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Boring and Stroking a Hand Start JD A???

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pat

11-16-2002 13:18:14




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Hello out there!

I have a '39 h/s A that I would like to bore out to 5.875 and stroke to 7.25. I would like to get about 9 or 10:1 comp.

My big question is: will I still be able to start it by hand or should I build up one of my E/S A's.




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lynn

11-17-2002 09:17:49




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 Re: Boring and Stroking a Hand Start JD A??? in reply to pat, 11-16-2002 13:18:14  
pat..one thing to do is stop the top ring at the bottom of the spark plug hole..if you are careful you can drill out the petcocks or some parts stores have some drain valves..did two 38s last winter..one had 8 inches of stroke and the other had 7 1/2..used 329 rods..on the 7 1/2 machined rod cap down where top bolt goes in and ground off top of rod bolt and everything cleared..no grinding in tractor..8 inch had to do some grinding in case..lynn

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pat

11-17-2002 10:05:50




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 Re: Re: Boring and Stroking a Hand Start JD A??? in reply to lynn, 11-17-2002 09:17:49  
Lynn,
Good idea about drilling the petcocks. Who did your stroking work?



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lynn

11-17-2002 15:11:43




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 Re: Re: Re: Boring and Stroking a Hand Start JD A??? in reply to pat, 11-17-2002 10:05:50  
pat..merfeld did one and had one done at local machine shop..they usually charge about the same for any stroke so you can put in as much as you want to work on it..my a has 5.875 and 8.375 with 9.5:1 and i hand crank it..everthing is right and it starts pretty good..lynn



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Jim F.

11-16-2002 15:46:16




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 Re: Boring and Stroking a Hand Start JD A??? in reply to pat, 11-16-2002 13:18:14  
Build the hand-start. I had one that was 5.625" x 8.25" with 10.5:1 compression. You will need large petcocks. It will start... sometimes though they can be a b!@ch when they are warm to start.



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pat

11-16-2002 17:57:45




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 Re: Re: Boring and Stroking a Hand Start JD A??? in reply to Jim F., 11-16-2002 15:46:16  
Jim,
Thanks for the info-how strong was yours, and where do you get the large petcocks?



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Jim F.

11-17-2002 05:04:52




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 Re: Re: Re: Boring and Stroking a Hand Start JD A??? in reply to pat, 11-16-2002 17:57:45  
Mine ran fairly well. Put it together in 1996, I had alot of fun on that machine and the first few years was top dog but you have to keep up with the "Jones'"!!!

I had alot of other things done to mine, it moved quite a bit of air but it was a small A, Horse Power was, well up there... The tractor now is put back with a stock crankshaft... Don't worry it will be back!

If you are going to run high compression... watch your journal size, keep it as big as possible and keep the radius on the rod journals as big as possible. That is were mine failed. And the tractor literally exploded!!! Once you have the cubes were you want them, air flow... not too big! Carb work, good spark and timing, timing, timing!!!

As far as the large petcocks... they used to be advertised in the Hook but I have not seen them for a while, they are like a steam valve.

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pat

11-17-2002 07:17:27




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 Re: Re: Re: Re: Boring and Stroking a Hand Start JD A??? in reply to Jim F., 11-17-2002 05:04:52  
Thanks for the info, about the rod journal. I was thinking if offset grinding for the "b" rod to gain the stroke (I guess that would only be about 7" though would'nt it), but now i don't know. Who do you recommend for stroke work, there is no on around here that has even seen a crank like the A has. I hate to spend gobs of money on stroking, because we have speed limits, and stock tractor can still be very competitive around here--but i just hate leaving good enough alone AND I just like the way they sound!
Thanks Again,Pat

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CASEPOWER

11-16-2002 15:33:51




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 Re: Boring and Stroking a Hand Start JD A??? in reply to pat, 11-16-2002 13:18:14  
I don't know about a 2 cyl. but my 4 cyl. is a bi*ch to start. I would say No build the electric start. I am changing blocks so I can go that way. You will find it is easier to pull start than where yourself out.



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