Haven't run a 455 but have ran several 350 Pontiacs back in the day. I switched from the rope seal to the 2 piece seal and never had an issue with leaks. The only time I had an issue with a rear seal leaking like you describe when it gets warm was with a SBC. Was helping a buddy and he was supplying all the parts. After replacing the seal for the second time (after checking everything numerous times) and still having it leak I went to the store and picked up a Fel-Pro seal to use instead of the brand he had been buying. Replaced it the third time and no more leaks.

 

.....I heard that FEL-PRO didnt make a rear main seal..for the 455 PONTICRAPS..?? humm..??

 

I used that 2pc seal to fix a leaking rope seal and so far so good. I also ditched that pos 4 pc pan gasket and just used ultra gray rtv.

 

Hell, I always used the rope seal on 455's. Never had any problems with them leaking. It wasn't an all out race application but on the spray it probably made 700.

 

Same here. You need to install them correct and they work fine.

 

The Best gasket company graphtite rope rear seal works the best on oem cranks. DCI and Pontiac Dude both sell them and I think DCI is on Ebay

 

I have used a couple of the rubber seals in Pontiacs. I was told that the rope seals had asbestos, and it's not in the newer ones. I was told they are more prone to leakage without it (rope that is). Did you install the seal with the crank in or out? I installed them when assembling the engines. I had to put the seal in place and check the amount they stuck out of the housing bore (as the instructions said). I had to trim the ends to get them within specs. I ran them on my break in stand with no leaks.

 

I had the engine fully assembled (hadent run yet either) when we decided to change the seal out. I popped the caps off, lifted the crank a hair, rolled the new seal in and trimmed as the instructions said. It wasnt difficult at all, .020 thou on one side. Used a dab of silicone in the anti-rotation grooves and re-installed the caps.

 

try a big block ford 460 2 pc. seal.

 

try a big block ford 460 2 pc. seal.

Yep

Vacuum pump helps too. But not needed.

 

I use this seal in my Pontiac engines with excellent results. http://www.bopengineering.com/beltdrive_acc_topend2.shtml

If installed properly will not leak. I also heard the Best seal was good too. There are 2 different sizes. I also used the new BOP 1 piece pan gasket on my new engine. Fit great but haven't run it yet.

 

I use this seal in my Pontiac engines with excellent results. http://www.bopengineering.com/beltdrive_acc_topend2.shtml

If installed properly will not leak. I also heard the Best seal was good too. There are 2 different sizes. I also used the new BOP 1 piece pan gasket on my new engine. Fit great but haven't run it yet.

I've used these very successfully. I order from Butler. Offset the seal about 1/4" Zero leaks, no vacuum pump, and 150 shot.

 

Put the composite rear main seal in backwards. Don't ask but it works.

 

I'll let ya know. im popping the pan and cap off this week for a look-see and take it from there.




John have you had this issue? and what made you put it in backwards? any logic behind that?

 

.....Why MUST PONTIACS be so DIFFICULT..!!?? What duh FUCK..!!

 

But John - 20 in of vaccum puls the seal in place - LOL

 

Nah, just 14". I use the BOP and put it in backwards.

 

.....I heard that FEL-PRO didnt make a rear main seal..for the 455 PONTICRAPS..?? humm..??

I quit running Pontiacs some years ago and never had a 455. Your right, Fel-Pro doesn't have a 2 piece seal for the 455. But if anyone needs or wants one, BOP Engineering has a nice looking Viton 2 piece seal for the 455.

The "old" seals like that were typically reworked Cadillac rear main seals,and yeah those were made to fit the "large main journal" pontiacs (421-428-455).

H-O racing used to sell a seal like that back in the day as I recall.

I had one in my 455 H-O GTO.

Back then there was no rear main seal alternative for the "small main journal" pontiacs (350-389-400).

The BOP seal is indeed an excellent piece,but some installs will always be problematic,and have trouble sealing with them for various reasons,so the new Best "graphtite" rope style rear main seal is another excellent option to have @ one's disposal.

Some pontiac cranks have "serrations" on the rear main sealing surface,and those can sometimes make it hard for those cranks to seal well with the modern "lip" style seals,and then there are also some blocks that wont have a perfectly "concentric" seal bore,and those too can be problematic with the more modern rear main seals.

For those engines the "graphtite" rope seals are the best choice.

I dont think the problem with the older rope seals was so much the loss of the asbestos in them,more so it was the change in the actual "weave" of the replacement rope seals after that change,they went from a fairly fine/tight/dense weave to a coarser/looser weave,and the later rope seal itself just didnt seem to seal as well as the earlier rope seals did.

But the "graphtite" rope seals are excellent by all accounts,and seem to be doing the trick for the engines that are'nt sealing well with the BOP seals,so between those two options one should be able to get their rear mains sealed up nicely.

2¢

Bret P.

 

Thanks for the post Bret, I have this one bookmarked. I had a 70 & 72 LeMans that I wish I still had. I would like to do another 70 model with a 455 at some point in the future.

 

I also use the BOP seal that is mentioned above in my stroked 400(461) pontiac,and have not had a ounce of problems with leakage. Now,on the other hand, I had a 455 before I built my 461,and I ran the rope seal in it(not the better rope seal w/asbestos),and always had problems with it leaking. I will never use anything else but the BOP seal,just from my past experiance.

Brian

 

ive used the 460 ford seal backwards with good luck. I believe victor has a 2 piece seal for them aswell

 

Talk about thread revival....

I believe a Pontiac 455 has 3.25 mains, 460 seal would be a no-go. They say a caddy seal will work BS-40012

 

If I remember right, most old style crankshafts that used rope seals had "hash" makers around the crankshaft where the seal rides, if that's the case, the "hash" marks need to be "filled" with something (epoxy/silicone?).

 

For kicks I just set a 460 rear seal in a Pontiac 400 (3.00 mains) and it's still a no-go. Rope seal cradle is to deep and the 460 seal comes up about 1/8 inch short end to end.

 

I went ahead and used the rope seal that came with my gasket kit today. Biggest problem I had was even a new razor blade cut like shit. I took one and ran both sides across my grinding wheel then it cut the seal like butter.

 

BOP makes a 1pc seal for both size mains now.Used them on my last 2 builds with no issue.Tom

 

A 1 piece seal or a viton seal? The knurl on the crank didn't cause an issue?

 

if the block has been align bored, it is possible that the seal housing bore is not in perfect alignment to the crank shoulder where the seal should SEAL

this goes with just about ANY ENGINE....

 

I wonder what the gain in HP is because of less drag on the crank? :-D

 

I know this is a old thread, going to put my 400 back together, read lots of forums. I have had problems with the damn thing leaking oil from the rear main.... are these new teflon/graphite seals the way to go? or how are these 2 piece rubber ones working? this damn leak is driving me nuts....;(

 

I have found the Best gasket grafite and the BOP 1 piece seals the best.The BOP 2 pc can be great if your seal area is concentric,bad if not.Tom