Bore size

[Gray]

I have just roughly gauged the bores of my s block and it is reading about 72mm so does anybody know what size overbore that could equate to? Cheers Graeme

[steve1071]

Standard S bore is 70.6mm, every 10 thou of an inch extra is plus 0.254mm. Plus 60 would give you just over 72mm

[whistler]

According to the pdf file I have +0.060" is 72.17mm. How does that compare?

[Fanfaniracing]

Same for me.

72mm with +60

[251 ENG]

72mm is 2.8347"

+60 is 2.840 "

[Gray]

Cheers for the replies so it looks to be + 60 does that leave room for sleeving and if so what is the going rate?

[CooperTune]

I had a .060 Cooper S block under the bench for 20 years. I located a set of 73 mm pistons out of OZ. Have been running it since. Steve (CTR)

[steve1071]

Pretty sure Keith Calver sells the Oz 73mm pistons

[LuisM]

Keith Calver used to have a 72.5mm Piston, this would leave room for another rebore at 73mm .

cheers
Luis

[Fanfaniracing]

Here you can have almost every possible and impossible piston size custom made:

https://wahl-spezialkolben.de/

I heard a lot from this enterprise and if i remember right, whe got our piston-rings for my 998 Cooper engine from there...

[wantafaster1]

Calver ST also does 72.5 which would be an excellent save for +.060

[Gray]

Cheers for all the input I will nip along to Spamspeed for him to cast an eye on it.