Power Trac Replacement Engines Suggestions!?!?

bullitt · Mar 25, 2003

Re: Engines

Major obstacles?

I would say measuring carefully prior to cutting the crankshaft on the brand new engine.

Other than that, you have to buy or make a coupling half at each end, the engine cradle, and I elected to use the PT muffler due to cost and construction. Having lost count of the times I have had the engine in and out, installation is a relative breeze.

Also, the Kohler and Robin engines use different electrical connections. It seems you can swap the white and green wires at the engine connector and use the Robin key switch, but that is a "at your own risk" piece of information. Check it carefully or you may let the smoke out of the electrical parts.

Unless you like this kind of thing, buying the 425 in the first place could be a better option. In retrospect, that would have been a lot less hassle, but sometimes I can't help myself.

And, it is easy to make a 2 into a 7 to complete the important 427 badging. The upgrade to a 427 decal with checkered flags is a cool idea, and may be the next critical upgrade.

bullitt

GarretV · Mar 25, 2003

Re: Engines

I think with the articulation and green color, a Cobra emblem might be in order...

duane · Mar 26, 2003

Re: Engines

Bullit,

Admire your skills. Pictures are a definite. Did you re-use the gear pump mount, or have to fabricate a new one as well. Did PT help, or did you go it alone.

Duane

Schultz · Mar 26, 2003

Re: Engines

Yea, even some painted flames on the hood were the muffler gases exit would be cool.

bullitt · Mar 26, 2003

Re: Engines

duane,

I am not sure if I have skills, if my time is worth nothing, or if I am just a little crazy.

The gear pump mount for the Kohler has a machined recess on the engine side with a larger diameter than the Robin. I thnk it could be reused by machining it a little wider.

To minimize down time, I purchased the parts from PT with the exception of the engine. Except for the inexpensive PT muffler, all parts could have been easily made.

I started to make drawings of the parts with the idea of making a upgrade kit, but once I realized that the crankshaft needs to be cut, I figured the installation to be beyond the resolve of most folks.

PT was mostly helpful with the exception of the engine. They wanted me to also buy that from them, and to support that they would provide no info about the engine, dimensions, spec number, and so forth. This is understandable, but ...

I seem to recall they wanted around $3000 for the 25 hp motor, which is INSANE.

I bought the 27 hp motor locally with the 20 ampere charging system for $1399. However, PT did offer to perform the upgrade at PT for around $2000, but I think they were planning on keeping the 422 parts and motor. I am too far from PT, or I would have taken them up on it.

bullitt

johara1 · Mar 26, 2003

Re: Engines

bullitt,
why did you have to cut the crankshaft? dia. or lenght?
/forums/images/graemlins/confused.gif

bullitt · Mar 26, 2003

Re: Engines

johara1

Length. The crank did not extend through the center of the aft lovejoy connector as I expected.

The Robin that came out also had the crank cut by PT prior to installation.

bullitt

bryce · Mar 27, 2003

Re: Engines

I was wondering what you used to cut the crankshaft? Any pictures of before and after? how NERVOUS were you when you started cutting? /forums/images/graemlins/shocked.gif /forums/images/graemlins/cool.gif

bullitt · Mar 27, 2003

Re: Engines

I used the new coupler to scribe a line that was square on the crank at the proper location as determined by careful measurement.

I then took out a pack of hacksaw blades and carefully cut a channel around the crank using the scribe mark as a guide. Then I used the channel as a guide and cut through as I slowly rotated the crank in the correct direction. Once the crank was separated, I removed all ridges with a dremel tool to avoid future cracking. I beveled the edge carefully with a hand file. I THINK the crank is still close to balanced, but 7000 rpm is now out of the question.

This method was more low-tech than I would have liked, but the results looked better than I expected and comparable to the cut on the Robin engine.

I would have prefered to not have had to do this, but had no choice.

No pictures are around at this time, as it is spring and I had Ford 9 inch rear end that needed some attention right after the PT was done, so documentation was not high on the list.

scarg · Aug 31, 2007

Cool- A few years later what is your current status with the 27 HP Kohler? Can we see some pictures now? The crank on my 422 from PT looked like it was hacked off with a chainsaw. I don't think anyone was concerned with balance when they cut mine off. I have a current thread as my 3 year old 422 with 450 hours on it just siezed last week. Any comments would be great.

BR,

Steve