[AT] The way they sound

[Dean VP]

Dean,

The duplex carburetor did solve a minor issue that the letter series had and that was  since the
letter series had only a single barrel carburetor one cylinder did not quite get the same dose of
gas/air mixture that the other one did.  Primarily due to the firing sequence of the two cylinder
tractors. The firing sequence is not even on a JD Two Cylinder Engine.  That is what gives it such a
unique sound and why a very heavy flywheel is required on JD Two Cylinder engines.  The duplex
carburetor allowed setting each cylinder for optimum operation.  If I remember right the duplex
carburetor alone added 2 to 3 HP to the same engine that the A had when it  was used on the 60 with
duplex carburetion.    An interesting, but not well known, fact is the early 50 and 60 "All Fuel"
tractors stayed with the single barrel carburetor and manifold setup while the new 50 & 60 gas
tractors had the duplex carburetion and manifold setup.  I don't think I have ever seen an explanation
for why JD did it that way by any author. Therefore, I can only speculate that JD didn't have the
engineering/manufacturing resources to make both changers at the same time.  The duplex carburetion
set up for "All Fuel" Tractors came much later than the Gas versions.  I suppose there may have been
some doubt at JD whether there would be adequate demand for "All Fuel" 50 and 60's to justify the cost
of the conversion.  In either case JD did eventually offer duplex carburetion "All Fuel" tractors at a
later date.  

My guess would be that it would take a trained ear at an unusually low idle RPM to pick up the
distinctive sound difference between a single vs Duplex carburetion.  A very large part of the
distinctive sound from a JD Two Cylinder engine comes from the unusual firing sequence.  For those of
us in our more senior years we are just happy to hear anything at all. :-) 


Dean VP
Snohomish, WA

They say necessity is the mother of invention. 
Don't know who the father is, probably remorse.
Red Green

-----Original Message-----
From: at-bounces at lists.antique-tractor.com [mailto:at-bounces at lists.antique-tractor.com] On Behalf Of
Dean Vinson
Sent: Friday, August 01, 2014 5:13 AM
To: 'Antique tractor email discussion group'
Subject: Re: [AT] The way they sound

Dean VP wrote:

> It is obvious that you are delusional and need to spend more
>  time on the 620!  :-) Maybe a visit to a Counselor would help!  :-) 

Dean, you may be right.  I'll be sure to spend more time on the 620, likely
beginning today!    Of course, an off-list friend of mine advises me that
the duplex-carburetion 620 just doesn't have the musical beat of his 1950 A,
so perhaps I need to spend time on one of those also.

Ralph Goff wrote:

>  from what little I have heard those Olivers sound plenty smooth
> too. Of course I am also a bit biased toward the Buda six cylinders
> in my Cockshutts... https://www.youtube.com/watch?v=BuqkgJUVGKM

Ralph, no argument at all about the Buda sixes, and I've always admired
Cockshutt and that classic styling of the 20, 30, and 40 series tractors.
By the way, that's a very nice looking radiator shroud on your 40 in that
video.  :)

John Hall wrote:

> I think it is time for you to upgrade to a 4020 diesel

John, the 4020 has a permanent spot on my "someday" list, no doubt.  It's
become a running joke with my fiancee:   Whenever she mentions some chore
she needs to do, I say something like "That'd be an excellent job for a John
Deere 4020 with the [tulip planting attachment] [steam cleaning attachment]
[weed-pulling attachment] [etc]."

Dean Vinson
Saint Paris, Ohio

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