[Ian L FIC]

I have read several books that mention minimum piston to head clearance to be about .050". If this is the case, then how can the HKS 1mm (.040") headgasket work assuming a 0 deck height? My current engine (although broken) has LD28 crank, L24 rods, and Z24 pistons. This yields an overall deck height of 208.5mm and the block height is 207.9mm. This means that my piston to head clearance with the 1mm HKS gasket is only .016". I was only spinning the engine to 6400 rpm. There was no piston to head interference. What's the deal? Should I be worried when I replace with the same pistons?

Ian

 

[yo2001]

the piston and head should be fine considering late L28 with flat top pistons have positive deck height. you do need to check the valve and piston clearance. .080 on intake and .120 on exhaust I think.

 

[Q]

Expansion

Unless I'm wrong, the reason for the 0.050" clearance is that metals expand when heated. Cold clearance will be more than hot. It would be interesting to see how close your pistons and head get under the 6400rpm conditions you mentioned...

 

[craig_57]

Ian, The absolute mininum piston to head clearance is .040.. (forty thousands). I can"t believe you got away with.016.. This is way to close,are you sure thats right.?? I try to zero my deck hieght and use a head gasket thet will compress to as close to .040 as possible. Fel-Pro is one but most manufactures will be able to tell you compressed thickness of there product. Craig