I posted a while back on shaving the tops of my pistons and got lots of ideas ( Many thanks yall ) There will be plenty on top land and valve relief material left I need to shave around .083 off the top of my pistons I thought of buying a cylinder sleeve, putting an old top ring on the piston Installing a rod and pin then securing the end of the rod so the ring was tight against the sleeve Then putting the whole shebang in lathe and shave a bit Opinions, options ?? Ricky.
You might contact PackardV8 ,,( Jack Vines ),, he’s an expert on piston modifications . Great guy to know . Tommy
I would be suspect of the ring breaking and not sure the overall setup would be very accurate. Do the pistons have an internal register left from production?
What if you make a cut in the sleeve so when you clamp it in the lathe jaws it would squeeze the piston and hold it tight. You could also put a couple of small pins in the sleeve to locate piston depth for repeatable cuts. You would need to zero out for every piston due to the sleeve movement when loosening the jaws, but it should hold them pretty tight.
I use this concept all the time at work. Find piece of tube or pipe that has a heavy enough wall but not too heavy. Thin wall will not work. Something like 1/4-5/16 wall works well. Use a piece long enough so the section you want to use is out of the lathe jaws. Face/bore/turn OD. Bore to just fit pistons. Turn OD just to clean up,only for making ID and OD concentric. Either part of or pull and saw cut. Then make a saw cut to split bushing lengthwise on one side only. Usually stress in tube when saw cut will cause it to spring open. When this peice is put back in the lathe the amout that it springs open will let jaws hold it enough that the ID is big enough to slide part in and allow to tighten to clamp part(piston) You put back in chuck either sticking out(and re facing for squareness) or set back in jaws so you can use jaws for a stop for the top ring. This will only work if the ring OD is large enough to contact the jaws. Depending on wall thickness of tube used. Pistons are cam ground and not round, but it will grip it w/o issue. Just use enough force to hold not crush. I have used this same process to machine anything from odd size pipe OD's to rubber coated caster wheels to rubber/plastic parts that I dont need to turn prior to boring or other ops. Even when machining parts in a chuck mounted in one of our CNC mills and have used it in the manual mills as well. I have done some serious hogging using this set up,but you wont have hardly any cutting force,so a light grip will work. When I get to work tomorrow I will shoot some pics of what this concept looks like.
I have jaws to hold the piston by the ring lands. Took this pic to show a while back, but you can't leave the pin in. It will get you! Also a quick and easy way to measure piston thickness to see if you have enough to cut .083 off.
I also made a draw bar set up, that pulls on the pin, I will get pictures later today. Its just a piece of aluminum machined to fit the bottom of the piston to register it and a eye bolt to pull it tight through the spindle of the lathe.
Here is the draw bar thingie I made up. Most pistons have a register on the bottom, so I used that to locate the piston. Fast and repeatable.
Why not just take them to a machine shop? What does 2-3 hours of machine shop labor even cost where you are? That way you'd know that they were done accurately, and they can even re-equalize the weights.
Years ago, last 4 shops either screwed up my parts up or switched my parts for beat up stuff Then my Friend opened his own shop 40 years ago, he retired last year Anyway, I was a machinist at one time and I like doing my own work Thanks yall !! Ricky.
Doing it your self is the traditional way hot rodding started. They didn't pay other people to build their cars.
Yes, and no. Without proper machining, compression and quench will be all over the map. Without weight equalization, the rotating assembly will not be balanced. Machine shops predate the automobile. They have always been a place to go for precise work. We cannot revise that out of our history.
At work, the last 3 engines we sent out came back fucked up. One, the pistons the machine shop bought were too big to fit into the holes in the block they bored. On another double overhead cam MG that they assembled, they mixed up the cams. The 3rd one, a Hemi has a terrible noise coming from inside the engine, so we had to pull it and return it to the builder. Haven't got that one back yet. All this from 2 different machine shops.
I am trying to find a competent machinist nearby me to resize rods. Simple job… But more than half of the shops around here have reviews complaining about this same thing- the shop swapped out the parts they supplied or already had assembled for crap. It never occurred to me that a person could suck so badly and stay in business.
This!! There are infinite work-arounds, if your time is not on the clock. If a shop is trying to do good work and stay profitable, they will have the machines, tooling and jigs to do it quickly and accurately. For true. We don't solicit job work, but if you can't find anyone, send them to us. $6 each, plus return shipping, guaranteed to be within tenths of the ID you specify. jack vines
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