Identify spec's on re-ground camshafts (?)

[glokkk]

Hello all. I have obtained a package of Morris Minor spares from a deceased estate, amongst which are 3 camshafts. There are quite a few upgrade type items in the lot, like duplex gear sets, a new stainless steel high lift rocker assembly, late HS4 carburettors with matching manifolds, twin HS4 carburettors on an inlet manifold, to name just a few of the items.
I suspect the reground camshafts may be sport type regrinds.The camshafts are carefully wrapped in greaseproof paper with hand written notes "reground". But no other details, or stampings.
I can check lift ok, using a V-block and dial guage; BUT How can l check/measure the lobes to determine the timing of opening and closing ? Any advice from the forum would be appreciated.

[philthehill]

You can check the profile but it is a long drawn out job converting the cam profile to a flat profile. To be honest I would sell the cams as reground/modified. You do not know if they have been ground under the hardening and need re-hardening - so many unknowns.
To measure the profile - you need a pair of 'V' blocks, a digital Vernier gauge and a marked degree plate. Attach the degree plate to the front of the cam and have a indicator marker by the degree plate to mark off against.
Fit the cam in the 'V' blocks and use the digital Vernier gauge to determine the base radius. Turn the camshaft and measure the lift at the marked degrees. Transpose the information to a piece of paper and you should have the cam profile.

Measuring camshaft lift.jpg (54.08 KiB) Viewed 1726 times

cam profile.jpg (170.69 KiB) Viewed 1731 times

[glokkk]

Thank you Phil. Just what l needed, and it makes perfect sense after reading through your reply. This forum is such a valuable resource, especially with contributors such as yourself and others who are willing to offer their time and experienced advice.

[59Elva]

Wouldn’t using the dial indicator be more direct? Also doesn’t the diameter of the lifter result effectively in earlier opening and later closing , longer duration? Or is the cam spec a measurement of only the actual profile not the movement of the lifter?

[philthehill]

The actual profile (steepness) provides a line indicator (as shown in my simple line indicator schematic above) of the actual lift/closing at any particular degrees of cam rotation. The numbers can be obtained by using a dial gauge but using the Vernier is a simple way of getting the same measurements from the base radius.