M&W 4.125 AP-46 pistons
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Category: Allis Chalmers
Forum Name: Farm Equipment
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=12356
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Topic: M&W 4.125 AP-46 pistons
Posted By: Unstylish
Subject: M&W 4.125 AP-46 pistons
Date Posted: 12 May 2010 at 5:55pm
I just picked up an almost new set of AP46's and sleeves that were in a WD in the junkyard. What are the specs, especially the compression distance? Looking at putting them in an offset grind combo, so height matters..thanks..
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The problem with reading MLPANKEYS posts, is that they dont make boots that tall.
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Replies:
Posted By: CTuckerNWIL
Date Posted: 12 May 2010 at 7:04pm
The stroke, rod length and piston height from wrist pin to top are all numbers to take into consideration. If you have the pistons you can measure from the wrist pin center to the top of the piston.
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Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF
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Posted By: DrAllis
Date Posted: 12 May 2010 at 7:14pm
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If they are SP-46's, combine them with a 4 1/2 stroke crankshaft (WD45 or D17) they will need .170" or so removed from the tops to keep from hitting the cylinder head. This is a nice set-up and will require real good gasoline (like 100 octane or better). Compression pressure while cranking with the starter should be around 240 psi.
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Posted By: DrAllis
Date Posted: 12 May 2010 at 7:32pm
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Ignition timing will also have to be backed down to around 15 to 20 degrees BTDC (instead of 25 to 30 degrees BTDC) and should be adjusted on a dynomometer for best results.
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Posted By: Unstylish
Date Posted: 13 May 2010 at 6:26am
Thats roughly what I needed to know..thanks!
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The problem with reading MLPANKEYS posts, is that they dont make boots that tall.
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Posted By: ALinIL
Date Posted: 13 May 2010 at 11:27am
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Question for DrAllis. What is the difference between a AP-46 and a SP-48? Reason as I just removed a set of SP-48's from a WC? - AL
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Posted By: DrAllis
Date Posted: 13 May 2010 at 12:29pm
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I really don't know....I KNOW what SP-46's are.....AP-46 is a newer?? version or is it a typo?? ("S"and "A" are next to each other)
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Posted By: Larry(OH)
Date Posted: 16 May 2010 at 9:47am
I haev a piston showing where you need to fly cut for clearance with this setup (long story):( It definately cranked hard
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