Machine Shop Question

[Nessism]

Measuring the bores to see whether there is any 'out of roundness'/egg-shaped wear is highly recommended:I don't own an inside micrometer..
I had used a 3-stone spring loaded hone and done a quick glaze-braking in the past on many cylinders and installed new rings.A few of those engines started using oil even with new rings.A bore job is more expensive but if there is elliptical/out-of-round wear in the bores,this will give you back a fully round bore and the rings will break-in nice and you'll have plenty of excellent,consistent compression/ring sealing:the rebuild will last a long time. I would love to have a shop with machinist tools including a precision 4-stone hone such as an expensive Sunnen.. for now I live in a cheap apartment so I bring my parts to a professional machinist and pay the $.

A bore gauge is needed to check cylinder wear. An inside mic could possibly be used but it's not the right tool for the job. And when deglazing cylinders a ball hone is much better than a straight hone like you mention. With a straight hone any slight out of round or taper will result in missed spots in the cylinder where the hone is inconsistent.

Checking the cylinder head for flatness on a surface plate is not ideal because you will only be able to check the very outside edges. Honestly though, we are really splitting hairs in this thread. Just use a half way decent ruler and look for large inconsistencies in flatness. 95% chance it's fine. I'd be more concern with valve guide and valve/seat wear.

[RustyTank]

A bore gauge is needed to check cylinder wear. An inside mic could possibly be used but it's not the right tool for the job. And when deglazing cylinders a ball hone is much better than a straight hone like you mention. With a straight hone any slight out of round or taper will result in missed spots in the cylinder where the hone is inconsistent.

I need to pick up a bore gauge to check cylinder wear. If anyone has a particular brand they like let me know, maybe they're all the same though.

Checking the cylinder head for flatness on a surface plate is not ideal because you will only be able to check the very outside edges. Honestly though, we are really splitting hairs in this thread. Just use a half way decent ruler and look for large inconsistencies in flatness. 95% chance it's fine. I'd be more concern with valve guide and valve/seat wear.

Great note about priorities "I'd be more concern with valve guide and valve/seat wear". Thanks Nessism.

[bitzz]

[QUOTE=RustyTank;2639602]I need to pick up a bore gauge to check cylinder wear. If anyone has a particular brand they like let me know, maybe they're all the same though..../QUOTE]


Starrett or mitutoyo, but they are spendy
There are lots of cheap bore gauges on amazon.
... unless you're running a rebuild shop I don't see the need.

You can get a "good enough" read on bore wear using a piston and a feeler gauge.
It won't tell you the actual diameter but it will indicate wear.

A lot of talk about head gaskets and flatness... and no one has mentioned Cometic copper gaskets.
The GS has head sealing problems, copper gasket is an answer.
Better head studs help too.

[RustyTank]

I need to pick up a bore gauge to check cylinder wear. If anyone has a particular brand they like let me know, maybe they're all the same though..../QUOTE]


Starrett or mitutoyo, but they are spendy
There are lots of cheap bore gauges on amazon.
... unless you're running a rebuild shop I don't see the need.

You can get a "good enough" read on bore wear using a piston and a feeler gauge.
It won't tell you the actual diameter but it will indicate wear.

Thanks for your two cents bitzz. I looked them up and wow, those brands you mentioned are indeed expensive. I guess I'm just curious if one of the cheaper bore gauges is going to be even worth my time/money, but I hear what your saying.

A lot of talk about head gaskets and flatness... and no one has mentioned Cometic copper gaskets.
The GS has head sealing problems, copper gasket is an answer.
Better head studs help too.

I went to Cometic's website and found an 80 and 81 GS850 copper head gasket, but not a 79. Mine is a 79. It may not make a difference, I don't know the 80/81 engines well enough to know.

[Nessism]

Do NOT get a copper gasket if you care about oil tightness. Copper is for race engines where a little weepage is acceptable.

[RustyTank]

Do NOT get a copper gasket if you care about oil tightness. Copper is for race engines where a little weepage is acceptable.

I was wondering why I'd never heard someone suggest it before, lol. Thanks Nessism.

[metalfab]

Measuring the bores to see whether there is any 'out of roundness'/egg-shaped wear is highly recommended:I don't own an inside micrometer..
I had used a 3-stone spring loaded hone and done a quick glaze-braking in the past on many cylinders and installed new rings.A few of those engines started using oil even with new rings.A bore job is more expensive but if there is elliptical/out-of-round wear in the bores,this will give you back a fully round bore and the rings will break-in nice and you'll have plenty of excellent,consistent compression/ring sealing:the rebuild will last a long time. I would love to have a shop with machinist tools including a precision 4-stone hone such as an expensive Sunnen.. for now I live in a cheap apartment so I bring my parts to a professional machinist and pay the $.

If the piston clearance is to great, or if the cylinders are out of round then new rings can be futile. I do always tell people to scrub their bores with a brush, and a strong detergent after honing. Then you dry them with heat, like a hair drier and oil them down to prevent rust. Washing the cylinder with just solvent can leave behind abrasive residue, and that is a death sentence for a ring job.

I was wondering why I'd never heard someone suggest it before, lol. Thanks Nessism.

One thing I didn't see mentioned is if you can still see hone marks in the cylinders you don't have much to worry about in the cylinder wear department. Lots of good stuff in this thread, it'd always great when you can draw on others experience.