Cooper / Stover KA Update

This morning on this chilly Winter Solstice day I did some work on the engines I'm planning on exhibiting at this years Emerald Winterfest coming up on July 27th. One of the engines to be worked on was my long lost recently come home Cooper / Stover KA. I had resolved most of the problems with this engine both at the Heyfield National Rally and after bringing it home. I still had to get it onto skids, resolve the knocking, adjust the exhaust timing, fix the fuel filler, and resolve the whirring noise, and fix the leaky oiler...and...and...and... Well, I got some of the jobs done!

Skids

I made some skids out of some handy treated pine which was laying around the place. Treated pine is kinda ugly, but I've been using it for a while on smaller engines because it is light, strong, and lasts forever! I like to make my skids long enough so that there is ample protection for all the bits sticking out of the head, and long enough at the back to stash a fuel can and tools behind the engine in the trailer. My skids are 4' long, and 1' wide. This spacing suits the engine well protection wise, and is wide enough to be stable. Some people go to a lot of trouble with their skids - I just try for a bit of strength. They really are easy to make - about 20 minutes with a circular saw, power drill, and rasp to clean up the edges. The way I do it is measure out carefully (engine bolt spacing) then decide how long and how wide, then cut all your timbers. I put the cross braces on before bringing the engine over (that is why you measured, you did measure didn't you? yes? good :). The braces are put on at the right spacing, then made square with a tee. Measure it all up to make sure it is even (ever had one skid further forward than the other - looks silly). The braces are screwed to the main skids with long wood screws. These really only hold the skids square to each other. The main 6.5" long bolts do most of the work at keeping in once piece. I don't use spring washers with skids because I find they work loose between the bouncing of the engine and the shrinking of the wood, instead I use a removable thread locking sealant (Loctite Blue, which ironically comes in a red bottle, unlike the unremovable Loctite Red which comes in a blue bottle - go figure).

Walking on Skids - Tip

If your engine is like my Ottawa and likes walking around when running, you can pin the buggers down by using 10" nails - I have four of them which sit in holes in the skids - I just bang them in with a hammer when I want to run the engine and it stays where I want it to be. I don't need to do this on the Cooper / Stover because it is much better behaved - not to mention its piston is only about half the bore and stroke of the Ottawa - much less metal flying around to make it jump.

Oiler Overhaul

The oiler was next, I took it all apart, cleaned it out by hosing it inside and out with WD-40 - great stuff, dissolves all the old oil, and displaces any water. I removed the perished rubber gaskets. To make new gaskets I got some thick oil seal paper (about 1 mm thick) out of my stocks... You can get it from the auto parts store. To cut it to size I put the end of the oiler onto the paper on my work bench and whacked it with a mallet - this gives me a perfect marker to cut out. I cut that with good scissors. Next put the paper over the end cap and trim to size around the edges. The paper should be the same size in diameter as the cap (i.e.. does not fit inside the cap). Do the same for both ends, put the paper over the end cap and firmly push in the glass body. This makes a perfect seal as there is paper sandwiched between the glass and the cap. Once the central bolt is in and done up tight the oiler will be perfect - no more leaks. Next I cleaned up the needle valve on the oiler with a file to make sure it seated smoothly and sealed the oiler when closed. The seat on this one was still good so no hard work there. The spring clip and spring were fine. Finally after re-assembly I put the oiler into the vice, filled it with oil, and timed it to be right for the engine (I use 2 drips per minute plus 1 drip per horse power per minute - so for this engine being a 3hp I use 5 drips per minute - I've been told this is too much, but I've never seized a running engine and I never plan to).

Exhaust - where to pop?

Next up was the exhaust timing - the book says to have this open at 5 degrees before bdc and close 35 degrees after - this timing was making a sharp bark every time the valve opened because combustion was nowhere near complete. I changed it to open at bdc and close 40 degrees after - this is much quieter and the engine sits still now (no more violent jumping).

Knock... Knock... Anyone home?

Onto the knock - at Heyfield one of the list members tightened up the big end conrod bolts - they seem to have worked loose again. On checking, I could quickly see why - there was a paper(!) washer under the bolt head - of course this gets crushed and the gap opens up... knock knock knock.... I removed those, replaced them with metal washers and did up the bolts, pinning the castelated nuts with cotters. They should not come loose again. While I was there I noticed the grease cup was a little loose and tightened it up too. Remember to check the bearings periodically after you've tightened them up to make sure they are not getting hot. Slightly warm to the touch is fine, hot is bad.

Whirrrrr

The whirring had me perplexed - it comes from the timing gears. They seem ok on inspection, reasonably straight (as straight as a 80 year old cast iron gear is going to be anyway), and all the teeth are there on all three gears and in good condition. They all mesh well, they are not too deep into each other (bottoming out). Then I figured it out - the central (large) timing gear is from a different engine - the wear pattern is totally different. I'll just have to put up with the noise until they wear in after another 80 years or so.

Fuel filler and soldering a petrol tank without blowing yourself up

I was going to have a go at the fuel filler, but want to find a better way of mounting it than the previous owner who used hot glue to join the pipe to the tank. The pipe fittings he used were modern chromed fittings which won't take solder at all (hence the got glue I guess). I'll dig through my collection of brass fittings and find something which can be soldered into the hole. I'd always avoid soldering petrol tanks until Stan pointed out that I should fill the tank with water first - duh, now why didn't I think of that.... no air space... no air... no air, no explosion...

Status

The engine is now running very nicely, it coasts at 250rpm climbing to 350 every time it fires. It occasionally fails to fire after sucking in and you hear the timing mechanism ratchet up for another go - the mag fires twice in quick succession. I'm told by the engine whisperer Edd Payne that this is caused by the detent arm slipping on the main rod. The faces where the detent and the detent block meet should be machined square. A job for another day.

On a previous occasion I united the engine with the sub-base generously provided by SEL friend Ron Sullivan (who also baby-sat this engine for about two years while I was away working in the USA) - the engine is much better off on the sub base, now the flywheels won't dig holes in the ground!

The engine is pretty much ready for Winterfest - it needs a good clean, and a paint touch-up, and the fuel filler fixed (I can just see the safety officers reaction to me filling the tank through a gaping hole in the tank itself...

Other jobs today...

I also removed the fuel pump from my Southern Cross P to have a new brass plunger machined for it, and removed the head from the Ottawa 4hp because it had blown yet another gasket - combustion bubbles just don't belong in a hopper full of water... bugger... A good mate of mine, Stan Gunn is making both the brass and taking care of the head for me - thanks Stan, your efforts are appreciated. I also got to try out my new toy sent to me by an Indian company. A stud extractor - they sent it to me to review it - I tried it on the Ottawa and it works like magic - barely marks the stud at all, better than vice grips which is what I used to use. Maybe I'll tackle the Southern Cross P head now - I've always avoided pulling it because it already has broken studs and mushroomed over nuts (seemingly deliberately) - with this tool, getting rid of all the junk should be easy.

Last modified Sunday, 20-Jul-2003 15:28:00 BST

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