Cozzee

Hi, I've had some work done by a local engine builder but due to some problems I've collected my engine unfinished.

My question is, I have a 4x4 head skimmed to 138.2mm with a BD16 inlet cam and standard exhaust, I have accralite forged FLAT TOP pistons that according to Burton power measure 38mm from grudge on pin to the crown with a CR of 8.1:1, when I've done a dummy build with a 1.2mm head gasket the inlet valves make an impression of approx 1.75mm but don't cut through the putty I placed on top of them to see if they clash so Im probably looking at a clearance of 1.75mm between the valve an the top of the piston. At TDC the piston is approx 1.5mm below the surface of the block. What are people's thoughts.....do I go for a thicker gasket but what will compression be. Sorry for the long post but I'm pulling my hair out and it's already cost me a lot of money due to my old builder. Thanks

Mark Shead

Throw the pistons in the bin if they are sticking 1.5mm below the block. The Yb engine wants the pistons to be 15thou above the top of the block for proper squish.

Mark

Bart

What thickness headgasket you use with 15thou?

Mark Shead

Mountune hg.

Mark

Adam-M

If that builder supplied your pistons I'd be checking every part they ordered like bearings ect

Cozzee

Thanks Mark & Adam

Mark what pistons would you recommend, thanks.

Mark Shead

Depending on max hp and the rods used. Up to 500hp the stock Mahle piston is best suited over that cp pistons.

Mark

Adam-M

I have accralite low comp pistons on mines with valve cut outs which are a must, the surface finish on them was lovely.