Pushrod Hole Sizes
Turbo Mini Forums

Hi all, the pushrod holes cast into my head are quite varied in size, a couple are 1/2" diameter, the rest are a fair bit smaller, anyone know why, and how big the holes actually need to be so they don't touch the sides? I'm guessing just as big as the smallest ones!

www.topcatcustom.co.uk

The out side two on my spare block are 1/2" and the rest are about 3/16" smaller - how strange

Are the 4 inlets smaller? Is it a modified head?

The inlets are often sleeved when they are ported

I seriously doubt it!

Shamefully, I got a bit close when porting and just touched through into one, so I need to sleeve it/them.

I was wondering as I'm going to buy some tube, and found some nice 1/2" OD, very thin wall brass tube on eGay. I intend to ream the holes to 1/2", fit the tubes (with a little loctite) and flare the ends so there is no chance of them moving.

Reason for the question is that I wan't sure whether to use 1/2" tubing (preferable) or 17/32" which would eat into my runner more.

But as most of the holes are smaller I think I'll be fine with 1/2" tubing.

Sorry bit long winded!

www.topcatcustom.co.uk