bearings, bores, rings and things

[RichyBarber]

Excuse the TR6 newbie here - first engine rebuild so taking it slow. My engine condition was unknown totally, albeit records indicate some kind of rebuild in history - if I am right 23k from rebuild. So I have taken the head off and last night removed a few bits to get a feel for problems. Bores look fairly good - smooth / no ridge at top etc, albeit I need to measure / inspect properly. Photos below show pistons / bearings. The bearings look pretty good to me,

 

the engraving suggests' big ends +.020 U/S, Mains 0.010 U/S - so I m assuming has been ground at some time. £40 seems to but a new set, but I was thinking these look pretty good / be kept - any views ?

 

rings similarly look ok, but need to measure properly . Anyone give guidance on the staining on the pistons - is this normal wear and tear / can I just clean them up etc. ??

 

Any views / comments appreciated. Thanks

 

[YankeeTR5]

those don't look bad, but you should check them all. Recently changed all rod and mains on my sons 74 6. The #1 main was unworn, the others were showing copper on the bearings. Apparently its nearest the oil pump so gets best oil flow. All rods were showing some copper and were evenly worn. Bearings are cheap, relatively, so since you've got things apart, why not just replace them all. Its pretty simple to do.

Can't comment on pistons, but a good cleaning always helps everything. You could always re-ring them and hone the cylinders and now you've got yourself a "hillbilly rebuild"! What the heck, you're already there

[Motorsport Mickey]

Hi there Richy,

 

Steady there boy, you might just be dismantling an excellent rebuilt engine with a view to putting it back together worse.

 

What were the engine compressions ? ( gives an indication of bore/cylinder/valve wear).

How much oil did the engine use in a thousand mile use cycle ( gives another indication of the same)

What were the oil pressures when you used the car in the heat of the day at tickover and under load (gives indication of bearing/crank wear).

So with this information in hand you can go into the engine looking for the particular parts or their running clearances which may be wrong and need altering/replacing....What... You've not told us any information so I guess you may not have it, maybe you've posted it before or the engine isn't in the car in which case this thread should have been attached to the other where we then would have had all the info.

 

As regards the bearings they look fine to me and more importantly they may well be much better quality than bearings that are available today, (23k from rebuild at 3k a year means 8 years old at least and availability of better bearings than available now) any markings on the back ?

Now for pistons and bore wear, you do know Pistons aren't round ? Buy yourself some micrometers and telescopic gauges and mic them up and compare, like a hot cross bun across the piston. X and log the largest diameters you can find, the liners should be round but check them in the same way to define out of roundness or wear. Compare against the figures in your workshop manual ( you have one...yeah) and then you can start to decide which way to go forward.

 

Mick Richards

[RichyBarber]

no compression tests as engine / car had stood with the previous owner for a few years / had not run. turns over the crank smoothly. yes - next step as you say Mickey, is some measuring etc. Based on what I have seen so far I am thinking of keeping the current bearings - anyone recognise the following engraving on the shells / who would have manufactured them ?;

 

mains;

 

149550

 

D MX T/B

G S2920 SA

.010 U/S

 

B Ends

 

G S 202022 SA D AX

+ 020 U/S T/B

149549