It was done since the 60s and everybody did it,
017 over is a convenient piston ring size and aftermarket piston size. The narrow race rings were more available in a popular step too, like DYKES and lo tension oil rings, and narrow 1st and 2nd rings
Here is a good example, Kalitta raced his blown Cammers out of Stroppe's when he was out West. He had no crew, our guys helped him in any way because he is awesome
He was well known, since around 66, as were others, for honing the block hole by hole to the size she needed. Then mixing sizes to work. And this happened too, if the 4240 hole got loose due to the bore scuffing or wearing faster, but the piston was still in tact, it could get moved down to a hole that needed honing to the next step. Pistons could get shuffled
The factory service manuals for the FE's also allowed such a practice. And FORD sold oversize stem valves for service use. No new guides needed, you reamed the head to plus 003 on the guide and started over
So his average block might go like this so did ours STD then plus 001 then 002 then 003
This is all about ring sizes and what rings you can buy
So his blocks, and many Drag blocks got freshened a lot, and many blown SOHCs could 4.234 and 2 holes could be 4.240 some 4.250 some 4.260 and depending on the piston co, you could get , say a 4.24 plus 001 or 002
Ron is an old pal and we dig him. I sold him parts way before he ever had a shop.
Always cool and a nice guy
He would tell you that a lot of us did 017 over for a real simple reason, you could find the latest and greatest ring combos in 425. This is a very popular bore, due to it being on a million 426 HEMIS, 427 Rodents, 454's and so on
guys went to 017 over at the suggestion of the piston companies. It was easy to make slugs off tooling for the chev and dodge guys set ups
But the race teams took several steps on the bore size way before going to 017 over ,,,,,to maintain as much wall as you could
It is a nice step, 017,,,,many more rings available, and when Total Seals were popular, they factored in to the choices too.
So funny, we did the original Dyno R and D for Total Seal before they formed their business. They started with a small ad in a magazine and an article or two
The Dyno results showed less blow by, yes, but little to no power at first. After more testing and tricks, they did show gains, for later guys
But you guys know, maybe some don't...so, our Pro Stock Clevelands? We did std, then 30-50 runs, hone it, taper, then all the Pro Stocks could get the 1st step pistons 003 over
More runs, honing, then 006 over,,,,,more passes, then 009 over,,,,,,then 012,,,,,then junk it and start over
If you call a good piston company, they will make you a standard size, and usually any step you want within the rang of the rings, often plus or minus 001,002 003
On a 427 FE 4240 is still a step too
When SHELBY standardized the next generation all aluminum 427, and that helped many later FE parts follow to us, this same ring availability issue, and the reduced cost of a 4.25 piston, and sleeve availability was a factor in their choice to make these blocks 4.25 to begin with
PS, on the use of a race FE with 3 or 4 different size pistons, they all got balanced within 1/4 gram to each other and if blown, the slight difference in cubes hole to hole is not an issue
If injected the FE ran fine
On a Pro Stock style FE, or a NASCAR style FE, compression balancing was very popular and kind of key we felt, for an endurance race. Same deal on Off Road and the GT or Pantera race builds
And for history, only TRW pistons came in the shop miking within a tenth, or 0001
All trick aftermarket pistons, which were great and fast and awesome, usually ranged in size up to 0015...that is 15 tenths We fit to the tenth. So the range on many trick pistons was , usually about 0007 7 tenths So we select fit them anyway. Number them all then hone to fit right, and the block might end up with 5 slightly different size holes anyway
I have a 427 here, a famous one
Order 003 over pistons, from std FE
I can get 4240s plus 001 002 003
I would advise you do not jump to 017 over unless you have no other choice
Take the baby steps and save the bore and metal. Just call the good piston companies
ARIAS for example will make these, so will VENOLIA and many more
On 390s and 428s, we NEVER go 030 as a 1st step We order customs in the same small steps if possible
A few of our best engine men here stock such pistons at times, so check with our engine sponsors here too. They can provide more logical and less wasteful choices
Thanks
Just a little background in case it helps a new guy
You old fast guys got this all 45 years ago ! maybe 50 !
Geritol please
