[Bill Eveland]

Are you guys drilling the cap for the pin or just setting them in place with rtv? Also was there a factory deal to put some rtv on the rear main cap somewhere, thought I read that on here. Don't have a factory manual to go off of.

[Formula8]

I skipped the pin and used RTV grey. We'll see shortly if it works.

[Schurkey]

If the seal groove is concentric to the main journal, why would you waste effort and enthusiasm with 1890's technology? Put a lip seal in that engine. The only question is "Neoprene" or "Viton".

[Sun Tuned]

Bill,
Rope works fine if installed correctly.

The pin is for aftermarket blocks. That do not have the anti rotation holes the factory blocks and caps had.

The holes allowed the rope to impress itself into holes which kept seal from spinning.

I just got through making the factory type kent Moore tools for this and our own rocky rotella even has one for the 3.25 main blocks I sent him.

I don't know if he's had a chance to use it yet but I've used mine twice already, and it worked flawlessly. You can do same thing with large piece of pipe or wooden dowel etc.

All I've ever done is make sure cap and block register is very clean. Shorten up seal by compressing it together some( think shortening it) more on this later if you want.
Then install and compress trim ends with new razor blade so that it makes a very clean cut with no strings.
Apply just a touch of aviation permeated to each seal end only and a very small amount of ultra copper rtv at seal end of block ( about a pinky nail spot)

Install cap and torque. Very small bit of rtv will barely be visibly squeezed out.

Not had any leaks on the last 2 I've done. Last one was done 4 months ago.

[gtofreek]

I use anaerobic sealer[green or red Loctite] in place of RTV to seal the cap to the block. It spreads out thinner than RTV and doesn't cock the cap, so bearing wear is much more even. Just a thin line from edge of seal out to the edge of cap.

[Sun Tuned]

Paul I had wondered about that. Never tried it yet. Good to know it works.

What number is the green??

[Bill Eveland]

If is the key word here, this is a fresh build with a Viton seal that's not holding.

Originally Posted by Schurkey

If the seal groove is concentric to the main journal, why would you waste effort and enthusiasm with 1890's technology? Put a lip seal in that engine. The only question is "Neoprene" or "Viton".

[gtofreek]

Originally Posted by Sun Tuned

Paul I had wondered about that. Never tried it yet. Good to know it works.

What number is the green??

It is #290. It is the wicking grade. It seeps into porosity and already fastened threads.

[Sun Tuned]

My dad and I have never had any issues with the rope seals... Original or the best gasket seals.

We've used two lip type bop seals and had no issues there either.

Key is cleanliness and following directions.

The. Fiberglass seals were terrible... Seen two or three of those causing probs.

Also not just Pontiac but Chevies too if the Pcv System is not functioning properly and you change it up where it is you will almost be guaranteed to start a leaker.

[Schurkey]

Originally Posted by Bill Eveland

If is the key word here, this is a fresh build with a Viton seal that's not holding.

That makes all the difference. When the seal groove is non-concentric with the journal, a rope is the only solution I know of.

I just hate rope seals. The only advantage they have over a lip seal is that they accept some amount of abrasives in the fluid being sealed...and they tolerate some non-concentricity. If your oil is abrasive, the seal is the least of your worries.

[gtofreek]

One other thing to point out with rear main leaks. Crankshaft seal surface concentricity. I have seen cranks that were bent, then straightened, then the mains ground by centering up the crank off of the main journals. This can cause runout in the seal surface and crank snout. I saw a 390 Ford that would just spew oil out the rear main. Customer tried new seals with no luck. When I tore it down, I measured the runout of the seal surface. It had .004". We had the crank re-ground, and he centered the crank up off of the rear seal surface and the snout. That way the mains could be ground on the same centerline.

Mains should always be ground after being centered off of the seal surface and snout. I have seen some crank grinders just center off of the mains, and that is not good.

[428GTO70]

I went with the Best rope rear seal as well. Did NOT use the roll pin that came with it just a little rtv in the groove. Yet to find out if it leaks or not though, hopefully before winter. I had to align bore my block which is one reason I decided against trying the Viton rear seal, figured the groove was no longer concentric.

[Tom Vaught]

General Motors PONTIAC Engineers did stuff for reasons

They used that same seal design for the life of the Traditional Pontiac Block design.
Think about it. I have seen many stock Pontiac engines that did not leak at the rear main
with 100+K miles on them. I personally think using the tool (and shop manual instructions)
makes a big difference vs a typical rebuild installation.

Tom Vaught

[mrennie]

On my 455 I tried the BOP seal and "tilt tested" it before running it, and it leaked like crazy.

Took it back apart and found the seal groove was not concentric to the crank journals, which caused the problem. To be clear, I do NOT blame the BOP seal.

I installed a Best Graphtite rope seal and I've only run my engine 6-7 times on a test stand, but so far no leaks!

[Schurkey]

Originally Posted by Tom Vaught

General Motors PONTIAC Engineers did stuff for reasons

Sure...they selected a rope seal because they knew the tooling used in production couldn't guarantee proper concentricity of the seal groove to the main saddle.

Doesn't make the rope seal a better choice if the groove IS concentric. How many other manufacturers dropped the rope seal when the neoprene lip-style proved itself?

[66 Gas Tires Oil]

i purchased a rear main seal from butler perf. the other day for my 455 build. i was going to get the viton one. they said to look at my crank surface and if it is smooth use a viton seal but if it had lines on the surface to use the newer teflon/graphite seal. mine had the lines.

Jim

[rexs73gto]

The lines on the crank are there to keep the oil back into the oil pan thats why the lines are angled towards the pan, it's to direct it back into the pan. I've used the vition seal on my last 3 engines & have had no problems with leaks at all. If you follow the directions & make sure the seal is off center by at least 20 degrees & have put the rtv in the seal groove you will have no problem. The rope seal is just old tech, it will work just as well but why use it now. The new seals are designed so you don't have to work the roap into the groove & hope you have cut it square so no strings are left over & caught between the cap & block to cause a leak. Both types of seal are ok but for me the vition seal is the way to go. If you follow directions & don't install the seal in backwards it won't leak & it will have less drag on the crank. I know that it's very little to be able to measure the amount of drag from the rope to the vition seal & only if your tyeing to get every little bit of HP, but again for me if installed correctly the vition seal is the way to go.

[Sun Tuned]

I think they went to a lip seal because of ease of installation and cost.

I don't know why but more people have trouble with a rope seal than probably timing carb problems it seems.

I can't count how many i've seen that when you remove the cap you see a chia pet wad of seal strings under the cap surface.

What were they thinking at least trim it or pack that mess out of the way.

You dont have to have mega dollars worth of tools to do it correctly. But you do have to have a touch of common sense or the ability to read a shop manual, and pride in what your doing.

I think most ive seen were hurriedly thrown together by people that didn't know.

With a fresh (new) never cut anything in its life razor blade, that graphite seal slices like a piece of licorice with no strings at all.

The key is a NEW SHARP razor blade.

Follow rest of instructions.

Lip seal good too if you can get measurements to do right.

By the time you get dial indicator out though Ill have installed the rope... but then the tool the factory had makes that real nice to do but not mandatory.

[Sun Tuned]

Ill tell ya though the nice little orange blade cutter that comes with the seal is cool for the tool box, but I no likey.

I bought a box (100) single edge razor blades like you clean glass with, had em for years.

Works very very well, as the blade kerf is very thin and cuts so easily you'd not believe it.

Kerf on supplied box cutter that comes with seal is almost 3x as thick.

Nice cutter but I like my single edge razor blades way better.

[PunchT37]

Iv`e never had a problem with a rope seal that I installed. Even, the Buick that has a rope seal in the rear AND the front. Soak them in oil and pack them in good in the groove. Cut them about 1/16 inch higher than the surface with a NEW razor. Clean the cap/block surface with a clean rag with a little brake cleaner. I use Form A Gasket #2. Spread a light amount on the block/cap around the rope ends. Assemble. The 1/16 extra you left will finish packing the seal after the cap is torqued down. Crank will be a little hard to turn but, it will loosen over time.

The engine and crank was designed for the rope seal. Use em. Engines that were designed for lip/garter spring seals? Use those. Both work. Use them where they were designed to be used. The lines on the factory Pontiac crank were made with a rope seal in mind. Use a rope seal on those. You will prolly be good to use the garter spring seal on the aftermarket cranks wothout the lines. The lines, over time, will tear up the lip and the lip has a hard time reaching down into the lines to seal. The grooves in the pontiac engine were not made for the outer case of a garter spring/lip seal.

Also, on all garter spring type seals, there is a surface finish spec. to be followed. Too rough, OR too smooth, and the seal won`t seal, OR, won`t last. The seal HAS to be centered AND square to seal. On a lot of cases, the outer shell of the garter/lip seal needs to be sealed as well so the lube can`t go AROUND the seal.

The rope seal is more forgiving to machining/install tolerences.

I`m not a big typer by nature. I chimed in because of all the problems I keep hearing and would throw in my 20 yrs. auto experience and 10 yrs. in industrial. LOTS of seals out there. So, the above tech I use for all seals I come in contact with, not just Pontiacs. The seal is a seal. It doesn`t know where it is. Just watch your install and think about what you`re doing.

Side note;

I work in a potable water plant for the city now. There are big gear boxes above 2 milllion gallon treatment units. There is a shaft comming down through 2 stacked lip seals with a huge prop on the end to agitate the water. It`s got 6 gallons of ISO 220 wt. gear oil in em. If I make a mistake and those seals leak into the water that the poor AND the rich drink, what happens? Not to mention the hospitals, pools, process plants etc. that use our water. And how hard is it to clean out and dissinfect? Thats how I look at seals now.


Pretty sure this is the longest post Iv`e ever typed on this board? LOL