Farm Stock Engine Question January 30, 2020 03:58AM
Building a 'farm stock' tractor. Tractor is red but question is theorhetical.

Here are the rules:
466 cubic inch limit
3LM-466 box turbo
10 MM A, 450 Roosa, 13 MM Bosch
No Speed Limit
20.8 or 24.5 uncut

What is the best bore and stroke combo for this type of set up? Bigger bore so as to not shroud the valves? Longer stroke for more torque? Square engine? Would love some opinions, and personal experiences. Thank you
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Re: Farm Stock Engine Question January 30, 2020 04:06AM
4.3x5.35 is the best choice for that particular application
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Re: Farm Stock Engine Question January 30, 2020 04:20AM
Yes, I am sorry, 3000 RPM limit.

Feel like I need torque and the ability to lug because its hard to get the tires singing. Usually run in High 3rd (IH) 18ish MPH, but need more lugging power to finish run and spin out.
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Re: Farm Stock Engine Question January 30, 2020 04:17AM
Is there an RPM limit?
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Re: Farm Stock Engine Question January 30, 2020 05:31AM
Bosch in-line 13 mm is what you need.
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Re: Farm Stock Engine Question January 30, 2020 05:40AM
there is no such thing as a farm stock class anymore. Its more like a hot farm class, gone are the good old days where kids could bring dads tractor to the county fair and have some fun.
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Re: Farm Stock Engine Question January 30, 2020 08:05AM
Its just for a local brush group.

I guess I'm just more looking for info on whether a larger bore and smaller stroke would be better for this type of class or a longer stroke and smaller bore.

I am new to this and learning how it all works so was just hoping to get some insight on which way to go.
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Re: Farm Stock Engine Question January 30, 2020 11:39AM
The subject of bore versus stroke relationship to horsepower and torque has been debated for years with no consensus of opinion. There was an article in Hot Rod years ago on a NA gasoline V8, where they compared an over square engine and an under square engine with the same valves, heads, carburation etc. It made no difference in torque or horsepower.

I would suggest doing what makes sense to you and the engine you have, make sure the valves are not shrouded and the crank is stout.

Rich
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Re: Farm Stock Engine Question January 30, 2020 03:29PM
Thanks Rich!

Is there a specific clearance that one would want to maintain to ensure the valves were not shrouded and able to have full flow?

Someone told me anything less than 0.125" is limiting flow?? Valves come straight down so clearance is the same at any lift.
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Re: Farm Stock Engine Question February 02, 2020 12:28AM
Would be interested to know what the clearance between valve and cylinder wall need to be to maximize flow as well.
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Re: Farm Stock Engine Question February 02, 2020 03:12AM
Run as big of valves as you can that will clear each other and the cylinders walls. Ideally put your intake valves in the center of the cylinder however we all know this is not practical. Go big and use common sense. If it clears it's good to go.
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Re: Farm Stock Engine Question January 30, 2020 09:30AM
Quote
old case guy
there is no such thing as a farm stock class anymore. Its more like a hot farm class, gone are the good old days where kids could bring dads tractor to the county fair and have some fun.

In line with your point, I saw a "farm stock" tractor listed for 10K more than a Brian Patton's hot farm tractor...


John Murray
Two-time Pedal Pull World Champion

Let's Go Pulling, covering the sport of pulling in Kentucky, Tennessee, and Alabama.
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Re: Farm Stock Engine Question January 30, 2020 07:35AM
Where is this class it sounds pretty interesting
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Re: Farm Stock Engine Question January 31, 2020 01:34AM
Litteraly everywhere in the upper midwest lol
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Re: Farm Stock Engine Question February 02, 2020 06:16AM
I agree with you "old case guy". I miss those days also. Many different names for many different classes, hard to understand the name "farm stock". Unfortunately the last farm stock that we put out was about 500 hp and pulled road gear in 9000 lb class. Advice to 1456, if your looking to build a high power engine, unless you're running 14,000 pounds, you're going to need faster than third gear. And no matter what the stock third gear won't be strong enough and you'll need a lower shaft support or get heavier gears
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