists, we use the GraphTite seal in stock blocks.

The GraphTite seals comes WITH instructions. Follow them and it is the best seal out there (IMO).

Much misinformation and "myth and superstition" surrounding this subject. Between BOP and Best, one can today, seal up a Pontiac as secure as a modern V8. Check out BOP's 1-piece pan gasket, too.

Jim
 
#11 ·
RED FLAG!!!! The seals in the Flepro sets are NOT the GraphTite seal. Best Gasket makes them. Many sources for the Pontiac. We get them from BOP. The Felpro is fiberglass and basically worthless.

The BOP Viton seal is made specifically for the Pontiac. The Caddy seal "works" in the large journal blocks (421, 428, 455) with minor "fitment". It does not fit the 400 (3" main). Installing the "rubber" seal is iffy at best, in stock blocks. The seal "groove" is not machined close-tolerance, as the builders knew they were using a rope. About 1/2 of the reports we get say they leak. In aftermarket blocks, they're excellent. Unless a customer insists, we use the GraphTite seal in stock blocks.

The GraphTite seals comes WITH instructions. Follow them and it is the best seal out there (IMO).

Much misinformation and "myth and superstition" surrounding this subject. Between BOP and Best, one can today, seal up a Pontiac as secure as a modern V8. Check out BOP's 1-piece pan gasket, too.

Jim
thanks, so on a stock block 400 the rubber seal (50%) chance that it might leak? so rope seal is the way to go on stock blocks ? thanks
sal
 
#12 ·
Yup. Lots more stuff specific to Pontiacs that make them what they can really "be", instead of a sluggish leaker that blows up... :)- Among the very best of the muscle car era engines when properly prepared. It's like a small block on steroids...

If you haven't "found" them yet, go to BOP Engineering and look at their offerings. MOST Pontiac engine parts are still readily available through "normal" parts sources. Not rare OR expensive. BOP has the "upgraded" stuff needed to make it modern.

You ARE putting forged connecting rods in it, right? Even if it's a 2-bbl. in a Tempest, put forged rods in it...

Jim
 
#14 ·
For a rope seal the square cut graph tite works good if you follow theyre directions. Main thing to watch for is to not cut a rope too close to the block and cap, it needs to stick above a bit so it compresses slightly when the cap is tightened down. We had alum. disks about a inch wide and same diam. as the seal journals to use to seat the ropes in the cap and blocks using a dead blow. You can roll the ropes in to place using a close fitting piece of round stock, too. Don't offset a rope seal.

The big journal cranks can cause probs with the crosshatching for the rope if using a rubber seal but on the small journal cranks the rubber seal lip rides away from the roughness. Still it pays to check the crank seal surface and castings of the cap and block when a rubber seal is going to be used cause not all of them will take a rubber seal that good. Since the graph tite seal works good this isnt a big deal.

In the old days using a Caddy seal for large journal builds was the hot set up. The seal was actually a little too big so the seal halfs had to each be ground down on one end. Not enuogh and itd leak and too much off and itd leak. Ends not square and id leak. Real pain in the ***. Plus the Cad seal was too skinny so had to be helped with sealer. Now there are good rubber seals made to fit a Pont but their expensive. Worth it specially on a small journal build tho in my opinion.
 
#17 ·
For a rope seal the square cut graph tite works good if you follow theyre directions. Main thing to watch for is to not cut a rope too close to the block and cap, it needs to stick above a bit so it compresses slightly when the cap is tightened down. We had alum. disks about a inch wide and same diam. as the seal journals to use to seat the ropes in the cap and blocks using a dead blow. You can roll the ropes in to place using a close fitting piece of round stock, too. Don't offset a rope seal.

The big journal cranks can cause probs with the crosshatching for the rope if using a rubber seal but on the small journal cranks the rubber seal lip rides away from the roughness. Still it pays to check the crank seal surface and castings of the cap and block when a rubber seal is going to be used cause not all of them will take a rubber seal that good. Since the graph tite seal works good this isnt a big deal.

In the old days using a Caddy seal for large journal builds was the hot set up. The seal was actually a little too big so the seal halfs had to each be ground down on one end. Not enuogh and itd leak and too much off and itd leak. Ends not square and id leak. Real pain in the ***. Plus the Cad seal was too skinny so had to be helped with sealer. Now there are good rubber seals made to fit a Pont but their expensive. Worth it specially on a small journal build tho in my opinion.
thanks this is pretty good info,,, :thumbup:....
i ordered the rope seal,. so we will see how this thing would work were shooting for no leaks lol thanks
 
#15 ·
Here's a video of how I was shown to install a rope seal, it's for a Holden V8 but it's the same for any engine. I never had the special tool and always used the crank for seating etc. A section of pipe is essential to hammer the seal tight though, you can MyGyver that any number of ways.

I can attest this method works very well and it takes time to do properly, a razor blade usually fits inside the seal journal area when you don't have the fancy tool and use the crank to compress the seal.



Good luck and take your time, it's a bugger to fix after the engine is installed!
 
  • Like
Reactions: 81camaro1
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top