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Sears ST/16 ? K321 Repower

10K views 60 replies 7 participants last post by  KennyP  
#1 ·
What is the diameter of the pulley for the drive belt? I know the belt is a 5/8" width, just need an approximate diameter for a possible project. Thanks!
 
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#3 ·
That may be something you'll have to guesstimate at. "I'm sure you already know" I'm assuming this is for the Predator swap..?
The crankshaft height will (might) be different from the other motors that were used so that makes a difference in belt lengths.
Yep, going to put the Predator in it. I'll have to drill mount holes for it, just be nice to know what size the pulley originally was. I would imagine the SS/16 drive pulley would be the same size (just different ID).
 
#5 ·
Whilst waiting on an answer for the pulley size, I brought the old girl up and swapped the rear tires. I also garnered a 30# weight off the tiller to use somewhere.



Here's the size difference:



And on the tractor:



Then I got to thinking. I happen to have a good running B&S 16 HP (cast iron). It would take more effort, but that could be installed. May take more mods to get it to fit, but I'd have electric start.



Decisions, decisions!
 

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#7 ·
Well, I gotta quit thinking so much. Just remembered I also have a good running Kohler 14 HP. That may be what I go with as I do love the Kohler engines.

All of my Sears/roper tractors with the Onan engines have 3 step pulleys. The outside step is 3". The next step in is 4 3/4". The Inner step for actual drive is difficult to measure exactly but seems to be about half way between the other two.

Don
olcowhand has one of those pulleys he is sending me. I'll have to get a bushing for a 1" shaft for it.
 
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#8 · (Edited by Moderator)
I have decided to use the Kohler. It's a K321S-6013B spec. engine from the Jacobsen 1450 Super Chief, I am trying to get the wiring figured out. This has the breakerless (trigger) ignition. The white wire from the trigger goes to the ignition switch, but I have been unable to figure if it is grounded when the switch is off. I DO NOT want to put 12V to it if it is a grounding (kill) wire. The trigger is a NLA unit. So far, testing with an ohm meter shows the wire as open to ground, but that may be a bad connection. I'll mess it more today until I am sure what this wire needs. I have not found a wiring diagram for this anywhere and the Jake wiring is to vague. If anyone is familiar with this type of ignition, please post.
 
#9 ·
Well, it looks like olcowhand has helped me find the answer on the wire. The WH GT14's had the same engine around 1970. Found a wiring diagram for it and it shows the wire going to the M terminal of the ignition switch which should be grounded when the switch is OFF.

 

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#10 · (Edited by Moderator)
Well I tried the Kohler K321S and it's a no-go. If this had been an SS/16 it would have worked I think.



The battery/fuel tank tray won't let it come back far enough and it has the belt pulley for the clutch welded on the bottom of it.

Guess it will get the Predator.
 

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#11 ·
After going back out this morning and looking things over with fresh eyes, I can move the Kohler back about 2.5-3". It will take some mods to the Sear parts (that I hate doing), but I can make this work. Just have to find a fuel tank location. Probably behind the seat.
 
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#12 ·
I hope to get the new battery tray made today and see how far back I can move the engine.
 
#14 ·
Are you sure it's welded on? That doesn't sound right.
Yes it is welded. I'll get a pic later.

I got started on the new battery tray. Cut 2 pieces of angle iron and got mounting holes drilled for them. Put the plate on top (needs trimmed some yet).



Welded that together along with a small angle for the back.



Slid the engine back after trimming the 'ears' for the old tray.



Right rear bolt hole would be impossible.



Then I looked at the front hole locations. Had to move the engine to the left side and back more to compensate for 'under' framework. This is where it will sit.

 

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#15 ·

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#17 ·
Cut the clutch mechanism off the old battery tray this morning and located it to the 'new' battery tray. Just tack welded it for now. Got some trimming to do plus possible 'remodel' of clutch components.



Here's where the trimming needs to be:



And this is how that clutch pulley is in relation to the crank pulley.



Right now to declutch & stop, you will be tensioning the belt. Gotta think on this a bit.
 

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#18 ·
Got an idea working. I did received the new flat idler yesterday, that may help things some.
 
#19 · (Edited by Moderator)
Here's my idea on the clutch. Using the clutch from a vertical shaft mower, V-pulley is bigger and mounted higher.



In the first pic, notice the bolt in the upper left and the distance. And the second pic.



The two pinned together at the pivot:



Both flipped over:



Wanted the PTO clutch off and remembered my bushing puller. The PTO had grooves in the outer part, found the right size insert and tightened it up. A few 'love taps' on the slide hammer pulled it right off there.



Crank pulley came loose as well. That is a 5" pulley.



Emory cloth cleaned the crankshaft.



I did start doing a 'fix' for the hood, no pics of that yet. Using some strap to mount new hinges on it for now. Can't do much more til I get the engine bolted in place and the grille bolted in. Have a job to do so it will be a few days before I get back to this.
 

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#20 ·
I have sad news on the ST/16. Tranny is bad! I pulled a tire off, put it in gear and the pulley did not move. I have a Draftsman III out back, Not sure if that tranny is good.
 
#22 ·
Something is stripped in there and I am not going to waste the winter finding parts!
 
#23 ·
Well, I forgot to check the Hi/Lo lever. It was in neutral! All is well!
 
#24 ·
TSC did not have a 5/8" X 83 belt. Got home and the internet was on the fritz. Was bored, so I wired the engine. Shot a short shot of carb cleaner in the carb and it barked to life! Been sitting for over 3 years. Has a 'new' carb and fuel pump. Hooked up a temporary tank and it starts easily and runs well. Idles real low. Knew it was a good engine! Belt is now on order.
 
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#25 · (Edited by Moderator)
Not much happening due to work & wind issues! But here's what I plan for a fuel tank.



I got part of the mount made up this morning before the North winds hit and the rain was blowing under the canopy.
 

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#26 ·
I had to move the ST/16 out from under the canopy to work on something else. I stuck the hood back up there for grins. Looks like it will work once exhaust clearance is worked out. I will be using something different! I know it is higher on the RH side!



Had to make a bell crank for the choke so it worked right.

 

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