K-321 rebuild/reassembly help needed.
 

I've read on some posts that the governor gear should be replaced upon rebuilding a Kohler engine. Is this necessary? Unless I'm mistaken, the governor gear doesn't seem to be put under much stress during operation.

:Morning: No, if your feeling lucky. You have to remmeber that heat makes plastic/and all composites brittle and I am not a fan of having to tear down again to replace one. When I am rebuilding/re-freshing any engine regardless of the make, a new gov'r gear is the 1st thing on the parts list. :American Flag 1:

What he said! I'd like to add that sometimes when the gear fails parts of it try to fit in places that won't allow that to happen then you end up with a see through engine. The horizontal twins are notorious for that problem. Your engine and your wallet. :beerchug:

Sometimes the gear on the governor fails. But the "K"s aren't really known for it tearing anything up. Usually just strips teeth and quits working. Unless you have a steel one and it fails. If they look good, I usually use them over, but that's just me. The twins are the ones that it breaks and really tears stuff up, busts holes in the block. It's not a bad idea to replace though.

Thanks for the input, Guys! Not sure what I will do yet as costs are getting much higher than expected.

My block is at a machine shop and I've got my fingers crossed. I'm looking at the crank seals that came with the rebuild kit - not impressed! Must I buy OEM Kohler seals? NAPA doesn't seem to have them.
Also, Can I install the seals before I reassemble the engine. I don't want to make a special seal driving tool.
Thanks Guys,

I would replace the plastic governor gear if it was me.
Main reason as stated because plastic gear will go on the brittle side. The governor is close to the exhaust port. That area is one of the hotter places on the engine.

Napa rebuild kit?

I usually buy the Kohler seal(s) when I rebuild an engine.

If you look around you can find them...(cast gear) i got mine from a guy who has a "cub boneyard" , was 30bucks shipped to my door..i bought a cast pan too, same price...i recommend when you think of what it does/takes....

Thanks, Guys!
What about crank seal installation, can I install the seals before I install the crank?

I would put them in after or you will probably damage them .

Thanks Brian,
Do you make your own tool out of a water pipe?

If you haven't installed many oil seals before prob be a good idea to use a piece of PVC pipe or something similar. I"ve used a brass punch or regular large flat flat punch.

seals are about the last thing I put in the motor. I just freehand them in with a hammer

Thanks Guys!
PVC pipe sounds good! Not sure I trust myself with a hammer next to the crankshaft.

That's how I do it too....

Got the block back from the machine shop and all looks well. I should be reassembling it soon. Three questions.
The Kohler engine manual says to torque the rod nuts(cap screws) to 20% over nominal value (260 in./pounds aftermarket rod), loosen and retorque to nominal value. Is this the correct procedure for the aftermarket rods?

The aftermarket piston I received has a 3-piece oil ring, 2 scrapers and a separator. Do I end gap these thin scrapers same as compression rings?

With the Kohler solid cast iron oil ring, the ring end gaps are spaced at 120degrees around the piston. How do you space the end gaps with 4 rings, (2 oil scrapers and 2 compression rings)?
Thanks for the help!
Rick

did you get instructions with the rod ? if not what kind of hardware holds your rod cap on? yes it makes a difference

space the compression rings 180 and the oil rings 180, the oil ring gaps can line up with the compression rings since one is oil control and the tops compression. put your expander 90 to your oil gaps. it explains all this in the manual.

Thanks DV,
The note included with the rod just says 260 inch pounds torque. no info. on procedure.
Sounds good on the ring gaps!
Thanks,
rick

Three piece aftermarket oil ring question. Has anyone had to trim the separator ring to allow the scraper rings to collapse enough to fit into the bore?
The separator ring has shoulders on each side that keep each oil scraper from touching the piston. Unless I trim/shorten the separator ring, the scrapers will not collapse to the .010+ end gap I adjusted them to.
1st pic.: shoulders on separator ring ( both sides are the same)
2nd pic.: oil scraper ring fully expanded and still not large enough (I.D.) to fit over shoulders around entire separator ring.
Sorry for the crappy pictures.
Thanks,
Rick

Have you tried installing them on the piston?

the oil rings really have no tension to them. that's the expanders job. it holds the oil rings against the bore. your ring compressor will squeeze it all together to get it into the bore.

When you install it on the piston, it's one piece at a time.

Sounds good! I'll see how it looks with the ring compressor on it.
Thanks,
Rick

The ring compressor compressed the rings easily, and the piston went in without any problems. The engine is reassembled and should be installed tomorrow.
The only mistake I made (as far as I know!), was to leave the crank bearing in the block at the machine shop. It came back packed with grit - No surprise. But after flushing/washing/flushing/drying/lubing the block/bearing, I noticed some play in the bearing that I don't think was there earlier! So I installed a new crank bearing.
I intend to try to break-in the engine as described in this thread: http://www.onlycubcadets./forum/show...k-in+procedure
I'll let you know how it goes!

I'm not much of a break it in guy. set up the idle, set up the hi idle and governor drive it around 5 min or so, retorque the head. change the oil and flog the crap out of it

HaHA!! :ThumbsUp::ThumbsUp:

I plan to find something I can drag around the yard to put some load on the engine after the first oil change. Mower deck doesn't put much load on it. I'm assuming, of course, that it will run!:biggrin2:

This is exactly the way I broke in my best running engine.

Yep, break them in as they will be run. One of my SB 383 Chevy's on the dyno. :beerchug:

That's the way to do it Sam Mac! On the dyno to give them rings plenty of back pressure to seat.

Rings don't need back pressure to seat. They need run. You could break them in by hooking an electric motor up to the engine and just spinning it. Temp plays an important factor, but not as much as use.

I think you need cylinder pressure under load to get ring seal. if you were to use a electric motor is would do the same if not worse than leaving it idle?

I dunno Don......

I didn't put a lot of thought into that statement TBH. But thinking more about it now....

I think that ring/piston expansion under load (from the heat) has more effect than anything. I agree that I wouldn't let a new motor idle.... but only because with it idling the cylinder temps would be so cool it wouldn't allow for proper expansion. If you were to spin a non running engine and just let the friction heat the block (so block at operating temp) I think they would seat. It's not like combustion pressure puts more outward force on the rings. A new ring in a piston should be tight, so you shouldn't get any more "rocking motion" out of a ring under load, than not under load. :bigthink: I really think engine/cylinder temp plays more of a role than load. I do also understand that cylinder temp is DIRECTLY affected by load...... Hmmmmmm

I believe my flippant remark about the electric motor is debatable..... :biggrin2:

do you know the theory behind gas ported pistons?

Allow cylinder pressure to hold the ring to the cylinder wall?

I am in unfamiliar area here as I don't build high performance engines.... but I'm going to say that using a gas ported piston lets you run less ring tension because when it needs the tension the ported piston allows for it. Thus reducing unnecessary drag?...... How close am I, LOL!?

the more cyl pressure you develop the more pressure that makes it down behind the top ring to push it outward to create a better seal. you may achieve the same result with no cyl pressure it would take allot longer. a gas ported piston just makes it easier to get the pressure behind the ring to create a better ring seal.

Bingo! We have someone that knows what he is talking about. :beerchug:
Pic is the dyno run from my last road race engine. It was built to have a wide power band. Nothing wild just a nice wide power curve. It also had to live for the season. It did what it was designed to do and then some.

that's a nice solid torque curve.

I'd say you have the nice wide power band you were looking for. That's very impressive.

It runs! I installed the rebuilt K-321 and it started right up. No noise, no smoke, just ran "normally"! I've got 2.5 hours on it now and all seems well.
I could not have completed this rebuild without the help of this group! Thank you for your patience and expertise. Is this a great site , or what!
Bottom line: Rebuild kit( +.010 piston, rings, -.010 rod, valves, one crank bearing, gaskets) - $140.00. Machine shop( bore, turn crank, lap valves) - $100.00. $240.00 total, not counting shop supplies, carb. rebuild, etc. Note - my second machine Shop estimate was for $320.00! Pays to look around.
Thanks again, Guys! :beerchug:
Rick