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Engine basics => Engine set up tips => Topic started by: James Holford on January 22, 2017, 06:55:04 PM
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Might be getting a OS20FP but low and behold the guy says it needs crank bearings as its really loose by the prop washer judging by the video he sent me.
Is it worth to get and fix? Costly fix? Only engine itself only gona run me $20 bucks.
Ideas?
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The 20 FP is a bushing crank engine (no Ball bearings) Case has an integral non-replaceable bushing that the crank runs in.
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Describe loose? Does it go in and out or up and down? If it's in and out, that is normal end play and is necessary. If it's up and down, and not too bad, just put a little more oil in your fuel. For twenty bucks it's worth the gamble. And you could always keep your eye open for a parts engine with a good case.
Type at you later,
Dan
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Describe loose? Does it go in and out or up and down? If it's in and out, that is normal end play and is necessary. If it's up and down, and not too bad, just put a little more oil in your fuel. For twenty bucks it's worth the gamble. And you could always keep your eye open for a parts engine with a good case.
Type at you later,
Dan
In and out
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Video he sent me of it
https://vimeo.com/200651625 (https://vimeo.com/200651625)
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Yep,thats normal,it's even the ABN one,if it has the right muffler I'd definately buy it.
E-2030 muffler I think
Mike
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The 20 FP is a bushing crank engine (no Ball bearings) Case has an integral non-replaceable bushing that the crank runs in.
Which an accomplished machinist might replace on a bet, but which isn't a cost-effective repair given all the engines on eBay. Save it for 50 years; then it'll be a Valuable Antique and someone who isn't born yet will do the job just to have their very own running example.
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I used to have a 20fp on a 6ft Telemaster that would start on the first flip everytime no matter how hot or cold... think Dane Martin has it now.
I don't really need this engine as I now have a nice assortment of .25s . But hey another engine can't hurt.. may make good trade bait ;)
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Some people whine that the 20s better than the 25 . AND the guts are transferable - either way .
As it hasnt got a prop to lock the drive washer , half the slacks the prop driver loose . LL~
looks like theyres another two hiding behind it . Ive got a couple of butchered for classic B T/R cases spare . Wouldnt take a muffler unless it was custom curved in as the stacks are gone .
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I wouldn't use the muffler anyways:)
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For what it's worth, I've re-bushed quite a few engines with excellent results.
I make the bushings from a special manganese bronze alloy, which is formulated for high speed sliding motion.
Here are a few photos but I can publish the entire article if anyone is interested.
Bob Z.
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That's nice work, Bob.
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Thank you, Russ.
Most of the mods I've done have been McCoy and Fox.
When I do McCoys, I also polish the crankshaft but before polishing, I put a .010 deep oil groove opposite the intake port and 3/16 inch from the front.
Bob Z.
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Is that pinned or otherwise indexed, or just a press/shrink fit?
Phil
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Hi, Phil.
I machine the parts for a line-to-line fit.
Then, I freeze the bushing and heat the case to around 350.
It usually slips right in.
Next step is to bore the intake port.
Finally, bore to accept the crank.
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And, if you went into business and charged even a nominal sum for your hourly rate, you could buy several new engines for one bushing. A fun job if you do it for yourself, though.
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Thank you Robert. That is a straightforward process.
Phil
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For $20 if it runs well, that's a good price. Even if you have to eventually replace the piston/liner the cost is still reasonable for what is a very good engine.
The end play is nothing as long as the crank doesn't visibly rock while running. That makes lot of noise and erratic running that even extra oil won't fix.
OS made the FP's very well for the price. Kept clean with adequate oil they run a very long time.
IF you already have the needed machines and tooling or a buddy willing to donate the time to do it, as Bob Z. says, it's pretty straight forward. Figure a day for someone doing it that knows what they're doing.