# Panther Pup Crank Bearings



## jpaul (Mar 5, 2008)

I am building the Panther Pup, a 4 cylinder 4 stroke IC Engine which was designed by the late Bill Reichart. The original engine was built in bronze and it was intended for display as opposed to the engine powering a craft. My build is based on Aluminium Castings as you can see in the attached picture .







My intent is to run this engine at exhibitions. But I am concerned that there are no provisions for crankshaft bearings in the plans. I could use R-8 ball bearings, which have an od of 1.125 and a thickness of 5/16" which maybe a little tricky to accommodate. Or I could use a much smaller bearing machined in bronze. The roller bearings can be sealed bearings where as the bronze bearings have no sealing provisions and would leak. 

Do you guys and/or gals have any thoughts?


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## Speedy (May 19, 2008)

hi Jpaul
I cant be any assistance to you with your question. (im a newb :big
but I realy like your engine your working on. do you have anymore pics? 8)


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## rake60 (May 19, 2008)

jpaul 

Ed Miles is our resident bearing expert.

He'd be the man to ask.

Rick


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## kf2qd (May 19, 2008)

How are you going to lube it? Aluminum and steel with a bit of oil between makes a pretty good bearing - Briggs&Stratton, Tecumseh Lawson and a few others have make lots of engines with nothing more for the bearings. Biggest thing is to have adequate lube as the film of oil is what supports the shaft.


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## GailInNM (May 19, 2008)

If you do want to use ball bearing, consider R1212. For your intended use of this engine they should be adequate. They are the same bore as the R8, but only 3/4 inch OD. They are also only half as thick as a R* bearing.  If loading was a concern, and I don't think it would be, you could back to back a pair of them and be at the same thickness of the R8, but would only be 3/4 inch diameter. They are available with seals also to help control oil movement.

Gail in NM, USA


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## Bogstandard (May 20, 2008)

jpaul,

You can make phos bronze bearings fairly oiltight by screwcutting a very fine oil groove along the shaft part that sits in the bore, something like 4tpi. It could be cut by turning the lathe by hand and it would only need to be 3 or 4 thou deep. It will be either left or right hand, depends on which end of the engine and crank rotation.

It works on the archimedes screw principle, but in reverse, and is very effective.

It just might solve your space problem.

John


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## jpaul (Jun 2, 2008)

Thanks guys for your suggestions. I didn't know of the R1212 bearing which would have been a better choice than the standard R8 since it is considerably smaller . 
But I opted to use the standard R8 bearing. The thickness, 5/16", and the Outside Diameter, 1-1/8", makes the installation of the R8 bearing a little difficult. The cam journal is relatively close to the crank journal.  However, I think I have the task well under control. I installed a bearing in the flywheel side and currently I am machining the Distributor side for its R8 bearing. 
I will post pictures.


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## jpaul (Jun 6, 2008)

Back in the shop I completed the machining of the crankcase for R8 roller bearing and end caps. 






The machining went relatively well on my DRO equipped milling machine. A lot of indicating to centers and traversing to a bolt location on the bolt circle. I like DRO's






Next it was only of mater of fine tuning the fits to get the crank shaft to turn smoothly. Thank you all for your encouragement.

Paul


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## Bogstandard (Jun 6, 2008)

Lovely work Paul.

DRO's make an amazing difference when doing jobs like this. Before I fitted mine, the last casting engine I made was a nightmare to set up for all the crank, cam and gear locations.

I have a full set of everything to build the Westbury 'Seal', a 15cc 4 cylinder side valve petrol engine, even down to the rings and a moulded dizzy cap. But I think it is one of those jobs that will never get started.

Do you have your cam in hand, if you need the plans for a cam and crank grinder, I am sure they could be found on my comp somewhere. Or are you going to be doing it on the lathe?

John


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## Bookmaker (Jun 6, 2008)

Paul,
What are you using for the center bearing? Beautiful work by the way!
Best regards,
Roger


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## jpaul (Jun 9, 2008)

Correction, I am using R8 "BALL" Bearings not roller bearings.

John, I would be intersest in reading your plans for a Camshaft Grinder. HSM featured a camshaft grinder designed by Jerry Kieffer, in the Oct 2004 issue.

Roger, currently the center crank journal rides in the Aluminium casting. I could fit the center with a Bronze split bearing. If nothing else, making a split bearing maybe a worthwhile experience.


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## Bogstandard (Jun 9, 2008)

Paul,

Check your emails


Anyone else while I have them to hand, send an email.

John


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## Bookmaker (Jun 9, 2008)

jpaul  said:
			
		

> Correction, I am using R8 "BALL" Bearings not roller bearings.
> 
> John, I would be intersest in reading your plans for a Camshaft Grinder. HSM featured a camshaft grinder designed by Jerry Kieffer, in the Oct 2004 issue.
> 
> Roger, currently the center crank journal rides in the Aluminium casting. I could fit the center with a Bronze split bearing. If nothing else, making a split bearing maybe a worthwhile experience.



Hi Paul,
The aluminum bearing will probably be just fine. I would put a small grove in the shaft and drill a hole in the bearing cap for oil. I personally would make a rabbeted split bearing. Bronze on a soft crank is probably not a good idea. Oilite (spelling?)may be a better choice.
Best regards,
Roger


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## RonGinger (Nov 17, 2008)

Looks like very nice work, is there any recent progress?

I hope the bearing you used are sealed units. I built the panther pup with the plain bearings as drawn. It throws oil out both ends. There is no way a plain bearing without a seal can do anything but throw oil.

I modified mine to water cooled, so I call it Water Pup. The original air cooled engine would only run for about a minute without overheating- I saw it a couple times at NAMES.

Also the rocker arm geometry is about as bad a design as possible. Its a T shape, pivoted at the bottom of the T. That makes it do more rocking than pushing on the valve. I made more conventional rocker arms. 

All up I consider the Panther Pup to be about the worst design ever published, to bad so many guys have been enticed to build it- it looks like a neat engine, its just bad details. After a lot of work you wind up with a poor engine.

There are photos of mine on my web site, plsntcov.8m.com/pup.htm


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## Maryak (Nov 17, 2008)

Jpaul,

Great looking engine. :bow: :bow:

Regards
Bob


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## jpaul (Nov 20, 2008)

RonG,

I have made a little progress as you can see. I also, am making a few changes which hopefully are improvements.







What I want to do is modify the design of the heads to allow for more fin area. I have not figured that out to a point to make chips. It would be a lot simpler with a 3D modeling program. Looks like more delays!

Thanks for the tips


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## vlmarshall (Aug 23, 2009)

Any progress on this interesting engine?


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## deverett (Aug 23, 2009)

Vernon  said:
			
		

> Any progress on this interesting engine?


Vernon
Ref. my reply to you in the Gyro Engine topic, I knew that I had read somewhere about the valve gear design. Read Ron Ginger's post about it earlier in this topic.

Dave
The Emerald Isle


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