Model Engine Maker

General Category => Chatterbox => Topic started by: gbritnell on May 07, 2019, 02:17:41 PM

Title: Holt from bar stock
Post by: gbritnell on May 07, 2019, 02:17:41 PM
 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.

Title: Re: Holt from bar stock
Post by: b.lindsey on May 07, 2019, 02:49:53 PM
Will be looking forward to it George. Do you have a picture of your original engine that you could add to this thread?

Title: Re: Holt from bar stock
Post by: fumopuc on May 07, 2019, 04:15:46 PM
Hi George,
I am very much interested to build this engine, latest after my retirement end of next year.
Title: Re: Holt from bar stock
Post by: gbritnell on May 07, 2019, 06:16:27 PM
Hi Achim,
I will keep everyone posted on the progress of the drawings.
Title: Re: Holt from bar stock
Post by: jeff l on May 08, 2019, 03:19:40 AM
Hi George , I'm interested in this built for sure .Jeff
Title: Re: Holt from bar stock
Post by: michelko on May 08, 2019, 12:06:39 PM
Hi George, i am also very interested in this engine and the plans.
One Question, from what material is the dizzy cap?
I like that red/brown appearance. I didn t find such plastik for my
Bugatti / seal dizzys.
Regards Michael