Hey Jon, I attached the Pony motor parts diagram FYI. Looking for part nos. 7F4944 and 5F7647. I’ll call you later, thank you!

Good evening, Anybody know of a machine shop I can send CAT Unfinished Piston p/n 2F-3668 (3.19") to have turned down for my Pony Motor rebuild?  Was able to round up a pair but having trouble finding a shop willing to take the job on. One guy I was recommended to said the last time they did that was about 20 years ago and I got turned away. I understand they are to be turned down round and not cam ground from previous post but am told there is a bit of an OG 3 step process to it in order to do it right. Any help with contact info is appreciated!! Scoop

the crank journals should not be out of round. that needs attention.

the exhuast is unobtainium so just go to a local exhuast shop they should be able to make you one using the original flanges the gaskets are still available. or get new flanges laser cut from stainless and use stainless exhuast tube.
have that crack on the valve port checked.
the valve seats need cutting.
as for pistons jp pistons (part of naranda automotive) in south australia will make them to what ever oversize you need or sleeve your back to std and they can supply std pistons too.
the old ways still work just fine ive done that many times with studs. use plenty of penertrating oil and time for it to soak if you can imerse the thing in diesel it works very well. the machinist is correct heat on studs can make it worse if you use heat you have to heat the casting not the stud do it wrong and you can crack the casting.

note the method for the crank bearings reqires them to be machined to lenght to give correct end float clearance. they are sold over lenght to allow for this.

use the pns listed in the book if you look them up on the cat parts website note some need a zero added after the first 2 characters to show up since cat now uses 6 digit part numbers. also some part no have been superseded over the years and now have new numbers as improvements were made thats why it important to have a parts book for your machines serial number but be aware some machine are a hienz varities job and have been made of different models just to keep them running so parts can be different.

 

Thanks Neil, I spoke with JR this morning and looking into it. Appreciated 

March 27 Rebuild Status: Still waiting for machinist to give me the bore and crank status for sizing pistons and crank bearings  🤷‍♂️  He's a little backed up but said in a week or two. I've been able to purchase most parts I need for rebuild ... appreciate the Florin contact great to work with. Also worked with CAT dealer from Cleveland Bro. In Wilkes Berra PA - Tom ... he put a lot of heart into getting hard to find stuff and located the unfinished CAT pistons for $49.00 each that I may have jumped on to soon. If I continue to have an issue getting pistons turned I'll go with JP Piston ... going with JP includes rings and pins which may be less expensive overall in long run and less risky ... we'll see after I speak again with machinists this week ... still not throwing the towel in.  TBC

Thanks Trainzkid ... Are you referring to the lines shown in both valve ports on left side of block or did you notice something else? Also, you mentioned the crank bearing are oversized in length ... are referring to the main bearings on timing gear and flywheel side of the block? Thanks

Scoop wrote:

Thanks Trainzkid ... Are you referring to the lines shown in both valve ports on left side of block or did you notice something else? Also, you mentioned the crank bearing are oversized in length ... are referring to the main bearings on timing gear and flywheel side of the block? Thanks

yes it was on the left side. it looked like a crack in the photo so i would get that checked. being cast iron/cast steel it is possible to repair if it really is a crack. to check whether it is, it might be a idea to get some fine emery cloth and a little kero and clean up the area. you can also use flawcheck(dyecheck)aerosol spray system to crack test it. what i saw was in the valve recces but above the valve seat.

and yes i was reffering to the main bearing. edb another acmoc member and retired dealer mechanic posted something about this the just the other day.
from what i remember only one of the bearings is supplied over length (semi-finished) and the distance from crank shoulder to the outside of housing is measured and so is the bearing which is then machined shorter to give the required end play. maybe the others can confirm this.

Trainzkid, ok will look into possible cracks and compare old vs new bearings when installing. Didn't notice possible cracks until you pointed out ... clearly something is going on in the photo, so thank you!

Good evening,
I'm working on D69U pony motor., my question is how can I set the timing gears.