Just another deck height question Options

[Joe Ricard]

Been wrestling it for days now. Here is what I think I have. .040 shim under the cylinders. Mocked everything up with heads and valve train for #1 cylinder. Put clay (playdough) in the combustion chamber. Rolled engine through a complete cycle.
Pulled it apart and measured as best as I can .045 squish to the piston crown to head. Stock 2.0L valves have plenty of room 1/4" or more. Pistons are U.S. with 5 cc dish.

Heads have never been flycut I cc'ed them at 62.5 (as close as I can tell. This gives me 8.02 : 1

I have been playing with a dial indicator, big fat ass square stock bolting down across both cylinders one across the top one across the bottom. Measuring with feeler gauges I was getting .035 to .036 deck.

Obviously having an accuracy problem. However I feel pretty confident I am consistent between all cylinders.

So after all you gear heads evaluate my work also tell me if I am in the ball park or need an adustment somewhere.

[SLITS]

If you are trying to get the deck height on all pistons equal........just measure with a sliding venier(as I call them) and subtract the thickness of the bar. Measure at the edge of the piston.

(IMG:http://www.rccauto.com/ebay/p1010003.jpg)

If you are determining piston to head clearance, the clay should have been on the edge of the piston, not the center. Playdough would not be my choice.....modeling clay would be. I oiled all surfaces so the clay would not stick to one or the other when pulled apart.

The dial indicator is great for determining runout, end play, cam timing and finding TDC...not much else.

[Joe Ricard]

Thanks, I did make the clay extend to the edges of the piston. Oiled both surfaces no sticking. Got to use Green Playdough because my 4 yr old said so. Sump'n about Green Rangers (Power Rangers) I guess.

Been going through all the past threads about deck height. LOTS OF THEM. So I know I am not alone. I seem to have done all the different methods each giving different maesurements.

Yes I have a vernier caliper.
The different deck specs are amazing some say they use .030 on race motors, found someone swears by .037 others .040 another said .057 I have been playing witha new compression ratio calculator and the deck makes some difference not drastic. CC's of the head make significant changes even .5 CC's

[SLITS]

Deck height to me is the distance from the top of the piston to the top of the block (cylinder in Type 4) or conversely, how far the piston is down in the bore at TDC. It is not significant except in two cases, but you want them all to be equal (blueprinting):

1.) Determining the piston to head clearance.

2.) How far the top ring is from the top of the cylinder / block.

Why?

#1.) In our racing engines, we figured at max rpm, the rod would stretch. We allowed for 32 thousandths, figuring the piston would just touch the head and knock any carbon off. (IMG:style_emoticons/default/biggrin.gif)

#2.) The higher the top ring placement in the bore (cylinder), the less loss of compression as it seals the cylinder.

I guess everyone has their number............

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