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MG Midget and Sprite Technical - Offset bore

My current 1275 +60 is very tired and I need to start thinking about a refresh so it looks like I'm going to have to get it offset bored and I have a few questions:

Do I need to use a special head gasket or is it within the capabilities of the standard one?

Can anyone recommend a firm to do the machining somewhere in the south?

Do any other parts require changing / maching (rods?)?

Are there any reliability / wear issues? Presumably the pistons put higher side loads on the cylinders for some of their travel?

Cheers

Jeremy
Jeremy Cogman


Jeremy
"In the South" is a large area, but if you are willing to come over to Kent way, I can recommend B.D.S. Engineering in Edenbridge. They did some work on my 1275 pistons and head. Contact Chris.
They have a website, just google B.D.S. Engineering.

Dave
Dave Barrow

www.southern-rebore.co.uk runs a midget. Dont call on monday as I believe he is at a track day.
Alan
A Anstead

Boring to 73,5 mm (1380) is no problem fo a good machine shop.
You can use a std HG.
And offset boring is no must!
It can even cause HG problems because the bore gets to near the edge of the HG.
My machine shop just made sure each bore was perfectly centered in the HG (from stock the vary quite a bit).
That way there is the least risk of HG failure and the piece between 3 and 4 is just fine.
The biggest risk is at no 4 wher you come verry close to an rear oil line but if this ends up being to thin you will notice whne you get that first 80 pound oil pressure.
Becaus that is when it snaps

But remember to crack test the block prior to machiening!
Onno Könemann

Have an offset bored 1480 that has been running for upwards of 18 years without any HG or cooling issues.

Still revs happily to 8k but it is in need of some stem seals now

If you offset bore it now, it will mean you can always go further in the future should you want to.
PeterJMoore

This thread was discussed on 21/01/2011

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.