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OS Surpass 91


Old 07-19-2012, 09:59 AM
black alder
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Default OS Surpass 91

I have a Surpass 91 that a friend gave to me. He has completly stripped down the engine, removed everything, pushrods, pushrod cam, rockers etc.
I am attempting to rebuild it and would appreciate instructions as to how to get valve timing and engine timing correct, and any tips regarding re assembly
Thank you, Jim
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Old 07-19-2012, 04:00 PM
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Default RE: OS Surpass 91

I 'invented' a tool for installing the split collets - I'm sure that it's nothing original. But it was easier to use this to push down the spring and cap in order to install those split collets. By the way, you don't need an expensive nut driver to fab this took. In fact, the cheaper (softer metal) the better.

There are three tricks that you need to use. The first one (my original idea) is to put a piece of soft wood into the inside of the cylinder to hold the valve snug against the head while you reassemble the valve spring/collets. This keeps the valve stem from dropping out when you push on the spring and collets.

The second idea, which I stole from someone else online, was to use a toothpick to pick up some grease. Use this grease to pick up one of the split collets at a time to install them. The grease has to be thick.

A third idea would be to do this inside a plastic ziplock bag (that's been suggested about a million times by various people). If one of those pieces gets away from you (Twang!!! ) you have a fighting chance to capture it.

I also uploaded a txt file that came from the web (possibly the OS site itself) about timing. It's in txt format so might need some massaging in Microsoft Word.

Give it a day or so and see if other guys chime in here with good ideas. Keep us in the loop as to how you are making out. I think that my old Surpass is turning about 9300 on a 14x6 prop if I recall correctly.

Just my $.02


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Old 07-20-2012, 05:58 AM
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Default RE: OS Surpass 91

That's a good idea for a "custom" tool. We usually use a hemostat and just grip the outside of the retainer and push it down when the cylinder head is on a piece of wooden dowel that's about 1" tall. The valves rest on the dowel and so they don't move when we press down on the retainer.
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