When using aluminum rods what are the required clearances from the piston to head,piston to valve and rod side clearance min/max?

Contact the rod company your using and use thier recommendations I think BME on there forged rods recommended .055 piston to anything clearances and .030 rod side clearance on a normaly asperated (no power adders)drag motor. More side clearances is better than not quite enough I had a BME forged aluminum drag motor that had .050+ side clearances, it ran fine and had no indictaions of problrems when inspected after multiple dyno pulls and races

Thanks for the info.

Many rod manufacturers make their aluminum rods about .025 shorter to compensate for expansion. So ask your rod supplier what the actual C-C distance is.

I was always told that the length of the rod added into the equation.

I have a 6.535 rod and therefore have .065 piston to head clearance. A 7.100 rod would need .070..

Don't know if this is real world, but has worked for me. I have used aluminum rods for over 20 years in every engine I have.. Zero failures.. Knock on wood..


Chris..

We run a 6.123 BME @ .058, BME recommended .060