Knurl pistons or not

[redtom]

Im restoring an engine, not a tractor, ok it's an IH Scout 4 cylinder. The pistons and bores are round and just at the high spec of wear. New oversize pistons are only found it one place and pricey plus boring. I've not seen knurling in a while but this seems like a good place for it. Many pass it off as a hack repair but it's still done in some racing circles. It's never going to be a high revving 100k mile engine. Opinions?

 

[sotxbill]

Its a long forgotton art?? Last time I remember that all but one of the pistons went in.. but one was over knurled... As this was back in the 60s...

 

[rustred]

Im restoring an engine, not a tractor, ok it's an IH Scout 4 cylinder. The pistons and bores are round and just at the high spec of wear. New oversize pistons are only found it one place and pricey plus boring. I've not seen knurling in a while but this seems like a good place for it. Many pass it off as a hack repair but it's still done in some racing circles. It's never going to be a high revving 100k mile engine. Opinions?

Long as the ring lands are not worn out , no reason not to do it.

 

[Duner Wi]

Knurl pistons ,cut and install ring spacers. .010 over rings custom fitted. It will work .

 

[NDIHC]

I didn't know anybody still knurled pistons. Back in tech school in the late 80s the instructors taught it but I've never heard of anybody ever actually doing it. Does anybody know what a machine shop charges for it?

 

[Gary Reif]

We did it at the NAPA machine shop I worked at. Did quite a few back in the 70's and 80's. We would knurl them and let the mechanic fit them to the cylinders. I knurled a set for my 292 Ford, honed the cylinders .005 oversize and fit the pistons, worked out OK. Seems like it was about $2.50 or $3/00 a piston back then but that was a long time ago. We had a Perfect Circle piston knurling machine. I've got some hand held knurling tools but not sure they work as well. Also have Perfect Circle ring groove cutters for installing spacers.

 

[Ultradog MN]

There is a place near me that still has the machine - or did - most of 20 years ago now.
They did a set of pistons for a Ford 3000 gas tractor for me. I honed the bores, hand lapped the valves and put new rings and rod bearings in it.
$300 "overhaul"
I ran that tractor pretty hard on the bush hog for a couple of years then sold it. It still ran good when it went away.

 

[UncleTom]

My Dad 352 Ford pickup had knurled pistons in it and they cut the ring groves and used spacers when his mechanic rebuilt it. Never a problem. Probably longer lasting engine compared to the new stuff blowing up. I heard locally a GM 6.2 blew up on a trip and the guy had to buy another truck to get going. NO engines.

 

[showcrop]

My local automotive machine shop has places to get pistons from that the "usual" vendors have no knowledge of. They saved me money too. After all they are doing it every day.

 

[Geo-TH,In]

Im restoring an engine, not a tractor, ok it's an IH Scout 4 cylinder. The pistons and bores are round and just at the high spec of wear. New oversize pistons are only found it one place and pricey plus boring. I've not seen knurling in a while but this seems like a good place for it. Many pass it off as a hack repair but it's still done in some racing circles. It's never going to be a high revving 100k mile engine. Opinions?

I used to rebuild my car and truck engines 45 years ago.
I would go all the way, new oversized positions, rings, cams, bearings. freeze plugs, water pump, hoses and oil pump.
I figured I had it apart, do everything.
Now, all the machine shops are closed because engines last 2 to 3x longer.
Good luck finding a machine shop in my town.

One second generation mechanic in town advertises Jasper rebuilt.
I know some will hate Jasper engines. I never had one.
Don't know anything about them.

 

[SkipperII]

I used to rebuild my car and truck engines 45 years ago.
I would go all the way, new oversized positions, rings, cams, bearings. freeze plugs, water pump, hoses and oil pump.
I figured I had it apart, do everything.
Now, all the machine shops are closed because engines last 2 to 3x longer.
Good luck finding a machine shop in my town.

One second generation mechanic in town advertises Jasper rebuilt.
I know some will hate Jasper engines. I never had one.
Don't know anything about

I used to rebuild my car and truck engines 45 years ago.
I would go all the way, new oversized positions, rings, cams, bearings. freeze plugs, water pump, hoses and oil pump.
I figured I had it apart, do everything.
Now, all the machine shops are closed because engines last 2 to 3x longer.
Good luck finding a machine shop in my town.

One second generation mechanic in town advertises Jasper rebuilt.
I know some will hate Jasper engines. I never had one.
Don't know anything about them.

When my 2000 Chevy 2500, 6 liter spun the front main bearing; I took it to a local shop, that I trust. I was going to put a GM crate engine in it, they refused to do it, due to many failures. They advised me to put a Jasper rebuild in it, gave me the same warranty that the crate engine carries, and said they would even stand behind the labor. Been 5 years, so far, so good.

 

[Fritz Maurer]

We did it at the NAPA machine shop I worked at. Did quite a few back in the 70's and 80's. We would knurl them and let the mechanic fit them to the cylinders. I knurled a set for my 292 Ford, honed the cylinders .005 oversize and fit the pistons, worked out OK. Seems like it was about $2.50 or $3/00 a piston back then but that was a long time ago. We had a Perfect Circle piston knurling machine. I've got some hand held knurling tools but not sure they work as well. Also have Perfect Circle ring groove cutters for installing spacers.

What did they do about the rings? They came in oversizes like that?

 

[wore out]

What did they do about the rings? They came in oversizes like that?

https://ringspacers.com/ringspac.htm

.

 

[buickanddeere]

My Dad 352 Ford pickup had knurled pistons in it and they cut the ring groves and used spacers when his mechanic rebuilt it. Never a problem. Probably longer lasting engine compared to the new stuff blowing up. I heard locally a GM 6.2 blew up on a trip and the guy had to buy another truck to get going. NO engines.

The Mexican built 6.2 from 2021 to June 2024 had out of spec rod journals . Some with trash left in the oil galleries . A few left the factory without the retainer clip on a wrist pin .
The cars using the LT1 and LT4 version of the 6.2 seem to be ok as they use 0W-40 . The trucks were speced with 0W-20 in an attempt for better mileage .
The blame lays with the Mexican staff who did not perform quality control .
Then there are the 6.2’s ruined by cheap owners . Instead of using premium as stated in the operator’s manual . The cheapskates use 87 octane tractor gas . Detonation over the long term ruins the rod bearings and cracks the pistons around the wrist pins .

 

[Fritz Maurer]

The Mexican built 6.2 from 2021 to June 2024 had out of spec rod journals . Some with trash left in the oil galleries . A few left the factory without the retainer clip on a wrist pin .
The cars using the LT1 and LT4 version of the 6.2 seem to be ok as they use 0W-40 . The trucks were speced with 0W-20 in an attempt for better mileage .
The blame lays with the Mexican staff who did not perform quality control .
Then there are the 6.2’s ruined by cheap owners . Instead of using premium as stated in the operator’s manual . The cheapskates use 87 octane tractor gas . Detonation over the long term ruins the rod bearings and cracks the pistons around the wrist pins .

Aren't there any knock sensors in 2021?

 

[JIM MN]

Taking Knurling one step further, we knurled engine head valve guides at our dealership. Knurling used valve guides would, tighten valves stem in there guide, center valve on its seat and control oil going down the valve stem. Knurling valve guides works!

 

[Russ from MN]

My dad had it done to a Ford 391 in a logging truck in the 60's, I think it extended the life a little, but a short block was the real answer, they would last 60,000 miles, pulling a semi with a GW of about 65,000 pounds.

 

[buickanddeere]

Aren't there any knock sensors in 2021?

don't matter when the air/fuel mixture ignites prior to the spark.

 

[Fritz Maurer]

don't matter when the air/fuel mixture ignites prior to the spark.

Retard the spark.

 

[wore out]

Retard the spark.

Re-read Post #18 by "Buick".