Sprint engine rebuild valve timing

[cleverusername]

I have all the valve gaps, is that the right term?, set. So I have to now put the head on the block, which means timing it all properly.

I think i can set tdc in the block with a dial gauge on piston one. I have lined up the marks on the head, but it doesnt seem right. Exhausts valve are slightly open on cylinder one and inlets on four. Surely one of these should have all four closed for the power stroke?

[tony g]

Sounds like the cam is 180 degrees off. Turn the cam 180 so you get No1 valves shut and a mark on the cam will line up with a mark in the front cam cap.
If you use a dti to set tdc (the best way) have a look at the crank pulley timing marks relative to the pointer. This will tell you if the original timing marks are correct and when you do ignition timing you can compensate slightly if needed to.

Tony

[cleverusername]

Thanks, that does sound right, I think it is 180 degrees out.. This is not something I want to screwup, bending valves after all this work would not be fun.

[soe8m]

180 degrees out will cause the same. Just switches between cilinder 1 and 4. More a 90 or 270 degrees out.

Jeroen

[Jon Tilson]

Jeroen is right...
TDC on 1 and 4 is every crank rotation and the cam goes at half speed.

Make sure you have the right mark on the cam, but then measure inlet valve peak opening point which is in the 106 ATDC region depending on your cam.

Jonners