Best replacement for a worn OS40FP
08-25-2012, 03:07 AM
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Best replacement for a worn OS40FP
Hi all, my trusty OS40FP, fitted to a nice control line stunter, is starting to wear out it's piston & liner [
]I know new piston / liners are not available and the alternatives (Tower 40 and Magnum 40) are also hard to find.
So, I need a new motor BUT, because of the cowling design and bearer design, it MUST be the same dimensions as the OS40FP.
Does anyone have any suggestions ? (don't mind going up to a 46 as long as mounts and exhaust stub is the same as to OS40FP)
or
Does anyone know where I can get a piston & liner that will fit ?
Thanks for looking
08-25-2012, 05:54 AM
#3
RE: Best replacement for a worn OS40FP
I would just look around, new and used OS 40FP engines are still easy to find.
If I remember correctly, the OS 46LA is probably a bolt in replacement though. But i could be mistaken.
If I remember correctly, the OS 46LA is probably a bolt in replacement though. But i could be mistaken.
08-25-2012, 06:24 AM
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RE: Best replacement for a worn OS40FP
Thanks for the input folks
I have been on the lookout for a new old stock 40FP but no joy to date. I am reluctant to buy a used one as you never know just how much life is left in the bore and piston !
I have read quite a few comments on the fact that the 40LA is not so good an engine and in particular is less suited to control line aerobatics than the FP.
However, since I posted my question I have found a Magnum GP40 (UK *bay) that I believe is an exact copy of the FP and this one is ABC and not yet run in. ( Hoping the seller isn't selling it because it has any "issues"...)
Will report back on whether it is the same and quality etc after testing it
08-25-2012, 07:12 AM
#5
RE: Best replacement for a worn OS40FP
ASP/Magnum engines are available cheap. Don't know about bolt patterns and such because they are BB. They have to get a C/L carb. made. LA .46 motors are popular in stunt here because of the 424 running.
08-25-2012, 07:24 AM
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RE: Best replacement for a worn OS40FP
ORIGINAL: aspeed
ASP/Magnum engines are available cheap. Don't know about bolt patterns and such because they are BB. They have to get a C/L carb. made.
ASP/Magnum engines are available cheap. Don't know about bolt patterns and such because they are BB. They have to get a C/L carb. made.
ORIGINAL: aspeed
LA .46 motors are popular in stunt here because of the 424 running.
LA .46 motors are popular in stunt here because of the 424 running.
I have to say that my FP, with the right fuel = 20% Castor and 5% real Nitro, a 4 stroke (Taylor) plug and an 10.5 x 5 APC does a great 424 and does not suffer from the often reported "run away"
Fingers crossed that the GP40 is identical, or at least I can / might just take the ABC piston & liner out and put it in the FP !
08-25-2012, 08:23 AM
#7
RE: Best replacement for a worn OS40FP
Just checked what I could because the FP is still in the plane. It looks like everything is the same. No worries. Bolt pattern, width of case, muffler bolts, and distance from front two bolts to spinner all look as close as I can see without removing the motor. Within a half mm anyway.
08-25-2012, 08:34 AM
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RE: Best replacement for a worn OS40FP
Cheers for that
Good to know, esp as I guess the 46 LA has a bit more grunt
Might even get a good used 46 LA as they are not expensive, just to try out
08-25-2012, 08:58 AM
#9
RE: Best replacement for a worn OS40FP
I have been picking up LA .40's for $20. Some look like new but have broken needles of course. Everyone says they are crap, and people believe it so they buy an AX or whatever, and pretty much give away the LA's, especially the smaller ones which are great. I always cut little slits on the plastic backplate so if (when) it crashes, the break is clean and it doesn't ruin the backplate. I tried hot glue to glue one back on, and it seems strong enough. I haven't flown it yet to test it. Fox has a remote needle that bolts on the muffler boss. I don't know if the carb fits on the GP or LA. The GP that I have is a pinch bolt, and the FP an LA have the through hole. My LA .40 seems narrower than the GP which is 1.275" at the lugs.
08-25-2012, 02:12 PM
#11
My Feedback: (90)
RE: Best replacement for a worn OS40FP
OS, Thunder tigre and Tower 40 plain bearing are all interchangeable as far as parts with one exception. The Tower Piston/liner is much preferred because it's an ABC and the Tower is the smoothest runner of the 3.
Now for the exception. The TT/Magnum has the needle valve used as a cinch bolt at the front of the venturi. OS uses screws to attach the carb. You will have to have a sprinkler type venturi fabricated but the OS or Enya needle valve assembly will fit fine.
dennis
Now for the exception. The TT/Magnum has the needle valve used as a cinch bolt at the front of the venturi. OS uses screws to attach the carb. You will have to have a sprinkler type venturi fabricated but the OS or Enya needle valve assembly will fit fine.
dennis
08-25-2012, 10:51 PM
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RE: Best replacement for a worn OS40FP
All good info folks
Looks like I will be swapping the GP piston & liner out as I don't want to alter the FP venturi setup as it gives me good 424.
So did I read this right, the LA has different mounting dimensions than the FP ?
08-26-2012, 04:31 AM
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RE: Best replacement for a worn OS40FP
G, here are the LA .46 specs to compare to your engine.
Construction: Aluminum 1-piece crankcase, piston, cylinder head
Bore: 23.0mm (0.906")
Stroke: 18.4mm (.724")
Horsepower: 1.2 PS, 1.18 HP at 15,000 RPM
Distance from remote needle to end of crankshaft: 4.5" (114mm)
Distance from center of engine to drive hub: 2.0" (51.2mm)
Distance from center of engine to end of crankshaft: 3.0" (76.3mm)
Height from crankcase bottom to top of cylinder head: 3.3" (84.7mm)
Height/crankshaft center to top of cylinder head: 2.7" (69mm)
Width including mounting ears: 1.9" (48mm)
Width not including mounting ears: 1.2" (32mm)
Width between mounting holes same side: 0.69" (17.5mm)
Width between mounting holes opposite side: 1.6" (40.5mm)
Width between muffler mounting holes: 1.4" (36mm)
Width of exhaust opening: 1.1" (29mm)
Height of exhaust opening: 0.3" (7mm)
Diameter of muffler body: 1.3" (33.5mm)
Angle of muffler in relation to engine: 4°
Weight: 272g (9.6oz without muffler)
Crankshaft Thread Size: 1/4-28
Recommended Props: Break In: 11x6
Construction: Aluminum 1-piece crankcase, piston, cylinder head
Bore: 23.0mm (0.906")
Stroke: 18.4mm (.724")
Horsepower: 1.2 PS, 1.18 HP at 15,000 RPM
Distance from remote needle to end of crankshaft: 4.5" (114mm)
Distance from center of engine to drive hub: 2.0" (51.2mm)
Distance from center of engine to end of crankshaft: 3.0" (76.3mm)
Height from crankcase bottom to top of cylinder head: 3.3" (84.7mm)
Height/crankshaft center to top of cylinder head: 2.7" (69mm)
Width including mounting ears: 1.9" (48mm)
Width not including mounting ears: 1.2" (32mm)
Width between mounting holes same side: 0.69" (17.5mm)
Width between mounting holes opposite side: 1.6" (40.5mm)
Width between muffler mounting holes: 1.4" (36mm)
Width of exhaust opening: 1.1" (29mm)
Height of exhaust opening: 0.3" (7mm)
Diameter of muffler body: 1.3" (33.5mm)
Angle of muffler in relation to engine: 4°
Weight: 272g (9.6oz without muffler)
Crankshaft Thread Size: 1/4-28
Recommended Props: Break In: 11x6
08-27-2012, 05:38 AM
#15
RE: Best replacement for a worn OS40FP
ORIGINAL: ghost123uk
Thanks for the input folks
I have been on the lookout for a new old stock 40FP but no joy to date. I am reluctant to buy a used one as you never know just how much life is left in the bore and piston !
I have read quite a few comments on the fact that the 40LA is not so good an engine and in particular is less suited to control line aerobatics than the FP.
However, since I posted my question I have found a Magnum GP40 (UK *bay) that I believe is an exact copy of the FP and this one is ABC and not yet run in. ( Hoping the seller isn't selling it because it has any "issues"...)
Will report back on whether it is the same and quality etc after testing it
Thanks for the input folks
I have been on the lookout for a new old stock 40FP but no joy to date. I am reluctant to buy a used one as you never know just how much life is left in the bore and piston !
I have read quite a few comments on the fact that the 40LA is not so good an engine and in particular is less suited to control line aerobatics than the FP.
However, since I posted my question I have found a Magnum GP40 (UK *bay) that I believe is an exact copy of the FP and this one is ABC and not yet run in. ( Hoping the seller isn't selling it because it has any "issues"...)
Will report back on whether it is the same and quality etc after testing it
The LA control line engines are popular. I don't think they have a good 4-2-4 break but they are high torque low HP engines which means a steady pull without much slow down in the up lines. I think that the serious stunters have been using four stroke engines for the same reason, and not using the 4-2-4 break anymore. Though some so. The only other thing Ican think of that is not real expensive, is the ABC Fox 35 stunt. As you may know this is alsomodified for more power with a hemi head andcrankcase mod. It has more power and is moreexpensive than the standard Fox .35 stunt. This probably has about the same power as the 40 FP but less than the 46 LA. It would cost a lot more than the OS FP or LA but a lot less than other serious stunters like PA and Double Star.
08-27-2012, 06:35 AM
#16
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RE: Best replacement for a worn OS40FP
ORIGINAL: Sport_Pilot
The LA control line engines are popular. I don't think they have a good 4-2-4 break but they are high torque low HP engines which means a steady pull without much slow down in the up lines. I think that the serious stunters have been using four stroke engines for the same reason, and not using the 4-2-4 break anymore. Though some so. The only other thing I can think of that is not real expensive, is the ABC Fox 35 stunt. As you may know this is also modified for more power with a hemi head and crankcase mod. It has more power and is more expensive than the standard Fox .35 stunt. This probably has about the same power as the 40 FP but less than the 46 LA. It would cost a lot more than the OS FP or LA but a lot less than other serious stunters like PA and Double Star.
ORIGINAL: ghost123uk
Thanks for the input folks
I have been on the lookout for a new old stock 40FP but no joy to date. I am reluctant to buy a used one as you never know just how much life is left in the bore and piston !
I have read quite a few comments on the fact that the 40LA is not so good an engine and in particular is less suited to control line aerobatics than the FP.
However, since I posted my question I have found a Magnum GP40 (UK *bay) that I believe is an exact copy of the FP and this one is ABC and not yet run in. ( Hoping the seller isn't selling it because it has any ''issues''...)
Will report back on whether it is the same and quality etc after testing it
Thanks for the input folks
I have been on the lookout for a new old stock 40FP but no joy to date. I am reluctant to buy a used one as you never know just how much life is left in the bore and piston !
I have read quite a few comments on the fact that the 40LA is not so good an engine and in particular is less suited to control line aerobatics than the FP.
However, since I posted my question I have found a Magnum GP40 (UK *bay) that I believe is an exact copy of the FP and this one is ABC and not yet run in. ( Hoping the seller isn't selling it because it has any ''issues''...)
Will report back on whether it is the same and quality etc after testing it
The LA control line engines are popular. I don't think they have a good 4-2-4 break but they are high torque low HP engines which means a steady pull without much slow down in the up lines. I think that the serious stunters have been using four stroke engines for the same reason, and not using the 4-2-4 break anymore. Though some so. The only other thing I can think of that is not real expensive, is the ABC Fox 35 stunt. As you may know this is also modified for more power with a hemi head and crankcase mod. It has more power and is more expensive than the standard Fox .35 stunt. This probably has about the same power as the 40 FP but less than the 46 LA. It would cost a lot more than the OS FP or LA but a lot less than other serious stunters like PA and Double Star.
Any idea which brand of four-strokes they are using? Saito would seem the obvious choice.
Ed Cregger
08-27-2012, 09:48 AM
#17
RE: Best replacement for a worn OS40FP
Yep, Saito. For their torque and light weight.
http://brodak.com/engines.html
Looking at that, the Brodak .40 might not be a bad choice either.
http://brodak.com/engines.html
Looking at that, the Brodak .40 might not be a bad choice either.
08-29-2012, 01:25 AM
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RE: Best replacement for a worn OS40FP
ORIGINAL: Hobbsy
G, here are the LA .46 specs to compare to your engine.
Construction: Aluminum 1-piece crankcase, piston, cylinder head
Bore: 23.0mm (0.906'')
Stroke: 18.4mm (.724'')
Horsepower: 1.2 PS, 1.18 HP at 15,000 RPM
Distance from remote needle to end of crankshaft: 4.5'' (114mm)
Distance from center of engine to drive hub: 2.0'' (51.2mm)
Distance from center of engine to end of crankshaft: 3.0'' (76.3mm)
Height from crankcase bottom to top of cylinder head: 3.3'' (84.7mm)
Height/crankshaft center to top of cylinder head: 2.7'' (69mm)
Width including mounting ears: 1.9'' (48mm)
Width not including mounting ears: 1.2'' (32mm)
Width between mounting holes same side: 0.69'' (17.5mm)
Width between mounting holes opposite side: 1.6'' (40.5mm)
Width between muffler mounting holes: 1.4'' (36mm)
Width of exhaust opening: 1.1'' (29mm)
Height of exhaust opening: 0.3'' (7mm)
Diameter of muffler body: 1.3'' (33.5mm)
Angle of muffler in relation to engine: 4°
Weight: 272g (9.6oz without muffler)
Crankshaft Thread Size: 1/4-28
Recommended Props: Break In: 11x6
G, here are the LA .46 specs to compare to your engine.
Construction: Aluminum 1-piece crankcase, piston, cylinder head
Bore: 23.0mm (0.906'')
Stroke: 18.4mm (.724'')
Horsepower: 1.2 PS, 1.18 HP at 15,000 RPM
Distance from remote needle to end of crankshaft: 4.5'' (114mm)
Distance from center of engine to drive hub: 2.0'' (51.2mm)
Distance from center of engine to end of crankshaft: 3.0'' (76.3mm)
Height from crankcase bottom to top of cylinder head: 3.3'' (84.7mm)
Height/crankshaft center to top of cylinder head: 2.7'' (69mm)
Width including mounting ears: 1.9'' (48mm)
Width not including mounting ears: 1.2'' (32mm)
Width between mounting holes same side: 0.69'' (17.5mm)
Width between mounting holes opposite side: 1.6'' (40.5mm)
Width between muffler mounting holes: 1.4'' (36mm)
Width of exhaust opening: 1.1'' (29mm)
Height of exhaust opening: 0.3'' (7mm)
Diameter of muffler body: 1.3'' (33.5mm)
Angle of muffler in relation to engine: 4°
Weight: 272g (9.6oz without muffler)
Crankshaft Thread Size: 1/4-28
Recommended Props: Break In: 11x6
I wonder if the FP venturi (through bar type) would fit into the LA case ? If it will I may well get an LA46 to try in this airframe.
Sadly the Magnum GP40 (ABC
) has a cinch bolt for the carb, so the FP venturi won't fit 
This just means I will have to strip the two down and just use the piston & liner from the ABC Magnum in my worn FP. Shame as except for that it would have just dropped in and this Magnum is "as new" !
08-29-2012, 06:37 AM
#19
RE: Best replacement for a worn OS40FP
I just make a new venturi. You would need a lathe though. I would make one for you for nothing but the postage to the UK would make it pointless. Maybe the old one could fit and push the spraybar through the top above the block, or drill a pressure tap and use a remote needle or something. The pinch bolt type is my preference anyway, with the needle valve going through that hole. The venturi hole should be substantially smaller than a carb with a spraybar going through if you get one made.
08-29-2012, 06:59 AM
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RE: Best replacement for a worn OS40FP
ORIGINAL: aspeed
I just make a new venturi. You would need a lathe though.
I would make one for you for nothing but the postage to the UK would make it pointless.
I just make a new venturi. You would need a lathe though.
I would make one for you for nothing but the postage to the UK would make it pointless.
ORIGINAL: aspeed
Maybe the old one could fit and push the spraybar through the top above the block, or drill a pressure tap and use a remote needle or something. The pinch bolt type is my preference anyway, with the needle valve going through that hole. The venturi hole should be substantially smaller than a carb with a spraybar going through if you get one made.
Maybe the old one could fit and push the spraybar through the top above the block, or drill a pressure tap and use a remote needle or something. The pinch bolt type is my preference anyway, with the needle valve going through that hole. The venturi hole should be substantially smaller than a carb with a spraybar going through if you get one made.
~~~~~~~~~~~~~~~~~~~~~~
Bearing in mind this is for control line aerobatics use.
I have now discovered what might be an "issue" with swapping just the piston and liner into the FP. On inspecting the Magnum, the transfer port that is visible opposite and slightly forward of the exhaust is noticeably taller than that on the FP. I think (but stand by to be corrected) that this is the notorious "boost port" ? I wonder how much difference that will make to the nice soft 424 and lack of "runnaway" the current FP setup has ?
08-29-2012, 11:09 AM
#21
RE: Best replacement for a worn OS40FP
I think it would maybe just be faster, you still set it slobbery rich like normal for the 424 thing, but others may be more stunt oriented than me and could tell you more accurately.
08-29-2012, 11:19 AM
#22
RE: Best replacement for a worn OS40FP
To have good 4-2-4 it needs an early blowdown or long exhaust, but a fairly short duration on the intake. Maybe I got it backwards, but the Magnum would have more agressive timing which would not be what you want with CL aerobatics.
I don't know if it fits but the timing would be different. The LA 40's were supposed to be CL stunt friendly and should fit the FP, I wonder if Tower has some LA 40 sleeves left?
I don't know if it fits but the timing would be different. The LA 40's were supposed to be CL stunt friendly and should fit the FP, I wonder if Tower has some LA 40 sleeves left?
08-29-2012, 11:49 AM
#23
RE: Best replacement for a worn OS40FP
Or try it and see. Maybe a lower pitch prop may be needed or longer lines, but I don't think the difference would be noticeable with the different sleeve. Just don't run it too long in case the cyl. wears and then you can't really use the piston/liner in the original motor.
08-29-2012, 01:22 PM
#24
RE: Best replacement for a worn OS40FP
I wouldn't hesitate to buy a used 40 FP that looks good in photos from someone with a good reputation who states that it is low time and responds well to questions before the sale. Yes, even with all that you could be disappointed, but if it doesn't meet the description you should be able to send it back. I've had pretty good luck this way, though not 100%.
Jim
Jim