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Harry Ferguson Tractors Discussion Forum
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overbore question

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overunder1

12-24-2006 08:58:50




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Interesting threads on rebuilding the last couple of days. If one is going to tear a Z129 down and freshen it up just how large an overbore kit can one install? Z129/Z134/ larger? without having to seriously modify the block. It would seem that there may be a few extra horepower available going this route. -Lee
1954 TO30




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Dan S (NY)

12-27-2006 09:23:52




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 Re: overbore question in reply to overunder1, 12-24-2006 08:58:50  

Engine			Bore			Stroke			Displacement Z120   Original		3 3/16	(3.1875)	3 3/4	(3.75)		119.7ci       Overbore Kit	3 5/16	(3.3125)	3 3/4	(3.75)		129.27ci
Z129	Original	3 1/4  	(3.25)		3 7/8 	(3.875)		128.58ci
	Overbore Kit	3 3/8  	(3.375)		3 7/8 	(3.875)		138.67ci
Z134	Original	3 5/16 	(3.3125)      	3 7/8 	(3.875)		133.58ci
	Overbore Kit	3 3/8 	(3.375)		3 7/8 	(3.875)		138.67ci
Z145	Original	3 3/8	(3.375)		4 1/16	(4.062)		145.36ci

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Dan S (NY)

12-27-2006 09:25:46




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 Re: overbore question in reply to Dan S (NY), 12-27-2006 09:23:52  
Well, the formating on the chart didn't take...oh well.



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ron tepoel

12-24-2006 20:32:33




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 Re: overbore question in reply to overunder1, 12-24-2006 08:58:50  
big bore kits are/were available.
Crank stroke is not interchangeable easy.

extra bore can be a had with dodge or other pistons
bigger valves a big plus for to-20



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Sam from WA

12-24-2006 17:29:48




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 Re: overbore question in reply to overunder1, 12-24-2006 08:58:50  
Some of the displacement is length of stroke. depending on how large you want the bore, you may not gain a whole lot. if you change bore size, most times, you have to get new pistons and all.



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Gerald J.

12-24-2006 10:58:09




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 Re: overbore question in reply to overunder1, 12-24-2006 08:58:50  
Part of the larger displacement is a longer stroke for the Z-145. A 1998 CT catalog only shows increased bore kits for TO 20 and TO 30 with Continental engines. For TO20 increases bore from 3-3/16" to 3-5/16". Claims up to 4.2 hp gain. Increases displacement 7.9%. For TO-30 increases bore from 3-1/4" to 3-3/8" which increases displacement 7.8%. 7.8% of 30 hp is 2.4 hp at best unless the pistons also increase the compression ratio, there's not that much help for crankshaft torque beyond just fixing a leaky old engine.

Gerald J.

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