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Davis Diesel 1/2A Parts
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Davis Diesel 1/2A Parts
We have acquired the majority of the remaining parts from Davis Diesel. These are primarily parts and accessories related to Cox .049 engines including the 'Killer' cranks, Bob's version of the reset tool, heads, fuel, etc. There are also some 010 and 020 diesel parts on a limited basis from what I can see at the moment.
I know some have noted that the diesel design could be improved with regard to the head assembly and this will be something I take a look at.
We will follow up to this thread once parts have been cataloged and are available for purchase.
Matt
I know some have noted that the diesel design could be improved with regard to the head assembly and this will be something I take a look at.
We will follow up to this thread once parts have been cataloged and are available for purchase.
Matt
Re: Davis Diesel 1/2A Parts
Matt, I've been interested in a .020 diesel head if available. Please let us know. I would really like to know as to the whereabouts of the Jet-X Powermax units Bob had.
Ken Cook- Top Poster
- Posts : 4161
Join date : 2012-03-27
Location : pennsylvania
Re: Davis Diesel 1/2A Parts
Ken Cook wrote: Matt, I've been interested in a .020 diesel head if available. Please let us know. I would really like to know as to the whereabouts of the Jet-X Powermax units Bob had.
Hi Ken, there are definitely some 020 diesel parts. Looks like there are two different head types that were used over the years so I have to make sure all the parts are there to complete a head, but will set one aside for you.
Not sure on the JetX items, but will check.
Re: Davis Diesel 1/2A Parts
I have the Davis Diesel Instruction Manual if anyone wants a copy. Here is the front and back covers:
I just ordered a "new" crankshaft and Drive plate for the TD020 that I recently acquired that came with the Diesel head and has a sheared crank-pin and bent rod! Looked good in the pictures...and I didn't ask any questions!!
Talk about timing!!

I just ordered a "new" crankshaft and Drive plate for the TD020 that I recently acquired that came with the Diesel head and has a sheared crank-pin and bent rod! Looked good in the pictures...and I didn't ask any questions!!
Talk about timing!!
Marleysky- Diamond Member
Posts : 2826
Join date : 2014-09-28
Age : 68
Location : Grand Rapids, MI
Re: Davis Diesel 1/2A Parts
Marleysky, I could always add a copy to the Instruction Sheets list on the forum.

RE: Davis Diesel 1/2a parts
About a dozen years ago, I bought out all the Cox parts and the shop junk box of a dying LHS. There was a DDD headed Pee Wee with a broken crank.
I called Davis for more info and fuel and mentioned the Pee Wee .020.
He strongly advised using his product an a Pee Wee and very strongly said never use a Davis head on a Tee Dee .020 !!!
I guess that's why he stopped production of .020 size DDD parts.
FWIW Steve...
I called Davis for more info and fuel and mentioned the Pee Wee .020.
He strongly advised using his product an a Pee Wee and very strongly said never use a Davis head on a Tee Dee .020 !!!
I guess that's why he stopped production of .020 size DDD parts.
FWIW Steve...
66 Malibu- Gold Member
- Posts : 444
Join date : 2012-02-28
Location : Georgia
Re: Davis Diesel 1/2A Parts
Thanks to Rene, the Davis Diesel conversion manual is now available: https://www.coxengineforum.com/h24-instruction-sheets#related_docs

Re: Davis Diesel 1/2A Parts
66 Malibu wrote:
He strongly advised using his product an a Pee Wee and very strongly said never use a Davis head on a Tee Dee .020 !!!
Yes, and that is because his heads are faulty.

The counter piston is to thick and the compression ratio cannot be reduced enough. On top of that, the Teflon gasket doesn't seal well and there will always be small leaks there. So when turning the engine over one will not realise that the compression ratio is too high (even with the screw fully backed out) and if you manage to get a pop from the engine anyway, something will break...
The fix is to put the counter piston in a lathe and to remove about 0.1-0.2mm from its height. Next step is to throw those silly teflon gaskets away and use a sheet of brass instead (lasts longer than aluminium ones). With that you now have a head that seals well and the compression ratio can be adjusted low enough. With a good diesel fuel you only need a compression ratio that is slightly higher than on a glow engine, nothing more.
Here is an example of how the PeeWee runs with these simple mods, it spins a 6x3 prop at around 10krpm:

Surfer_kris- Diamond Member
- Posts : 1754
Join date : 2010-11-20
Location : Sweden
Re: Davis Diesel 1/2A Parts
Surfer_kris wrote:66 Malibu wrote:
He strongly advised using his product an a Pee Wee and very strongly said never use a Davis head on a Tee Dee .020 !!!
Yes, and that is because his heads are faulty.![]()
The counter piston is to thick and the compression ratio cannot be reduced enough. On top of that, the Teflon gasket doesn't seal well and there will always be small leaks there. So when turning the engine over one will not realise that the compression ratio is too high (even with the screw fully backed out) and if you manage to get a pop from the engine anyway, something will break...
The fix is to put the counter piston in a lathe and to remove about 0.1-0.2mm from its height. Next step is to throw those silly teflon gaskets away and use a sheet of brass instead (lasts longer than aluminium ones). With that you now have a head that seals well and the compression ratio can be adjusted low enough. With a good diesel fuel you only need a compression ratio that is slightly higher than on a glow engine, nothing more.
Here is an example of how the PeeWee runs with these simple mods, it spins a 6x3 prop at around 10krpm:
Agreed and I am going to run new tests under both brass and copper.
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