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Old 08-26-2021, 06:21 PM
the Wasp
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Originally Posted by thailazer View Post
Jim... Thanks for those points. The prop seems heavy enough, and we did try a OS #8 and an OS #6 with no difference in the quitting. We first thought that it was loading up at idle so we leaned out the low speed mixture so a pinch on the fuel line has less than a 10 second run. It seems like something is quenching the plug or there is detonation at the wrong time as it stops so suddenly.

You mentioned that you had problems with your carb.... Can you elaborate on that?

my engine was very very finicky when the tank was half full or lower. if I ran it richer to compensate for it I lost a noticeable amount of top end power. the problem was rather bad. I have heard of people having this problem in smaller engines but never on an engine this large, some of these people raised their tanks.

now this^ reminds me, please check the high speed needle, Magnums are very well known to have loose high speed needles, just wiggle it to see how loose it is. if it is loose an OS 140 or 160 needle may fit well, this just may be your problem ?

sorry, I can not remember what OS needle it was that would fit my Magnum 180 4St, if I had to guess I would guess it was the OS 160 twin 4St ???

BTW, as for the 15% fuel, the engine may have had the Head Shim removed if it was worked on. "no shim" would give more compression, this could be the problem or just some of the problem, please first check that Needle.

good luck.