indoorff

My Feedback: (2)

After messing around with a Davis head conversion on a Cox surestart for a few months, and not getting a satisfactory run, I decided to try the RJL head. With the Davis, I just could not get a consistent run, it was quite leaky, and I was constantly burning out those flourocarbon discs. I got fed up with this, and tried the RJL head, and boy, the difference is like night and day. The engine now runs incredibly well with a 7x4 prop, very consistent, and EASY starting! It honestly starts easier than the glow version. I am using it to haul up my 2m glider, and from launch to the point where the engine cuts, it never sputters.

I would highly recommend the RJL diesel head for anyone wanting to convert from glow to diesel.

Chris

chevy43

Let us know if you get good life out of it. We have all heard how the crank can't take it for long...... I'm temped to try one myself. I have an RJL head already and I like the head too.

GrahamC

I have messed around with the Davis and RJL head - they both work, they are just different. My choice is the RJL head.

As to crankshafts, if you haven't broke one yet, you will. I broke a couple of the standard reedy cranks and one of the heavy duty car engine cranks. I have since started to use the Davis killer crank and it is a considerable improvement - yet to break one yet.

The picture shows the broken car crank - broke right across the smiley!

cheers, Graham in Embrun near Ottawa Canada

indoorff

My Feedback: (2)

I have a DD crank ready and waiting if there is a failure. So far it has been totally trouble free. The davis crank is a little too short or maybe the spline is not tight enough for the cox drive washers. Either way, tighteing the prop on causes the drive washer to bind with the crankcase. If the stock crank eventually breaks, I will have to machine a new drive washer so I can use the Davis crank.

Chris

GrahamC

Now that you mention that, there are two version (that I know of) of the Davis killer crank. One has a full circle crank web. I have one of those and I had to machine the front of a crankcase in order to use it so that putting on the prop drive didn't bind, the bearing surface of the crank wa just a wee bit short, perhaps 15 to 20 thou. The other version has a triangular web shape and this one fits a standard reedy case much nicer - I will not have to machine anything off.

I don't know the history of the Davis cranks, whether the one with a full circle is an older design and the triangular newer. Perhaps someone reading this knows. I think a quick email to Davis is in order as this has picqued my curiostiy.

cheers, Graham

indoorff

My Feedback: (2)

Graham,

You are correct, mine is the one with the full circle crank web. I bought it from DD a few months ago, so it may be the new one, or I guess it could have been old stock. It was kind of rusty.

Chris

GrahamC

Interesting Chris.

The crank I have with the full circle crank web I got over a year ago direct from Davis. The one with the triangular web I got just week also direct from Davis.

Hmmmm. I am off to send an email to see if he will share some details and insight.

cheers, Graham

gcb

Mine is the full circle and I got it many years ago.

George

Max_Power

I've just got the RJL head too, and a Davis to try. I'm new to diesel so I also got a .40 FP conversion head to learn on a engine I can get a crank or rod for instead of my Norvels. I got my gallon of Davis fuel yesterday . It's the "Plane" blend? Anyone know anything about their different blends? I can't find any real #'s on the DDD site, and my email reply seemed to leave that answer out from the few questions I asked. I'd like to know the differences so I can add castor, or A.N., etc and still use this stuff. I'm looking forward to mounting some heads and getting my first diesel runs in this weekend. Has anyone tried the RJL head on a AP Wasp?

GrahamC

I think DieselDan down Florida way has put a diesel head on the AP 061 but I couldn't find anything on a quick search; I did find a couple of his posts on his Norvel 061 conversion. Have a look through the "everything diesel" forum and you might have better luck finding it.

cheers, Graham in Embrun near Ottawa Canada

Jim Thomerson

The Davis plane fuel is fine. Just leave it alone and run it.

chevy43

Diesel heads don't seem to work well on Wasps. I couldn't get good results and neither can anyone else I've talked to hear on RCU.

gabe200

My Feedback: (21)

will diesel fuel attack foam or plastic im converting a .049 golden bee with the rjl head

GrahamC

The ether in diesel fuel with attack most plastics and foam as well. I recall reading somewhere, probably on the vintage combat site where they did not allow foam wing planes because of the problem of the fuel attacking the foam.

http://www3.bc.sympatico.ca/dieselcombat/index.htm

I had a quick look, more like a quick scan, but didn't see the reference. I will have to look more closely later as time permits

cheers, Graham