will an OS 91 backplate fit the OS 70SZ

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Home › RC & Power › ✈️Aircraft › 🚁Helicopter › Engines Plugs Mufflers Fuel › will an OS 91 backplate fit the OS 70SZ

04-01-2020 05:06 AM 11 months ago

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0Post 1

Gearhead

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will an OS 91 backplate fit the OS 70SZ

Guys, I have a NIB OS 70sz, I want to put a 91 Regulator on it, will the Pumped 91SX or Hz back plate fit the 70sz ?

I think they will fit, but I got to be sure.

thanks !Jim
Buzz Buzz Buzz

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04-01-2020 07:34 AM 11 months ago

0Post 2

ticedoff8

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Morgan Hill, CA. USA

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I don't know.
But, I bet not.
The .61 to 1.05 use the same mounting lugs (big block), but not the same crankshaft.
Buy the backplate for the .91 1st and try it before you buy the carb.
Or, drill and tap a nipple to the .70's backplate.+ > ÷
Believe 1/2 of what you see and none of what you hear.
Fake News will be the downfall of our Republic!

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04-01-2020 01:17 PM 11 months ago

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wjvail

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Meridian, Mississippi

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Like Ticed said, I don't think they will interchange. I don't know what is different but they are different part numbers.

Again, as Ticed suggested, I wouldn't hesitate to drill and tap your .70 backplate. If you do choose to tap your backplate, make sure the pressure nipple doesn't extend into the case too far and touch the rod. You may have to shorten the threaded portion of the nipple.

https://www.towerhobbies.com/cgi-bi...p?I=LXCM34&P=ML

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04-01-2020 07:32 PM 11 months ago

0Post 4

Rojoalfa

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Punta de Mata, Monagas-Venezuela

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/
/

Both rear bearing are the same for os91hz and os70sz.

https://www.amainhobbies.com/o.s.-e...7930000/p141309

Base on that dimensions, probably both backplate works without problem.

/Saludos cordiales,

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04-01-2020 07:32 PM 11 months ago

0Post 5

JLF92677

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Southern California

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Gearhead will an OS 91 backplate fit the OS 70SZ
Guys, I have a NIB OS 70sz, I want to put a 91 Regulator on it, will the Pumped 91SX or Hz back plate fit the 70sz ?

I think they will fit, but I got to be sure.

thanks !

No, it will not fit. Dimensions are different. Bolt center hole to center hole dimension is smaller on the 70 than 91.

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04-02-2020 06:59 AM 11 months ago

0Post 6

Gearhead

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OK, thanks ! I don't have a problem drilling and taping but I don't know how thick the back plate is, I will have to take it off and measure it, if it's too thin I will only get 1 or 2 threads in it. I have a friend that has been welding for some 55 years. I can have him put a drop of aluminum on it, them mill it flat and drill and tap it

thanks guys !Jim
Buzz Buzz Buzz

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04-02-2020 07:35 AM 11 months ago

0Post 7

JLF92677

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Southern California

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Deleted.

Jim, after reading your last post again this morning I realized that I misunderstood your post, as your response was to post #2

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04-02-2020 08:29 PM 11 months ago