littledarkone - well said mate!

There's the easy way and then there's the Datsun way.

DIY FTW!!!

...cos, we're Datto owners

y wouldnt u just take it to a machine shop... seems less dramatic. n they tell u everything. just a far more simple and effective result

So I measured the cylinder clearances and basically have 3-5 thou piston clearance on all 4 pots in the A14. So all I need is a quick deglaze and new rings/bearings etc and I'm away.

my dad always told me that the top ring could hit the lip on a big rev and break, hence the need to remove the lip. However only removing the lower part of it does sound like it makes good sence.
I've seen motors that were well worn but never thrashed turn into broken ringed pigs when revved to all buggery and the top ring eats it.

I know this will sound like I'm on crack, but if the ridge at the top is small, leave it, or at most remove just the bottom 0.5mm of it, and if it is large, go the next oversize. Even if you don't remove it, new rings never actually touch the top of the existing ridge (even though you'd think they will). The 'big deal' here isn't the ring hitting the ridge at all. What is a big deal is if you remove the hole ridge, it's a lot more of the top ring exposed to the flame, at/around TDC, where it'll lead to shortened top ring life. It's actually one of the odd things, and people see it doesn't last long, and think 'I shouldn't have just used a ridge remover, honed it and re-ringed, I should have gone the next oversize' - but in actual fact they would have gotten away with the same bore size, a quick hone and re-ring as long as the ridge wasn't totally taken away and the top ring wasn't exposed.

On the bore guages - the telescoping things that you later measure with an outside micrometer are the devil incarnate. inside micrometer for the win :) even if you have the inside micrometer, you should still measure it with an outside micrometer (not to determine bore size) just incase there is any difference between the two, That way you can use the outside micrometer to measure 'true' piston to bore clearance (hopefully that makes sense). You'd still take the inside mic reading for the bore size of course (as long as it's calibrated).

Thanks heaps lads, I agree with everything said above.

I'm hopefully getting an old mechanic mate to come round with his bore mic on Monday arvo.

I was worried that cos every measurement was 76mm that I was using the telescopic gauges wrong. Also there's the fact that my verniers are only accurate to 0.02mm, they're only a $40 pair... meh u get what u pay 4!!!

The $500 bore mic should tell me whats what tho...

So I'll be measuring up the A14 and an 18RGEU for a Hilux on Monday hopefully.

The A14's bearings have small amounts of wear (through to brass on a couple of rods and mains) so they will be refreshed.

Only taken the pistons out of the 18RGEU ATM and the bearings on 3 and 4 are shagged so we'll prob replace the mains as well as the rods, just to be confident in the engine.

Seeing as we found strands of permatex blue in the mesh screen over the oil pump of the 18RGEU its a fair bet there more of that #OOPS# inside oil galleries and what not that may have caused the oil starvation to three and four and thus the increased wear.

The peeps who built this engine went crazy with blue and red permatex its bloody everywhere. Grrrrrr

Anyway cheers (literally as its late Sunday arvo I;m on my seventh beer and I've got Pantera cranked) to DD, PIGDOG and NZDATMAN.

Datto Legends!!!

I think you should use an outside micrometer, it's more accurate and easier. It's not really easy to measure your tele gauge with a vernier and a good vernier is usually only accurate to about .02mm anyway. I know your .1mm doesn't sound like much but it could be a concern. If the bores were that much out of round or tapered, I would say it would be well outside tolerance. If it's just worn that much but the bores are still round and parallel you could probably re use.
I'm not an engine reconditioner though so I could be wrong. Telescopic gauges can be a bit tricky to use until you've used them a lot and have a technique that works and you know you're getting consistent measurements. An inside mic would probably be a better bet if you can lay your hands on one, or take you block in and let the pros measure it.

you need to actually measure it with a bore mic, verniers arent precise enough to measure the small variations that you are looking for. and you need to measure down the middle of the bore which you cant do with verniers

Thanks DD I was hoping that would be the case.