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Triumph TR6 - Maximum cylinder bore wear

Hi all -

My '73 is low on compression and has low manifold vacuum (~14 inches at idle). I suspect it's worn rings/cylinders so I'm considering a rebuild. How do I determine how much cylinder wear is allowable? I've got the Bentley manual but I'm not finding a specific reference to bore wear - just the spec's on the bore as new. Do I assume that if my bores measure within the spec's listed (pg 101) that I'm OK to simply hone and re-ring - and if I'm out of spec, that a rebore up to the next size over is the necessary cure? Maybe I haven't studied the manual enough?

The car supposedly has only 63k miles but it uses alot of oil and as above so I suspect it's had at least one owner who didn't pay much attention to oil changes. Thank you for any advice!

Chris
Chris Nelson

Hi Chris

As you suggest check what you have. Make sure that the cylinder is not ovaled. There is a tolerance for how much oval is allowed. Compare to original specification.
Check what oversize rings are available and what best matches. I can't remember where but there is a specification for the gap on the ring when it is in the cylinder. That gap will determine what size rings to go with.

If not ovaled, honing should do the job. If ovaled you probably want to bore

I assume you will do the head as well. You may be losing compression there.
Michael Petryschuk

Hi Chris

These engines are very long lived. I have seen engines with in excess of 100,000 miles successfully re ringed with only a light hone. Check your valves first, 63k miles does not sound like cylinder bores to me unless it has a poor service history. How long have you had the car. Was it driven much before you got it or was it laid up, might be gummed up rings, if so take it for a long hard drive.

Colin
C J Norcott

This thread was discussed between 17/07/2013 and 04/08/2013

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