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Cropmaster petrol to diesel

Posted: Tue Oct 25, 2011 3:34 am
by cobbadog
If I have the engine to do so is it possible and or practical to change a 30C Cropmaster from a petrol kero engine to running a diesel? Is it a straight out unbolt and bolt up change over? We are looking at buying a 30D but they are few and far between out here in Oz so I thought of changing it over to diesel as this will be a tractor for trekking only and only used on a few occassions during the year.
Cheers John. :D

RE: Cropmaster petrol to diesel

Posted: Tue Oct 25, 2011 8:37 am
by Madders
are you watching thism post mr Torley???????????????

RE: Cropmaster petrol to diesel

Posted: Tue Oct 25, 2011 9:02 am
by Guest
Back in 1950 John when the diesel engine Cropmaster was first introduced, David Brown offered farmers an option through the dealerships to change the kerosene engine for a diesel in their existing tractors under a 'service exchange' system, they would supply a new diesel engine and your kerosene engine would be then returned to the factory 'up-dating your existing tractor without having the expence of purchasing a new one' was the way they put it. What I'm saying is, yes, the diesel engine will bolt straight on as will the 25 engine. You can also convert a kerosene engine to diesel providing that the block has the bolt-on blanking plate for the fuel lift pump and of course, you also have to change the cylinder head and the timing case and front engine plate for the injector pump mounting and drive.

RE: Cropmaster petrol to diesel

Posted: Tue Oct 25, 2011 12:30 pm
by erkki
Hmmmm. Wasnt there a thick extra plate between the engine block and bell housing in early diesel Cropmasters? I think in the very beginning when a more powerful starter was needed with compared to petrol engines. In order to make enough space for the longer starter, the wheelbase had to be extended by an inch or two by adding the plate there??? The story is written in some DB-related literature. I do not know if 30D has the same feature.

RGDS erkki

Posted: Tue Oct 25, 2011 1:21 pm
by Eric_T
I was thinking the same as Erkki, I'm sure there is a difference in length between models due to starter and some other bits...

I looked into this ages ago, back when I wanted to own a Bench Seat Diesel, but only p/p's were available. I came across a fairly big stumbling block that wrote that particular project off. What theat block was I cannot remember...

Posted: Tue Oct 25, 2011 4:34 pm
by erkki
The story about the starter is told by Herbert Ashfield in his book "More on my Career as engineer at David Browns" in chapter Design of a diesel: "The solution to fitting a larger starter proved to be somewhat unorthodox but worked very well. We put a packing piece, two inches wide, between the flywheel and crankshaft flange and lengthenend the tractor frame by the same amount. The starter motor mounting was also moved back, thus giving the extra clearance required between the starter motor and oil pump boss."

Posted: Tue Oct 25, 2011 10:32 pm
by broadsword
Hi Erkki and Emyr.

I thought the spacer was to allow the fitment of a bigger clutch but heres a picture of what you mean - the starter is allmost up against the oil housing. All the Cropmaster diesels have this 2" spacer - you can see the grimy thing below the battery carrier, its also the reason the bonnets and side panels are 2" longer than the TVO`s.

I have a copy of the Conversion book (original) and according to that all the conversions came from the factory with the AD4 2.5 litre engine whereas the 30D`s and later Cropmaster D`s had the AD4/3 2.7 litres - mine has a AD4/3 later engine but suspect the original engine replaced.



Posted: Wed Oct 26, 2011 4:50 am
by cobbadog
Thank you to everyone who has replied to my enquiry, I appreciate it very much. Now it just makes me want to ask even more questions so here I go;
1- So if the engine has a blanking plate so that a lift pump can be bolted on and I cahnge the head and front timing covers etc a petrol engine can be converted over to being a diesel ?
2- Are the crankshaft, conrods, pistons, cam all remain the same with no need to replace or change them?
3- If this type of conversion is made do I still need the 2" spacer mentioned?
4- Is there an aftermarket 'high torque' starter motor available to suit this application without having to space back the flywheel and lengthen the tractor?

Posted: Wed Oct 26, 2011 6:28 am
by erkki
Hi cobbadog,

You have many question on which I cant answer but the story written by Herbert Ashfield included also knowledge of different type shells to the crank and later on also the crank was modified to achieve better fatique resistance.

RGDS erkki

Posted: Wed Oct 26, 2011 8:50 am
by Guest
We are talking about the conversion of a Cropmaster VAK 1C to Cropmaster diesel here, the 30D was a different animal so using one as an engine donor should be immediately discounted. As I said previously, the Cropmaster diesel was just that, 'dieselised'. If you want a diesel, then why not look out for a 25 or 30D as attempting the proposed conversion would in effect be building one. If a Cropmaster diesel engine can be found, why not use that, bolt it in and no modifications needed.

30c kero

Posted: Wed Oct 26, 2011 10:00 pm
by tedwood
have you considered fitting the hicomp streight petrol comercial head? its 5.5 to one and improves economy,will run e10 fine and its easyer to find out here.

RE: 30c kero

Posted: Thu Oct 27, 2011 3:24 am
by cobbadog
Thank you once again for the replies. The reason for so amny questions is that I have been looking for quite some time for a Cropmaster diesel and they are very few and far between to find. Petrol/kero models are easier to find but a friend has 3 tractors all in bits and one is a Cropmaster the others are a 30D and something else, I will know more after this weekend. I was considering that since I may be buying something in pieces and if the parts are available that I might build a Cropmaster diesel with the available parts. Might be getting my self into some bother with this project but I should be closer to answering that question soon.
Also as with all my engines from cars to stationary and even mowers I always run Premium grade fuel, it saves me a lot of dollars by doing so but thanks for the tip ted.

Re: Cropmaster petrol to diesel

Posted: Tue Jan 14, 2020 6:43 pm
by woody
Hi everyone I am new to the forum. I have a 1956 30d with a cracked engine block, can I convert a vak tvo block with the parts from the original engine ? Are the bore sizes the same ? obviously I would be fitting new liners. I am considering this as I know of a sound tvo block.

Re: Cropmaster petrol to diesel

Posted: Tue Jan 14, 2020 6:54 pm
by ollek
Woody, the original topic was about changing a petrol engine to a diesel and you are now hanging on to this with your question regarding a different problem. Please, open a new topic for your problem.

Re: Cropmaster petrol to diesel

Posted: Wed Jan 15, 2020 1:24 am
by Gard
I have parts lists for a 900, large sections are broken out for the different fuel types, diesel, TVO and gasoline. I think the 900 engine was similar or the same as the cropmaster engines but do not know for sure. It would not be too hard to look up part numbers between the gas and diesel engines. I have a microfilm version of the 900 parts list that I scanned into a pdf file, a little hard to read. If anyone wants a copy, PM me and I can send a copy.