valve clearnce

[81 clark racing]

im putting in a stage 2 hot cam in my 400ex and when i go to adj my valves can i adj them to hotcam specs or is it different because i have a curtis sparks adv timeing key (+6) ?

[GPracer2500]

The timing key will have no impact on what you should set your valve clearance to.

[81 clark racing]

so i can set it to hotcam specs and be all set even tho i have the adv timeing key in?

[GPracer2500]

Yeah. Ignition timing and cam timing are two seperate things. The Curtis Sparks key relates to ignition timing. Setting the valve clearances relates (sort of) to cam timing. Cam timing, ignition timing; not the same thing.

The only impact a flywheel key could have on setting valve clearances is on the procedure you choose for finding TDC. Most people use the marks on the flywheel to find TDC when setting the valves. I'm pretty confident you could still use the same "T" mark on the flywheel to find TDC when a timing key is installed even though the key shifts the flywheel a bit. You don't have to be exactly on TDC to stay on the base circle of the cam (which is where you need to be to set the clearances). You've got a bit of wiggle room on either side of TDC. Although I haven't checked for myself to be 100% sure, I doubt a 6 deg change in flywheel location will cause trouble if you still use the same "T" mark. Just make sure you've can feel a bit of up/down play in the rockers when you go to adjust the clearance and you can be assured you're still on the base circle of the cam.

You can always just turn the flywheel a tiny bit past the "T" mark when finding TDC. Actually, turning it 6 deg past the "T" mark would completely compensate for the key. Or don't use the "T" mark at all and find TDC an alternate way.

But none of that has anything to do with what the valve clearances should actually be adjusted to. You adjust the valve clearance to the same spec no matter how you've got your ignition timing tuned.

[81 clark racing]

awesome thank u