Measuring deck height on a dish, looks like a wrist pin bore issue Options

[bbrock]

I searched and couldn't find an answer about where on a dished piston to measure the deck height. I have Euro spec Mahle "flat top" pistons for 8.0 compression, but in reality, they have a slight dish in them. I'm following Tom Wilson's book and he just says to measure them "at the crown."

I measured deck height with the single metal gasket/shims that came with the gasket kit installed only because they are already on there and I just wanted to see if I was close. Deck heights at the center range from .052" to .07" which seemed like a decent starting point but height out at the edges is only .02". Of course, I can get any number in between depending on where I measure. I just want to make sure I have the right clearance.

Also, how important is it to cc and calculate precise compression for a street ride? I'm just looking for a reliable engine and not concerned about squeezing every HP out of the motor UNLESS it will improve fuel efficiency without sacrificing reliability. I'm happy to go through the drill if results in a better engine for my needs, but reading Wilson's book, it seems the important thing is to have enough clearance to keep the valves and piston tops safely apart.

Finally, is it normal/acceptable/desireable to mix and match barrel base shims to even out variances in deck height?

Any advice welcome. I just get confused trying to separate basic build best practices from performance tuning.

[VaccaRabite]

Measure where the dish isn't. In this case its the crown around the edge that you have measured at .02.

When you compute the CR, you will "fill in" the dish by computing its volume (which you will need to measure unless you know that number already).

With a head gasket in place and dished pistons, you won't have a screaming CR. What you want to do is go for the CR you want and let that dictate your deck height (within reason - as you said you do not want valves to touch the pistons). If you are targeting a stock CR, that should give you a nice cool running engine (not knowing any other variables).

Zach