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Discussion Starter · #1 ·
I take it when trying to find TDC on a dome piston, the stop does not need to contact the dome, but the area that is not the dome. Is this correct?
 

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Discussion Starter · #3 ·
Reason I ask is this.

I did it once with stop hitting the dome and when I got TDC the dome was flush with the deck.

When I did it with the part of the piston that is not the dome then I got that part even with the deck. The dome was sticking up over past flush with the deck.

Which is correct?

I kind of think the second is.

Is there one better for degree a cam?
 

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66 El Camino 57 Chevy pickup 2004 Tahoe
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you can use a short 7/16 (1/2 or 3/4) coarse thread bolt with a big flat washer for stop if you have a dome piston. just snug the bolt up on the washer where the washer will hang out over the dome and stop the piston.
 

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Discussion Starter · #5 ·
So..its's better to allow it hit the dome?
 

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Discussion Starter · #7 ·
Don't have the balancer on.

I lined up the dots on the crank and cam gears and then proceeded to find TDC. Then I need to check my degreeing.

So... Do I let it hit the dome or not.
 

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66 El Camino 57 Chevy pickup 2004 Tahoe
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you don't seem to understand the process. bring the #1 piston to TDC by eyeball. install your degree wheel and set a pointer to zero. then turn the engine so the dome is well below the deck and install the bolt/washer. turn the engine clockwise til the piston hits the stop. Mark the degree wheel or write down the number at the pointer. THen turn the engine CCW until the piston stops again. mark the degree wheel again. halfway between the two marks is TDC so add them them and divide by 2. bend or move the POINTER to that halfway mark, then repeat the process. you may need to adjust the pointer a couple times until you get the same number of degrees on both sides when you turn the engine both ways again.

At that point you have perfect TDC and can remove the bolt/washer. Don't bump into or otherwise move the pointer from then on. If you move the pointer or the wheel at all, start over.
 

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Discussion Starter · #9 ·
Tom

I understand the process, but what I'm confused on is the hitting of the dome or the hitting of the "rest of the piston."

From my early post. When I hit the dome, then the TDC ends up being flush with the top of the dome. When I hit the "rest of the piston", then the "rest of the piston ends up being TDC with the dome sticking out of the deck.

I don't understand that. Of course, it probably does not matter at all.

However, I did not check the # of degrees from TDC each way to see if I was off.

First time degreeing by the way.
 

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66 El Camino 57 Chevy pickup 2004 Tahoe
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>> However, I did not check the # of degrees from TDC each way to see if I was off.<<

there you have it.

do it again per the procedure, it will work.
 

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Tom. As TM said, It doesn't matter how far the piston moves up. The key is to stop the piston at a point (any point) on the clockwise and counter clockwise rotations and record those #'s. Add them and divide by 2 to get TDC.
EX. clockwise stops at 160*, counter clockwise stops at 200*, 160+200=360 divided by 2=180* TDC
You need one of these
 

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To answer your question, the dome will stick up into the chamber, above the deck when you are at TDC. But for the purposes of finding it, it doesnt matter what part of the piston is bumping the stop. You only use that to find your two points of measurement, as Tom described.
 
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