37 Mystery flathead crank

[rgtharley]

Hello All!

I have a very perplexing problem, that so far, none of my local experts can answer. I have pulled the original 35 motor from my Tudor, and planned on re-installing this 37 motor I bought from a guy in Virginia last year. I bought it before I really knew what I was looking for, or at. No crank pulley came with this 37 motor, which looked like it had been gone though years ago, then put away. This guy had it 18 years, and never used it, and maybe this is why. I noticed that the crankshaft "snout" was quite a bit longer than my 35, so I got my calipers and started measuring. Not only is it longer, it is a bigger diameter,(35 crank is about 1.185) and as you can see from the photos, it actually has a larger diameter, (1.305,about .020 bigger than rest of crank) on the outward end of the crank. As you might expect, I have no idea what pulley to look for, or why this crank is like this. I already bought 37 style water pumps to use, and the bores and valves look great, so I don't want to pull this motor apart.
I hope someone knows the answer to this mystery, so I can proceed to put this engine in the car.
First pic is "new" 37 motor, second is original 35, and last is my 35 crank pulley next to 37 crank end.
Thanks

Bob

 

[flatjack9]

I would say someone put a 39 or later crank in when it was rebuilt.

 

[rotorwrench]

The late long snout cranks can be modified/shortened to the early specs with some careful machine work. It is the only way you can use the early pulley. The other option is to use a later pulley such as the 42 thru 48 and remove the fan sheave from the front but the snout will still stick out there a ways.

 

[37 Coupe]

If it is the later crankshaft all you need is the pulley that you would use if you were using a later engine,the 81C ,1939 Ford Standard,only year and model this was used,in short it is exactly like the single crank pulleys like a stock 37 85hp used but with inside diameter to fit later cranks 39-53.

 

[rgtharley]

I'm liking all the great answers to my problem, but as a machinist, I'm still confused why the outer most end of the crank is .020 bigger than the diameter where the seal lives. How do you bore a pulley to go over the bigger diameter, and still have a close tolerance fit on the rear section?

 

[37 Coupe]

It is either worn down from where the pulley had spun on the shaft or the crank grinder touched it for some reason. You may have to go to auto parts store and get a Redi-sleeve. As far as length the 37 engine looks about correct to me,the other one looks short but I am not familiar with 35 engines and earlier,does not look like enough room to get a single groove pulley on it.

 

[Brian]

As the other guys are saying, simply use a 39 or later crank pulley. The crankshaft used in 21 stud English motors, eg, V8 Pilots, whilst dimensionally identical to regular 21 stud crankshaft in all journal sizes, has the longer, larger dia snout as the later 24 stud cranks. Probably what you have.

 

[Brian]

The larger dia you refer to [1.305] is also further along the snout, the gap in between being undercut the 20 odd thou you refer to. Just score yourself a later pulley and it'll slip right on!

 

[rotorwrench]

Those 39 standard pulleys 81C-6312 aren't so easy to find now days but there are likely still a few out there. They were used in standard cars, commercials, and smaller trucks. The 8BA type pulleys use a sleeve for the oil seal but the sheaves are usually too big to work in the early cars plus many are for 3/8 belts (way too much trouble). The 21A types cut down will work or the 91A with the fan mount cut off would be similar.

 

[Walt Dupont--Me.]

Bob, after seeing your pic I think Brian is correct. i think you'll find another big dia. inside the cover. Get a pulley 39-41, and cut off the part on front that holds the fan on your lathe. The seal has nothing to do with the crank, it rides on the pulley. I don't think the length will bother. I had two 35's when I was a teen and install 59AB engine with no problem. Walt

 

[rgtharley]

Gentlemen,

Thank you so much for the help on the post, and thanks Walt, for the phone support!! Any chance anyone can post a picture of an 81C-6312 1939 style pulley? That way, I'll know what I'm looking for. I guess I should check Drake's and Mac's catalog to see if anyone re-pops it. Brian, I'll take a close look up under the timing cover, to see if in fact, there is an undercut. That would make perfect sense to do so along a long diameter.
Thanks again all! Ford Barn is awesome!

Bob

 

[Ol' Ron]

Yup, put an 8BA crank in Av8 pauls engine, had to modify an early pulley.. Not a problem. be interesting what the rods and bore is. Might be a 239.

 

[G32]

Hello All!

I have a very perplexing problem, that so far, none of my local experts can answer. I have pulled the original 35 motor from my Tudor, and planned on re-installing this 37 motor I bought from a guy in Virginia last year. I bought it before I really knew what I was looking for, or at. No crank pulley came with this 37 motor, which looked like it had been gone though years ago, then put away. This guy had it 18 years, and never used it, and maybe this is why. I noticed that the crankshaft "snout" was quite a bit longer than my 35, so I got my calipers and started measuring. Not only is it longer, it is a bigger diameter,(35 crank is about 1.185) and as you can see from the photos, it actually has a larger diameter, (1.305,about .020 bigger than rest of crank) on the outward end of the crank. As you might expect, I have no idea what pulley to look for, or why this crank is like this. I already bought 37 style water pumps to use, and the bores and valves look great, so I don't want to pull this motor apart.
I hope someone knows the answer to this mystery, so I can proceed to put this engine in the car.
First pic is "new" 37 motor, second is original 35, and last is my 35 crank pulley next to 37 crank end.
Thanks

Bob

Bob: How did you solve this ?--got picture?
I think the 37 had a rebuilders (maybe FMC) extension to run engine
with crank-mounted fan application.
Did it have the original 68 series 2.4" main crank?
Love these Flatheads!
Gene Tulsa

 

[Lawrie]

All you need to do is get a later model crank pulley with the two pulleys on, then cut the outside pulley off in the lathe, it then will fit straight on and line up with the water pump pulleys.
The twin pulleys I used had a removable sleavel sleeve so they would either fit the early crank or later one.
Let me know if you want pics.
Lawrie

 

[Zeke...PA]

Here is a picture of a 39-41 crank pulley which used the fan mounted to the crank. Zeke

 

[OLD...BILL]

There is a pulley on e-bay for bid as today for $31.00 ...do a search on e-bay item number
251470437137... good luck ..... OLD....BILL

 

[G32]

All you need to do is get a later model crank pulley with the two pulleys on, then cut the outside pulley off in the lathe, it then will fit straight on and line up with the water pump pulleys.
The twin pulleys I used had a removable sleavel sleeve so they would either fit the early crank or later one.
Let me know if you want pics.
Lawrie

Lawrie: Yes please I'd like the pictures---I need to learn something every day---Thanks! Is this after market in Australia only --manufacturer name?--Sleavel?
Fun with Flatheads!
Gene Tulsa

 

[Kahuna]

Just get a 59 type double pulley and machine off the froward pulley. Done

 

[G32]

All you need to do is get a later model crank pulley with the two pulleys on, then cut the outside pulley off in the lathe, it then will fit straight on and line up with the water pump pulleys.
The twin pulleys I used had a removable sleavel sleeve so they would either fit the early crank or later one.
Let me know if you want pics.
Lawrie

Here is a picture of a 39-41 crank pulley which used the fan mounted to the crank. Zeke

There is a pulley on e-bay for bid as today for $31.00 ...do a search on e-bay item number
251470437137... good luck ..... OLD....BILL

Just get a 59 type double pulley and machine off the froward pulley. Done

Thanks FH guys; Any good pic of standard? 81c 6312 39. No big deal --I have other pulleys that will do as you say --trying to salvage a beat up one.
Bucket list:
Learn to run old Atlas lathe
Learn to weld --I can trust-practice-practice
Learn to run Van Norman valve grinder
I'd like a valve seat grinder that works for 73rd B-day in May.
Oh--tour Australia on a right hand drive motorcycle
Gene Tulsa

 

[Bruce Lancaster]

No pic, but the 81C looks like your original '37 pulley except for a protruding snout about 1" long beyond face of pulley and of course inner diameter to suit late crank. A carefully pruned '39-48 pulley cut back to where the crank ratchet and washer seat (crank ratchet is a different part too! Look for 1 1/8" hex.) will look about the same.