SuperTiger G21 .35

I have had for some time a G21 .35 that came in a box labled to identify it as a combat engine. It has a small venturi I.D. (approximately .152 or .153) and three head shims. I would think for combat, the venturi would be bigger and have fewer shims. What really is the difference in the combat and stunt versions?

Thanks, Herman

Because of the "sprinkler" style restrictor, the Slow Combat and stunt insert has a small-looking cross section. The NVA doesn't block any of it off. But there should've been TWO inserts, with the second one having a large bore for use with pressure.

>I have had for some time
>a G21 .35 that came
>in a box labled to
>identify it as a combat
>engine. It has a
>small venturi I.D. (approximately .152
>or .153) and three head
>shims. I would think
>for combat, the venturi
>would be bigger and have
>fewer shims. What really
>is the difference in the
>combat and stunt versions?
>
>Thanks, Herman

Are you ready for this, Herman? The .154 venturi is on the big side for stunt (although probably OK for some applications. Combat is not so concerned about fuel draw and a "stunt run", but only in achieving maximum power.) The stock stunt version came with a .120 venturi (which is on the small side for stunt). As Kiwi mentioned, this is all that is needed when the needle valve assembly is not blocking off part of it.

As to head shims, I don't know without looking how many were supplied with the stock engine. How big are they (thick)? There may be several if they are thinner ones. If not, are you sure that someone else didn't add some to try to tame the engine? In additon to the venturi differences, there should also be timing differences on the Stunt version of the engine. Still, you could run this engine with a lower pitch prop. Let it run the way it wants and use prop pitch to tame the lap speeds. Alternately, you could have it retimed by one of the engine rebuilders familiar with this engine or trade it off to a combat guy or engine collector and get a different engine more suited to stunt.

I think Leonard may be thinking of the ST .35C, which also had a
stunt version. This is a plain bearing engine, I have two of each
version. The ST G.21 .35 is a whole 'nuther engine, and in fact,
there were two distictly different engines called the G.21 series. The early version had a bolt-on front housing and rear cover, a nearly vertical venturi, and a baffled piston. The later version (and probably the one you have) has a one piece crankcase
and a flat topped piston. I had one of those, but it didn't have
a whole lot of torque, and even a 9-7 was too much prop. It could be there was a ringed version with a baffled piston, but I've never seen one. I don't think there was a "stunt" version of the G.21 .35, ever. Bob Baron did use one in his "PA-8", circa 1968. It flew with a 4" pitch at 15,000 rpm. The .40 and .46 versions were ringed/baffled. Tho the .46 was a legendary stunt engine, the .40 was more suitable for rat race. Steve

I have two G21 .35s and they out-perform the C.35 combat and stunt. They're definitely a different breed from the standard C35s. I've been flying one on a Super Duper Zilch for years and have decided to replace it with a "tamer" engine. I used a 9-7 prop and the revs barely changed through all manouvers - - power and torque plus!). The other is on a Flite Streak with a 9-7 prop. It flies like a knife throught the air. It's like having a 396 on your airplane. What a rush!!! I can't imagine anyone not being impressed with this engine. Have another look at it, I'm sure something has been overlooked if you're not happy with it. By the way, I also fly ST C.35 stunts and combats on various other planes. They too are great engines, but not G21s.
Mo

One more thing about the venturi: pull the restrictor, leaving a great gaping hole, pressurize the fuel and WATCH OUT !!!!!
Mo

Wow, Steve, I didn't know anybody else remembered the earlier G21. I still have one.

The G21 was the top combat engine from 1965 until 1980, when the Fox Mark III took over. I flew a whole lot of combat with those things. I can't imagine flying stunt with one. It would be like making a pickup truck out of a classic Ferrari. It could be done, I guess, but wouldn't be the best way to use it.

My first G21 35 ran very well on suction feed. Using a 10-6 T.F.
nylon prop, it ran smoothly rich, something the later ones wouldn't.

Are you interested in selling your G21-.35 ? Or trading it for something. ? I'm looking for another G21-.35.
Thanks,

I have one G21 .35 left NIB and several used ones. Let me know which one you are interested in.

Interested in any and all..depends on the price..what $$$value are you asking for rhe NIB and then the worse one? Also..do you have any interest in trades ..like for a kit ? Voodoos, Ruffy,Green box Nobler etc?

>I have one G21 .35 left
>NIB and several used ones.
>Let me know which one
>you are interested in.
>
>"SAVE ALL THE PIECES"-Phil Brown
can you email me ?????
norm

Hi!
My pal jim and I have been trying to stuntify a ST 35 combat for a while now... Its in my 'new'(Two year old.) 33oz Prowler. If our experience is a measure, don't bother with this conversion!
Weve tried venturis, head shims, and timing changes and dont have a combo yet...
It will swing a 12/5 byo EASY but theres no 'stunt run'. I'm lookin for a 35-S...
Good luck,
Ken