Greetings all from a damp but mild Charente in S.W.France.

Advice please . Was there any difference in the 'timing' etc between the R/C version and the C/L version of the G21 46 please ?

Would an R/C version just need the appropriate venturi and NVA to make a good stunt motor ?

   As far as I know they are the same. My best engine started as an R/C version, put my standard venturi in it, and it worked perfectly and never touched it afterwards.

     Brett

Bob and Brett ......

Very much obliged for your contributions. Just what I wanted to hear !

Kind regards from the French countryside ,

Robin.

The reports which have come to my notice are that the real differences depend on which model you have. Basically the older the better. Somehow the latest ones were not as good as the early ones?

Old vs new 46's. I preferred the two ring (old) for stunt and the single ring for rat race. The two ring had a shorter rod and thus a longer dwell time at tdc which may or may have been a better match for lower rpm. Little known fun fact. My dad (Big) actually made the first long rod single ring st40. We used it rat race. John Kilsdonk talked to John Maloney at World engines about it and the parts magically appeared in the next engine run from ST. My dad also built the first rear rotor 40's out of rr 29 cases. The 29 cases are identical to the 40 cases with the exception of the rod clearence grove for the longer stroke of the 40. John Kilsdonk took them to the King Orange that year and the next run of st40's included rr 40 race engines..... One other "trick" the old 40/46's had was the prized "O" crank. The "O" crank had an 0.806" stroke while the later cranks had a 0.799". The reduction was to get the engines actually legal for rat race. the 0.806 made the displacement slightly over .40..... Because the 40/46 shared the same crank all later 46's also had the stroke reduction.

Whats the true displacement of a later .46 then , Dave. ?

Will two of em be under the .90 Cu.In. , 15 c.c.  F.A.I.

Limit for stunt .

Should I use two K&B  SRII 7.5 c.c. s (Just kidding there )
alledgedly 2.2 Hp @ 22.000 .( What line lenght for 5 sec laps ? !)

Hi Matt. Sorry it took so long to get back. My age addled brain got the stroke numbers wrong. DOH! The difference was correct .007". The correct stroke numbers are .779 for the shortened stroke and .786 for the "O" crank. This makes the "40"  (.807"bore) a .3985 with the short stroke and a .402 with the original "O" crank. I'll get the 46 numbers in the next post. Gotta go measure the 46 bore to do the calculations..... Don't trust my memory at this point........ I can tell you that the "O" crank engines were winners..... I believe AMA ok'd the "O" crank right after ST made the change to the shorter stroke. They never went back to the longer stroke in the G21 40/46. The .786 stroke made a re-appearence in the G40 case 51 rear rotor....