Model Diesel Engines - Page 132 - RC Groups
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Apr 08, 2011, 06:25 PM
Good Better Best quest.
olmod's Avatar
What type of temp' device ? I find IR types on silver alloy are incorrect when compared to HP stick on.
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Apr 08, 2011, 07:36 PM
Registered User
NX-687, for a .15 size engine to pull 65 ft lines around, and do fig. 8's, I'd say you have more power than a glow. What's the all up model weight?
I remember I once had a 1/2A model with an OS Max.15 on 52 ft lines and it moved right along. It was more like an under powered rat racer. If your diesel is running cooler than glow,I wouldn't worry about the head temperature, that what keeps the diesel firing up there.
Apr 08, 2011, 11:39 PM
Registered User

Hi John

Yes 24.5 Ozs ,

It would be hard to measure a diesel head temp as the contra piston is usually buried inside an aluminium cooling jacket,

with 30% oil my engine is pretty well protected even with a lean run it seems no ill effects

just richen it up and it springs back to life for the next flight with no aparent damage done
Apr 09, 2011, 02:23 AM
Voices through wires? Ha!
Chas's Avatar
I don't see how a diesel can have a lean run. If it goes too lean it stops.
Apr 09, 2011, 04:32 AM
Registered User


Originally Posted by Chas
I don't see how a diesel can have a lean run. If it goes too lean it stops.
Ive got an Enya 35 NVA in my OS 15 diesel and on one flight it was sputtery and a little slow , so next flight I opened up about between 1/8 and 1/4 turn and the power came back ,,

I just flew,,,,,,,, and the model is slowing a little thru 8;s it may be rich or my homemade piston may be stuffing up, it flips over nice so I hope its just the tune , also my baffle is so close to the head that I didnt expect it to last what 12 flights that its had so far , if it stuffs up I dont know what to get , a little, more power would be nice,

and after the engine starts I always try to remove the glow plug leads
Apr 09, 2011, 06:35 PM
Who let the dogs out?
Phil_G's Avatar
Originally Posted by phil_g
Could I just ask does anyone know if there are any new small diesels being made or imported to the UK at the moment?
Just a follow-up, my nice shiney brand spanking MP Jet 040 arrived today and its lovely. Lovely, lovely, lovely.

Happy chappy. Many thanks to Sion for the tip-off

Apr 09, 2011, 06:48 PM
Registered User

Need more power

I opened the venturi up from 6 to 7mm with a 4mm spray bar going through it

and took out the 0.15mm head gasket , but then the piston was hitting the head

so couldn't run it like that , Its pretty black in there ,,,,, wonder what that means,

not much more options except to get it right on tune

My piston fit may have slackened because I did not clean the lapping paste out well enough or maybe the piston matl is not good or the leanish runs may have lost a little power . I will try and tune for max power today and see if it comes back

I dont want this engine to slow down , it was a lot of fun
Last edited by NX-687; Apr 09, 2011 at 07:54 PM. Reason: Add
Apr 09, 2011, 10:56 PM
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Mills 1.3 instruction sheet

Guys, does anyone out there have a nice set of original instructions for an English Mills 1.3 Mk. II, that they could scan and email to me ? I have a NIB 1.3, but for some reason it came only with a .75 specific sheet. My email is - Many Thanks in advance ! BOB
Apr 10, 2011, 03:49 AM
Registered User


Can you use a brass contra piston in an aluminium head ?
I have to put one in , these fixed comp diesels can be hard to start at times , Ive got 2 blood blisters
Last edited by NX-687; Apr 10, 2011 at 03:51 AM. Reason: Add
Apr 10, 2011, 08:11 AM
Registered User
NX-687, the black soot is common from burnt fuel/oil; synthetics [oils] don't leave much.
Try the brass inside the aluminum, but maybe keep the brass slightly less than real tight.
ABC engines are such that the expansion rates keep the engine from seizing when it gets hot. If the "new brass contra piston" is too loose, it may show up when the engine gets won't seal. If that is the case, then you will need a tight fit which may stick when cold. Cold starts...try a prime with more ether in the mix (50%?).
Apr 10, 2011, 10:08 AM
Registered User
earlwb's Avatar
I have seen a number of engines that used a brass contra piston, so yes you can use them.
yeah the black soot is pretty common. It usually is not a problem, I don't remember it building up over time like you see with gasoline engines etc.
As JohnAV8R stated maybe a prime with more ether in it would help.
The early era Drone model diesel engines with fixed compression heads used 75% ether and 25% oil to run no kerosene.
Apr 10, 2011, 10:18 AM
Registered User
My experience in flying control line stunt stunt with diesels is that loading up in maneuvers is a sign of over compression, missing in maneuver is a sign of a hair too lean.
Apr 10, 2011, 01:43 PM
Voices through wires? Ha!
Chas's Avatar
And another thing....why do contrapistons wear out? They only move about ten metres in their bores in a lifetime of use.
Apr 10, 2011, 04:35 PM
Registered User
earlwb's Avatar
The wear on a contra piston, comes from the tiny up and down movement during the combustion process. It gets a hard hit upon ignition that tends to cause it to flex and move ever so slightly in its bore. It is where the outer circumference moves up and down while the center stays put (due to the screw that sets the compression). Sort of like a reverse drum, as the center stays put, but the outer edge moves slightly. So the contrapiston is moving hundreds if not thousands of times a second up and down in a tiny fraction of a inch. Then there is the expansion and contraction as it heats up and cools off. So eventually it wears down in the bore where it is at. Usually the contra piston is made from a material that is more soft than the cylinder bore.
Last edited by earlwb; Apr 11, 2011 at 07:24 AM.
Apr 10, 2011, 05:18 PM
Registered User
Originally Posted by Twin-Stack
Guys, does anyone out there have a nice set of original instructions for an English Mills 1.3 Mk. II, that they could scan and email to me ? I have a NIB 1.3, but for some reason it came only with a .75 specific sheet. My email is - Many Thanks in advance ! BOB
I do have what your after, but we have a problem with the scanner not scanning into the 'puter.

If you PM me your address I'll copy it and post it to you if you have no joy somewhere else.

My 1.3 is a late one with the RC carb. on it, and the instructions are for both 1.3 and .75.

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