blown 87

I have been wondering how accurate the indicator on the crank hub is, now I know that it is off by a degree or two.

Everything will get cleaned and painted or powdercoated before it goes back together.

Here is the dial indicator for finding TDC.



The degree wheel



The hub at TDC, you may not be able to tell from the pics, but it is off by a couple of degrees.



I really need to clean the shop up, maybe tomorrow.



Here is the project 928, it is getting ready to go to the body shop the first of next week, I have to pull the door panels, mirrors, front and back covers, ETC.



I hope every one has a great weekend.

Greg Nettles

ZEUS+

A dial indicator is very accurate, for exact TDC the piston stop method is exact. Degree wheels are not always perfect either. You can check a degree wheel by laying it flat on a piece of cardboard. Make a mark every 90 degrees. If the wheel is on the marks will line up as you rotate.

Bill Ball

I saw the comment that the crank TDC mark can be off 4 degrees. How does this happen? Is the balancer two-piece?

worf928

There's probably enough 'wiggle' in the screwed-to-the-water-pump indicator to make it a +/- 1 degree indicator. Looks like it's off by about one degree.

blown 87

I will check it again after I get the heads off, but you can get very close with a dial indicator.

There was only a couple of degrees with no piston movment. Some of the motors I have done have had a bunch of "null".

blown 87

It does not look to be a two piece unit, I think Worf928 is right about the indicator, plus the usual stacking of production tolerances.

ZEUS+

Piston stop can be done with heads on.

blown 87

Have you ever found a large degree wheel to be off?

I had never thought of checking it, hmmm, maybe I better do that.

ZEUS+

One from cam dynamics.

blown 87

You are right, of course. I will kill a spark plug and make one tomorrow.

I just normally do it with the heads off, and check the crank to make sure there is nothing off there between cylinders.

blown 87

Damn, was it a pro one or a small one?

I just really want to see how far off the cams were, anybody out there got a Porken 32 valve tool?

ZEUS+

Use a bolt that is close to the wheels center hole diameter for rotating. Hopefully moroso makes a better wheel !!!

ZEUS+

Dont remember, it has benn tucked away since my hot rodding days. You just compensate if the difference is minor. From what I do recall larger wheels are the most common for not being accurate. Things are more precision now, it will be fine.

Mike Simard

Do they make degree wheels any bigger than that? Just think how accurate that would be!

blown 87

Got to be big for a old fart like me to see the little lines.