Jack from HCI informed me that he can provide cam data for plans purchasers. This data was not included in early versions of the plans but HCI has provided G-code upon request. The engine I'm making is different than the original plans so a little research was needed. I found that cam design was an advanced science and required math skills which were beyond mine so I took the simplest approach which would yield acceptable results... I copied another cam with values close to what I needed. This is not an ideal way to approach the problem and the ramps are probably a bit gentle for a roller follower but at least it should work.
After finding an automotive cam close to the specs desired I cut it up and used one lobe as a master. For lack of a better description I built a cam translating tool which generated a four lobe cam using a single lobe as a master. All I needed were some numbers so the plate cam was cut from wood using a cutter the same diameter of the follower that the cam was going to use. With the wood blank cut to size I then scanned the plate into CAD and proceeded to measure the rise/run data. The radius of the plate cam and it's roller follower is what made this machine necessary. It would be a pain to plot otherwise. (Unless you had some expensive software) This method seems to be the most foolproof means of getting a decent profile for the average Joe.
On my seven cylinder radial there will be two identical 4-lobe cams.The final cams will be machined one degree at a time using a convex cutter which has the same radius as the follower will. After machining, the cams will be heat treated and then lightly ground using a wheel the same diameter as the follower.
Cam translating tool with micrometer adjustment. It is missing the bearings and cutter because it was pulled it out of storage for the picture. Half of the aluminum parts I cast and machined. It got the job done! :)
The translating assembly also allowed for varying the lift of the cam. ( I kept it 1/1 for accuracy) One great stroke of luck was finding the linear bearing assembly at the local salvage yard. Frictionless and VERY smooth!
Data for 4-lobe cam with 6" base circle 1" diameter roller follower/cutter and .405 lift.
This data is for half a lobe. Simply reverse to get the other half.
Deg Lift/degree
333-270
334-260.0023
335-250.0055
336240.0097
337230.011
338220.012
339210.013
340200.0137
341190.0156
342180.019
343170.0218
344160.0239
345150.0335
346140.0518
347130.0793
348120.1148
349110.1531
350100.1939
35190.2396
35280.2731
35370.3044
35460.3296
35550.3519
35640.3713
35730.3863
35820.3955
35910.4038
36000.405 - max lift
The lift is much higher than the plans called for. This was taken into account when designing the combustion chambers for casting. My thought is that more lift is needed since the L-head design breathes poorly. Only the finished engine will tell.
The following picture is shown on another page but I thought it would be appropriate here as well.
Valve has had it's face machined flat and took the place of a flat follower. A greatly reduced drive turns the cam master about 8- 10 RPM. For the four lobe cam a 1/4 reduction was used. (12 & 48 tooth gears)
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