I built my '52 331 hemi in the late 80s. It had rough cylinders so Ernie Hashim who had a shop in Bakersfield suggested I bore it 1/8" over and make it a 354. He bored it and found a coupe sets of used 354 pistons (aftermarket stockers weren't available then) to fit. He balanced the crank and did a valve job. Car has been reliable daily driver since '95. And steel has a finite fatigue life as do all metals.
Hadn't thought about it for years, but when I was in school we had a piston knurling tool and a ring grove cutter that re-cut them square and you had shims to put under the rings. We also knurled valve guides.
Here is what one looks like Here is the tool that does the job. It actually squeezes the aluminum up into peaks and valleys.
Most unique use of knurled pistons, this comes from a hot rod magazine circa 1959. The writer had a hopped up Chevy 283 with forged, solid skirt racing pistons. They were supposed to be installed with .012 clearance. Of course they would slap like crazy when cold, as they got hot heat expansion took up the clearance. This did not matter for a racing engine but this guy ran them on the street. His solution was to fit the pistons with .012 clearance, then knurl them. They never slapped when cold and did not seize when hot. I suppose they quickly wore to a perfect fit, and the knurling retained oil to keep them from seizing.
The knurling tools I have seen are of different designs . Some cut diagonal grooves,,,some cut straight grooves,,,,some diamond pattern . They are usually inserted into a tool holder in a lathe,,,,,and you can make it as deep as you need . I have never done it,,,,but have seen it done,,,,,,,it always seemed to work good . Tommy
Old drag racing bud Frank Martinez had a '57 Cad in his '40 Ford Street Coupe. He built the engine 'sloppy', also had .012" wall clearance. It'd rattle at cold idle, but when he stepped on it, (low gear in '37 LaSalle box, 3.54 rear) 4500 RPM and this loud, threatening rattle would tickle your eardrums. ("Whatatatatata") Sounded like death. I suggested knurling the pistons. Frank did, and all the bad stuff went away. ...even the children were happy. (Santa Clara, CA. 1961)
I bought a used lathe about a year ago and it came with a knurling tool. A friend of mine who's a pretty sharp machinist says it gets used by manually turning the lathe chuck back-and-forth, not rotating under power. I messed with it a bit on a round piece of some sort, and slightly increased the pressure on the knurling tool (turned it inward) as it made the knurl pattern. Didn't actually check for an increase in diameter over the knurls though, but I suppose it did raise some material. Not rotating it 360 degrees made sense since it would be rather unlikely that the knurl pattern would ever rotate 100% accurately to leave a "single" pattern. What say the HAMB experts? Lynn
I found knurled pistons in an 11-1 LT-1 with the big cam and whatever else they came with. probably powerful when new. guess it had a knurled crank as well as I spun one bearing inside the other trying to start it one day. I'd say knurling is good only when when selling a car.
Knurling pistons is the same concept as a chawed musket ball. Wadding is desired for best accuracy out of a Smoothbore. It also helps to have as close to bore size as feasible. The American Indians, masters of the Deerskin Trade (where the term “buck” meaning dollar originated), discovered that they could get good accuracy if they chewed on the musket ball. This allowed a smaller ball to be shot accurately out of a larger bore. The teeth marks on the ball, knurled it. Think about this.... The musket ball only had to make two trips down and out the cylinder bore. A piston, millions.
Skip Redio 34 Ford sedan. He still has it. Two charging systems as it has both 6 volt and 12 volt parts. So it has a 6 volt generator, and a 12 volt alternator. Last I knew he was doing wiring for Dave Simard
I temember back in late 70s, early 80s...knurling used pistons was as common as reground stock oem cams. Both ran OK. I put a reground cam in my 454 suburban...ran that for 20k miles.. never quit 3x long trips Dallas to Cleveland and back. 10mpg...60mph.
I hope you can use used pistons! I have a set of forged .030 over pistons for a 428. I planning on boring my standard block to fit these pistons! Bones
After reading all this I can’t imagine how many of these engines were out of balance. I was wondering how far out in grams a single piston can be if the rest was in balance before a replacement was put it. Many many years ago I saw a guy use a hone to bring a .040 over 292 yblock out to the spec of a standard bore 312 in the car which was just .010” and put in a stock 312 piston and ring set.. the pin heights are the same. Don’t think ever thought checking the piston weight difference. Any thoughts guys on the weight difference you can live with on a street engine?
If they admit it, I'll bet a lot of guys here assembled engines without checking any balance. I think a lot of it depends on what rpm range you plan to max the engine out. The imbalance effects are exponential as rpms rise, so something that might get by in a daily driver won't work in a higher rpm scenario. Its obviously going to vary with the components being used. I would match balance the used components at the very least.....but even if I reused pistons in another build, I think I would get the assembly balanced.
knurling the piston on the non-thrust side is a great idea. All the pistons that were done in the shop where I hung around as a kid, did both sides. I have a beater project on the go, and I am going to give that a try. Nothing to lose on this one. Bob
Unsure on a piston, but under power for a rod/handle/etc. BTW, even before knurling pistons, the use of a spreader bar on them was used. I'll try to get time to post a pic tomorrow.
Since most of the aircraft engines were air cooled and had LARGE pistons in them, the cyl wall tolerances were a lot bigger than water cooled auto engines. Most GA aircraft engines have their oil changed more regularly and its pretty much expected that they will use some oil during each oil change interval. But, they last a long time under some pretty difficult conditions, and reliability is what its all about.
And yes what they did in war does not compare to street/race/ driven/built in your garage or shop. The conditions -like Pappy's boys - the way they built them would not match at all as well - but the planes flew thankfully and completed their missions.
I get where youre coming from, but consider all production engine parts have weight ranges, and thats OEM. Its much better now than it was in the past. Consider how many 0.30-0.60 bored engines go together without a thought of balancing them. None of the stuff in this thread is a great idea, but it does work.... for a while. Ive been amazed at a pile of garbage parts going together and running hard - expected some not to make it thru break in - ended up running for years in a street car or making a season on a dirt track. Lot of times it comes down to making it to work, or making it to a race. Can you wait for funds to make it perfect, or do you go with "goodish".
Got a set of forged pistons with 6 " Carrillo rods I traded for at Jefferson swap. (the guy said they were 350 pistons) Appeared like they were hardly run. Got home and measured the diameter found out they were 434 pistons Took a long time to accumulate all the rest of the parts but built it and bracket raced it 5 years, replaced those pistons when freshening it up. Still running those rods
I am going to reuse used pistons in a Y block,was given a set of standard 292 pistons that were in for less then 1000 miles. Will try to punch out a 272 to 292.
People wanted to see a knurling tool I bought a hastings unit like this from a shop that quit for $25 It rocks the piston back and forth so you only do one side. I got it because I bought a ford 428 short block that didn't have any oversize marking on the pistons. It turned out I had a .060 over unit with wear with no pistons bigger so I bought the machine honed the walls and knurled the pistons and went. The motor went in a pickup to pull a camper at 80,000 miles it is still going strong.
First engine build I was heavily involved in was a 302 for my maverick in high school. Bores and pistons were still in spec, the cam died and.crank had issues. Turned the crank, new cam kit, bearings and rings. That 302 is in vehicle #3 and still going 30 years later
My friend and modified driver Jim needed a 302 SBC for a sportsman car years ago. We had a friend with a auto salvage yard (not to be confused with a junk yard, at least that's what the guy said...), and went "shopping" there. We took an early 283 for the crank, and a small journal 327-300 hp out of a wagon. Another friend gave us a used set of 30 over 302 pistons (TRW forged 11:1 or so). Another friend who had an engine shop bored and honed the block to fit the used pistons. Pressed the 327 pistons off of its rods, pressed the 302 pistons on. Don't ask how it would make you cringe. New rings, bearings and a Chevy 754 off road cam and lifters I had on the shelf, and a Z28 pan with wing welded on (Jim was a fabricator so no problem there), pickup made to match. And no we didn't balance it! The heads were 462 castings with 1.94/1.50 valves, and not bad. The engine shop guy did the valve job, andlined the valve guides with those bronze helicoil type guide liners, I don't remember their name. I actually liked them and used them in quite a few heads back in the day. When honed correctly, they held oil and lasted really well in alcohol engines. So the final engine was a mish-mash of stuff not worth a lot. We had a Z28 intake and an old Holley 3310 vacuum secondary 4 barrel, and I had a Vette cast iron dual point distributor with the tach drive and no vacuum advance. Jim used it 4 times: a 3rd a 2nd a crash and a win. Got affraid it was going to spit out a rod as we were seeing 8000+ rpm at times. Never put a tatle tail tach in a dirt car, they will scare you! The engine was pulled out, put under a bench and sat there until Jim sold the car 2 years later. It was put in the car so the guy could get started racing. It lasted the whole season for him. Ah those were the days...
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