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  • October 26, 2020, 04:23:00 PM

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Author Topic: OS 46SF engine  (Read 258 times)

Offline Joe M

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OS 46SF engine
« on: February 13, 2020, 06:12:47 PM »
I have a OS 46SF engine that I made a venture for .  I need a needle valve assembly and would like to know where you guys put the valve on the venture. 

Offline Dave Hull

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Re: OS 46SF engine
« Reply #1 on: February 13, 2020, 07:03:55 PM »
Joe,

I would first consider how you will mount the engine and what type of tank you plan to use.

If you mount the engine inverted in a full-fuse plane with wood engine bearers, you will likely want a 1" tall tank--which means that you should put the NVA thru the hole in the engine case. Measure your case from the bottom of the mounting lugs up to the existing hole to confirm.

If you are going to put it in a profile fuse, then putting the NVA thru the venturi a bit above the case may be appropriate. Look down from the top on the overall setup. The NVA might best be located at the center-width of the tank. So for a 2" wide tank you might want it up to an inch "above" the lugs.

There is some latitude in the above, especially as you reduce the venturi diameter, or if you are pretty much flying it right side up. The more you expect a consistent, steady engine run, the more details like these matter.

Dave

Online Brett Buck

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Re: OS 46SF engine
« Reply #2 on: February 13, 2020, 07:09:50 PM »
I have a OS 46SF engine that I made a venture for .  I need a needle valve assembly and would like to know where you guys put the valve on the venture.

  Through the existing hole in the case, thats where they were on the factory CL version.

    Brett

Offline Joe M

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Re: OS 46SF engine
« Reply #3 on: February 13, 2020, 07:52:11 PM »
I am going to put it on a profile so engine will be side mounted.  The black tick mark is .8 up from the top of the mount lugs.  I really appreciate the reply's guys.

Left a message to a Aero Products on a NV

Joe

Offline Air Ministry .

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Re: OS 46SF engine
« Reply #4 on: February 13, 2020, 08:32:29 PM »
Side Mounted , Id try it level with the outer edge of the fuel tank .

My SF clone with a 330 or 350 venturie runs superb , if it does chew the juice .

About where youve got that pilot hole'd be fine.

Minell pull a 80 Oz Strega on a 12 x 6 , 4/2 .
Had me almost straight off building a Phantom , side mounted, as described . regreted cross drilling the case . got a El Cheapo new SF case for it, now .



The Royal .46 is a Clone. Near exact copy . the Parts'll interchange . was about  4 or 5 clicks lean , in the movie . To ensure it fueled the whole schedule .

Offline Air Ministry .

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Re: OS 46SF engine
« Reply #5 on: February 13, 2020, 08:44:27 PM »
This clapped out 15 U S Gallon FSR 25 Clone , is a very similar engine .
Still running fine, but pretty loose . Picked up a FSR water marked case for it , too . Plus theres a new P/L there . May go in the 262 now, with another .



That set up , outer tank edge level with spraybar - mounted . ( A Co incidance actually. at the time )
Goes full 4 stoke - level . Full Lean ( for what its worth ) overhead .Progressive between , with load variations working favourably .

So the .46 ended up with a 8.8 mm Enya Venturie . For comparable size Vs Capacity . ( The .25 is a Fox 25 Schnurle 7.5 mm bore one . )

But .320 is likely as big as youd go . Tho my .46 was a wet rag , even in the 60 Oz Magnum ,Id just about thrown out . using .280, .290, & .312 venturies .

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Id find how it whistles around the overheads , to determine the venturie bore . Set up outboard like that , she richens up lower down .

Everyone else'll say use a .280 , see how you go .  H^^

Offline Motorman

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Re: OS 46SF engine
« Reply #6 on: February 13, 2020, 09:20:27 PM »
That's a nice venturi. When you retro fit the PA spraybar I would get the longer one and make brass spacers to center it unless of course Randy has one that's an exact fit.

Motorman 8)
Remove victim to fresh air

Offline Joe M

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Re: OS 46SF engine
« Reply #7 on: February 13, 2020, 09:54:12 PM »
The bore currently at .270 but easy enough to open it up.  Will see how it goes when I get some props and NV from Randy. 
 Joe

Online Peter in Fairfax, VA

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Re: OS 46SF engine
« Reply #8 on: February 14, 2020, 07:53:14 AM »
Great discussion; thanks for bringing up this topic.

My first thought was to use the existing set screw holes in the case, as in Brett's comment.  However, I'm seeing that the higher location could be a benefit, as in Dave Hull's comment.

Which SF is it, in terms of the timing?  As I understand it, the stunt version is timed differently from the R/C version.

Peter

Offline Joe M

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Re: OS 46SF engine
« Reply #9 on: February 14, 2020, 09:57:43 AM »
Peter my motor is the RC version that I am installing a venturi on, Not sure on the timing of it. It will probably be a revving motor with a low pitch prop. 

Offline Air Ministry .

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Re: OS 46SF engine
« Reply #10 on: February 14, 2020, 07:49:32 PM »
Theres a OS ' SF - S ' crankshaft .

Sleeve timings around 140 Ex 120 Trans . STD.  lower than a VF .

The ringed version seems to be the sworn by one .

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Tank Fully Inboard of needle, say a recess between the bearers ./ -The outside edge was dead level . You get a solid 4 strokein level flght, and a good ' break ' set by needle .

Think the head wants to be close on these SF's . Some say 10 - 15 Thou Max , for squish band to be a squish band . Didnt like a extra gasket .

( Might pay to open out chaber with 1.5 wide squish , if youre wanting to lower the compession. Maybe.) LA 46 liner interchanges,
Tho If had a few ' DONT DO IT's mentioning bloking the by pass . It almost a one piece case FSR 45 / 50 , with lower sleeve timing .
Only got the good run after going to 15 5 N , one gasket & the big 8.8 mm intake . Tho mayve just been settling in , after overhaul . Std Spec.
on the 25 ,
Tank vent straight out the side , end cut 45 Deg . uniflow - tin tank . Bent 90 deg. into airstream & was irregular . to normaly blowing , itd do
the lean of downwind / rich into wind . LOW & LEVEL . So a small thing but experiment there may produce disproportionate results .

Down Proped when  wind  howling , to get it into the powerband , so it didnt go backward overhead .

Today in the 60 Oz Mustang. Not the best . Not nedling to right .  >:(

TIMING FIGURES for the CLONE royal 46 . ABC .

Ex 140  , Trans 114 , Boost 108 . Crank opens 35 closes 45 . Id assume thats within a few degrees of the OS R/C crank .

Liner had rotated . tediously centered when fit. Not clamped enough to tear the heads off the screws , but cautiously tightened .
So THE PEG is for more than just assembly accuracy of alignment .rotated 1/4 Ex or 1/2 trans  .

All these FSR , SF & T Tigre 46 cranks interchange , bar ( I think its ) the SF ?? has a larger flywheel- counter weight diameter , So
some go in some, others dont, unless you machine down the diameter 7 some need the big end trench to clear the big end .

The SF is 19.5 stroke , 22 bore . near enough S tigre .46 dimn's.   G-51 matches SF mount & V.c.V.  backplate posn. mounting holes , ex stack hight etc .
for interchange .

Was almost awake sunday , a bit slow , of woulda picted a better setting .
« Last Edit: February 16, 2020, 06:37:53 PM by Air Ministry . »

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