# Holt tractor engine



## gbritnell (May 7, 2019)

Gentlemen,
 It seems like there is some interest in building the Holt tractor engine. The question has come up about Coles demise and the subsequent loss of castings and drawings. Discussion has come up about copyright infringement on selling copies of the drawings and to the point of selling one's legally purchased prints.
 When I took an interest in the Holt engine quite a few years back from seeing several versions at old engine shows I spoke to the builders about the engine and found out what they liked and didn't. The biggest issue was the way the crankcase had to be machined for the main bearings. It required some reasonably accurate filing, mounting the main bearings then line boring them. This meant that the main bearings once mounted had no real way of relocating should they need to be removed or replaced. Other issues were with the quality of some of the castings.
 With this in mind I purchased a set of drawing from Coles (the original business in California) along with the large flywheel, intake and exhaust manifolds. I then started making drawings to build my Holt from bar stock.
 Since completing and running my engine for many years I have discovered things that I would have designed differently from the original drawings.  With these thoughts in mind and seemingly some interest in the engine I have started making drawings based on my scratch built version.
 The engine will have a split crankcase making it easier to machine. It will have O-ring seals on both ends of the crankshaft. The ignition will be triggered by a Hall transistor setup. The plumbing will be a little larger to provide better cooling.
 All the parts will have some detail to them (bosses and shapes) but will be able to be made without the extra work to create a running engine. The majority of the parts will be made from aluminum with 1144 steel for the cranshaft, W-1 drill rod for the camshaft, and 932 bronze for bearings.
The drawings will be done in Autocad in 8-1/2 x 11 format. (Approximately A4 size) and will include drawings for a water pump, radiator, plumbing, fan and brackets.
 I have the crankcase drawings complete and hope to have the remaining drawings finished by at least late summer. (August-September)
 So for those of you who would like to build a Holt, hang in there for awhile.
gbritnell


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## gbritnell (May 7, 2019)

I was asked to post some pictures of the engine.


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## aonemarine (May 7, 2019)

PM sent


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## chrisscuttingz (May 8, 2019)

i have castings and drawings for this engine,
I am very curious as to what you produce and would be quite interested


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## aka9950202 (May 9, 2019)

I would like to built on of those engines someday soon. The question i have is can it be made using a Seig 7x10 lathe? I do have a small mill as well.

Could i produce my own casings insread of hogging out bar stock.

Cheers , 
Andrew in Melbourne


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## Rod Cole (May 9, 2019)

George, when ready I'll order a set~!!!
                  Rod


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## gbritnell (May 10, 2019)

HI Andrew,
The crankshaft would be a little over the capacity of a 7 x 10 but I certainly can't judge what some people are capable of.
gbritnell


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## dnalot (May 10, 2019)

I will be ordering a set for sure. I am reserving next Winter for the project.

Mark T


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## CFLBob (May 10, 2019)

This could be a big revision to my plans for the next year!   

Sign me up for updates so that I know when they're available.


Bob


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## kadora (May 12, 2019)

Hello gbritnell
Could you please send detail picture of Holt engine water pump?
Thank you


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## DavidLloyd2 (May 12, 2019)

George,
               I will order one set of drawings for this engine for sure.

DavidLloyd


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## CFLBob (May 13, 2019)

George,  I meant to ask you a question.  

One of the reasons I got the idea to build the Holt 75 was from seeing one at Cabin Fever back in 2015.  In fact, I took a video and a photo, which doesn't show it very well.

I can track down that your POTM for the engine was before this.   My question is if this is yours?  







That would be  a remarkable "it's a small world story".


Bob


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## gbritnell (May 13, 2019)

Yes, that's my engine.
gbritnell


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## olympic (May 14, 2019)

"So for those of you who would like to build a Holt, hang in there for awhile.
gbritnell"

Hanging in....


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## G54AUST (Jun 24, 2019)

Hey George.

          Very interested in purchasing a set of plans for the Holt.

          Please place my name on the "gunnah buy" list.

          Stand by for PM.


Kind Regards,


Trevor,
Melbourne,  AU.


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## gbritnell (Jun 24, 2019)

As an update to this thread I have finished the drawings for my engine. I say my engine because of the many changes and modifications that have been done to the original. Bad weather in this part of the country, and other things, allowed me more time at the computer. 
Please contact me at: [email protected] for further information.
Thank you,
gbritnell


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## dnalot (Jun 24, 2019)

Hi

I purchased a set of drawings from George a week ago. They are nicely done and I am looking forward to getting started on the project this fall.  I think there are going to be a lot of little Holt's before long. 

Mark


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## dnalot (Jun 24, 2019)

Hi

I have my fingers crossed that Aonemarine will be casting intake and exhaust manifolds. 

Mark


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## aonemarine (Jun 24, 2019)

dnalot said:


> Hi
> 
> I have my fingers crossed that Aonemarine will be casting intake and exhaust manifolds.
> 
> Mark



  Something told me that those would be the most wanted castings, and likely the hardest ones to cast.  Ill have to grab a set of drawings from George just to verify the measurements to the originals before getting started.
   I probably wont be able to get started on them until September due to my current work load though.....


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## JRR (Jun 24, 2019)

G’ Day George
I am also interested in purchasing a set of drawings for the Holt. Please add my name to the “gunner buy” list.
Regards 
John 
Bannockburn Vic Australia


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## gbritnell (Jun 25, 2019)

The manifolds on my Holt were purchased from the seller when I bought the original drawing set. When I made my drawings I drew up the manifolds to be a fabrication from either steel or brass. The design of the originals are very curvy and almost impossible to duplicate without using CNC, drilling and plugging. When I built my 300 six engine I made the manifolds as a fabrication from steel and silver soldered the parts together. They turned out very nicely. There is a build thread on it. The bottom line is that my manifolds aren't the same curvy shape as the originals. A drawing would have to be made to copy the originals and I don't want to go there. If someone else wants to be my guest.
gbritnell


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## Jack3M (Jun 25, 2019)

I am also interested in set of drawings.  Will you be offering them in digital format?  I use Fusion360 so it should be compatible with Autocad.


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## gbritnell (Jun 26, 2019)

Hi Jack,
I supply them as PDF files. 8-1/2 x 11 format. I would prefer not to supply my original drawings. I do have some of the parts modeled in an early version of Solidworks that I have supplied to several fellows who want to use CNC to build it. I can do that. 
gbritnell


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## MOTOXFAMILY (Jun 26, 2019)

I would be interested in the solidworks files as well as the pdf files. Great build. I do have a small cnc.
 Thanks,
Ron


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## Jack3M (Jun 26, 2019)

So how much for a PDF plan set?


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## chrisscuttingz (Jun 26, 2019)

from what i can tell these plans are looking nice,  I will be modeling this in fusion 360 so any solidworks parts will help me.
I love to model almost as much as i do machining.lol


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## gbritnell (Jun 26, 2019)

I don't like to get into prices and particulars on the forum so please contact met at: [email protected] for more information.
Thanks,
gbritnell


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## Jack3M (Jun 28, 2019)

Very pleased with the drawings, worth his price, especially after paying an unnamed British company twice as much for garbage drawings for a traction engine


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## bobden72 (Jun 29, 2019)

I will also say "gbritnell" Holt engine drawings are very good and well worth it.


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