21-03-2018, 03:11 PM
(21-03-2018, 01:14 PM)Ruairidh Dunford Wrote: Stuart - do you find you need to put a spacer under the block, when taking off material from the top?
It's rare in my experience to have the pistons actually coming above the block face after a skim on an A7 motor, but obviously that can happen, especially where the block has previously been skimmed. When this does happen, I just skim the piston crowns. Here's the jig I made for this job. I have knocked up several sets of the grips from guage plate so that they are always a snug fit in whatever the ring groove width happens to be.
![[Image: 36409488175_3e2974c2cd_k.jpg]](https://farm5.staticflickr.com/4369/36409488175_3e2974c2cd_k.jpg)
Apologies for the non A7 piston in this photo, but you get the idea.
![[Image: 39129256530_089a302b56_c.jpg]](https://farm1.staticflickr.com/797/39129256530_089a302b56_c.jpg)
One of my abiding memories from when I was 12 or so, was one of my elder brothers skimming a piston which was held in a 3 jaw chuck on our prehistoric Brittania lathe at home. The lathe tool must have dug in, and when the chuck spat the piston out, it ricocheted around the garage for what seemed like forever. Unfortunately, the skirt was a most peculiar shape when Chris retrieved the piston off the floor.