sleeving oil journal when offset boring 1380
Turbo Mini Forums

Gents,

I found many info about offset boring blocks for 73,5 pistons.
Also know there is a risk to enter an oil journal at cil.4. or an unacceptable thin wall thickness to this oil journal. I am planning to convert my 12H block to a 1380.

There are many good and welle experienced A series machine shop in the UK, here in Tulipland we have to deal more with general machining shops.
Therefore I am thinking of a preventive sleeve in the oil journals.
Sure some well respected Einsteins here have done it before, so here my questions:

- what material should I use for this sleeve / tube?
- what wall thickness of the sleeve/tube should I use?
- any other trick to keep in mind when installing?

thanks in advance for your help!

Dont bother, its not needed

I seriously doubt it!

Hi Paul,

Thnaks for your swift reply, I appreciate your opinion however:

"Five blocks were measured for suitability. Two blocks, if bored would have resulted in the cylinder exposing the oilway. Two blocks resulted in 10 and 11 thou cylinder to oilway clearance. So far this block is the best"

that's what I read on http://www.minifinity.com/forum/viewtopic.php?f=182&t=78243

Sounds like clear maths doing the story: it can be a problem. And by sleeving the journal I might avoid double labour costs, porosity etc...

Any other remarks, gents?

regards, Bart

Edited by Streetscreamer on 21st Feb, 2015.

Bart as paul says "DONT BOTHER"

i have done over 30 73.5mm blocks and not one has gone through

as you know offset bore the two centre cylinders as per the book and you will be ok,

I stand by what I said. Stuff what Minifnity say. Ive had a fair few 73.5 blocks myself, the only size Ive ever known of that needed it was a 74.5mm bore

I seriously doubt it!

I wouldnt worry, ive only had one block offset to 73.5mm, but the machine shop I used had done plenty and no issues. the offset boring is important tho, and it took a while to find a machine shop who were willing to take it on locally and do it properly.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.