Author Topic: Poulan 46cc Porting Plane conversion  (Read 1323 times)

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Online 660magnum

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Re: Poulan 46cc Porting Plane conversion
« Reply #20 on: August 10, 2014, 06:16:12 pm »
I use the Stihl Dirko (Like Yamabond) on the joint between the top and bottom. Don't make a mess with the Yamabond. Just spread it real thin and neat. Let the sheen dry off before putting the two halves together. I then let the engine set around until the next day so I don't get into the squeeze out and then it gets all over everything.

You don't want any sealer squeezing into the engine.

The fins will be just fine to leave them bare metal after reshaping.
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Re: Poulan 46cc Porting Plane conversion
« Reply #21 on: August 11, 2014, 08:11:35 pm »
I have always used Yamabond when sealing the crank cases back together on a Poulan clamshell.   Some other makes of clamshell crank cases use an oring and on those I use nothing.
PP 505, 475, 445.

Offline aclarke

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Re: Poulan 46cc Porting Plane conversion
« Reply #22 on: August 11, 2014, 11:25:31 pm »
Joe makes a good point on the port velocity in regards to improving power at lower  rpm which would be advantageous for direct drive props and keeping the tips in an efficient subsonic range.  Bringing the power curve down in rpm won't necessarily require bigger ports...

Offline 1manband

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Re: Poulan 46cc Porting Plane conversion
« Reply #23 on: August 12, 2014, 11:05:44 pm »
re-reading my post including the the torque link to the paper was not very informative.  the paper is a  dry read, but has some vgood points, imo.

delivery ratio causes the torque.  torque output is the result of delivery ratio.  the curves look like one and the same. shapes look the same, etc.  so, by changing the delivery ratio curve, you change the torque curve to the same shape, vice versa as well.

-joe

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Offline Spruce_Goose

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Re: Poulan 46cc Porting Plane conversion
« Reply #24 on: August 14, 2014, 11:23:52 pm »
thanks all for the help. I'll have to look into this lowering of the rpm in the power curve. As of now its a bit over my head, but I'll try to find some time to look into it.

Offline Al Smith

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Re: Poulan 46cc Porting Plane conversion
« Reply #25 on: August 16, 2014, 08:42:47 am »
For what it's worth McCulloch used either Indian head gasket shellac or later RTV to seal the crankcase halves .It must work because I've never found a leaker .

Offline Spruce_Goose

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Re: Poulan 46cc Porting Plane conversion
« Reply #26 on: August 16, 2014, 06:06:00 pm »
Looking to the muffler... it is sort of looking like zinc coated steel? would that be correct? If I want to close up the old holes and attach a pipe to this thing can I braze with mapp gas? (I have no welding set up)

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Re: Poulan 46cc Porting Plane conversion
« Reply #27 on: August 16, 2014, 06:41:02 pm »
No!  You will need to really rotary wire brush that cadmium hard to get it off. Brass will not stick to cadmium or even the black oxide coating
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Offline Spruce_Goose

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Re: Poulan 46cc Porting Plane conversion
« Reply #28 on: August 29, 2014, 07:26:10 pm »
Is it normal for the bearings to just slide around? I can literally just slide (not even using any force to speak of) the bearings along the shaft (off in the case of the flywheel side and into the worm gear on the clutch side). Was like this upon opening the case...

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Re: Poulan 46cc Porting Plane conversion
« Reply #29 on: August 29, 2014, 07:38:08 pm »
Something is wrong? They are supposed to be a slight interference fit. Maybe .005 interference with both the case and the crank when the cap is on the case.

I just took apart and Stihl MS250 clamshell engine tonight and the 6202  C3 bearings were made in Turkey. The clutch side bearing fell off the crank. I had to use a bearing pulling clamp and puller on the flywheel side and that bearing fit tight on the clutch side. The new bearings were tight on both sides.

Look at the crank and see if it is shinny in the bearing seat area or galled? My Stihl's bearing area on the crank looked normal though the bearing fell off.
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