Weekend Repairs/check - Setting the valves

[cp1969]

It's in what you quoted. I'll underline it.

Hydraulic Flat Tappet and Hydraulic Roller Camshaft: First turn the engine in the normal direction of rotation. Start with cylinder number one (1). When the exhaust valve begins to move, adjust the intake valve to zero lash plus an additional ½ turn more. Rotate the engine over again until the intake valve reaches maximum lift and is almost all the way back down. Then set the exhaust valve to zero lash plus ½ turn. Adjust the valves on each cylinder in this manner until all valves are adjusted. If the engine has nonadjustable rocker arms, a lifter preload of .020” to .040” must be aintained. See “Non-Adjustable Rocker Arms” section for proper preload instructions.

Mechanical (Solid) Flat Tappet and Solid Roller Camshafts: Follow the same adjustment procedure. Instead of lifter pre-load, use the prescribed valve lash clearance found on the cam specification card.

The procedure is the same for hydraulic or solid lifter cams...only difference is you're setting hydraulic pre-load instead of lash.

 

[RobJ]

There are acceleration ramps built into other areas of the lobe.

I guess I was looking for more ramps on the cam info. All the ones I've replaced are flat except for the lobes. On some there was a weight on the cam that opened the valve slightly as a compression release. As the engine speeds the weight moves out and awsy from the cam lobe.

Setting one valve while the other is open is just another way to set them.

Thanks,
Rob

 

[cp1969]

I can't find it at Comp Cams site, either. Their paper catalog was much better than their website.

Anyway, I typed in "cam lobe acceleration ramp" into Google and found this

So what's the deal with the cam lobe's center? Why not just track that critical intake valve closing point? The answer, in a word, is ramps. All cams have them. Acceleration ramps which gather up the clearances in the valve train before the valve is shot off its seat, and deceleration ramps which cushion the shock of the valve's closing. The problem is that these ramps move the valve so slowly that determining when it has opened or closed is very difficult. Because of this, engine builders have developed a method of ignoring the ramp portions of a cam when measuring valve movement. The ramp isn't there to move the valves anyway, its sole purpose is to babysit the valve train. These tuners disregard the valve's movement until it has moved a certain amount, which ensures that the valve is well clear of the ramp. That amount is represented below by the dotted line. It is called the "checking height."

at this site: Lobe Center; What is it?

Some good stuff here, too: Cam Doctor - Camshaft Education by: Don Terrill