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70 head

A

Anonymous-0

Well-known Member
I have had a few people inquire about a FLAT HEAD for the JD 70. Just asking for feedback as to how many people would actually be interested in such a part. Depending on interest I would possibly consider such a project. Please send an email to me regarding such.
Thanks
Jeff
Murphys Motor Service
 
I assume that the design would be very similar to your G head? Thick deck, big runners, big valves, similar price?

What about a short block for the 70 with a 7 inch bore? That would be nice.
 
Won't one of these work. I'm certain Murphy's would drill the block for a 70 cylinder head pattern.
I'm looking at a Murphy 7" bore 70 on LP with some stroke for the next project.
Those Murphy A rods with the offset bolts look like the ones to use. Kind of wish they could be had in factory G/70 dia but that does worsen clearance issues.

http://www.murphysmotorservice.com/JD_2Cyl_Performance.htm#John Deere “G” blocks:
 
I believe that the G blocks are quite a bit longer than the 70 block. Would be easy to tell that the wrong block is in there. Would be tight to get the valve cover off. Would need a custom exhaust pipe too.
 
Jeff, I don't think there would be much business here. The 70 weighs quite a bit more than the G and all the pulls I've been to your lucky to see even one JD 70 there.
I think you would do better offering your bigger blocks with a JD 70 block base pattern. That way you could use the same head and customers would get a longer block for better rod ratio.
If they are serious about pulling they need a much bigger engine before they need a different head.
 
IF I were to build such a head it would have larger runners, bigger valves, and a thicker deck. Designed much like my G head. Yes the G & 70 share the same crankcase to block bolt pattern. The 70 ALL FUEL shares the same 9 head bolt pattern as a G. The 70 gas has a different 10 bolt pattern. If we know ahead of time when machining blocks we can drill the 10 bolt 70 gas pattern in my block. We also drill an oil passage to feed oil to the head/rocker arms in a "70" type block that the G block does not get. The problem with a 70 length block is you run out of room for stroke, compared to my G block. 70 gas blocks are 10.187 long, Styled G blocks are 11.56 long, and my UnStyled G type block is 12.56 long.
Jeff Asbury
 
Jeff, I wasn't sure on the block pattern but with difference in lengths you think it would be a no brainer.
As for the head, would it have independent runners all the way to the duplex carb? I believe this would increase velocity a ton as long as the runners were not to large. We have to keep in mind these tractors were designed to run full load or wide open throttle at about 1100 rpm. Wave pulses slow down dramaticaly with runners to large and do not fill cylinders the way they can and should.
 
I for one would be interested and I am sure others would be as well, the 70 is a more economical (not that economy and pulling ever go together) entry level choice than the more sought after G for some people(probably why I have one). The quench style head would open up alot more possibilities though! Just my opinion and we all know what that is worth.
 
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