Old tractors; low compression

Does one assume that antique tractors are considered low compression.
I never thought about it, but this question was asked of me and a couple of other guys at the local county fair.
I personally have CASE SC and DC. We concluded that they are low compression. Newer ones high. .??

I'm not sure what you mean. Case had both low and high compression heads for the S and D series. I have two Sc's. One has gasoline manifold and high compression head. The other one has fuel burner manifold and low compression head.

A lot of the tractors built in the 40s or 50s had about a 6 to one compression ratio. Ben

Farmall M and H for kerosene had 4.4 to 1 compression ratios, distallate 4.6 to 1 and gasoline (after 1940) about 5.6 to 1

Define 'antique'.
Define 'low compression'

What can be said is that newer tractors have progressively higher compression.

JD Ds initially had a 3 to 1 compression ratio. That is the lowest ratio I am aware of on a tractor.

Yes, most old tractors have low compression. Especially by today's standards. Many were under 100#. Would not be able to use the hand crank if much higher than that. I have seen Moline have a gear reduction on the hand crank on some of the later U so they could be hand cranked. At maybe 120#, that is still not high compression. Early "high compression " heads were up a bit from the standard gas head but still nothing impressive or that required high octane fuel.

Compared to car engines old gas tractors and industrial engines were low compression so yes I would say old gas tractors had low compression engines.

I consider high compression to be over 10-1, probably requiring premium fuel, now with fuel injection there are some exceptions. Most old tractors are way below that.

If you want to dig into this deeper, you can find out the various compression ratios on tractors from the Nebraska Tractor Test results and on Tractordata. Simply do an internet search for something such as, "M Farmall." I just did that search for a 4020 John Deere. On Tractordata you will need to click onto "engine" and it should show the specifications on the various engines. A 4020 gas tractor has a compression ratio, according to this source, of 7.5 to 1. I tried Tratordata on the 806 Farmall and it only showed the compression ratio on a diesel tractor. I then did a search by typing in "Nebraska Tractor Test for 806 Farmall." It showed the compression ratio to be 7.7 to 1. I went further and looked at the 4020 LP tractor, which showed a compression ratio of 9 to 1. I know the 2 cylinder Deere tractors and probably everything built from the mid-1950's and earlier had lower compression, especially anything designed to burn kerosene or distillate. As gasoline became more popular, the compression ratios starting gradually increasing. I believe the late 1950's and well into the 1960's, is when the compression ratios probably peaked out and lower octane fuels started becoming more mainstream, while high octane fuels were increasingly scarce, as well as costly. My grandfather purchased one of the first 806 Farmalls in our area. It was gasoline powered and was rated to operate on a minimum of 93 octane gasoline. Tetraethyl lead was an octane improver, but as the lead content of fuels diminished, and ultimately no longer available, octane ratings dropped, and these higher compression and higher performance engines (just like in the muscle car era) wouldn't run on these lesser quality fuels. My father and grandfather had to buy premium gasoline in those final years the 806 was on the farm in order for that 806 to run and perform properly. Today, 87 octane is mainstream fuel, and 91 octane is the premium fuel with a cost of around 60 cents a gallon more. The Tractor Vet on the IH forum has commented about the gasoline made today versus the 1960's when tractors, such as the 806, were new and being used for all jobs, including hard pulling work. I have read some comments as to the fuels available back then, particularly the various grades of gasoline produced by Sunoco. I did some on-line investigation and one can purchase Sunoco branded fuels with octane rating exceeding 100. They are available and marketed as racing fuel, but there are multiple grades available. Sorry for going off track. I guess once I got going on this topic, I went further along with it.