G.T.A. Rebore.

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Obviously I can’t help with your question, but, if taking to an unknown borer, do take care.

Some (many) think they know best and being more familiar with modern engines, will ignore your instruction for what they think is excessive clearance, with the consequent problems.

Best is to NOT take the pistons and say you need X clearance. Best IS to get an exact bore size figure for your specific pistons from Jim, and instruct your borer to bore to that specific measurement.

And don’t forget to ensure you still have a good chamfer on the bottom to aid piston / ring fitting.
 
What is the expected outcome of boring 850 barrels without using a torque plate? Not many engine workshops will have these laying around. Even L.A. Sleeve asked me to furnish my own torque plate.

-Knut
 
And ask him to bore bottom down /top up , and thus check paralellism between the two flange faces .
 
What is the expected outcome of boring 850 barrels without using a torque plate? Not many engine workshops will have these laying around. Even L.A. Sleeve asked me to furnish my own torque plate.

-Knut
Although there has been strong cases put forward re the benefits of using torque plates, the fact remains that the VAST majority of Norton‘s are bored without them. And they seem to run ok.

So, IMHO, if you’ve got some, use them. If you haven’t, keep calm and carry on.
 
Who can I contact for a rebore of my 850 barrels in the Greater Toronto area ?
Gord Bush is a good bet, he knows our brit bikes (did a magical job of installing new valve seats in my T140 head). Just ensure he does the work himself and doesn't pass it onto an apprentice.


Alternatively, I've had good luck with Nash Machine:

 
Gord Bush is a good bet, he knows our brit bikes (did a magical job of installing new valve seats in my T140 head). Just ensure he does the work himself and doesn't pass it onto an apprentice.


Alternatively, I've had good luck with Nash Machine:

Thanks Acadian . I've dealt with Gord Bush before 25 years back when the old Shop was close by the newer location in Etobicoke.
Yes indeed , there were several apprentices there doing things from a local college program , perhaps Sheridan.
I sent him an email with a heads up that I will deliver the JS pistons and barrel in December.
 
Thanks Acadian . I've dealt with Gord Bush before 25 years back when the old Shop was close by the newer location in Etobicoke.
Yes indeed , there were several apprentices there doing things from a local college program , perhaps Sheridan.
I sent him an email with a heads up that I will deliver the JS pistons and barrel in December.
He doesn’t need the pistons dude… just get him to bore to the EXACT measurement Jim gives you…
 
He doesn’t need the pistons dude… just get him to bore to the EXACT measurement Jim gives you…
25 or so years back it was called Leitner & Bush.
They asked for the pistons. Both got marked with machinist's blue dye dots up top to prevent any confusion on assembly.
I think the left one got one big blue dot on the crown and 2 big blue dots on the R. piston.
My telephone talk with Jim went well , I told him this and he seemed to think it wasn't so necessary too.
 
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