MTFCA Forum

I purchased a 27 engine which is suppose to have a model A crank. What is the best way to tell if it an A crank??

Thanks Mike

I would drop the inspection cover at the bottom of the pan and peek inside.

A good first clue, the pan should have 4 dents out on each side in line with the connecting rods just below the block skirt. The extra stroke and bigger bearings needs the extra space

The dimples Les is speaking of are at the top section of the oil pan going down. In this photo you can see right at the bottom of the silver frame rail. You may need to zoom in a little.

Hope this Helps.

Hank

Easiest clue is the threaded hole in the snout of the crank.

Andy

Here’s a pic of pan dimples. Will usually have a 3/8” - 1/2” thick spacer between the pan and dipper tray also

Thanks every for all the information. I guess I have a hopped up looking 27 engine. No model A crank.

Thanks again Mike

Andy makes a valid & easy observation - what's so "hopped up" about it ???

Sure do not see any dimples! Just saying.

All the Best,

Hank

Or spacer for the lower inspection cover.

Steve
With those “SPIFFY” aluminum side covers it is OBVIOUSLY hopped up!!
Uh huh.

I wonder if it might have a 28 Chevy crank? I know people have done them (not me).

You aren’t going to know unless you drop the crankcase inspection cover. Take so pics and show us what you got

I have heard about the pan dimples from many people. However, the engine that I purchased that had an A crank installed already didn’t hit the side of the pan. The rods were ground to clear the cam and the inspection cover at the rear did need to be bent and the rear cover horseshoe is now 3 pieces rather than 2. The inspection cover definitely needed the spacer plate. Still wonder why the crank cleared the side of the pan.

I have heard about the pan dimples from many people. However, the engine that I purchased that had an A crank installed already didn’t hit the side of the pan. The rods were ground to clear the cam and the inspection cover at the rear did need to be bent and the rear cover horseshoe is now 3 pieces rather than 2. The inspection cover definitely needed the spacer plate. Still wonder why the crank cleared the side of the pan.

Time to pull pan cover and take pictures.

Your first pic shows the threaded hole in the crank snout... definitely a model A crank. The finned aluminum inspection cover is made to clear the A crank and rods... no spacer required. A crank may have been ground down to T rod and main journals... wouldn’t need dimples then

The pan dimples are usually required as the rod nuts tend to hit the pan. If you look closely at my pic above, you will see that I use 12 point aircraft nuts on my A rods to minimize the size of the pan dimples. Never seen one that didn’t hit before. And I can’t imagine how much material you would have to grind off the rods to clear the pan without dimpling

Thanks again for all the information.

PS I said hopped up LOOKING Does not mean it was hopped up. The picture i am posting is a HOPPED engine.

Mike

I have done some measurements and I believe that if you use a 13 or older pan they are just wide enough that possibly the 12 point nuts that Kevin mentions will clear. I will be exploring this soon as I acquired a 13 pan that had the back gone. So I welded it to a later 3 dip pan. I have installed a A crank into a 13 block and hopefully this winter will button it all up!!

Michael Davis wrote: ↑

Tue Aug 27, 2019 2:19 pm

PS I said hopped up LOOKING Does not mean it was hopped up. The picture i am posting is a HOPPED engine.

Never seen a hopped Franklin before. 1929?

29 130 sedan. Daily driver

I pulled the head and pan cover, Crank is threaded. Engine is bored 120 over measured 3.865. Pictures of crank below.

Thanks for looking and all information .

Mike

more pictures

Very interesting engine, different than I would do it (but that doesn’t make it wrong)!
Pressure mains, but dipper rods
The mains use T caps. I figure 1-7/16” is the maximum safe diameter there.
Are the rods A? Must be considering the dippers.
Interesting
Thank you for the pictures

Model A rods for sure, and they look full length. That means it’ll have the high wristpin Jahns pistons in it. Pistons are really good for top end oiling! Valves look oversize, and there must be a VW pump on the back of the cam

Thanks for your replies. Now I know what it is. I will be posting it for sale soon.

Thanks again
Mike

Thanks Michael for posting, first for me without dimples. We learn something new every day if we keep our minds, eyes, and ears open. Very unique.

All the Best,

Hank

Thanks Hank