MJD

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What parts do you need?

CafeenMan

Well, I ordered on the 14th and got it in the mail on the 17th. Pretty quick service.

Now does anyone know if the TD uses different glow heads than the rest of their engines? I have parts from Babe Bee's, Black Widows and Golden Bees but the heads are all mixed up. If there is a difference are there markings or something?

ffkiwi

Yes it does-it uses the #1702 high compression head. Essentially there are four different Cox 049 heads-all of which are interchangable and usable-but not necessarily 'optimum' for any particular engine-especially if you get the wrong head on the engine. The TD head-the #1702 has a small conical combustion chamber with a squish band-and on the top of the head has a circular knurled ring about 10mm diameter and about 1.2mm wide. This is purely decorative but it does allow you to distinguish a TD head when fitted to an engine without needing to remove it-all the other 049 heads do not have this knurled ring. The other types are (obviously) the standard 302 reed valve head-which has a lower compression broad cone shape, and the 5-fin Texaco head-which is readily distinguishable by its extra fins-but inside is exactly the same as the standard 302. There is also a 'plain' head-with only one vestigial fin intended to be used with a finned clamp on heat sink for cars-this too is just a standard low compression head on the inside.

Now depending how old your accumulation is, you might find the earlier 302 heads with a hemi chamber rather than a shallow conical one-the change from hemi to shallow cone occurred ca 1975. Much rarer still are the ones with a W-shaped element, not a coil (Cox was a bit naughty-and pinched someone else patented idea-and lost the subsequent patent infringement court case) and the very earliest pre 1955 049 heads had a smaller diameter threaded section.

Simple rule-if it's knurled on top, its a TD head, if it isn't it's one of the others...this rule also applies to the 09 and 15 engines-but not the smaller 020 and 010s

ChrisM
'ffkiwi'

MJD

My Feedback: (1)

Good info from our Kiwi friend.. I realize how little I knew about Cox glowheads other than that there are TD plugs and reedie plugs.

aspeed

Yep he is right. I don't use anything but the TD heads unless I want to run a huge prop. Merlin plugs are ok too, and cheaper. They only fit the .049 and .06.

CafeenMan

ffkiwi - thanks. I thought I saw one or more of my glowheads having some knurling on top around the stem. After reading your post I looked in my bag of glowheads and sure enough there it was. I have no clue if it works - didn't put any juice to it yet. I have to get some prop bolts before I do anything else.

A few years ago I put together a Black Widow on my test stand. I changed out every cylinder I have until I found the one that gave it the highest RPM with whatever prop/fuel I was using. So somehow I was attaching a prop but I can't find a 5-40 bolt anywhere in my ten gazillion pieces of hardware and none of my .049's have a prop bolt. A couple have that stud and I don't even know if it comes out or not. It's stuck solid in all my engines. Will take a good soak or heat to loosen them up assuming they are supposed to come out.

Thanks for the post. It was very helpful.

aspeed

Sometimes you can find a 1/8" stove bolt which is a #5-40, at the hardware stores.

CafeenMan

I'll take a look next time I'm there. Thanks.

ffkiwi

A quick minor correction to my previous post-the ORIGINAL Cox 049 reed valve head was the #302 (up till 1955) and the #302-1 afterwards-(the only difference was the 302-1 had a larger diameter threaded portion) -both with a 'hemi' head profile, the ca 1975 replacement I mentioned earlier was the #325 head, which had a shallow cone profile and was also produced in Texaco (5-fin) and car (1-fin) variants-with different part numbers. My earlier post might not have been quite clear on the distinctions......

ChrisM
'ffkiwi'

rcokie

Hey, I have one of those. Not in a display case but completely functional.