Black Widow Question

gvc Today at 12:46 am

I have two black anodized engines but both can’t be Black Widows because they have different cylinders and glow heads. The lower one on the right has a thin wall cylinder with a two fin head. I think this is a true Black Widow. The other has a thick wall cylinder and a three fin head. Did Cox release black engines that weren’t Widows? Are these different versions? Did someone hybridize? Any insight from you Cox experts would be appreciated. Thanks.

balogh Today at 1:12 am

I think by the time the Black Widow was first released around 1974, the thin wall cylinder had been replaced by the step wall cylinder, and later, the thick wall cylinder. Even if some may have had thin wall cylinders which I doubt, that should have been a No1 cylinder i.e. with 2 bypass ports, that you can check..either a No1 stamped under one of the exhaust ports ( I can see that under the port of the rear side of the cylinder,though a bit blurred), or there should be 2 bypass ports visible with the glow head removed and piston cranked to the Bottom Dead Center.

Thanks to the wide interchangability of COX engine parts, the previous owner may have hybridized the one with any glow head and the thin wall cylinder. The No1 thin wall cylinder had taper bore that maintains its excellent compression over long period if usage, so even if not stock on a BW, I would prefer that in use rather than the non-taper, but stock thick wall cylinder, if longevity matters to you.

If one of the heads is knurled around the center electrode, that indicates a high compression head with which the engine output is ramped up a few 100-s rpm.

P.S.: I would bend the top hook of the starter spring to a bit smaller radius so that it should have a better grip on the cylinder base..

GallopingGhostler Today at 6:33 am

As far as I know, just as András said, thin cylinders were obsoleted by 1974. The one on the bottom, appears someone did some mixing and matching.

However that said, if bottom one has only one cylinder bypass, then you have Golden Bee power, which is still a decent engine. If 2, then you still essentially have Black Widow power.

If the cylinder has like András said or P40 stamped, you have Black Widow power.

Back early 1960's, the dual port product engine was used on the heavier Cox C/L RTF's like the P-40 so they'd fly the circle decently. In 1964, the Cox Spitfire debuted. It had a non-stunt 8 cc plain aluminum tank with Babe Bee style Zamac metal tank back with 2 fueling nipples and dual bypass port cylinder and plain aluminum crankcase. It had Black Widow power.

I had one, a Christmas present.

If it has decent compression, it just depends on how much of a purist you want to be. (Both qualify for Cox Engine of the Month Contest.)

Ken Cook Today at 7:05 am

My best running Black Widow engines were like the one shown on the top of your picture. One thing to note about them is that the piston needs to be reset with regular frequency. Typically, when reset the material work hardens and the need to reset lessens. If left unchecked, the rod will poke a hole through the top of the piston and I've experienced this on several of mine. I've experienced this problem more on the engines made from 1989-1995. This would be about where I date your particular engine.

Seeing that both of your engines are equipped with plastic backplates, I will also comment on them. I personally prefer the plastic. I've found that they don't leak as bad and they also don't corrode like the pot metal. However, the early versions didn't use web stiffeners in and around the screw bosses. Cracks would develop and one can't see them or at least not easily. Pressure testing the tank quickly reveals them. In your bottom example, you can see the left bottom engine lug is distorted. This can be due to a few things but generally, it's a result of the case screw being overtightened. It's pulling the material inwards and distorting the engine lug outward. This can also be a result of the cooling when the part was made. These types of issues can cause leaks or not it all depends . It can also be a result of a cracked backplate which no longer yields it's strength due to being stressed. As I mentioned, this can be a non issue if it's not impacting engine run. It can be a real problem if it is because it can make you crazy due to not being able to detect the problem.

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