Engine bearing questions

[Synchro909]

Originally Posted by alexiskai

Isn’t Plastigauge thought to give unreliable readings when the motor is still in the car?

IMO, plastigauge is near useless in the rear main bearing unless you take measures. The weight of the flywheel will give a false reading less that reality. I overcome that by drilling and tapping a hole in the under side of the flywheel housing just near the drain hole. I put a bolt in it (1/4" is plenty) and do it up to take the weight of the flywheel. It doesn't need much torque - not much more than finger tight. You can't turn the crank while it is there but you don't need to with plastigauge.
Damn it - there goes another secret!

[katy]

Originally Posted by Flathead

Uh Oh, My mistake, it is on a different site.

Got a link?

[Pamodelaroadster]

Engines out and I have some some numbers with plastigage.. With no shims the rear main is .0015”. The middle main with the existing .007” shims on each side has a clearance of about .002”. the front main started with .007” shims on both sides, with two .0035” shims left clearance is about .001”.
Is the front modern crank seal SNYDER’s sells any good?
Is the small hole in the middle of the rear main worth worrying about, I think they got a little too aggressive with their groove work.

[rotorwrench]

Most oil groove cuts start near the rear side but don't extend all the way. The front of the grooves continue to the thrust face where it can get a bit of out flow as the bearing leaks down.

The little hole in the cap bearing likely accesses the drain tube so I wouldn't worry about it too much. Most don't have a hole there but they do have feed holes at the top bearing up into the cam chest.

I've not used the late rubber oil seal on the front so I won't comment on that. I just use the plain packing seals in the front the way Henry's guys did it but they are harder to use.

Your engine may be a bit loosey-goosey but it wouldn't be the first model A to run that way. I knew of a fellow that packed leather shoe tonques in his rods every other week or so to keep one from knocking,

[nkaminar]

0.001 in the front is fine. 0.0015 in the rear is fine. 0.002 in the middle is a very slight bit loose but OK. Hole is OK. Check thrust clearance. Replace oil drain tube with new. Assemble with assembly lube.

I cannot comment about the Snyder replacement seal but the one engine that I have had with a rubber seal leaked. The seal was worn out. So my conclusion is that rubber seals wear out eventually.

How are the rods?

[katy]

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Is the small hole in the middle of the rear main worth worrying about,

It should be cleaned up to allow oil into the drain tube.

[Synchro909]

By modern front crank seal, I assume you mean this one. https://www.snydersantiqueauto.com/p...8848&cat=41694
I have used those for years - never a failure and easy to install. Of my 4 Model As, 3 have that seal and one of those engines has done about 60,000 HARD miles (Towing a trailer weighing as much as the car at 50mph all day, every day for months at a time.)
I have only one engine with the original type seal and I used that because the area of the pulley where the seal runs was slightly pitted. It seems to be performing quite admirably.
Conclusion: Both work well.

[CWPASADENA]

Originally Posted by Pamodelaroadster

Is the front modern crank seal SNYDER’s sells any good?

The "Modern" front seals work well but you have to polish the surface where the seal rides on the pulley. Any roughness will cause the seal to fail.

My experience,

Chris W.

[BillCNC]

SANDING 101:

When sanding something like a bearing cap, it's EASY to NOT sand it level. One needs to constantly rotate the part in their hand while sanding. Rotate the part around 22.5° every 5-10 strokes. To much pressure at the fingertips and/or your palm are to hard to regulate by constant sanding in the same direction causing uneven/unlevel surfaces.

Regards
Bill

[ModelA29]

Originally Posted by alexiskai

Isn’t Plastigauge thought to give unreliable readings when the motor is still in the car?

You should use a jack to hold the crank against the upper bearing surface. It needs to be zero clearance at the top or that space will give a false reading on the plasti gauge.

[Pamodelaroadster]

Thank you everyone for the great advice! Still waiting on parts.I’m so glad I listened and pulled the engine, I couldn’t be doing a good job from underneath with all I found wrong. All the bearing clearances are down to .001”–.0015”. Things that I found wrong that were contributing to the oil leak.:
1. A shim .007”on only one side of the rear main.
2. Excessive clearance on two of the main bearings.
3. The rear upper main bearing “seal “was sticking above the block several thousands creating a gap under the cap.
4. The oil return tube was only half as long as it should have been, and where it screws into the main has a small piece missing and probably was not sealed well.

[nkaminar]

Yeah. It seems like extra work to pull the engine but in the long run it results in less work and a better job. Not to mention less oil and grease in your hair.

[dansluck]

Working under your car gives your hair that oiled and combed back 1930's look.
But I would pull the engine it is more enjoyable.
Dan

[Dodge]

Using this front oil seal, it uses a real seal instead of the solid rubber one.

[Patrick L.]

Originally Posted by ModelA29

You should use a jack to hold the crank against the upper bearing surface. It needs to be zero clearance at the top or that space will give a false reading on the plasti gauge.

Yep. Just slight pressure to hold the crank up. Then fresh plastic-gauge works great.

[Phil Brown]

Originally Posted by Dodge

Using this front oil seal, it uses a real seal instead of the solid rubber one.

Nice looking seal, who's is that one ?

[Pamodelaroadster]

Went for a test drive, not expecting perfection, but so far no leaks. Also, the new Mitchell transmission is working really well. Along with a synchronized second and third gear it also has a higher ratio first and second gear. A V8 pressure plate is also working well.
Thanks everyone!

[dansluck]

Dodge
Who is the supplier of that seal, and do you have a part #?
Thanks

[arhyne07]

Hey Congrats on getting the oil leaks fix! I am about to embark on this journey myself with my 29 coupe. If you wouldn't mind, could you share the link to the seals you ended up using? Hoping to get my pan off in the next few weeks and once i get eyes on things i'll be ready to order parts.

Thanks

[Pamodelaroadster]

I used the rope seal from Snyders for the front. I’m glad I did because the modern seal I do not believe would have worked because the crank was not centered in the hole, it was much closer to the timing cover than the pan.