Piston Rings questions

[driver_dav]

Background on this project:
I have a Maxum 2100sr with a 350 engine in it, it sat for 10+ years and was rough turning by hand after having some fogging oil sitting in the cylinders so I have decided to rebuild the engine, upon teardown I have found water had sat and rusted in the Intake, Heads, and cylinders 7 and 8 had some rust. Everything has cleaned up very well rust wise, and I have regrinded the valve seats down and got them all cleaned up now my next part is the block, Most all the rust came off with oil and scotch pad there is a very minimal layer that I think will come out when I hone the cylinders because the rings need replacing. I have found a tag on the front of the block that says reman # also the top of the piston says .040 does the mean it has been bored over?

So my main questions is if they are bored over what size rings will I need?
Do I have to have Marine rings?

 

[driver_dav]

Also as I hone the cylinders I know its one second down ones second up, but how long should I hone overall per cylinder, also should I compensate honing for getting the new rings

 

[Bt Doctur]

that usually means the engine bores have been opened up .040 thousands more . boring .040 over stock would make the bores 4.040 You need to measure the bores with the inside mics, then mike the pistons. this chart lists the piston to wall clearance. if the piston to wall clearance is too large you need to use bigger pistons and bore/hone to the new finished size.
the number stamped on the piston is usually the size of the rings needed . 20 over, 30 over, etc.

 

[driver_dav]

Also as I hone the cylinders I know its one second down ones second up, but how long should I hone overall per cylinder, also should I compensate honing for getting the new rings

 

[Volphin]

What doc is saying is that you should measure before honing because if the clearance between the piston and the cylinder wall are too much, then the engine will have to be bored and new pistons installed. And if that is the case, honing is not required at all. If the clearances are within spec, you can hone it lightly to remove the cylinder glazing, and that's as far as you should hone it. Do NOT overdo it. Just a light crosshatch will do.

 

[muc]

How fast you go up down while you hone depends on how fast the hone is spinning. Proper cross hatch is the important thing.

 

[Fishermark]

To add to the above, no - you do not need marine rings. Normally a machine shop with ask what kind of rings and pistons you are using and finish the cylinders appropriately. If you end up doing a simple hone and clean up of the cylinders, basic iron rings will do fine.

 

[driver_dav]

None of the piston rings are broken they all have there springiness if you will, only one cylinder had some oil leaking through in a very minimal space, question is can I clean the rings, pistons perform a minimal hone can I salvage the rings? To me they look very good

 

[driver_dav]

None of the piston rings are broken they all have there springiness if you will, only one cylinder had some oil leaking through in a very minimal space, question is can I clean the rings, pistons perform a minimal hone can I salvage the rings? To me they look very good

 

[Bt Doctur]

That depends on the cylinder bores. You install just the ring, use the top of a piston to push it squarely into the bore and measure the ring gap.
(0.0098-0.0259 in.) top compression, 2nd compression (0.0181-0.0354 in.) oil control rings (0.0098-0.0350 in.)

 

[driver_dav]

That depends on the cylinder bores. You install just the ring, use the top of a piston to push it squarely into the bore and measure the ring gap.
(0.0098-0.0259 in.) top compression, 2nd compression (0.0181-0.0354 in.) oil control rings (0.0098-0.0350 in.)

So if its within those specs they are good?

 

[Bt Doctur]

correct. the amount of wear will affect the gap. those are the minimum gaps. the larger the gap, the more blow-by you will see.
If someone tells you to use slighter bigger rings on a smaller piston ,punch them in the nose

 

[driver_dav]

correct. the amount of wear will affect the gap. those are the minimum gaps. the larger the gap, the more blow-by you will see.
If someone tells you to use slighter bigger rings on a smaller piston ,punch them in the nose

Can I hone if I reuse the same rings to get rid of the minimal lips from the rust?

Thanks for helping so much