TDC / decking block

[Divers]

If the engine block is decked then the alignment marks (triangle tips) no longer are valid....Correct?

If true, then TDC is something closer to the 10 degree advance mark, but really is unknown until measured...Correct?

Depending on how much was removed, this could put timing MANY degrees off? Correct? Mostly WAY advanced?


To establish TDC with the head on, I would have to remove 1 or 4 plug on eyeball it (or wooden stick) or better yet find a dial gauge to install and put the stem on the piston head. Correct?

[maytag]

Divers:
the marks are somewhat imprecise from the factory, but decking the block will have no effect on how precise or imprecise they are. If they were "right-on" before, they'd be "right-on" now, after decking.

What you may've read elsewhere is that when you deck the block (or mill the head) without adjustable cam gears, you are moving the cams in relationship to TDC, because the "teeth" on the belt won't allow for very-fine adjustment. So your marks would no-longer line up the way they did.
How far off they are depends on how much you've had milled.

This is EXACTLY why adjustable cam gears are such a necessity.

The real point to take from this though, is that simply finding true TDC with a dial indicator and degree-wheel will not achieve anything for you, unless you also intend to find true Full Lift on your cams the same way. Once you've done that, then you can line everything up EXACT.

Let me say this though: if the marks were close-enough for it to run before, then they are close enough for it to run now.

[Divers]

I don't get it?

If the block material has been removed shouldn't the piston reach TDC sooner than a stock head? So as the crank pulley mark rotates clockwise to the alignment pins TDC will happen BEFORE the 0 degree mark?

[So Cal Mark]

at tdc the crank journal and con rod are straight up, doesn't matter about deck height

[Divers]

thanks...I get it now.

[maytag]

I don't get it?

If the block material has been removed shouldn't the piston reach TDC sooner than a stock head? So as the crank pulley mark rotates clockwise to the alignment pins TDC will happen BEFORE the 0 degree mark?

Divers:
TDC is the point at which the piston is as high as it can go (when you find it with a dial indicator, you'll notice that there is a "dwell period" where it actually SITS there for a few degrees. TRUE TDC is exactly HALF of that Dwell-period) and has NO BEARING on the deck height, cylinder height, piston height, rod length, etc etc etc. it is ONLY a function of crank rotation.

edit: looks like Mark beat me to it.