Have a question going back over 50 years- I had a Rupp kart with a Mac 6 engine. I bought the engine used at a kart shop. The owner said that sometimes these engines fail and the rod's small end needle bearings would try to come out the exhaust port. He showed me the improved piston that didn't have a wrist pin hole on the exhaust side. I didn't think much about this until mine did the same thing he described several months later. My question is- Why would it do this?
Wrong length wrist pin or neglecting to ever do a rebuild. At some point the piston and bearing need to be replaced, or a loose wrist pin shifting . The side to exh was never an open bearing. It was a closed bearing different than the intake side. I have never had a small end failure and I've done this a long time. While on the subject of bearing the big end rod bearing are getting really hard to get so you mic those and if in spec you reuse them. Don't just throw them out. those haven't been made in 30 years.
Steve- in a former company I had we bought pins for knock out dies (I use to make rivets) we could buy these pins 3" long in .001 size increments from .020 up to .250. All you would have to do is cut them close to length with a Dremel cut off disc and then kiss them on a grinder to length. If you want the source for the pins I will dig it up. E-mail me at work since I only visit the site on days that end in a "y".
Jim
(10-17-2018, 07:04 AM)Jim Donovan Wrote: [ -> ]Steve- in a former company I had we bought pins for knock out dies (I use to make rivets) we could buy these pins 3" long in .001 size increments from .020 up to .250. All you would have to do is cut them close to length with a Dremel cut off disc and then kiss them on a grinder to length. If you want the source for the pins I will dig it up. E-mail me at work since I only visit the site on days that end in a "y".
Jim
Jim, With the needle bearing for the rods getting low that may be an option. I would be interested in looking in to this. do you recall what the minimum order would be? Can you post the company name here or not? I will send you an email for it. The thing is you would have to run an undersize pin so you better have a crank and rod that's not to worn.
(10-17-2018, 07:51 AM)Tom Day Wrote: [ -> ] (10-17-2018, 07:04 AM)Jim Donovan Wrote: [ -> ]Steve- in a former company I had we bought pins for knock out dies (I use to make rivets) we could buy these pins 3" long in .001 size increments from .020 up to .250. All you would have to do is cut them close to length with a Dremel cut off disc and then kiss them on a grinder to length. If you want the source for the pins I will dig it up. E-mail me at work since I only visit the site on days that end in a "y".
Jim
Jim, With the needle bearing for the rods getting low that may be an option. I would be interested in looking in to this. do you recall what the minimum order would be? Can you post the company name here or not? I will send you an email for it. The thing is you would have to run an undersize pin so you better have a crank and rod that's not to worn.
Tom -- the company I use to buy from is Royal in Warren, RI 401-245-6900. They have a catalog, or I should say they did when I use to buy from them. I don't know about minimums because we use to buy in quantities of 25 punch pins at a time. They are harden ground rod and I am sure they would be just fine for the needles. They are damn hard and the only way you will cut them is with a cut off wheel
They have distributors here in in IL but I am sure they change so give the company a call to get their contact here in IL.
Jim
(10-18-2018, 03:46 PM)Jim Donovan Wrote: [ -> ] (10-17-2018, 07:51 AM)Tom Day Wrote: [ -> ] (10-17-2018, 07:04 AM)Jim Donovan Wrote: [ -> ]Steve- in a former company I had we bought pins for knock out dies (I use to make rivets) we could buy these pins 3" long in .001 size increments from .020 up to .250. All you would have to do is cut them close to length with a Dremel cut off disc and then kiss them on a grinder to length. If you want the source for the pins I will dig it up. E-mail me at work since I only visit the site on days that end in a "y".
Jim
Jim, With the needle bearing for the rods getting low that may be an option. I would be interested in looking in to this. do you recall what the minimum order would be? Can you post the company name here or not? I will send you an email for it. The thing is you would have to run an undersize pin so you better have a crank and rod that's not to worn.
Tom -- the company I use to buy from is Royal in Warren, RI 401-245-6900. They have a catalog, or I should say they did when I use to buy from them. I don't know about minimums because we use to buy in quantities of 25 punch pins at a time. They are harden ground rod and I am sure they would be just fine for the needles. They are damn hard and the only way you will cut them is with a cut off wheel
They have distributors here in in IL but I am sure they change so give the company a call to get their contact here in IL.
Jim
McCulloch bought kegs of 52100 taper ground needle rollers. I think they were sourced from Timken. Keg = 100 lbs.
of needle rollers.
Not sure if this will help to get your Mc6 back on the track, but...
I believe that the needle bearing businesses of both Torrington and Timken were bought by Koyo. Koyo Bearings formed a joint-venture with Toyoda Machine Works so now they operate as JTekt North America.
https://jtekt-na.com/products/koyo/needl...-bearings/
I think US Motor Power went through the ringer when Koyo stopped making the needles that the US820 used. I recall that US Motor Power ended up ponying up for a run of the uncaged needles they needed.
USMP minimum order was 20,000 sets I had heard to get them made