Locating TDC on 452 heads

[Speedbird]

Let me try and keep this stupid question simple.
452 heads.
I did the following last week.
I used a quickly improvised piston stop made from a spark plug in an attempt to locate true TDC and see if my dampener markings were spot on.
The stop has no "play" in it though.
The method we use is to go a little past TDC and set the stop.
Then continue rotating the same direction and look for the piston to stop again before reaching TDC.
Then mark halfway between the two points. That is true TDC.
And even I've got a valve cover off to watch the valves.


When I did this I was able to turn the engine past where it should stop as I continued rotating and then further past TDC.
I'm going to try again tomorrow with more time and a better stop.
I'm sure there is nothing wrong with the engine.
My only question is it appears that on these heads the spark plug seems almost if not completely parallel with the top of the piston.
So I'm wondering if the stop isn't going back and forth in relation to the cylinder instead of up and down.
I have done this procedure with heads where the spark plug is more perpendicular to the top of the piston with no problems.
Does this head design make this method somewhat tricky?
Thanks and keep the faith.

 

[747mopar]

When I did my 452s the piston stop had to be extended quite a bit, that was with flat top pistons and a deck milled to zero deck height. Sounds like you need a longer stop?

 

[moper]

Yeah, it's laid way back in relation to the piston. Plus, those big open chambers leave a lot of room, and if they are stock pistons they're deeper in the hole... So as was said - get a longer stop.

 

[IQ52]

When using a piston stop through a spark plug hole it is always best to remove the rocker arms from the cylinder in which you are using the stop. Depending upon the cam lift, the valve diameter and the spark plug angle a valve will hit the piston stop and bend the valve. Yep, I forgot to remove the rocker arms once.

 

[khryslerkid]

When using a piston stop through a spark plug hole it is always best to remove the rocker arms from the cylinder in which you are using the stop. Depending upon the cam lift, the valve diameter and the spark plug angle a valve will hit the piston stop and bend the valve. Yep, I forgot to remove the rocker arms once.

I totally agree and I had the same thoughts before useing the stop that I made. I have the 452 heads also and with stock valves, there is no way the valves will contact the stop useing a 3/8" dia. bolt.

5/16" drill, 3/8" tap
And it is very flat to the piston. You have to play with it a bit. Not enough it will go past on the way back...

 

[coloradodave]

Great write up, khryslerkid. Super high def pictures. Thanks.

 

[khryslerkid]

Thanks Dave. I posted making the stop in this thread. A little more detail...

http://www.forbbodiesonly.com/mopar...ade-tools-lets-see-them.56433/#post-910446556

 

[Cranky]

Over sized valves won't hit the stop either?

 

[khryslerkid]

Over sized valves won't hit the stop either?

I only stated that on my stock 452s and stock valves, it didn't. I had the same thoughts about the stop interfering with the valves and checked it out before useing it. Other applications and valve sizes it might and in IQ52's past experiences it has. It's something you can safeguard yourself by removing the rockers or pushrods for that cylinder.

 

[IQ52]

Aftermarket aluminum heads point the stop right at the exhaust valve.

 

[Cranky]

Aftermarket aluminum heads point the stop right at the exhaust valve.

That was going to be my next question since I didn't think about it before