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Author Topic: Question for the learned G-21 fans  (Read 757 times)

Online C.T. Schaefer

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Question for the learned G-21 fans
« on: November 30, 2018, 02:47:07 PM »
A friend asked  "what is a G-21 .35  Mk2?".  My memory says maybe a bigger crank? Let's hear from the guys that used to pound the ground with these babies on a regular basis.  TS


Offline jim welch

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Re: Question for the learned G-21 fans
« Reply #1 on: November 30, 2018, 03:04:53 PM »
Perry port..
AMA 89335

Offline Paul Smith

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Re: Question for the learned G-21 fans
« Reply #2 on: November 30, 2018, 05:34:10 PM »
As I recall the SuperTiger C35 and Stunt 35 (plain bearing) came on the market in the early 1960's.
They were soon followed by the ball bearing G21.
Some time before that there was an older G21 with a front & back plate.  I never saw one of these is use, but only displayed by collectors.

Over the years, G21's were produced in short production runs with changes every time.  There didn't seem to be any change in the names, always G21./35.  I remember PDP (Perry directional porting) as being one of the later revs.  Many of the revs involved muffler ears and other changes in favor of RC, which had become the focus of the ST business.  I think PDP was a low cost way of competing with schunural porting without making a whole new engine.
Paul Smith

Offline phil c

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Re: Question for the learned G-21 fans
« Reply #3 on: January 03, 2019, 05:38:26 PM »
CT- Super Tigre did build a schneurle 35 with a 15mm shaft.  It was on a 40 case and about 10oz.  I had one, but it was never a spectacular runner.

Henry came out with his 36 and it completely blew away anything else.  We were able to get a Fox Mk VII competitive but it was never better than the Nelson.  They still are the best handiing, most durable combat 36's.
phil Cartier

Offline Motorman

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Re: Question for the learned G-21 fans
« Reply #4 on: January 06, 2019, 11:51:59 AM »
The G21-35 Mk2 was the same as the original ball bearing G21-35 except it had a bigger crankshaft and Perry ports. It was the same crankshaft found in the SuperTiger Como .40 cross flow with perry ports. The Schneurle ported engines came later.


Motorman  8)
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Offline Paul Smith

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Re: Question for the learned G-21 fans
« Reply #5 on: January 06, 2019, 04:46:14 PM »
Originally, the ST G21/35 was a great engine.

But later on, when everybody had them, guys started trying to gain advantage by "leaning on them".  Then the trouble started.  Spitting out the crankshaft and bearing failures, which effectively destroyed all the working parts.  It was possible to upgrade the bearings if you did the fix before complete failure.

Paul Smith

Online C.T. Schaefer

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Re: Question for the learned G-21 fans
« Reply #6 on: January 07, 2019, 04:57:22 AM »
MM, That's kind of what I thought but confirmation is good.  PS, Yes, I too broke the shafts but after we went to 10% fuel no breakage!  Hmmm.......   Thanks for replys,  TS

Offline Motorman

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Re: Question for the learned G-21 fans
« Reply #7 on: January 11, 2019, 08:49:54 AM »
I cracked a few crankshafts on 10% before I got the compression ratio right. The original bearings had the folded tab cage and the tabs would crack and come off.


Motorman 8)
There will be a sunny day and we will fly our airplanes.


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