Determining TDC on Vortec heads

[4C FED]

Since I switched to a Fluidamper and a Tavia adjustable pointer I need to set the pointer & damper & TDC.

I tried to use the TDC stop tool from Summit/Jegs but it seemed with the dished pistons and the angle of the sparkplug holes, the piston would never reach the TDC stop.

Anyone else ever noticed this and how did you get around it?

 

[Blake]

Determining TDC on Vortec heads

I'm getting ready to do this myself. I've read that lots of people do first what you have already done for one reference and then turn the engine the OTHER way and then get your second reference. Then you find the center between these two reference points and that is true TDC and that is where you will put your pointer.
Hopefully I'll be doing this real soon.
HTH
If this does not look right please answer up so I don't dork up mine
George

 

[4C FED]

OK, but at what point does the TDC stop come into play?
You need some way to physically determine when the piston has reached TDC.
The motor is assembled and in the truck, so I'm limited in the methods to determine TDC.

I recall seeing something that was like a whistle that went into the sparkplug hole. So when it reached TDC, the whistle would stop.

Anybody tried/seen this?

 

[Blake]

That will be your TDC. As the piston comes up in one direction, it will hit the stop before it make it to the top. Then, as you turn the crank the other way, as it comes up, it hits the stop. I try to imagine it as a circle. It would be like you drew a circle and left a small arc out of it. The you could eyeball the mid point of the arc where you think the circle would pass through if it were completed and put a dot there. This is your TDC on your balancer you just found.
Hope that made sense.
George

 

[smeagol]

Blake - I think he's aware of that method, just that his piston stop isn't hitting the piston.

Might need a longer piston stop?

 

[myclone]

Is this the piston stop you have? If so it should reach.. FWIW.. I don like the whistle thing.. Tooo much "guess work" involved with that one.

 

[Blake]

I think I see what he's saying now that I've reread it but it seems like he could just run the bolt out farther or put in a longer one. It doesn't seem like the dish would matter as long as he could make some kind of contact. This is the first time I've heard of someone having this kind of problem with a TDC stop.
Most just make them out of a tapped spark plug with a bolt in it and have no trouble. That sucks. I tried anyway.
:roll: George

 

[4C FED]

Is this the piston stop you have? If so it should reach.. FWIW.. I don like the whistle thing.. Tooo much "guess work" involved with that one.

That's the one.
But I had it screwed all the way in and it just wasn't hitting the piston.
I'm thinking maybe I can wrap some tape around the end, just enough to still fit through the plug hole and see it I get any contact that way.
Or maybe, like Brian suggested, I'll try using a longer bolt instead of the one that came with it.

I'm thinking I might be able to start it this weekend and this is one of the loose ends I have to take care of. Granted, it's not imperative to know before I start it, but I'd like to get it taken care of.

 

[4C FED]

I think I see what he's saying now that I've reread it but it seems like he could just run the bolt out farther or put in a longer one. It doesn't seem like the dish would matter as long as he could make some kind of contact. This is the first time I've heard of someone having this kind of problem with a TDC stop.
Most just make them out of a tapped spark plug with a bolt in it and have no trouble. That sucks. I tried anyway.
:roll: George

I just looked at my old stock heads and the Vortec's on the truck, as best as I could.
It looks like the plug hole on the Vortecs is parallel to the deck surface on the head, whereas the plug hole on the stock head angles downward slightly towards the deck surface.
Maybe it's just an illusion. :-?

 

[myclone]

Is this the piston stop you have? If so it should reach.. FWIW.. I don like the whistle thing.. Tooo much "guess work" involved with that one.

That's the one.
But I had it screwed all the way in and it just wasn't hitting the piston.
I'm thinking maybe I can wrap some tape around the end, just enough to still fit through the plug hole and see it I get any contact that way.

I'm thinking I might be able to start it this weekend and this is one of the loose ends I have to take care of. Granted, it's not imperative to know before I start it, but I'd like to get it taken care of.

Hmmm. First time Ive heard of that.. Here's what Id do (not that you'd wanna do ANYTHING I would do ). I have access to a lathe so Id find a nut that fit the center "bolt" part of the stop and turn the nut down so it wouldjust barely go through the plug hole. Screw the nut on the center "bolt" and sucure it with some tape/loctite/whatever. Install said nut, "bolt", etc in the #1 cyl. Hopefully the now "bigger" bolt would contact the top of the piston. Other than that I dunno since its already screwed all the way in. IMO tape would "give" once the piston contacted it and your TDC readings would be off a few degress. Thats just MO though..

HTH...

[note to self: DO NOT quit drinking while trying to quit smoking]

 

[Blake]

I don't know if this will help at this point, but I read where someone had a helper wrench the engine over while they held a new pencil in the spark plug hole. When they felt it touch the pencil, they new they had it. With the small diameter of the pencil, you could could probably get a steeper angle on it. Didn't mean to imply you were a dumbass when I explained the process before Didn't realize it wasn't making contact with your stop.
George

 

[4C FED]

I don't know if this will help at this point, but I read where someone had a helper wrench the engine over while they held a new pencil in the spark plug hole. When they felt it touch the pencil, they new they had it. With the small diameter of the pencil, you could could probably get a steeper angle on it. Didn't mean to imply you were a dumbass when I explained the process before Didn't realize it wasn't making contact with your stop.
George

No, sometimes I am a dumbass (see my post about blowing DM fuse).
Sometimes what I'm thinking is not what I'm typing, so I may not 'splain it so well.

I'll have to play around with it this weekend, cautiously.
My greatest fear is that I don't want to mess up a piston trying to get this right.