[Fot] Piston to head clearance

[fubog1]

 Steve nailed it, both on the ##s, & the importance of it.It depends on what rods & crank, piston to wall clearance & what RPM, but for most applications that's right in the ballpark.
I've run as little as oops not enough ie .025 or less, .028 minimum (you won't get any carbon deposit on the squish area), but to play it safe nowadays I use .030-.032Also on these engines it's not only a CR related issue, the squish is very critical, you want to minimize the clearance between piston top & head to maximize the squish effect, which creates turbulence, which assists in good combustion...

Glen Efinger.

    On Thursday, January 11, 2024 at 01:00:50 PM EST, Steven Belfer via Fot <fot at autox.team.net> wrote:  
 
 You want as little as necessary because this is where your high CR comes from.  The thickness of the head gasket is the major part of P to H clearance.  I ran .026 P to H clearance at Cal Speedway and the piston kissed the head and I spun a bearing.  My machine shop guy likes .040 for safety but I’ve been running .032 and it’s working out great
~Steve


> On Jan 11, 2024, at 9:13 AM, Lorne Fritz via Fot <fot at autox.team.net> wrote:
> 
> 
> Hi.  In the past I have had pistons hit the head and leave a mark(TR3/4).  What piston to head clearance are most of you running? Thanks in advance,  Lorne
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