Mark,  I tried some time ago to find one of those heads. Every now and then they show up on Ebay. You would probably have to contact Henry Nelson direct. I believe if you do a search for competition engines or one for the National Speed Society there is a direct e-mail link for him. I used to have the e-mail address but I can't locate it. The one thing to expect with this is a fairly high cost in the area of $30.00. Then you have to purchase the plugs if you don't already have them. Larry Renger suggested this inexpensive mod and I tried it with good success. You just use the stock head and drill the threads out. I believe he was using a letter drill to do it, but I just used the closest size I had available. You can then use any button type glow plug; AP, Norvel, Merlin, Glo Bee etc. Insert the plug onto the landing in the cylinder and use the stock head as a clamp. In my case, I flattened the plug on a piece of glass using 800 grit and did away with the stock head shim. This increased the performance of the engine and enhanced the startability of the engine. In any event the mod is not a costly one as the stock heads are inexpensive and available. In my case I never changed it and never looked back. I run the engine pretty hard with a Apc 4.4x4 prop. Ken

I have used Nelson plugs in Nelson and Jett RC Pylon engines in the past.  One thing to consider is that are designed differently than standard glow plugs, ie they seal on the beveled part of the bottom of the plug not by the gasket or threads.  The heads have an internal bevel to match the base of the plug

You can get a lot of this stuff from Larry Driskill - - http://www.kittingittogether.com/glow-plugs/

    The problem here is not finding the Nelson plug itself. The Brodak or CS engines have a large head which holds the cylinder liner down. The Galbreath head is designed to fit into a Cox like cylinder which accepts the Nelson head. All of the engines as stated above AP, Norvel, Cox, Stehls etc. can utilize the Galbreath head setup where the Brodak can't. Henry Nelson didn't make many of these heads but could make them on request. I'm not sure if that is still correct today as I inquired about them almost 2 years ago. The biggest factor is the cost. When you weigh in the cost of the head which is probably now $30.00 or more plus a $5.00 plug you've added more than half the cost of the engine here. You are probably less than likely to achieve the same performance as the AP.061 at the cost of anywhere from $39.99-$49.99. The Ap is by far the best choice of the currently available engines as its powercurve is more than suitable for several types of flying. Not everyone is happy with the r/c carb on the AP including myself but these obstacles can be hurdled quite easily as others have already done. Ken

     Henry's contact is nelcomp@fyi.net. Competition engines is the company name. I recently found it looking through my favorites. Ken

  Mark , I have two Brodak .049's with  Nelson heads & plugs and they increased roughly 2000 RPM's from stock.
   Bill

 Ken , I was using a Cox 6-3 on my Brodak .049 's with the  Nelson heads & glow plugs . Just checked the website , Brodak sells the .049 needle valve assembly for $5.00 .
      Bill

          Mark,  I'm fully aware of what the instructions state to use. I found that I couldn't get a sufficient needle setting using the 10%. I then switched to 25% which made the engine start easier and also gave a bit more rpm's. I ran out of the 25 and started using 35% all the time. I would add shims only if the engine is being overcompressed or blowing the plugs. I'm not sure how the Nelson head isas I went the other route. I used no shims and mine had considerable compression. I was using the AP wasp plug which worked for a while untill it got smoked.  This could have happened from the 40% I was running in it or the prop was slightly out of balance. The difference here is the Nelson plugs are very durable and tolerable to this kind of abuse.  I would try it and see if its sagging or blowing plugs then adj accordingly. I've had the Nelson plugs come loose repeatedly when the engines were overcompressed. In any event I would think your 20-20 fuel would be a good choice. I'd like to hear your success when you get it ironed out. Ken

    Mark , checked my two Brodak .049's , one has one gasket the other has none. Be aware when starting the Brodaks they are very prone to flooding. Small amount of prime is all you need .  Do run them with the original head and then switch to the Nelson, definite improvement .
   Bill