How To: Locate TDC Cylinder #1 on a 2.7 or 2.8 Liter PRV

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Odd fire PRV's have a nifty way to locate TDC #1 (unfortunately not available on 3.0's). It is fast and 100% accurate:

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This is how to do it on an engine with the water pump in place (heater core return line cocks a normal length drill bit over just slightly so it won't slide through the indexing hole in the engine):

Use a 3 inch long 5/16 bolt:

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Bolt before and after dropping into the index hole (index hole is only about 1/4" deep -- bolt doesn't drop far at all):

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Using this method the engine will be 100% TDC Cylinder 1 for whatever purposes you may have thereafter.

Bill Robertson
#5939

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I made a GIF to better show what a bolt looks like dropping into the index hole (it doesn't drop far at all):

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Bill Robertson
#5939

[spikeygg]

Hahah, joke is on me for staring at a fixed jpg that says "MakeAGIF.com"... :P

When it drops, does that mean we're at TDC? If you keep turning the crank it will raise back up?

[DMCMW Dave]

Hahah, joke is on me for staring at a fixed jpg that says "MakeAGIF.com"... :P

When it drops, does that mean we're at TDC? If you keep turning the crank it will raise back up?

No. It will lock the crank.

[content22207_2]

Hahah, joke is on me for staring at a fixed jpg that says "MakeAGIF.com"... :P

I promise you: it was a GIF when I uploaded it. vBulletin changed the first frame into a JPG. I guess vBulletin can't handle GIF's.

It was only a two frame animation -- just load both pictures into a JPG viewer and toggle between them.

Bill Robertson
#5939

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No. It will lock the crank.

I wonder if you could lock the crankshaft this way to break the pulley nut free? Or would you just end up cracking the block?

Bill Robertson
#5939

[Morpheus]

I wonder if you could lock the crankshaft this way to break the pulley nut free? Or would you just end up cracking the block?

Bill Robertson
#5939

I had to do it that way, since I had removed the flywheel prior to the pulley. It worked, but I wouldn't try it again.

[spikeygg]

I promise you: it was a GIF when I uploaded it. vBulletin changed the first frame into a JPG. I guess vBulletin can't handle GIF's.

It was only a two frame animation -- just load both pictures into a JPG viewer and toggle between them.

Bill Robertson
#5939

I made a youtube video of the same thing but I'm not positive what I'm doing yet... :hmm:

https://www.youtube.com/watch?v=yfQWUvmthFo
https://www.youtube.com/watch?v=yfQWUvmthFo

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When the bolt drops into the #6 counterweight hole Cylinder #1 is 100% TDC. Position your timing scale so zero on the scale lines up with #1 cylinder timing notch.

Pretty nifty PRV feature I've never seen on any other engine.

Bill Robertson
#5939