Can a B crank be used in an A engine?

2

29FordRoadster

Member
I currently have an A engine with the modern seal in the rear main. The slinger has been ground down to accept the modern seal. It leaks really bad. I have access to a "B" crank and wonder if it can be ground down so as to be used in an A engine. If so, can anyone tell me just what needs to be done for this to work? Any help would be appreciated. Wayne
 
29FordRoadster said:
I currently have an A engine with the modern seal in the rear main. The slinger has been ground down to accept the modern seal. It leaks really bad. I have access to a "B" crank and wonder if it can be ground down so as to be used in an A engine. If so, can anyone tell me just what needs to be done for this to work? Any help would be appreciated. Wayne
Click to expand...

Hey Wayne,
As Jim B says above...you should look into getting a copy of his book titled..Bangers and Me. Money well spent, IMO and after reading it twice to date.
 
29
Sure it can
Grind the mains to the size of your good journals, use B rods and you are good to go.
You might need to get smaller rod nuts, or "index" the originals. OR, have the entire crank ground to the A dimensions and use all your original stuff.
Kinda seems a waste of a B crank, unless it's counterweighted. Why not get another A crank?
 
It would be a lot easier to bye counter weights for the A crank and have them welded on and balanced. I've done a few of them. If the rear main leaks bad something is wrong. Maby needs crank ground and rebabbitted and line bored correctly, The last couple of A's I built I used the rod inserts and rods from Snyders. Walt
 
I took a "B" crank and ground it to 1.850 on the mains.
Used a thick rear main cap and McEachern front/center caps.
Put insert bearings and plumbed oil feeds.
Runs really good with light flywheel and V8 clutch.

It is a lot of work, but only has to be done once.

J
 
Thanks for the info CarlG. That gives me some food for thought. Thanks also to the others that offered suggestions. For further explanation, as I said in my original post, I have free access to a B crank, I don't presently have an A crank. I wanted some info on whether it is cheaper to grind a B to fit my rods and mains, or buy an A crank on line and pay shipping and also possibly grinding to get it to fit. I know it costs money either way. I also agree it would be kind of bad to ruin a good B crank. Thanks again to all that replied. For kicks and giggles I will post what we wind up doing. Any further replies appreciated. Wayne
 
What ever you wind up using, I would make sure you have counterweights. It will help the life of the babbit considerably, and the price of a good babbit job isn't cheap.
 
it sounds like your initial problem is the leaking seal. If the main bearing saddle was line bored out of concentricity to the block seal, changing the crankshaft will not help the leak. Or if the seal was installed incorrectly in spite of a good crankshaft and block, that would cause a leak. I had one leaker that was leaking from between the aluminum seal and the block. All it took to fix it was some permatex#2 on the aluminum seal when installed into the cast iron. Have you determined why the seal failed in the first place?.
 
Pat in Santa Cruz, You are correct in that my main problem is the leaking seal. As background info, the modern seal was put in the engine at the time the motor was rebuilt. It leaked from the first time the motor was run. I have replaced the seal two times and it has leaked badly each time. You may be onto something concerning the line boring of the block when it was rebuilt. The mechanic working on my motor will get to it hopefully the middle of this week. I will know more at that time. If the leak can be sealed, I have no need for turning a B crank to replace the one in my motor now. Thanks for your reply. Wayne
 
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