Bottom end advice

[gitters27]

I have a C16SE I'm building with modified head,can and other bit and now I'm onto the bottom end.bores look rather shiny.im going to replace shells and so on but don't want to do that if bores are shafted.they have no marks on them.do I need to measure bore size for wear or will hone and new rings do???? Help please

[Andy]

measure everything.Do it once,do it properly.You need a 25-50mm,50-75mm and a 75-100mm micrometer.You also need some bore gauges,these are cheap enough on ebay.
Have everthing spotlessly clean,measure the oil pump too.The blue Haynes manual is a fantastic help.
Easily doable at home in your garage,iv done 3 now.If anything is out of tolerance,get it machined and use oversize bearings.
Good luck.

[meritlover]

Always keep your big-end clean.

[Iain]

I've never quite trusted my own measurements and found the precision difficult to work with. Plenty of places will be able to measure things and advise, a good indication on the bores is the lip size.

[gitters27]

What amount of wear is acceptable on the bores.i will have no problem measuring the bores but when it comes to measuring crank for shell size I'm out of my depth.

[Andy]

why? its harder to measure the bores lol
All the tolerances are in the haynes

[gitters27]

Hehe must be me then,just won a blue Haynes on eBay so should be a big help

[mk1nova_rich]

I've never quite trusted my own measurements and found the precision difficult to work with. Plenty of places will be able to measure things and advise, a good indication on the bores is the lip size.

With an external micrometer on a diameter with a good surface finish, you should aim to be able to twist the micrometer around slightly and get a 'squeak' when you do. Another trick is to look away when measuring as you are more likely to get the actual dimension rather than what you are hoping it is lol

[Iain]

It's got a little handle thing that clicks when it touches, are you meant to tighten it with that?

[mk1nova_rich]

Yes that stops you overtightening it and getting incorrect measurements, although I'm not convinced they always go tight enough. I use micrometers all the time at work so have a really good feel for using them without that little handle. Just practice using them til you get more confident - they are easy to read, its just getting used to feeling when you are on right

[therealnovaboy]

An easy way to tell is get a new piston ring and put it in the bore. Push it down about 10mm with a piston so it is square in the block then use a feeler gauge to measure the gap. If a new ring is out of tolerance then it'll probably be the worn block thats at fault. You should check it top middle and bottom of the bore to get a good idea of the wear. if the bores seem ok Hone it after you've finished cos chances are you'll scratch the bores with the rings putting them in and out.

Its probably not the best way to do it but but pretty good if your not confident with a bore gauge.