Gemdozer, darn I believe the 2f3669 are standard sized pistons for D318 (DW10) if one number down to 2f3668 (semi-finished Piston that may be finished up to .060” O’sized) that would be gold! I’d like to take 2 of them if there are any out there. Anyone know if the pony motors have a model and serial number anywhere other than by reference to the Dozer model number? Scoop

Scoop wrote:

Hey guys this is Scoop, I’m also in the middle of a Pony Motor rebuild. It’s a D318 out of a D6 8U Dozer with 3-1/8” bore x 3-1/2” stroke pistons. Waiting to see how the tolerances come back from machine shop but my measurements indicate it will likely need to be oversized .02” to .04”. Doing very well with many parts I need from Florin and some from local CAT dealer. Toughest part now is locating O’size piston supplier. Spoke with JE Piston, the guy there said I would have to send them a Piston to reverse engineer it ... ain’t doin that. Also contacted someone from JP Piston, guy there said to send specs to This email address is being protected from spambots. You need JavaScript enabled to view it.. Looks like a stateside JP Piston rep from website. Having a tough go at it, hopefully here back from JP soon. Any other sources out there if anybody listening in and may know of would be greatly appreciated. Also wonder just how much getting those darn things to the house is gunna cost, anyone care to venture a guess?

Hey Scoop, I also emailed JP Pistons.au and got this auto reply from them:

Please note Nornda Automotive (Rollmaster, Romac, JP Performance, JP Pistons)
Will be closed (as usual on Friday)
from Friday 22/01/2021, until Tuesday 26/01/2021
HAPPY AUSTRALIA DAY

Eisenhart, didn’t hear back from This email address is being protected from spambots. You need JavaScript enabled to view it. so I sent spec info to This email address is being protected from spambots. You need JavaScript enabled to view it. for good measure and got same reply back. Australian Day aye, Cheers Mate

Hi Team,
here is the Cat Chart for pony engine piston sizes.
I feel that back in the day at the Dealer we could purchase the JP pistons semi-finished and that they would clean up at 0.080" oversize--if needed then I suggest that you please check with JP if this still so or ever was so.
Cheers,
Eddie B.

Morning Eddie, I spoke to JP Pistons about 6 years ago, I reckon the pilot motor pistons were available up to 60 thou oversize at that time, you told them your bore size and they machined the pistons to suit and supplied the correct rings and gudgeon pin, and I reckon they were $A120 a piston back then, about $US90.
Regards
Mike

Sorry I make a mistake it was 2f3665

Neil, what size pistons were they for and did that come with rings and pins? For my D318 Pony 3-1/8 x 3-1/2 I was able to get a price of $255 for set of new 2F-2669 standard pistons incl. rings and pins ... plus s/h and tax. In addition to JP Piston I have a couple of other requests out there for oversized unfinished 2F-2668 pistons with 2 sources attached. Anyone know if a machine shop in general can typically finish an unfinished Piston? Not sure of process and equipment and expertise needed but would love to know. These O’size pistons can be finished down to .02” to 06” oversize from std.

another big piston manufacturer is Wiseco, very extensive list of applications....just throwing it out there..

Thanks Kitty. Sorry Eddie, not trying to bootleg your posting here but getting real good feedback on Piston topic! I spoke to my guy at the machine shop, he said special equipment the piston manufacturer already has would be needed to finish an unfinished piston to specified size which would mean an additional step and cost to source (assuming I can find an unfinished one which he thinks would need to go to a piston manufacturer to finish); at least he does not have the means to do it not saying others out there don’t. He mentioned to contact Egge in California as a stateside source he uses for old equipment. Their website looks good and will check out along with Weisco. Anyone out there use these sources successfully?