Roger,

Sorry I don't have dimensional info on this engine. However, you might also consider that you will be keeping the crank rotation direction the same. This means that instead of swirling the fuel mixture toward the bypass, it will be spinning it away. So it may run somewhat differently. This engine probably has a notched disk crank web for counterbalancing. That might also make a difference in the bottom end gas flow. But people put reverse cranks into a lot of different engines (without rotating the case) and it seems to work just fine.

The rod will have to mount on the crank the same way, but if the piston has any asymmetry to it, it will have to be rotated with the liner. (If it has been previously run, it will also have to be rotated with the liner.)  Unless the piston has a cutout for it to clear the backplate. If both of these are true, then you will have to modify the piston.

Which FSR (size and vintage) are we talking about?

Will be interesting to hear your results.

Dave


Early .40 FSR engine review:   http://www.sceptreflight.net/Model%20Engine%20Tests/OS%2040%20FSR.html

Thanks fellows.  That review is indeed my engine, single pinned ring etc.  My conrod is chamfered on one side so I had to take the piston off and rotate it 180 degrees and put it back on the rod.  I tried it without doing that first, but the ring gap ended up in the exhaust port.  Once I restored the original piston-cylinder orientation, all went back together well.  Huge compression and it doesn't even appear to be broken in yet.

 

  Roger- is there a notch in the bottom of the piston? Several people have assembled the pretty similar 40/46VF with the piston in backwards, which had dire effects on the performance. The notch goes on the bypass side of the case, opposite the exhaust.

     Brett

There's two large notches opposite one another.  It's the same on both sides up inside the piston too.  I couldn't even find the arrow that points to the exhaust port, that some folks saw on their piston crowns.  So I'm pretty sure on this engine it doesn't matter as long as I keep the ring gap in its original alignment inside the cylinder.  There's excellent compression that way and the engine turns very smoothly, ring doesn't hang up anywhere.     

The Thick Plottens , . . .

Its IMPORTANT on the FSR's to run the TANK 1/8 inch LOW , or itll runaway on outsides . ALWAYS 1/8 inch .



Heres my rowdy pirate copy of Bob Hunts C.S.C. 40 FSR Toungue Muffler . It was actually dicidedly QUITER when it fell off on one flight . 

Im thinking the 2 in x 30 dia tube muffler with the 10 x 2 mm holes will be the go , let & breathe and MUFFLE the thing .
The Stock 45 Magnum muffler , it ran lean inverted / outsides WITH the tank at the 1/8 in .
Brodak tank , all youll get IS 1/8 in the Strega . Next flight the toungue above evened the run decidedly .  if a trifle loudlyer .

ALWAys THE SWINE SPEED UP THROUGH THE FLIGHT . For decades & centuries and years . So a drilled a 3/8 hole , slotted to 1/2 ,
in the Top of the NOSE of the STREGA . ( these are said to allow better cooldown between flights , as hot air goes UP .
Casell & Baron both prattled about cooling vents ( Through Bearers ) saying engine would drop speed after a few laps from take off
as it dropped to OPERATING TEMPERATURE .

Most of Urtnowskis plans show the breather , as per Gieske , Giadini etc .

FINALLY , last weekend



Copy of THIS muffler , but 2 mm Not 2.5 holes , was a wet rag , with the gutless run , but Even though the Flight with the Breather .
Next Flight the C.S.C. back on and audable , but the cowwl off as my battery was flat & the bludged one wouldnt fit the plug hole in the cowl ,

Power Back & a even steady run . on a 12 x 4 3 blade Bolly on the FSR 45 Bitza .

The 40s seem to like the FIVE INCH pitch , tho . Hunt s ran a 11 x 5 three blade . Std Crank ? ( Not S )

Tempted to block / remove rear iof std muffler & drill 10 3/32 holes in a x pattern , and whittle a few fins .

BE WARY of the WEENEY MUFFLER SCREWS . most common complant on S/H FSRs , stripped freds .
Ive now one gen u wine from new FSR S , a Magnum 45 , & a TT & Magnum 40 , from bits .

As I mayve said , the Tank 1/8 down & the C'Case Breather are MANDATORY , or itll lean off , & not drop back . the 45s'l near 4-2-4 .

The Gardner 40 FP P/L will drop in the 40s, tho I havnt in minee yet .

Wanted OS Front Housings ( for the center spray bar bore ) & 40/45s , dead or alive . Must be nuts . 

"The Gardner 40 FP P/L will drop in the 40s, tho I havnt in minee yet ." (Matt)

My recollection is that in PW's "Impact" article, he told of using an FP/FSR hybrid built for him by Tom Lay, until the .40VF/pipe came along. Have you used any RE donks with a tuned pipe? If not, why not?  Steve

P bleedy S , the FSR FOUTY FIVE & the HP have the same liner O.D. AND Head Bolt P.C.D. , and closely comparable port hights .

Thus you get .42 Cu. In. with HP Sleeve , in the 45 FSR case .

or FOURTY FOUR cubes , Seven with FSR 45 P/L in HP case . ( 1/32 " overbore - 0.8 mm )

Rods are same big & little end diameters , might need radius on piston cutout edges to clear crank / backplate / disk .

ALSO tho the OS 45 FSR ABC piston is LONG and alows ' dropping the liner ' the magnum is definately not so . 

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With the 40 OS your stuck with the FP as a non ring swap out , unless someone comes up with something else .

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Ive found the overspeed / inabilty to stay on lap time insufferable with the OS FSR & clones . The cowl top vent seems t 've finally licked it .

Cant be bothered with the complexity ( structurally ) of a tuned pipe , or the expense . More'n one ways to skin a cat . As they say . 

All my FSR blocks are reversed - Ex Out . Couldnt find a picture & gotta ' diss load ' a few pictures to get anymore on the phone camera .

The fussy part of the FSR/FP swap is because the ports are rotated on the FP and not on the FSR. The wristpin has to be retained by clips, so slots need to be cut inside the wristpin holes on each end...from memory.    Steve

Std FP LEFT , Gardner ABC RIGHT . There DUAL small by pass ports there , if you glare .

This is why the Gardner FP 40 P/L looks like a go , if you have FSR's on the brain . Circlipped , Full Skirt , AND fancy ( Smith / P A ) Porting .

Wil let you know HOW IT GOES , but it wont be soon ( unless Im donated anther OS FSR 40 ( hint hint ) . AS MY 40 is a ( or was a n.i.b. )
FSR-S with the ' Stunt ' crank , and Im loath to de originalise it . Tho I may be tempted . To prattle further , The Strega at 5 ton ( or 76 Oz)
may be o.k. for the 45 FSR but not likely a good test to normal FSR 40 use .

Further Again , the Gardner HP 40 abc P/L & head , would drop in the FSR 45 case . but youd have something like a 42 ,
loosing 0.8 mm on the Bore . In case anyones in that boat .