Because of the crown hight of the pistons.

Acording to the JCC piston cataloug, the RB20 slugs run a 32.4mm crown height. (A14's are 32.5) But the rb20 pistons run a domed top. I'm told the rb20det slugs might be flat top, but if the deck has been decked like he said, then the might not be able to use them.

so the RB pistons are 1/2 mm difference in crown height than A14 pistons. Doesn't that indicate the A14 rods should be used? Because A12 rods are about 12mm shorter.

He's blockis allready decked a few mm.

ROConnor is right..

There will be no issue if i'm using the standard A14 block height..

from what i've known, in a standard A14/15 block height + A14/15 conrod,the RB piston will exceed 3mm off from the top of the block..and we only have to shave the top of the piston 3mm off,and it will still be safe..

i'm afraid in my case,my A14's block has been decked 2.3mm off.. so,i have to shave off the top of the piston more than it should (3mm + 2.3mm = 5.3mm)..which i dont think i would be safe anymore..

my point is that i'm trying to figure out is it possible if using a shorter conrod (A12)?
And it would safe the piston from being shave off 5.3mm..



i'm so sorry if i'm confusing you guys..

I once looked into using some forged A14 slugs in an A15 by using a12 rod, but it would have taken too much block decking to work.

If you were to take 5.3mm of the piston, how much land would the be to the first ring? and do you hav the ability to messure the thikness of the crown?

a guess would be that it is far to much, but theres no harm in makeing a few messurements.

and in malaysia I belive they are quite commen motor (maybe just relative to australia?) it may perhaps be the easyer/cheeper option to start with a fresh(undecked) block?