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OS Max Plugs, Really Good

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Old 11-13-2011, 07:49 AM
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Honker1
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Default OS Max Plugs, Really Good


Hello,

Just resurected an Old OS Max .15FP. This engine had not run in about 10 years. I installed it on an old Sig Senorita and got it running OK. Flew it a bunch lately, engine didn't seem like the old OS I was used to. It would cut out at idle on approach sometimes. Took it all apart, sealed the carb, cleaned everything, ran OK when I was done, still not great. I was at the LHS and purchased a #8 OS Max glow plug and swapped it out with whatever brand plugs I had screwed into my glow plug driver over the years and WOW!! What a difference, the engine runs stronger at full power,idles so low and reliably now I can't believe the difference. I do remember over the years everyone always said the OS plugs were the best and in this instance I definately agree. I had Tower, Fox , Thunder Tiger plugs but the OS ones seem to really make a profound difference.

I always remember with the OS engines you could land pretty hard, if you didn't hit the prop the engine just kept idling. It would not do that with the off brand plugs but now it does. Am I imagining things or has anyone else had such good fortune with these slightly more expensive plugs. Get what you pay for?

Thanks,

Pat
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Old 11-13-2011, 07:56 AM
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Default RE: OS Max Plugs, Really Good

Yes the OS #8 is one of the best all around plugs out there.

I only use it in all my planes except ones with pipes that get a plug one step cooler.
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Old 11-13-2011, 08:27 AM
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Default RE: OS Max Plugs, Really Good

Ditto on the OS # 8 plug for general sport flying. The Thunder Tigre plugs are quite good too.

Karol
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Old 11-23-2011, 04:51 PM
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Default RE: OS Max Plugs, Really Good

Yea the O.S. plugs are the best, worth the money. My two strokes get the no.8, my Saito gets the F, my car engines get the A3.
Only the Supertigre .61 gets another brand: a Fox miracle idle bar.
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Old 11-23-2011, 05:37 PM
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Default RE: OS Max Plugs, Really Good

I agree with this all, though I have used the A3 in some 2S engines under certain conditions.

Does anyone have any info or feedback on the new OS numbering system, or any of the new plugs (i.e., the #7, and I think there is/are one or two others) ???

Bob
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Old 11-24-2011, 03:20 PM
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Default RE: OS Max Plugs, Really Good

I've been experimenting with the no. 7 in an FX .40 and Magnum .25. Good results on the test bench, but I havn't flown it yet.
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Old 11-25-2011, 05:40 AM
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Default RE: OS Max Plugs, Really Good

Which plug were you comparing it against, the #8??? What differences have you noticed?

Bob
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Old 11-26-2011, 09:27 PM
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Default RE: OS Max Plugs, Really Good

Mmmm, I'll run a quick comparison and post it.
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Old 11-30-2011, 03:24 PM
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Default RE: OS Max Plugs, Really Good

O.K. here's what I got.
I ran a quick comparison with a well used Magnum .25, APC 9X5, 15% Wildcat, temp 40 degrees.
With a No. 8 it reached 13,800 rpm briefly and ran 13,600 to 13,750 consistantly.
The No. 7 gave me 13,500 to 13,600s consistantly and could reach 13,700 briefly.
For a sport modeler like me the diference is negligable. This was hardly a complete or scientific
test, but the results for the No.7 are promising. Not to mention that the No. 7 plug costs just
over half the price of the No. 8
I'll try this in an FX .40 as soon as I can.
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Old 11-30-2011, 05:22 PM
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Default RE: OS Max Plugs, Really Good

Thanks for that info. I agree with your use of the #7. I'm going to try that as well when I get the chance.

I'm wondering what the issue is that makes the #8 so much more expensive than the #7. In the end, it could just be marketing and too much margin. So, they introduce the #7 to get some of their market share back because people are buying other folks plugs instead of the OS #8... that's just my conjecture.

Can anyone else jump in on this and tell me if this is a plausible theory?

Bob
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Old 11-30-2011, 05:49 PM
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Default RE: OS Max Plugs, Really Good

My guess is that the material used to make the fillament in the No. 8 costs more, and that makes it more
costly to produce.
BTW both my AX .46s were shipped with A3s and they run well with them. I plan to do more in depth
testing of the No.7 plug next spring as I'm about to take down my engine stand for the winter. It looks
like the No.7 is going to be a winner.
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Old 11-30-2011, 06:42 PM
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Default RE: OS Max Plugs, Really Good

I can't see that a difference in wire would amount to much real cost but for a few pennies. Other than that, the construction and materials are the same, from what I can see.

It will be interesting to find out... Thanks for that info. Now that I think of it, I may have already installed a #7 in one of my planes. I'm going to have to check. It might be in my Escapade...

Bob
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Old 12-15-2011, 09:58 AM
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Default RE: OS Max Plugs, Really Good

Here's the O.S. Glow Plug Chart:

http://www.osengines.com/accys/glowplugs.html
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Old 12-15-2011, 10:12 AM
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Default RE: OS Max Plugs, Really Good

I love O.S. and like their plugs too. I like Saito engines as well.


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