Piston clearance spec for rebuild

Posted by Tobs On 2012/5/31 14:40:02

Hi Guys,
A question from my engine builder. He is getting ready to bore my cylinders for the +.020 pistons I got from Kanter, and he didn't believe the original spec from packard for the skirt to cyl wall clearance of 0.0005" to 0.001" He says this is like the clearance a modern engine runs, and that the engine would sieze shortly after start up if we run these clearances....

I already got a reccomendation from Ross that this spec is still valid. (with closer to 0.001" or 0.03mm being preferred)
A call to Kanter and they also stood by the original packard spec.

So, before I convince my engine builder who is pretty experienced (albeit more with old daimlers and the occasional SBC or SB Ford) that this spec is correct, anybody want to weigh in on this?

If I understand correctly, the steel (Steel is correct?) struts in the pistons keep the thermal expansion low, which allows these tight clearances of the cyl?

The engine builder speaks with a pretty strong bavarian accent, so I have to struggle to understand him, and convincing him on this is also going to be fun.

Thanks! -Mike