"B" cam in "A" engine

[deuce295]

A quick question for those that have run a model B cam in their model A engine. On the B cam the forward cam bearing surface has a spiral groove cut in it that stops just short of the end of the bearing surface and the A cam forward bearing surface has a spiral groove that is cut all the way across the bearing surface. Does anyone know if it is important to grind the groove to the ends on the B cam when using it in the A engine or perhaps it does not affect the oiling of the forward cam bearing.
Any input really appreciated.

[Kurt in NJ]

the B cam has been in my A for over 25 years, I left it as Ford made it, also the oil in the valve chamber spills over the thrust surface on it's way to the pan ---and if I remember correctly there is a notch in the block there so the spilling oil gets to the thrust surface.

[deuce295]

Appreciate the input Kurt.

[Benson]

Originally Posted by Kurt in NJ

the B cam has been in my A for over 25 years, I left it as Ford made it, also the oil in the valve chamber spills over the thrust surface on it's way to the pan ---and if I remember correctly there is a notch in the block there so the spilling oil gets to the thrust surface.

Kurt,
I know it was a long time ago but:

Do you remember if you used Model A lifters (1.117) or did you use the larger Model B lifters (1.187)?

[Pete]

Originally Posted by Benson

Kurt,
I know it was a long time ago but:

Do you remember if you used Model A lifters (mushroom lifters 1.117) or did you use the larger Model B lifters (1.187)?

Use "B" lifters with the "B" cam.

[pat in Santa Cruz]

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The stop at the end of the spiral groove is because the B engine had pressurized cam bearings and main bearings. Pressurized oil would still find its way beyond the end of the oil channel in the cam bearing. At the back end of the cam, the stop was intended to diminish the tendency of the rear cam bearing to leak out the flywheel cover. At the front end of the B oil galley, there is a hole that dumps oil on the timing gears and feeds the rod dipper tray. On an A cam, since they are gravity feed, the groove extended beyond the bearing to a notch at the base of the block cam bore at the thrust and onto the spinning timing gear which threw it all over tarnation and the teeth as well. The dipper tray was replenished by oil return from the return pipe and what ever came down the timing gears from the top.

You can interchange the camshafts with no harmful effect, except that an A cam in a B engine is a step backwards in performance. It would not hurt anything if you used an A cam core with a B grind in an A engine and cut the groove to help oil the cam timing gears, but with the oil mist all over in an A engine, I doubt if its necessary.

BTW, An A cam reground to B specs will not actually perform as well as a good B cam or a new B grind camshaft. You cannot duplicate the original grind on a reground cam shaft, you can only get close to it. You will either have correct lift and diminished duration or diminished lift and increased duration. If the cam was heavily re ground, you will find you have to extend the adjustable lifters to near the top of their range. If you used the small foot adjustable lifters on a B grind, you would decrease duration even more.

[Pete]

"BTW, An A cam reground to B specs will not actually perform as well as a good B cam or a new B grind camshaft. You cannot duplicate the original grind on a reground cam shaft, you can only get close to it. You will either have correct lift and diminished duration or diminished lift and increased duration. If the cam was heavily re ground, you will find you have to extend the adjustable lifters to near the top of their range. If you used the small foot adjustable lifters on a B grind, you would decrease duration even more."
You CAN duplicate exactly but not by using masters made off of a stock cam. You have to design a new master with the smaller base circle. Just like a racing profile is designed to run with a small base circle.

[JoeWay]

Didn't we go through this toward the end on the old Barn? IIRC, by the time you get a B grind onto an A cam the tip of the lobe is so sharp you can almost shave with it, and it wears out very quickly.

So it is apparently technically possible but not practical.

Joe

[Pete]

Originally Posted by JoeWay

Didn't we go through this toward the end on the old Barn? IIRC, by the time you get a B grind onto an A cam the tip of the lobe is so sharp you can almost shave with it, and it wears out very quickly.

So it is apparently technically possible but not practical.

Joe

Ho hum.....Once again, you use a master designed with a smaller base circle...The nose will end up with the original radius.
And yes, we did go through this not too long ago...
And yes, I still maintain everything you would ever want to know about cam design and grinding can be found in the library.