RCRAINMAN

I have read a good bit on diesel conversions and the parts that you can buy to make the transition (ie heads, mufflers, etc.). My question is this: Can I use my existing glow head and run the ether/diesel/oil mix or do I have to buy the expensive new head. As far as I can see, the new head only sports a compression knob where the glow plug is on a glow head. Could retrofit my exsiting head with a homemade compression knob and get it to run right? Any repsonses by people that actually run diesel? (no "I think" or "I heard" responses please.)

ksechler

A deisel engine needs higher compression for ignition to take place. The deisel heads are machined such that this higher compression is acheived. Your stock .46 AX will not run as a deisel without the aftermarket head.

RCRAINMAN

If you increase the amount of Ether in the fuel mix, can you lower the point at which the compressed fuel air mix will ignite? IE- Don't have a need for incredibly high compression?

Davis Diesel talks about how you can fiddle with the fuel type to change performace. I'm interested in how your diesels perform. Do you buy premixed Diesel fuels or do you make your own. Can you tell me what your percentages are if you use a home mix? I've seen numbers like 33% Ether, 50-60% Diesel, and 15-30% Oil. All these questions I have not been able to find the answers to, thats why I'm asking.

Thanks for your help Ksechler.

RCRAINMAN

Well tonight I got out the .46AX, used the stock head, and made me a mix of about 25% Ether, 60% JET-A, and 15% Marvel Mystery Oil. Its awesome! The engine will not yet start as a pure diesel, but it runs pretty well on this crazy fuel! It has about the same RPM range as on standard glow and runs considerably cooler. Plus the exhaust smells like a turbine I lowered the amount of MMO in the mixture and almost got it to start without an ignitor. It fired a few times and wouldn't sustain. Tomorrow I will try some different oil amounts and types. Maybe standard two cycle engine oil will work better. Who knows.

I also want to back down on the amount of ether until I get it to around 5-10%, as ether is the most expensive ingredient. My job at the airport supplies me with up to 5 gal/day of Jet-A for free and the oil is relatively inexpensive at walmart. Once I get the ether concentration down and the thing to start by just explosive compression alone, I will know that I have done it! Muhahahahaha!

Of course when all is said and done I will most likely just order a conversion kit from Davis Diesel. lol Just thought I would let everyone know how my trials went.

Jim Thomerson

Actually, the difference in diesel and glow running compression isn't all that much. I've run a couple of K&B 4011's on on the bench with Davis 1/2A diesel fuel. One, after leaving the glow plug lit about 20 seconds would run fine. The other would run undercompressed when I took the battery off. I'm pretty sure the second one had a thicker head gasket, but have not taken it apart to check. Performance was exactly the same on an APC 11x5 as with Sig Champion 10% nitro fuel, but at much greater fuel economy.

So I am not surprised by your results. Sounds like you are having fun.

Jim

RCRAINMAN

Well I am having a hard time finding a M6 x .8 Bolt from anywhere. I've checked Home Depot, Auto Zone, and Advanced Auto Parts. Most people only carry M6 x 1.0 bolts. Once I get the new bolt I will use it to adjust the compression like I had originally planned. If it doesn't work, I'm considering just drilling and tapping the head for a new bolt size (bigger) and using some of my own creative engineering to adjust the compression. The only problem is once you go bigger, there's no going back. At this point the question is: is it worth it.

But remember, the whole point to this experiment was to see if you can create a good running diesel engine using a stock head.

I'll post more tomorrow after I continue my search for a M6 x 0.8 bolt.

BTW- M6 x 0.8 is the type of bolt and thread combinations found on a glow plug. Don't try the all-to-common M6 x 1.0. You will cross thread and end up retapping your head

XJet

I think you'll find that the thread for a glowplug is 1/4-32 which, admittedly, is *very* close to M6 x 0.8 -- but you may find it easier to pick up a 1/4-32 bolt than an M6 x 0.8 one.

Jim Thomerson

I think you may have a problem with leakage around your bolt threads as there will be no washer as with a glow plug. You might try a 1/4 x 32 rod made of aluminum which would eexpand as the head expends with heat. Also, and I'm sure you have thought of this, put a stop on so that the bolt can't hit the piston. As the late George Aldrich said, 'Taking off a head and changing gaskets is not brain surgery."

Jim

bigchap

there is no such thing as a 6x.8 mm thread,6x1 is standard,6mm fine is 6x.75,it will definitely be an imperial thread.

Luftman

My Feedback: (1)

There is a device called the gadjet made by Lou Furco, it utilizes the original head and simply screws the compression adjusting device into the existing glowplug hole. From what I've heard from Dr. Diesel, the gadjet requires a much higher ether content and lower kero content, im sure it will run with your mix but i dont think you'd want to put it into a plane, the transition is likely horrendous.

jessiej

Interesting stuff! I enjoy tinkering with projects from time to time purely for relaxation. If there is no practical reason for what one is doing there is little pressure to succeed There have also been times when I discovered something useful.[X(]

jess