Degreeing cam's on milled heads?

[Streamln1]

I have been reading some posts about degreeing cams for milled heads even on stock cams.

Can someone explain to me how a stock cam and gear can be off zero even with milled heads? The lobe position is not different from stock, I understand the total travel of the belt may be slightly different.


Not sure if its even necessary for my build but its something I want to look into, I know I am still slightly under the max milling spec, even though I am running thicker gaskets.

[RealMcCoy]

I did the math on it at one time, but I don't remember the exact measurements... One tooth of the belt was about .250" IIRC. Each tooth = 15 crankshaft degrees. .250/15=.0167 so .017" = 1 crankshaft degree.

One camshaft degree = 2 crankshaft degrees.

If you mill the max allowed by factory spec, (.008") you will move the rear cams .5 crankshaft degrees.(.025 cam degrees) Due to the fact the belt crosses the plane of the head three times on it's way to the front cams, that number is multiplied by three for the front cams. (1.5 crankshaft degrees, .75 camshaft degrees) Those numbers keep the variation under 1 degree, and are acceptable for a stock application.

Run those numbers with .020" milled off, and you'll see why you should degree your cams....

If you have thicker head gaskets to compensate for what is milled off, then you may be pretty close to stock cam height... If so, It's probably not a big deal for you.

[Streamln1]

Im back to the stock milling limit with headgaskets to compensate, at a total height at 5.85" if you add in the gaskets extra .015".

So, basically whats going on here is the front and rear heads are actually closer together slightly so the timing belt would be a bit shorter so the timing marks will not line up perfectly as they would at stock height and would need to be degree'ed with adjustable cam gears to get back to acceptable spec?

[RealMcCoy]

When you mill the heads, or deck the block, the distance between the cam sprocket and the crank sprocket changes. (They get closer together) the belt didn't get any shorter, so what is going to change? The cam gear is going to turn the amount of the length difference... (times three for the front head)

[Streamln1]

Gotcha. Puts the cam gear half a tooth off of so from the crank sproket