new pistons and rings / 40k mi bore

[Drewster]

I have a block that has 40k mi on a 30 over bore. I also have a new rotating assembly with 30 over piston and rings. Can i swap in the new pistons and rings without having sealing issues?

(I can still see the cross hatch from the last hone)

Andrew

 

[TurboDave]

Double and Triple check the clearances to make sure everything's in spec, and check to make sure there's no ridge up at the top of the cyl.

 

[Nick Micale]

Let me get this straight, you are going to put new pistons and rings in a block that has 40K miles without doing anything to the block?

I would be VERY suprised if the rings ever seated.

We have seen crosshatch on 100K blocks, so that means nothing.

 

[bison]

I have a block that has 40k mi on a 30 over bore. I also have a new rotating assembly with 30 over piston and rings. Can i swap in the new pistons and rings without having sealing issues?

(I can still see the cross hatch from the last hone)

Andrew

You will need to have the block honed or use the rings that came out of it and put them in the same cylinders they came out of. This is only if the ring grooves are the same as the pistons you previously had in there. I would still have it plate honed or just plain honed minimum even if it leaves a little shadow at the top of the cylinders where there is a little taper. The replacement pistons may rock a little more or less in the bore causing the rings to be at slightly different angles in the cylinders at TDC causing a lot of blowby if not honed if reusing old rings on new pistons. NO hone+new rings= a detonation nightmare from all the oil in the cylinders and the excess blowby in the crankcase.

 

[Drewster]

light hone removes how much bore?

how much diameter am i going to loose in a light hone? Im at 3.832 now.
i dont know the end gap on the rings right now. its in a fresh 30 over rebuilt block that has been over line bored and i want to swap the rotating assembly over to another block.
Andrew

Thanks for the info

 

[bison]

how much diameter am i going to loose in a light hone? Im at 3.832 now.
i dont know the end gap on the rings right now. its in a fresh 30 over rebuilt block that has been over line bored and i want to swap the rotating assembly over to another block.
Andrew

Thanks for the info

You will need new rings no matter what if going to a new block. A light hone wont take off much but you need to remove the glazing on the walls.

 

[Grumpy]

Let me get this straight, you are going to put new pistons and rings in a block that has 40K miles without doing anything to the block?

I would be VERY suprised if the rings ever seated.

We have seen crosshatch on 100K blocks, so that means nothing.

thats sums it up :biggrin: why would ya go to all that work and not re ring it and hone it

 

[Drewster]

i wasnt sure. i thought the rings might not seat so i thought id ask.
i was hoping to resize the bore to .030 over but it turns out im already there. so i would like to use the same size pistons.

can i hone cylinders that are at 3.832 and still use .030 over pistons w/ new rings?

 

[bison]

i wasnt sure. i thought the rings might not seat so i thought id ask.
i was hoping to resize the bore to .030 over but it turns out im already there. so i would like to use the same size pistons.

can i hone cylinders that are at 3.832 and still use .030 over pistons w/ new rings?

What is the exact diameter of the pistons measured? Ive run .005 clearance but it rattled when cold. Ran it like that for years with no problems.

 

[Drewster]

i havent had a chance to measure the new diamond .030 pistons yet. they are still in the fresh rebuild short block which has been over line bored. (un usable block, a .010 undersize timing chain is still way to loose.)
i just finished disasembling the 40kmi motor with bad bearings. i'll disassemble and measure the fresh unused short block this comming weekend.