Polini Case Matching 2.0

02Apr11

I first built this Polini bottom end 2 years ago. It was clean, but the case matching left room for improvement. Here’s the original case match.
polini case match 3

That will not stand, man. The top ports especially. Here’s an ok photo of comparing a before and after. The right channel is mostly done, and the left is untouched from my previous case matching.


All done.

There’s a lot of slop in the cylinder stud holes on puchs. I made some ghetto brass shims to make sure the cylinder was centered and then smoothed the cylinder to case transition one half at a time.

I ended up only using the top two sizes. 9/32 inside 5/16 (or just 5/16 for m7 studs) gives you a snug fit.
3 different sized tubes for puch brass cylinder inserts
Cut them while one is inside the other and they meld together nicely.

Tap them into place, file them down, and boom goes the dynamite.
brass inserts for proper port/piston alignment
Case match away.

Once I got into that, I started to see how I could take the transfers back and make the transition a lot smoother. There’s a large bump that didn’t have any business getting in the way. Half done.
IMG_1558
SEE YA. This just need to be patched, smoothed out and it’ll be good to go.

I got a little too zealous and broke through the case wall in one of the case bolt channels. You can see it in the above photo on the left transfer. At first I was bummed, then realized it was probably better to break through now, than to be terribly close and have it cave later and have to go back and fix it. The hole is about the size of a partially used pencil eraser. I’m looking for some advice on patching this up. Will JB weld work for this? or QuickSteel? or do I need to aluminum weld that in? I have zero experience with having to patch something like this up, so any knowledge you guys can share would be radical.

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4 Responses to “Polini Case Matching 2.0”

  1. 1 Evan

    Id go with quicksteel. That ought to do you.

  2. always wanted to do the brass spacer trick, now i dont have to think!! bigups.

  3. 3 Paul

    Did u ever figure out which worked best to cover the hole in the case wall? I’m in the same position now. Thanks.


  1. 1 GUIDE: Pro tips to building a Puch Polini « MAGNUM DASH!

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