Rear main oil seal Model B engine

[PatrickTA]

I’m working on a Model B Engine, and I’m curious what your opinions are on having the crankshaft ground for an oil seal. Also if you choose that route what seal is recommended.
I’d prefer to leave it stock. Just want to make sure it doesn’t leak too much oil out the 3rd main.

[CWPASADENA]

I am not aware of any actual options available for an actual seal for the rear main in a B Engine.


If the rear main is set up correctly and the drain back tube is open, the rear main should not leak. Just take a good look where oil may leak around the shims and the rear main cap, use a little sealer and that should be good.


My experience,


Chris W.

[johnneilson]

There are a couple options for actual seals, look up the Burtz seal at Snyder's and also Dan McEarchern (DMC gears).

Both require modifications to the crank.

Take your pick, personally I use Dan's on 3 bearing motors and a modified one on the 5 bearing.

If you are just building a stock type motor, CW above is correct, if not do some research.

John

[Jim Brierley]

I use the Burtz seal. For the B, 2 full-circle seals are included in the package, the I.D. is the same but different O.D.'s because the cap and upper insert piece are different shapes. Instructions say to split both halves and use 1 of each. DMC makes a new upper piece that allows the use of 1 full circle seal, that is the one I use, and recommend. The crank must be machined to a certain spec. The seal slips over the rear of the crank, and into the new piece and cap.

[Dan McEachern]

Just to clarify things, my seal adapter uses a standard small block Chevrolet 2 piece seal. The installation requires some machine work- the cap needs to be modified to accept the lower adapter, and the id of the adapter must be line bored at the same time the mains are linebored. As with most seal conversions, the crank needs to be modified where the seal runs. This is a robust and reliable modification, but it needs to be installed as part of an engine rebuild, as its not a "bolt in" installation. Dan

[Terry Burtz, Calif]

Sponsored Links (Register now to hide all advertisements)

Dan, thanks for your description of how the 2 piece Chevrolet rear main seal can be adapted to a Model B engine. There are millions of Chevrolet seals in use every day and they are available (after-market) in exotic materials that are better than stock (nitrile).

As many know, I have been making rear main seals for Model A's and Model B's since 1976. They are made from nitrile and just like the Chevrolet seal, the crankshaft needs to be machined to provide a smooth rubbing surface that is concentric with the rear main journal.

The Burtz seal does not require machining to the cylinder block or rear main cap, and the crankshaft does not require welding for either Model A or Model B.

The Model A seal is 1 piece that stretches over he flywheel mounting flange, and the Model B seal can be used as either a 1 or 2 piece seal.

The internet is your friend. Do a Google search on "Ford Barn Burtz Seal" and you will find a lot of reading that will help you make a decision.

[johnneilson]

This might help
This is finished crank showing 2pc Chevy seal running surface

There are two ways of building up this area
1 to make a split collar and weld into place then true machine surface
2 weld up entire area and machine this also strengthens the flange for higher hp levels

Then for budgetless racing applications use billet custom crank

Enjoy the holidays, J

[slozano]

Hi Jim.
Changing out the rear main seal on the rail. Thinking of going with the Burtz seal, but i have questions.
1. Does it come with instructions for the crank? I will need to have it modified
2. Using the 1 piece seal, the upper piece. Where do I get this?
3. Who do u use for your machine work?
4. Confirming, I will not need to have the block or cap modified??
Thanks in advance!!

[Jim Brierley]

slozano, It does come with instructions. All other questions are answered above.

[Terry Burtz, Calif]

slozano,

Dan Price (http://www.dan4banger.com) makes the upper seal holder that has a groove like the rear main cap and allows the use of a one-piece seal. Dan also has the seal for sale.

Snyder's also has the seal (B-6335-M) and seal holder (B-6335-X).

Most Model A retailers have the seals, but not all have the seal holder.

If you want the instructions, reply to [email protected]

[Terry Burtz, Calif]

By coincidence, I received this email yesterday:

I have a newly rebabbited B-engine and have the Burtz one-piece seal and seal holder insert ready to install but note that the lower block surface and pan rails were trued up with 0.010 taken off and the rear main cap was trued up with about 0.003 taken off. The journal where the slinger was turned down has a diameter of 2.365 inches.

Will these modifications present any problem with the fit and performance of the Burtz seal? Any suggestions would be greatly appreciated. Thanks much!


My reply follows:

Thanks for your email.

I think that you may have several problems.

On an original engine, the crankshaft centerline coincides with the bottom of the cylinder block and the pilot bearing is in the center of the flywheel housing.

I assume that the bottom of your cylinder block had 0.010 inches taken off and then the mains were line bored using a setup that locates the crankshaft from the camshaft bearings and the bottom of the cylinder block.

I'm thinking that your crankshaft centerline is high by 0.010 inches and located off-center towards the generator side of the cylinder block. Your pilot bearing will not be centered in the flywheel housing. Your clutch and transmission input shaft will be in a bind. Your pistons will protrude an additional 0.010 inches above the top of the cylinder block, and you will have to shorten your expensive seal holder. The ring gear/Bendix pinion tooth clearance will also be reduced.

With 0.003 inches off of the cap. I see no seal problems. With 0.010 off of the cylinder block, the seal will be distorted a little, but again, the seal is compliant and I think things will be OK. If distorted too far, the seal will buckle. Just be sure to follow the directions to test the seal for leaks after the final assembly.

Your machinist should have added 0.010-inch shims at the bottom of the cylinder block and 0.013-inch shims at the rear main cap when line boring to keep everything centered and in the correct location.

Your crankshaft dimension is good as long as it is concentric with the rear main journal and has a good surface finish as specified in the instructions.

Before going any further, please print this email and discuss it with your machinist. He should guarantee his work and repour your bearings at no extra cost using the shims as specified above.

If you have any questions, please reply or call me.

[Terry Burtz, Calif]

Another email and reply.

Terry,
Thanks much for your help and response. The guy who poured the babbitt was aware of the -0.010 taken off the bottom of the block as it was done at his request. He was pretty experienced in this work so I am hopeful that he made the appropriate use of shims to compensate and maintain the crankshaft centerline. I do note that the camshaft gear has the appropriate 0.003 inch tooth clearance with the crankshaft gear throughout its circumference. I will check with the babbit fellow when I am back in town. Thanks!
Bxxxx



Bxxxx,
I would expect to see timing gear mesh correct as it is set by 2 fixtures that index from the front and rear cam bushings and set the centerline of the crankshaft at 4.154/4.156 inches from the centerline of the camshaft.

If a 1/4 inch were machined off of the bottom of the cylinder block, the 2 fixtures would still set the distance between the camshaft/crankshaft centerlines at 4.1554/4.156 inches and the timing gears will mesh correctly.

Please print this email and go over my concerns with the machinist that did your main bearings.

I cannot think of any reason to machine the bottom of the cylinder block. Rust pits, gouges, and other surface defects are normally filled with a little epoxy. Even if your machinist compensated by using shims, what will happen the next time main bearings are poured?

Terry Burtz