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AC 616, 620, 720, Simp. 4040, 9020 Engines


JBLACK

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Les - Makes me a little ill to find out that my fears are fact. Am partly disassembling my '71 CCKA 16.5 to get all the pertinant measurements. Haven't removed fan yet but looks like a .875" shaft in the rear, .875 ???? and a 1 7/16 clutch (Stub not know yet)in front. If you wish I'll give you all the numbers when I finish the job Mon or Tue night.

Stan
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We need engine information on these tractors. It is a major area of concern form many members as the Onan CCKA and CCKB engines are very problematic. I am requesting that any member who has information to share please do so, we will then summarize it and add it to the site. Here is what I know(right or wrong),

The CCKA&B Onan engines used by Simplicity were special built. Parts are not readily available and will probably have to be machined. The crankshaft is a special size, causing a problem with pully replacement. The many problems raise the question of engine replacement. I have heard of replacements being made(that included special machining) but I have no details. Please help me form a concensus opinion on how to deal with this problem. Thank You.
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Les, It looks like we're not going to like this one bit. But it does have one saving grace (later). The crank shaft isn't just custom, it's crazy. CCKA, 16.5hp, 0471xxxx, MS/2026G. The front shaft is 1-7/16"x4", tapped 3/8-24 w/3/8" key. The clutch is attached directly to the block face w/5 studs and nuts. The tolerance is tight enough to require a 6" gear puller to prevent damage to the studs. From the clutch the shaft cones out to about a 2" dia. (forgot to measure it) and disappears into the counter balance. Distance from the block face to the 6.75" pulley center is 4.875". The distance from the front block face to the rear fan face is 10.25". The rear shaft is 15/16" and inset to the fan face a 1/4". The double 4.5" pulley is held to the shaft/fan by 3 bolts in line. Shaft and fan is tapped 7/16-14 and the two outside bolts are spaced 2-5/8" C to C. Fan face to 1st pulley at C is 1.125" and face to 2d pulley C is 1.75". The overall depth for proper alignment of belts (C of clutch pulley not engaged to C of 2d rear pulley) is 16.875". The base mounting bolts are spaced in a rectangle of 7"x12.25". Seems that if one did not desire a front PTO it should not be too much trouble to find a suitable engine, however, if ....... If this is enough so someone will pick up the ball (engine) and run like heck with it, OK. If not then just ask for more.

Stan
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Les,

Shaft height: 8.5"
Engine width at shaft height: 20.25"
Height overall: 22.25" Air filter butts to shroud intake vent.
Engine platform to shroud clearance 22.25"
Muffler & pipe extend forward 10.25" past PTO pulley.

Yes, seems to boil down .... double rear pulley and front pulley w/clutch properly aligned.

It should not be asking too much but the industry must think so.

Stan
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  • 2 weeks later...
  • 1 month later...
Our 4040 Sim. ONAN 16 Took a crap back in 93, So i went out and bought a Kohler Mag.18. We don`t have a mower, Or a blade for the front, So i did away with the front power PTO. Also had to do away with the front Hydraulic lines. We have a bucket on it so i just put a pulley on the PTO to run the front pump all the time, We also have no use for the rear PTO on the tractor, I could only get 1 belt to line up with the pulley clutch, So i thought what the heck why not try it with just one drive belt, In 6 years we have only had to replace the belt once and we use the bucket on the front hard like to dig out tree`s. Now i only have to raise the hood to check the oil. !!
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Just to let you guys know: I completely overhauled my CCKB in 1995 or 96, don't remember the exact year. Slight scoring in both cylinders, had to have it bored and fit .020" oversize pistons and rings. Camshaft was worn beyond tolerance, had to replace it. Installed 4 new valves. Also had to replace the stator. It had been bad for some time, but decided to replace it while I had the engine apart. Also had starter overhauled at the same time due to ease of access. New clutch belts. Total cost (including a set of 0 - 6" micrometers) about $1200. Purrs like a kitten. Power like it never had before. Worth every penney too.
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