B or C, Cams, Question ?

[Ron in Quincy]

A few years ago I acquired a almost new B cam; when I set it in V blocks to check the lift I found the following:

All intake lobes had a lift of .321
All exhaust lobes had a lift of .329

A old National Book I have says for the clearances settings of the valves on a 32 "B" engine:

Intake setting: .011 to .013
Exhaust setting: .018 to .021

I know the "B" engine had a high compression head, and was rated at 50 HP.

I used this cam in a rebuilt A engine with a new High Compression Head.
I set the intake valves at .014 and the exhaust valves at .018 . The valves were not noisy and I never had a problem with a burnt valve. The engine ran very strong with good excelaration. I had lightened the flywheel to 39 lbs.

My Question is ? Due to the high compression head of the 32 B did they think the additional heat would cause the exhaust valves to grow ?

Thanks for any thoughts !!!!

Ron

 

[Ron in Quincy]

Forever 4,

I'm aware of the valve lift, both intake and exhaust, on the A engine being the same and the valve clearance settings being the same. Thought someone might have an explination for the different profile of a B or C original cam ?

Ron

 

[Kurt in NJ]

I have a B cam in my car, 3 years ago I had developed a slight miss with a hot engine, I never checked the compression with a gauge, but hand cranking cold, then hot told me that it was compression loss.

I decided to check the valve adjustment and found that #3 ex valve clearance was .010, , I have adjustable lifters, with original ford valves, the later ones that I think are a form of stainless (the ones that are never rusty even when exposed for years) adjusting the clearances brought back the smoothness --I still have not checked the compression with a gauge.

Is it possible that the change in clearance for the B is more because a change in valve material ---stainless expands at a rate of about 1.5 times that ordinary steel expands.