SupraSport

Guys,
I need your advise on installing my ajustable cam gear I bought from LC.

The head has been decked .030" and I need to adujust the timing, since this has created some slack in the chain.

If my thinking is correct the height reduction will cause the valves to be slightly retarded? If so, I should advance the cam gear to compensate.

Is this correct?
How many degrees should I compensate?

Thanks
Aaron

SupraSport

Oh, in case it matters, it's on an 89 Runner.

Thanks for the help, I'm dieing to get back on the trails!!!!

javadoody

there may be a simple function to figure this out, but: if we consider an angle created having the opposite side at .030 inches (your head) and the adjacent side of the radius of the cam sprocket (on the '93 it's 2.24 inches), the tangent is approx 0.013. this is the angle, so you would attempt to advance just over a tenth of a degree. blow it off.

i know i'm generalizing with this, but close enough . . . .

there are a lot of intelligent folks on this site, let's hope some of them chime in too, cause i can stand corrected.

superjoe83

to do it correctly you will need a degree wheel

Yoda

Yes it would need some advance on the cam. I don't know how much (2-3 deg?)

javadoody

OK, i finally figured out what i did wrong. i skipped a step.
i needed the inverse tangent to tell me the angle whose sides have that ratio ( 0.1339). i just did it, and got .767 degrees.
advance about a degree.
sorry, this mind has never been a terrible thing to waste.

SupraSport

Hhaha!!! great thanks. sounds about right.

84sr5yoty

I belive engnbldr stated somewhere that the gear should be advanced 1 degreee for every .010 shaved off the head/block.