I use the rings supplied by or recommended by the piston manufacturer.  My last several builds I've use Mahle pistons and rings and been very happy. 

Hastings always made me smile ......no issues

With new pistons I would have gone with the thinner lower friction rings (like used in the newer engines) to maybe cut down on friction inside the cylinders.
It always make me frown when I 'test-spin' the rotating assembly and realize the amount muscle required to turn it over a revolution or two. (gotta use a looong handle breaker bar to turn it!........measure with a torque wrench to see

I doubt a ridge ring will have formed with 30,000 miles on engine.........I had a 289 with over 30+ YEARS torn down and had ZERO ridge! Knocked all the pistons out the top!
6sally6

Rudi wrote:

I use SRP forged pistons with Sealed Power 1/16 top, 1/16  second and 3/16 oil control rings in my 331.
Forged pistons are supposed to be more tolerant to preignition than cast or hyperutectic slugs.

Aren't they heavier?.......therefore messing with the assembly balance?!
  Not arguing....jus' wonder'in
6s6

BobE wrote:

Watch for any ridge at the top of the bore.  If your doing a dingo-ball hone, I'm not sure it will remove the ridge.

No, it would not, but honestly, I've never seen an engine that had a ridge in it.  I'm sure it happens, but even some of the garbage I've torn down (high mileage, poor maintenance) didn't have a ridge.  I've always bored engines to restore a fresh, clean bore for maximum ring seal.  Always with a torque plate, and on a seasoned block (a block that's been thermo cycled a lot in use so the casting takes its permanent set).  If you had all of that done before and there's no damage you should be fine to just knock any glaze off the walls and put it back together. 

I would not change the component type you are using, and doing a spot weight check would be a good idea even then.  Typically balancing is done with a common bob weight.  They find the lightest rod/piston/pin/ring combo then match all the others to that and use that bob weight to modify the crank/flywheel/balancer for proper balance. 

Forged pistons provide a cushion for a bad tune up, detonation, etc.  The key is that a forging tends to fail plastically and over time whereas a cast piston fails catastrophically.  Hypereutectics take a bit more than cast and can run super tight PTW clearance (why OEMs use them), but get carried away and they fail.  Though I will say my WRX has then in a turbo engine and at almost 200k when I had to remove the heads, other than cleaning some carbon off them, they looked just fine.  That's a mildly modified engine, but it does have EFI. 

Edumicate me on file fit and non file fit rings. The ring gap on the KB hyper pistons needs to be at least .026" gap. Hastings says their file fit rings are the race type. What's the reason a non file fit ring can't be filed?

I've got the same model piston for replacements, but they now include fly cuts for the valves instead of me having to fly cut them. No idea what rings I used back circa 2001 when it was built.

Last edited by Bearing Bob (11/08/2021 7:55 PM)

When in doubt ere on the side of a larger gap.  People get crazy about the gaps thinking going an extra .010" is going to cause the engine to consume oil and have poor ring seal.  I read an article once where they experimented with all kinds of ring end gaps and even up to 0.090" it made no measurable effect on power.  The ring end gap is only exposed for 1/2 the PTW clearance, which is usually 0.005" or so, half of which is 0.0025"  Let's say the top ring gap was spec'd at 0.025".  The difference between correct end gap and a gap twice as big as it should be is 0.0000625 sq.in.,  I know we get crazy with precision when we build engines, but think about a measurement that small.  Its much, MUCH more important that there be enough gap to prevent he ring ends from butting as the ring expands.  Such an event at best is a trashed bore and a broken ring and piston in one cylinder, but if they are all that tight...

You could file fit a non file fit ring in theory, but there likely won't be enough material to allow it.  The difference is the file fit rings are made so if you installed them as is they would have too little endgap.  Non file fit rings are made to have the correct gap for the bore out of the box, and if anything be a little on the wide side. 

TKOPerformance wrote:

BobE wrote:

Watch for any ridge at the top of the bore.  If your doing a dingo-ball hone, I'm not sure it will remove the ridge.

No, it would not, but honestly, I've never seen an engine that had a ridge in it.  I'm sure it happens, but even some of the garbage I've torn down (high mileage, poor maintenance) didn't have a ridge.  

TKO – well, I can say that I have seen ridges at the top of the bore that were easily felt, and easily seen on many engines, usually high milage street engines.  Now, my experience goes back forty to fifty years ago at two machine shops I had used.  Maybe materials used since than do not create the ridges any more, but that was my experience.

 

Piston knurling, had to look that up. Learn sumpin ever day. The police department motorcycle mechanic used to bead blast the pistons to get the same results. Old school rules!

Rudi wrote:

TKOPerformance wrote:

When in doubt ere on the side of a larger gap.  People get crazy about the gaps thinking going an extra .010" is going to cause the engine to consume oil and have poor ring seal.  I read an article once where they experimented with all kinds of ring end gaps and even up to 0.090" it made no measurable effect on power.  The ring end gap is only exposed for 1/2 the PTW clearance, which is usually 0.005" or so, half of which is 0.0025"  Let's say the top ring gap was spec'd at 0.025".  The difference between correct end gap and a gap twice as big as it should be is 0.0000625 sq.in.,  I know we get crazy with precision when we build engines, but think about a measurement that small.  Its much, MUCH more important that there be enough gap to prevent he ring ends from butting as the ring expands.  Such an event at best is a trashed bore and a broken ring and piston in one cylinder, but if they are all that tight...

You could file fit a non file fit ring in theory, but there likely won't be enough material to allow it.  The difference is the file fit rings are made so if you installed them as is they would have too little endgap.  Non file fit rings are made to have the correct gap for the bore out of the box, and if anything be a little on the wide side. 

 
Just because some rings are non file fit out of the box does not mean they should not be checked,
No way would I assemble any engine without verification in each bore. I have enough things to think about keeping me awake at night.

I think you guys know me well enough by now to know I would NEVER advocate putting anything in an engine without checking clearances.  File fit or not you ALWAYS check piston ring endgaps.  I go back to a guy I worked with at my family's business.  I was 19-20 at the time and he was rebuilding a 454 for his boat out in our shop after work.  I stopped out and saw he had the bottom end together, so I asked "what were the bearing clearances?"  He stared blankly, then said "not sure, but the bearings and crank came from the machine shop so they must have checked them."  I said "you didn't even check with Plastigauge?"  Then I started to get the "listen kid, I'm trying not to be a jerk because you're my bosses son, but you don't know what you're talking about" routine.  Ever seen what happens when you put stock sized bearings on a 0.010" under crank?  Well I have.  That engine lived a very short, very unhappy life.  On reassembly he was using a dial bore gauge and a micrometer to measure the clearances. I stopped out to see what he was doing, not to gloat or anything, but I definitely got a sheepish look and about five "I should have listened to you" from him. 

The killing off of the carburetor has pretty much done away with ridged blocks.  The correct fuel ratios now don’t wash the lube off the cylinders as bad.  Plus, better ring materials.

How many of you still have a ridge reamer in your toolbox?  You used to have to cut the ridge out before the pistons could be removed!

BobE wrote:

MS wrote:

The killing off of the carburetor has pretty much done away with ridged blocks. The correct fuel ratios now don’t wash the lube off the cylinders as bad. Plus, better ring materials.

How many of you still have a ridge reamer in your toolbox? You used to have to cut the ridge out before the pistons could be removed!

I don't have a ridge reamer, but I do remember having to remove some pistons from the bottom because of the ridge at the top.
 

Ok that brings up a trivia question.  If you WANTED to remove the pistons in a small block Ford from the bottom, how many of them could you actually get out the bottom?

MS wrote:

BobE wrote:

MS wrote:

The killing off of the carburetor has pretty much done away with ridged blocks. The correct fuel ratios now don’t wash the lube off the cylinders as bad. Plus, better ring materials.

How many of you still have a ridge reamer in your toolbox? You used to have to cut the ridge out before the pistons could be removed!

I don't have a ridge reamer, but I do remember having to remove some pistons from the bottom because of the ridge at the top.
 

Ok that brings up a trivia question.  If you WANTED to remove the pistons in a small block Ford from the bottom, how many of them could you actually get out the bottom?

 
4

Last edited by Rudi (11/11/2021 8:33 PM)