How to check condition of camshaft

[Fast31]

I am offered a Model B cam. As I read that those cams can be worn down badly at the nose and not deliver the power anymore, I want to measure the lobes before I buy it.

I found that model A camshafts give an intake/exhaust lift of .303” and model B camshafts give an intake lift of .334” and an exhaust lift of .341”. I don’t see how I can measure that on a separate cam though.

I would like to measure the lobes with a caliper from the bottom of the base circle to the top of the nose. Can anybody give me the dimensions for that for the model A and model B cam?

[wrndln]

What I do is measure with a mic the bottom to the top of each lob. It is also a good idea to measure the 3 or 5 cam bearing diameters. If they are all very close to the same, the cam is probably OK, but not guaranteed to be. I have seen cams that 1 or 2 lobs are worn more than the other ones. Also looking at the lobs for wear and pitting can also help determine if the cam is a keeper. There is probably some place where the bottom to top is shown.
Rusty Nelson

[ursus]

Go to http://www.fordgarage.com/pages/camshaftspecs.htm for the original dimensions.

To check, measure the total dimension of the lobe and base circle, then measure the base circle at 90 degrees from the lobe, and the difference is the camshaft lift. On a reground B-camshaft, the dimensions will be different than original, but the lift could be more or less depending on how it was ground.

[Fast31]

Ursus thank you for your help.

[Tom Wesenberg]

The Model B cam also used lifter with a larger diameter foot.

[100IH]

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Good thing do if you have never done it before, measuring with a micrometer. Dial indicator down through the empty guide hole would give a direct answer. Two other things to check out though. The journal diameters and block inside diameters for excessive clearance and the helix bear at the center of the shaft. Teeth get worn razor thin causing slop in ignition timing.

[Jim Brierley]

Measure with your caliper, side-to-side, then top-to-bottom, subtracting the first from the last will give you total lobe lift. B cams came in 3 different lifts, .304", .315", and .339" some were copper plated, some were not. Center bearing measurement is important too, 1.560" is standard, 1.556" is acceptable.

[Fast31]

Originally Posted by Tom Wesenberg

The Model B cam also used lifter with a larger diameter foot.

I was lucky, those were already in my block.

[Fast31]

Originally Posted by Jim Brierley

Measure with your caliper, side-to-side, then top-to-bottom, subtracting the first from the last will give you total lobe lift. B cams came in 3 different lifts, .304", .315", and .339" some were copper plated, some were not. Center bearing measurement is important too, 1.560" is standard, 1.556" is acceptable.

Jim, thanks for your reply. And thank you for taking the effort to publish the second edition of your book. I learned a lot and it’s also fun to read.

[Jim Brierley]

Your welcome! It was a fun project for me to do, and I am still in awe over the acceptance of it.

[Fullraceflathead]

You know its "Speed Demons" like Jim Brierley that make us Model A owners keep Voiding Our Warrantee's!!!

[zzlegend]

I will take speed over warrantee any day.

[Fast31]

The voices tell me babbits are bad and must be punished ;-)

[Jim Brierley]

Babbitt is not bad, Offies used it for years and I have many runs at Bonneville on it, 167 in 2013. Years ago my ambition was to qualify for the long course on the salt, 175 mph. Now I want to go 200 with banger power. A guy has to have dreams you know!