Originally posted by racerdrew43:
Mr GRJones-
You raise a good point about cam timing. I don't have a Kent motor,and maybe this is a stupid question, but, is there a procedure for checking the cam timing? I always line the crank mark to TDC at full advance (with the timing light)and there is a mark on the cam sprocket to line up at a dot in the head, but, how accurate is that, and what if the block was decked for the extra 1/2 point of compression? This may be fundemental but, you have to learn some how.
THANKS
Drew
Drew,
There is most definitely a procedure for checking cam timing it's called "indexing" or "degreeing" the cam and it is beyond my capabilities and equipment. I have to have a good engine builder do mine. The degreeing business (done with dial gauges and a good background in solid and plane geometry) checks to see that your marks are stamped in the right place due to wear on the keyways or whatever(and of course stock cams have some manufacturing leeway to deal with)to have the valve opening and closing at the right time in relation to the position of a piston in its cycle. (In my effort to put this simply, I'm probably confusing the hell out of the whole thing.)
In any case, you are probably doing the right thing with the marks if you are following your manual, but sometimes when lining up the marks, one can be off one tooth and it makes a world of difference. Also, to my knowledge at least with the Kent, you don't have to worry about ignition timing when you set the timing chain: the marks indicate the correct piston to cam lobe position is achieved. You just line up the marks. It's making sure the marks are indeed lined up and not a tooth off. Again, that's with the Kent, with your marks being on the head, it sounds like you have an overhead cam and TDC and full advance may be part of the process?
If the head (or block)is milled on an overhead cam motor, it will definitely affect cam timing (ask the Rabbit people about that business). The cam will have been brought closer to the crank and loosened the timing chain/belt and affected the geometry (and at least with the VWs the valve adjusting shims and tensioner don't correct the situation). On a push-rod motor (like the Kent)unless you have align-bored your block and deepened the crank in the block, I don't think the crank to camshaft sprocket relationship can be affected (the pushrod angle and length is corrected by the rocker arms and valve lash adjusters). I don't pretend to be expert in all this, I'm sure the real technicians would have a good laugh at my explanation but from what I understand, this is the good poop. Hope it helps and please don't call me "Mr.", I'm having a hard enough time dealing with old age.
G. Robert
[This message has been edited by grjones1 (edited September 17, 2003).]
[This message has been edited by grjones1 (edited September 17, 2003).]
[This message has been edited by grjones1 (edited September 17, 2003).]
