Deck Height (yet again...)

alphie · 06-20-2007, 10:50 AM

Putting together my engine. Its a 3.0 case with mahle motorsport 10.5:1 P&C.

These pistons are the high dome ones, they have a flat edge around the top of the piston. The measurement I get at the flat edge to the top of the cylinder is 1.0mm. Using solder on the dome parts I get 1.5mm.

Which measurement should I be using? I'm thinking the flat edge one.

thanks,

-Rob

304065 · 06-20-2007, 11:18 AM

Deck height (the distance between the top of the cylinder and the top of the piston NOT INCLUDING the dome) is different than piston-to-cylinder-head clearance (measured between the dome and the head, often with the solder method).

tom1394racing · 06-20-2007, 01:26 PM

Rob

I had this same issue with my RSR spec 3.0 build.

I was able to get much more reliable and repeatable deck ht measurements with a digital caliper measuring from the piston lip to the top of the cylinder deck than I could get from the solder method. using a dial indicator to find TDC is essential for good results.

See this post for a more detailed discussion.

Advice on Deck Ht, Comp ration and Shims for my 3.0

cstreit · cstreit's Garage

Alphie, if using a digital caliper, make sure you don't rock it "over level" when measuring... Also you want to measure on the sides of the piston rather than top and bottom. Measure each side and take the average as the piston can rock in the bore.

The "edge" method is the correct one.