I bought a NOS set of std bore, 265 Chevrolet, V-8 pistons. Only they need "finish" machining. Apparently this was common practice, along with knurling pistons, and babbitted bearings back in the day. Nowadays........... Does anyone know of someone that can machine pistons, NOT the piston head. I spent quite a while on the phone today with several piston manufacturers, and they could'nt help. EGGE was flat out R-U-D-E!!! Help me. Thanks, Butch/56sedandelivery.
Those are know as "Semi" finished pistons. Normaly cam be finished up to .080 OS or so. But in answer to your question look for a engine re-building shop that has been around a while. 50-60 years ago was a common operation in engine re-building. Not too long ago I ran across one of these machines ,can't remember just now where at.
Finding a machine shop to do this, and considering the additional cost, I think you're going to be money ahead by giving these away at Christmas to friends that need paperweights (as 73RR mentioned) and then buying a new set of finished pistons. You mentioned that these are "standard bore". Have they been measured to see how close they are to "standard"? If they're standard bore, and need some more taken off of them to finish them, they'll be undersized, won't they?
Metals Crank here in Cleveland OH has been around since 46 or 48. Maybe he has something. Hes doing my flathead now and I've seen some old stuff in there more than once. 216-431-5778. His name is Pat and some times he answers the phone with a, "HELLO!" Bob
those are most likely what they called "Semi's" they were oversized and could be cam ground to the proper oversize and shape , A -B -C-D were the normal cam grinds for different apps. from p*** car use to heavy truck. You see pistons of that era were not completely round as the expansion from combustion heat would change the shape. Some used slots cut into the skirt area, others like solid skirt types were cam ground so any expansion would be inline with the wrist pin axis thus keeping the pins from seizing. I learned this from a old friend Bill Robertson who was an ace -duece machinist during the 2nd WW. He worked for El Monte Auto Parts into the 50s and raced with Don Farmer and the midgets circuit. Those guys ran a V/8 60 with a 180 degree crank , it was a torque monster out of turns . These were the days that guys had no PAW ,Summit, to go to ,they got ideas and built it !!
Std bore 265 is 3 3/4" (3.750), these measure "about" 3 13/16" (3.81+) so they could actually go as far as .060 over by finishing them that way also. I did find a place in Ct. that does "piston turning and grinding" (complete opposite side of the country). The rings I have are std to .010, so they must be file-to-fit rings. I'm guessing the ring grooves would also have to be machined deeper with a std/.030/ and possibly.040 overbore. I'm thinking paper weights and large loop ear rings if I can't find someone to do the work. Butch/56sedandelivery.
Piston machining is complicated. Pistons are not round or straight; they have profile and ovality such that they expand to a more cylindrical form at temperature and so that they contact the cylinder bore on the intended thrust surfaces and not near the pins. This is done by copy machining off a master piston that has the correct form (referred to as cam machining above) or with modern CNC machines. You would need to find a shop that has a suitable pattern or CNC capability. We have a shop that does special pistons for us at work, but the cost would be shock to you. You very well might have a nice set of paper weights.
Probably not too many shops that would have the proper equipment or understanding to do it these days . My old pal Bill Robertson gave me set of 327 pistons and told me to have the shop down the street to bore and finish hone for a certain cam cut the pistons had so they had to run a looser fit. These were for a truck application and it ran like Jack the bear for more miles than I owned it.
Try Bud's Machine Shop in lakewood, Hes a great man and if he doesnt do it he would steer you to someone in the area that does.
Pistons were turned in a slight taper with the lower skirt part of it clamped slightly out of shape in a fixture, when undoing the piston from the fixture the material in the piston wil "bounce" back to a "misshape" that is correct again when thorroughly hot.
I bought a set of semi's from Northwestern Auto Supplyand they finished them to what was needed, very reasonable, but I bought them there, they've been doing it for years. Grand Rapids Mich.
This is getting frustrating, in an interesting sort of way. Hagen's Hi-Way Auto Parts, they deal in antique engines and parts, has the machine, but the only operator has retired and no one else is familiar with the technique. The place in Ct. has two machines, and still does the work, for $100.00 a piston ($800.00!!!); they'll finish them in any oversize up to .060. Course they need the exact block bore oversize and cam style of the piston desired. Looks like this is a dead issue now, but I did learn something new. Butch/56sedandelivery.
At least one guy here made his own pistons from scratch, including machining. His thread also mentions a book on making pistons, that explains machining. All you have to do is find it.
Turning the pistons round and to size is no big deal. Sizing rhe piston with the correct amount of taper, barrel, and ovality is another matter. That is some tricky machine work, and the dimensions for those parameters depends on the properties of the casting or forging, and how the piston will be used. Unless you are emotionally attached to those pistons, want to see what you can get away with, or are stranded in the desert, I would just buy a proven set of appropriate pistons from a reputable manufacturer. I remember reading that. I don't remember the guys name but he posts a lot. He probably won't like me saying this; I think his piston exploits are an exercise in how much can you get away with rather than anything to do with making good pistons.
That's our "Senior Dragster" Canadian fella, Dolmetsch. Maybe he'll jump in on this thread. If these pistons were'nt forged.................I bought them to use in a Pseudo-Junior Stocker build.Butch/56sedandelivery.
Thats HAMBer Dolmetsch. Great thread, learning a bit more all the time! Here is his thread http://www.jalopyjournal.com/forum/showthread.php?t=519792
Well, I found a machine shop in Spokane that still does this, and for $480.00 for the full set. Getting better, but still.......... My plan was to build a large journal bottom end 265 using a 4 bolt Canadian 305 block I have in storage (bored .014 oversize from stock 305 specs to std 265 bore), along with an "1178 302 crankshaft, and 350 rods. I know, off the wall, but better than a 265 block with pulse oiling and small rods. I have a pair of rebuilt #5306 heads, and the early 56, Corvette dual quad intake (no carbs yet). That idea may die however due to the costs involved with the piston work. Butch/56sedandelivery.
Rebco Machine, ask for Eric (316)440-2828, tell him Ric @ CP Pistons/Carrillo Rods sent you. Best job and best price period!
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