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Author Topic: OS 40 clones  (Read 1520 times)

Offline Clint Ormosen

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OS 40 clones
« on: February 13, 2007, 11:25:13 PM »
I have several OS FP40's and clone engines. Picked them up cheap here and there with the intent of making stunt engines out of them.
 
 3 OS FP40's
 1 Thunder Tiger 40
 1 Magnum  40
 1 Tower 40

 Are they all close enough in design to make the same basic mods to them? How about re timing them? I have one OS FP40 with a re timed cylinder done by Randy S. back about 10 yrs ago when he sold just the piston/cyl sets. This is the best running "stunt" motor I have and would like to duplicate it. I don't know if Randy does these anymore. The only other change to this motor is an extra head gasket. No blocked boost port or anything.
 I tried to get the TT 40 to work with a bunch of head gaskets and a true venturi, but it still wants to run away.
Help!

HEY! I just noticed Mr. Smith moderates this forum! If I'm lucky, he'll see it.
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Offline Mark Scarborough

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Re: OS 40 clones
« Reply #1 on: February 14, 2007, 12:01:02 AM »
I can only speak for the Tower .40, it is a direct parts replacement for the .40 FP so the same tricks would apply. I have um 8 .40 FPs, one LA 25, one Supertigre .56, one LA 46 , the best luck I have had with the FPs is to retime them, no extra head gaskets, and I run Powermaster 10 -22 fuel with an extra 6 oz of castor when its over about 80, below 80 degrees, I just add 4 oz. The oil makes a HUGE difference in controling these engines from what I have been told and what I see myself. The best prop I have is cut down from a Zinger pro 13 x 4, cut to 11.5 and cleaned thinned blades. I also run a stock muffler with the outlet opened up slightly and a .285 venturi with a ST needle valve. since I have started down this road, Scott Riese has steered me to this tune and I am very very happy.
best of luck with yours.
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Offline Jim Thomerson

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Re: OS 40 clones
« Reply #2 on: February 14, 2007, 07:57:46 AM »
I have flown the hound out of a stock Tower 40 with a venturi and ST NVA, Sig Champion 10%, 20% 50-50 oil, Supercool Petalblade 11 x 5 prop.  Stock muffler, muffler pressure to uniflow.  Really like it. Friend commented it runs like a sewing machine.  I took that as good. :)
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Offline Bill Little

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Re: OS 40 clones
« Reply #3 on: February 14, 2007, 08:06:27 AM »
Quote from: Clint Ormosen on February 13, 2007, 11:25:13 PM
(snip)
I have one OS FP40 with a re timed cylinder done by Randy S. back about 10 yrs ago when he sold just the piston/cyl sets. This is the best running "stunt" motor I have and would like to duplicate it. I don't know if Randy does these anymore. The only other change to this motor is an extra head gasket. No blocked boost port or anything.
 I tried to get the TT 40 to work with a bunch of head gaskets and a true venturi, but it still wants to run away.
Help!

HEY! I just noticed Mr. Smith moderates this forum! If I'm lucky, he'll see it.

Hi Clint,

Randy still does the rework on the OS 40FP and their clones.  Great engines.  Contact him through here.  "Paging" him will even work! ;D

Byron Barker also does a very good rework.  I have had one for 10-15 years and it is still a great running engine.

Bill <><
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Offline RandySmith

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Re: OS 40 clones
« Reply #4 on: February 15, 2007, 01:17:35 PM »
Quote from: Clint Ormosen on February 13, 2007, 11:25:13 PM
I have several OS FP40's and clone engines. Picked them up cheap here and there with the intent of making stunt engines out of them.
 
 3 OS FP40's
 1 Thunder Tiger 40
 1 Magnum  40
 1 Tower 40

 Are they all close enough in design to make the same basic mods to them? How about re timing them? I have one OS FP40 with a re timed cylinder done by Randy S. back about 10 yrs ago when he sold just the piston/cyl sets. This is the best running "stunt" motor I have and would like to duplicate it. I don't know if Randy does these anymore. The only other change to this motor is an extra head gasket. No blocked boost port or anything.
 I tried to get the TT 40 to work with a bunch of head gaskets and a true venturi, but it still wants to run away.
Help!

HEY! I just noticed Mr. Smith moderates this forum! If I'm lucky, he'll see it.

Hi

I still do these and  have  some  parts, however  with these type motors I will have to see  them first, and it really ins't  good to  run them  before  retimingPlease let me know if I can help you

Regards
Randy
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Offline Clint Ormosen

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Re: OS 40 clones
« Reply #5 on: February 15, 2007, 08:21:49 PM »
Randy, the FP's and all three clones have been run. Does this make it a "no go" as far as retiming? I do have one FP.35 NIB.
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Offline Bill Little

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Re: OS 40 clones
« Reply #6 on: February 15, 2007, 10:19:18 PM »
Quote from: Clint Ormosen on February 15, 2007, 08:21:49 PM
Randy, the FP's and all three clones have been run. Does this make it a "no go" as far as retiming? I do have one FP.35 NIB.

Hi Clint,

I have an idea as to why the engine should be NIB when a rework is desired.
(Correct me where I'm wrong, Randy!)

When an engine is run, the parts start "mating" to each other, developing "fits".  When it's "broken-in" completely and properly, these fits are what makes it perform properly.

When you dis-assemble the engine to do the work on it, the re-assembly is basically impossible to get those fits exactly as they were before, menaing that the engine almost has to be "broken-in" again to achieve the proper fits all over again.  This means the wear level has risen higher, and the engine's effective life span is reduced.  Does that make sense?

At least that's what I've been told all these years. ;D

Bill <><
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Offline Clint Ormosen

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Re: OS 40 clones
« Reply #7 on: February 16, 2007, 12:05:59 AM »
 I understand why it is better to do a new engine. I guess my question is "Is it not worth doing" to a previously run engine, or will Randy even bother with a non-NIB engine? I know the FP's and the Tower can easily have the pis/cyl replaced w/ new re timed pieces. But what about the TT GP40 and MAGNUM 40GP? Does the OS/Tower pis/cyl set fit them?
 After starting this post, I checked these engines and found the MAGNUM 40GP unused. So this one could be re timed safely. But, it's a whole lot easier to just have someone (Randy S.) just send re timed cylinders than to send him a bunch of engines. If they all use the same set, it's a piece O cake.
 Like I said before, the OS 40 that I purchased a re timed set for runs beautiful. It's not a super powerhouse, and it uses almost 5 oz. of fuel for a pattern (large venturi, ST nva, 2 head gaskets, Rev-Up 11-5 on 10/22 fuel), But it runs soooo sweeeet. Nice consistant 4/2 run and one or two flip starts.
 I could get through the pattern on just over 4 oz if the fuel was changed to 5/22 or changed to the small venturi. But, the Sig Akrobat it was in was 53.5 oz and I needed the power. Plus, it got REAL hot at most of the contests. (The weather, not the motor.) ;)
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Offline Bill Little

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Re: OS 40 clones
« Reply #8 on: February 16, 2007, 07:13:38 AM »
Hi Clint,

Good questions, all.  Randy will have to answer those!

As an aside, I took an old FP 40, a Dremel, and a set of needle files.  I took approx. .020. off the intake port (raised it) bolted it back up and it has the nicest 4-2 run you will see.  Not much power loss either....... 

Of course, you gotta realize that I operate mainly in the realm of "even a blind hog can grub up an acorn every now and then"!!  Will it work EVERY TIME??  I haven't a clue, but it did this time.  Sig 10%-22%, 11-5 wood prop, Thunderbolt plug.  Does it on profiles or built ups......

Bill <><
« Last Edit: February 16, 2007, 11:08:16 AM by Bill Little »
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Offline RandySmith

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Re: OS 40 clones
« Reply #9 on: February 16, 2007, 10:00:19 AM »
Quote from: Clint Ormosen on February 15, 2007, 08:21:49 PM
Randy, the FP's and all three clones have been run. Does this make it a "no go" as far as retiming? I do have one FP.35 NIB.

HI Clint
Yes and no depends on how much wear is on them, That is why I said I would have to see the engines, Also it is not just a retime but fitting everything properly and setting the comp ratio correctly in conjuntion with the proper sized venturie.
Bill had it basicly correct with why you sometimes do not want to retime an already ran in motor.
Never Raise the exhaust ports on these. It is high enough already, the intake ports are the ones that get retimed

Also for your information I now have  PA style NVAs  that are sized just for the FP LA and clones, they are much better than the ST ones that I also have

Regards
Randy
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Offline Bill Little

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Re: OS 40 clones
« Reply #10 on: February 16, 2007, 11:15:25 AM »
Quote from: RandySmith on February 16, 2007, 10:00:19 AM
HI Clint
Yes and no depends on how much wear is on them, That is why I said I would have to see the engines, Also it is not just a retime but fitting everything properly and setting the comp ratio correctly in conjuntion with the proper sized venturie.
Bill had it basicly correct with why you sometimes do not want to retime an already ran in motor.
Never Raise the exhaust ports on these. It is high enough already, the intake ports are the ones that get retimed

Also for your information I now have  PA style NVAs  that are sized just for the FP LA and clones, they are much better than the ST ones that I also have

Regards
Randy

OOOPPPPSSSSSSSS!!!!!!!  I didn't catch that when I first posted my reply.  It is the INTAKE port I cut.

Randy's PA NVA assemblies are the very best out there.  The nylon (??) insert in the "locking" collett makes the needle setting so much easier.  You do not have to tighten it more than finger tight (at least my "fingers") for it to hold the setting and not work loose or leak.

Sorry for the lack of concentration before........ ;D
Bill <><
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Offline Clint Ormosen

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Re: OS 40 clones
« Reply #11 on: February 16, 2007, 05:21:50 PM »
I knew what you were saying, Bill. ;D
 I'll be giving Randy a call.
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