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Engine basics => Engine set up tips => Topic started by: Leester on August 04, 2007, 10:36:42 PM
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I recently got an OS 35 S used that has been reworked by Big Art. The case on this one is a disaster, one mounting hole is missing, the rest are drilled all screwed up. I have a case in great shape so I want to change them. I've never done this so how about a correct order in which to do the swapping of parts. Also any other tips and proceedures I should follow will help a lot. TIA
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Heat it, to free the bits of , particularly the liner.
or boil it in antifreeze first .
Are those screws posidrive ?
get a screwdriver that FITS >
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1. Put an old prop on the engine and tighten it.
2. Removed the head.
3. With the piston at the bottom of the stroke, put a Popsicle stick into the exhaust opening. Rotate the prop until the piston traps the stick between it and the liner. Continue to rotate the prop until it pushes the liner up in the case. If really tight, try heating the case around the sleeve area (monkote gun or hair dryer works) until the sleeve is free.
4. Remove the back plate.
5. With the sleeve removed there is enough room to work the connecting rod off of the crank. Again it's easier if you have the piston near the bottom of the stroke bottom but skewed toward the transfer port a bit .
6. Remove the prop and pull the crank out of the case from the back. If the drive hub is stuck, a light tap with a piece of wood on the crank end should break it loose. Hold you hand over the rear of the engine to keep the crank from popping out on to the floor if you have to hit it.
Clean up the exterior of the sleeve while you have it out. Oven cleaner, Crockpot, fine steel wool all work pretty well.
Reverse the order to assemble and use a small amount of oil on the sleeve and be sure that it is free enough to be rotated while in the case. Air tool oil works well for this plus it is good for storage. The sleeve to case is a slip fit.... not a press fit and you will have to rotate the sleeve to position it properly after it's in place. Pay attention to which port is the exhaust and which port is the intake. I don't remember if the engine case has a position pin for the sleeve or not... I don't think they did.
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Thanks Dick, thats what I was lookin for.
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Thanks Dick, thats what I was lookin for.
Hi
You won't have much problems the OS 35 is is NOT a press fit sleeve, they normally come apart very easy, just follow the instructions already written. Write back how the job went
Regards
Randy
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I got the parts switched with no major problems, my $Kote heat gun worked just fine for loosening the sleeve. I didn't even have any parts left over lol. I'll put it on the bench after work and see if it runs. Am I correct in using 10/25 all castor fuel in this ?
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New and old
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Looks good. Yes to your question of using 10% Nitro 25% Castor Oil. Will work well.
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Just ran it and it runs great. I've just got a cheap Tower tach but it showed 9800-10,000 just before the break using a 10-4 Top Flite wood prop. Thanks again for the help.
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Today I ran it again but put a 10-5 Top Flite on it (was wrong before the 10-4 was a Zinger) It seemed to be happy at 8900-9000 and when I pinched the fuel line would go to a 2 and return immediately to a 4. Is that about the right rpm range for this prop ? Now to build a plane for it (Oh darn)lol.
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HI Lee,
All sounds good to me! Just get her in a plane and prop it to that plane. It should be a very good engine for you.