Who knows cam shafts ?

[pearljam724]

Thing is, at TDC there's about 4 degrees of rotation where the piston doesn't move.... so by using a dead stop bring the piston up till it stops, mark that spot, then rotate the other way till it stops & mark again, now find the mid point between those two marks & you have true TDC...

Ok, I ll take your word for it and I know you’re correct. With a dial gauge when it’s at tdc. You can move the piston within that 4 degrees and the dial won’t move until the piston is about 4 degrees in the other direction. The dial gauge is best suited for a piston rotation that is perfectly vertical. I was wondering about using it being a V-8’s rotation is not. I think the difference of each tool according to piston angle is important too perhaps.

 

[1 Wild R/T]

Ok, I ll take your word for it and I know you’re correct. With a dial gauge when it’s at tdc. You can move the piston within that 4 degrees and the dial won’t move until the piston is about 4 degrees in the other direction. The dial gauge is best suited for a piston rotation that is perfectly vertical. I was wondering about using it being a V-8’s rotation is not. I think the difference of each tool according to piston angle is important too perhaps.

At the end of the day my okie screwdriver method posted above will at least give you a good idea of whether the marks are close or completely wrong... Which would at least get you a starting reference...

 

[pearljam724]

At the end of the day my okie screwdriver method posted above will at least give you a good idea of whether the marks are close or completely wrong... Which would at least get you a starting reference...

And I ll take your advice also, my friend. Thank you

 

[moparedtn]

Yup, the dead stop works very well & is 100% accurate if used correctly.... Unfortunately I've seen a thread where the person used it wrong IE didn't go slow & cracked a piston....

Holy crap, they did that while just hand cranking?
That's a pretty ham-handed touch, right there.

 

[moparedtn]

And I ll take your advice also, my friend. Thank you

Here's a pic to demonstrate what I found when I did mine a while back.
This is a 440, but the idea is the same. Note the little hash marks on the balancer, before and aft?
That's where the TDC stop tool stopped the #1 piston in either direction of rotation. Split the difference exactly
and you get true TDC - and as shown, mine luckily wound up dead on the money in this case:

From there, set the mark on the indicators' TDC mark (as shown), then go about
getting the rotor button in the distributor to point at the #1 plug wire in the cap
(on the compresson stroke, of course) and you're in the neighborhood.

I could have gotten even more exact with the use of timing tape, but that stuff is aggravating as heck
to me to get it to stick to the balancer.
Yes, I'm a shadetree…
Hey, it works.

 

[BeepBeepRR]

Here's a pic to demonstrate what I found when I did mine a while back.
This is a 440, but the idea is the same. Note the little hash marks on the balancer, before and aft?
That's where the TDC stop tool stopped the #1 piston in either direction of rotation. Split the difference exactly
and you get true TDC - and as shown, mine luckily wound up dead on the money in this case:
View attachment 810719
From there, set the mark on the indicators' TDC mark (as shown), then go about
getting the rotor button in the distributor to point at the #1 plug wire in the cap
(on the compresson stroke, of course) and you're in the neighborhood.

I could have gotten even more exact with the use of timing tape, but that stuff is aggravating as heck
to me to get it to stick to the balancer.
Yes, I'm a shadetree…
Hey, it works.

Stick it on then clear coat over it..

 

[Dan64]

Use an inexpensive "piston stop" instead. It's much more accurate and makes checking the timing mark a lot simpler.

Install the stop and turn the engine in one direction via the crank bolt until it lightly stops against the tool; mark
where that hits on the dampner.
Reverse the rotation of the engine and when it again stops against the tool, mark the dampner there, too.
The point exactly halfway between the two marks is your true TDC.

This is the one I have:
https://www.summitracing.com/parts/pro-67581

Do this

 

[Lefty71]

If you have an OEM damper, you go through this process of finding top dead center, then marking it on the damper. If you find that the outer ring has slipped, then its junk and you need a new one. If you should go to the trouble of pulling the valve covers to identify the cam with the dial indicator and timing tape, you are going to want to do the damper troubleshooting first. This is really secondary, just to educate yourself as to what cam lies in there without teardown. You would put the dial indicator over the tip of the valve (or centered on a rocker over the valve tip) and then roll the motor over measuring the lift and using the timing tape to identify the timing events to learn the max lift and duration so you can compare it to popular cams that are out there. Youll have to do one exhaust and one intake, but all this is just for your knowledge.