Chainsaw Engine
 

I recently destroyed my 46cc Poulan Pro saw. The engine is fine but for what the saw will cost to repair, I'll use the engine in a cheap plane (GP pitts arf, Areoworks 29% 540).

I see mag adds to convert engines and wonder if I need the typical airplane electronic ignition or can I use the current ignition. I can machine any other pcs needed.

Are there any other concerns or considerations I should know about?

Thanks, Rick

Chainsaw Engine
 

There's some info here if you've not seen it already:

http://www.geocities.com/mhammersmith/poulan/poulan.htm
http://www.rcfaq.com/answers/engines...6/POULAN46.HTM
Seem to recall that there was also some info on prop sizing.

Good luck
Steve
http://www.skylites.freeserve.co.uk

Thanks steve
 

Steve, thanks that's a great website. I guess I picked a good saw to turn into a plane engine according to that site.

Thanks again, Rick

Chainsaw Engine
 

Rick,

This engine works fine either with the electronic conversion (RC Ignition or CH - both in the $200 range) or with the mag ignition. With the mag you will need to use an electric starter until you get the hang of your engine's habits on start (most like the starter anyway).
There are four of these conversions at our club - two with mag, one CH and one RCIgnition.
Mine is the RCIgnition version at 3.9lbs with mount and muffler. They pull a 20x10 MC at about 7100 or a 20 x 8 at about 7600. For sport flying most of us use the 20 x 10. Good luck with the conversion - I think you should be happy with the results.

Dave

Chainsaw Engine
 

canman: How smooth are the Poulan 46 engines compared tp others? Thanks Capt,n :)

Chainsaw Engine
 

Dave, thanks that's useful info. I think I'll try the stock ignition and make up a big starter to keep it a inexpensive project. I'm thinking a scaled up scratch built u-can-do for the airframe.

Thanks again, Rick

Chainsaw Engine
 

Hi Capt,n
Boy "how smooth" is a leading question on a single cylinder chainsaw conversion! The two with electronic ignition are actually very smooth at idle and high speed with a little roughness going through the 3000 - 4000rpm transition. The ones on mag are a little rough all the way up to about 5000.
I would say they are smoother than a Quadra 42 - rougher than a Quadra 400 or a G45. Sorry I don't see many of the higher end motors in our club to compare with.
We have definitely had better luck buying new saws - some of the "reconditioned" ones are well worn and lacking in compression. Best is the "Pro" model with chrome cylinder. It has a slightly larger carb and better bearings.

Dave

chainsaw?
 

I have done more than a few Homelite weed-eater conversions. I have never looked at the chain saws because I was told that they have the wrong type of bearings (roller?). I was told that the bearings in a chainsaw motor is fine for side loads but not for the pull of the prop. I guess I was told wrong? Inform me please.

Chainsaw Engine
 

If the chainsaw engines bearings are no good for RC, then why would weedies be any different? :) Weedie engines don't see much "side load" either.

The reality is that the 10-20lbs of thrust imposed by the prop is next to nothing compared to the forces within the engine acted upon by the reciprocating piston going nuts at 9000+ strokes a minute. I would not worry.

Chainsaw Engine
 

Most weedies use ball bearings on the crank...A bearing engineer told me a ball bearing will take half its rated capacity as a thrust bearing....The load capacity of most bearings used in our gassers is about 3000 lbs, so they could take 1500 lbs thrust...
Some of the small McCulloch weedies had roller bearings, as do ALL the Quadra/US Engines 35/41/42 cc engines.. The Quadra/US Engines have a small bronze thrust washer to take up the thrust....Works fine.....
Not many chainsaws use roller bearings..The later procuction 5.8 Sachs Dolmar engines had a big roller bearing on the clutch side..A ball bearing was a direct replacement, so the airplane conversions got changed to the ball bearing....

Oh.....OK
 

Ralph, thanks for clarifying the information.