Best Rear Main Seal

[johnneilson]

Originally Posted by Terry Burtz, Calif

Heat Treatment
Heat to 1560 deg F. Hold for 30 minutes. Cool to 1200 deg F in 30 minutes. Air cool to room temperature. Brinell 149-179. Center on the 3 main lines bearings & rough machine. Heat 1500 deg F & quench in caustic solution. Anneal at 650 deg F to meet a Brinell of 408-444. Re-anneal front end as indicated (Brinell 302-364). Brinell hardness of flange from 228 to 402-444 as indicated. Finish machine & grind.

Terry,
from the sounds of the caustic quench and subsequent anneal it almost sounds as if it is just to harden the surface. I do not know, however, I can tell you from cross drilling a few "C" cranks that the heat treatment is pretty consistent all the way thru the material.


G Baese,
something to keep in mind about using "B" rods in the "A" motor.
The "B" pan has clearance dimples to clear the rod nuts, by using small 12 point nuts on the rods you may not need to clearance the "A" pan.
The slinger and rear thrust ring will more than likely be too large to fit in the "A" rear main cap, check this while crank is in the shop.
Last thing is the fillet radius in the main journals, bigger is better.

John

[hardtimes]

My use of an A pan with B rods, is that you WILL have to dimple A pan for clearance...even with use of modern nuts.

Can a fillet radius be too big on a crank ?

[BRENT in 10-uh-C]

Originally Posted by johnneilson

Terry,
from the sounds of the caustic quench and subsequent anneal it almost sounds as if it is just to harden the surface. I do not know, however, I can tell you from cross drilling a few "C" cranks that the heat treatment is pretty consistent all the way thru the material.

I concur with your thoughts John. Several years ago I received couple of aftermarket Model-A crankshafts that apparently were not properly heat treated and failed within a short period with insert bearings. In discussions with the manufacturer this point was mentioned that the hardening process was just on the surface only based on the factory print however in my discussions with others who had drilled original cranks for pressure, their opinion was the original crankshaft hardening went much deeper than just the surface as indicated.