OSFS 1.20 Surpass Mklll

Today I was looking forward to a day flying at Cashmoor, unfortunately events turned out otherwise and I found myself confined to barracks for the day instead.
To ease my disappointment, I decided to rebuild the OS FS 1.20 Surpass. All the parts were now squeaky clean and lightly oiled, I'd even bought a new set of screws for the cylinder head. The rebuild went without any dramas, with a heated crankcase the four bearings settled in nicely, in fact everything was going so well that I thought I might be able to fit the engine to the WOT 4XL and fly it tomorrow. I got as far as trying to fit the cylinder head. The new screws are no use at all, they look very nice, but the 2.5mm hex socket heads are slightly oversize and its impossible to tighten them. Fortunately I found this before even trying to use them. Now I was left with a set of useless screws, and five original screws that were usable and one with a damaged socket. Seemed a pity to give up, I dug out every hex key I could find. Naturally nothing apart from a 2.5mm key went anywhere near. While drinking my second cup of coffee, I remembered that I have a tiny kit of "come in handy" screwdriver bits, hex keys and a few tiny sockets. Just to see if anything would work, I offered up a small Torx driver to the damaged screw socket, it almost but not quite went in. I drilled a 3.6mm hole in a piece of scrap alloy, put the alloy bar in a vice, popped the ailing screw into the hole and gently tapped the Torx bit into the screw head. I didn't think it would, but it actually did work, and now the engine is assembled and needs only a final check on valve clearances which I'm sure must have been affected by the dismantling etc.

Well I never! I wrote to Modelfixings about my problem and surprisingly received an immediate answer. Its all my fault for not reading the spec of the screws they supply. Seems they are made in good old US of A. The jolly Americans are OK with the 3.5mm thread but draw the line at a 2.5mm hex socket. What they do is make the socket close to 2.5mm, this is 2.8mm otherwise know in "proper" dimensions as "7/64in". My school reports frequently noted that I should try harder. I'm beginning to believe they were right.

This evening I had an email from Modelfixings, they asked if I'd like a 7/64" hex key. I replied "thank you, how much". They replied "FOC".
How good is that? I've used Modelfixings for a long time, their stuff isn't always the cheapest, but the goods are always spot on, and the latest offer of a free hex key shows that they care about their customers. How rare is that?
As a finale for the OS FS 1.20 Surpass tear down and rebuild, the engine was refitted to the WOT4 XL airframe, the recommended starting procedure was gone through, the glow stick was clipped on and the engine started as soon as the starter was applied. Tickover is good and steady, pickup is positive. All in all it has been a worthwhile exercise.

After all you hard work Brian i hope you will maintain the OS. I would want to ensure any nitro remnants in the blow past are regularly cleaned out. I wonder if its practical to inject and rinse out pure methanol / synthetic oil mix thru the cam case breather nipple item 13. especially if you're not going to fly the model on a regular basis.

The manual says -Quote (avoid kerosene based products that could find its way into the pump unit, carburettor, etc. Inject, sparingly, preserving oils, rust inhibitors, etc. unless approved for silicone-rubber products. An appropriate alternative here may be one of the high-quality synthetic lubricating oils)

I'm using standard "after run" oil Kevin. There's a useful tube connecting the nipple marked 23 in the diagram to a nipple on the carburettor intake manifold. It makes squirting a drop or two of oil through the tube and into the most needed areas quite easy.