Topic: Timing the Cam

[Phoenix]

All stock parts with JMR head and Cruzin 836 head.  Head/jugs shaved total of .010.All hooked up and ready for timing.  I centered the cam and set the ignition to “T 1-4”.  I hooked up the Timing wheel and set it to “0”.  #4 was at the top so I backed it up and inserted the piston stop.  Turning it forward, it stopped at 36 1/2, the other way I got 39 ½.  So…. If I add them and divide by two I get 38.  So I set the wheel to 38 at the stop.  That will then mean the “o” will be tdc and it will swing back and forth and stop at 38 on each side.  Then I set the timing wheel to “0” and tighten the cam sprocket and set the cam tension.  Is that correct?  Any insight will be greatly appreciated.  Been working on this since Memorial Day.  Can't wait to buckle it up and get rolling on it.

[Davez134]

What cam? Here's why it matters...Your way of finding tdc with the piston stop is correct. The initial numbers don't mean really anything except as a way to "average" where the true tdc is obviously. The important part is to note the position of the crankshaft at tdc (I used the marks on advancer plate) and set the pointer to 0 on your wheel. Now to actually time the cam (with adjustable sprocket) you need to make some adjustments and calculations to get the lobe centerlines of intake and exhaust as close to the same as possible. If you are using a factory cam, none of this really matters, and you don't even need a wheel. Just line up the factory marks per the manual.

[Phoenix]

Dave
Thanks for the quick answer.  It is a stock cam.  If your theory is correct, when I center the swing and have tdc, it should show that T 1-4 in the window.  I f that's the case, then I shouldn't have to worry about centerlines. My concern was with the fact that .010 was shaved off.  Thanks again.
Ed

[Davez134]

Correct. Any changes in deck height will effect the timing of the cam (however small in your case). I don't think there will be any benefit to you with the stock cam moving it a degree or 2. Do you have an adjustable sprocket? If you are using stock cam sprocket as well, there really is no way to degree it anyways. Just get 1/4 at tdc, line up the line on the cam with the marks on tower and call it a day.

[PeWe]

With std cam and not adjustable cam sprocket the true TDC will be useful anyway. Ignition mark F can be aligned with corrected case mark. My adv unit show correct at left side of its play, counterclockwise.

With ported head a hotter cam will do much. But the cheap cruzinimage 836 pistons have small pockets so the cam cannot have long duration/high lift. "Cams for stock engine"
 There are threads about it.

[Jerry Rxman Griffin aka MuthaF'er]

You've gone over to the dark side already with Mike's head. Now you need to drop another measley $300+/- on a cam. That is the cheapest upgrade you can do and SHOULD do with the head work. If your budget is tight just wait a little longer and do this right.