E: Engine Curved cam followers

vibrac

Well Known and Active Forum User
VOC Member
My understanding is the radius followers act like a "Roller follower" to reduce the savageness of the opening and closing of the valves. The timing of which should not change in reality.......... I have only had experience with those that Terry Prince sells, and his specs are to set the timing on the inlet valve at a certain amount of lift with the piston set at TDC. I would start with our usual method of equal lift inlet and exhaust with the crank at 4 degrees BTDC thus giving the cams an advanced setting. Bill may be right about the pushrod length, on the racer I had to have shorter ones made, and because they are shorter, they are harder to install and I used something like a piece of plastic straw to hang onto them. You might find it much quicker and easier to fit the pistons without the rings on, the barrels minus any base gasket, and fit the head with a couple of washers and hold down nuts ........ So no pushrod tubes to get in the way, this so you can check everything much easier. If you press the rear cam into the pinion only about half way, you can carry out the valve timing and piston clearance checks fairly quickly to see if you are going to encounter any issues, and the cam/pinion can be altered again much easier if the pinion is not pressed on fully. The piston/valve clearance can be done easily given you need to disassemble very little to remove the head without the pushrod tubes getting in the way. Once you get some results then you can aim to finish things off correctly and the base gaskets will give you another 6 to 8 thou extra piston clearance. It is possible that the radiused followers can lift high enough to clip the bottom of the pushrod tubes, especially if the cams have a lot of lift, this is easy to check, again whilst all the "Loose assembly work" is being carried out. Cheers and good luck .........Greg.
Fortunately the twin engine I am going to loose assemble next week is with MK2 cams it's the modified pistons I need to check.
I think it was Ron Kemp or one of the elders and wise ones of the 60's who had a cam wheel that a cam could press into by hand and secure with a low locktite grade to check its effect on the timing and clearances before being removed by a bit of heat, further modified or inserted in its real wheel.
 
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davidd

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VOC Member
An old gear (shown on the left below) can have the bore enlarged on the lathe. Press an aluminum ring in and then size it on the lathe for a good push fit. I don't think the cam can be damaged or altered going into the aluminum.

Updated Cam Machine 2017  (2).jpg


David
 
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