ap 46 pistons
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Category: Other Topics
Forum Name: Pulling Forum
Forum Description: Forum dedicated to Tractor and Garden Pulling
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=136671
Printed Date: 24 Nov 2024 at 2:17am
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Topic: ap 46 pistons
Posted By: jvin44
Subject: ap 46 pistons
Date Posted: 27 Mar 2017 at 8:40am
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Anyone know off hand hiw much to take off tops of ap46 pistons to put in a wd45 engine looking for around 11.5 to 1 compression
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Replies:
Posted By: mattb
Date Posted: 27 Mar 2017 at 8:51am
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Im thinking we took .100 off the set I did in my friends tractor came out to 11.5 to one when I figured it. Havent ran a compression test on it yet.
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Posted By: Big Orange
Date Posted: 13 Apr 2017 at 11:21am
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.250 will get you about 10.3:1, that's as hi as I would go with stock cam, & very hi octane gas, at stock 30 degree spark timing, + hi output coil & electronic mod.
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Posted By: Big Orange
Date Posted: 29 Apr 2017 at 2:53pm
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That's with Sp 46 M&W kit .
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Posted By: jvin44
Date Posted: 29 Apr 2017 at 2:56pm
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If u take .250 off u mights well not use the pistons might as well use 45 pistons. So im not sure
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Posted By: DrAllis
Date Posted: 29 Apr 2017 at 5:20pm
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Look, there are a dozen different piston molds. What you want to do is remove the minimum amount from the piston top just so it doesn't hit the cylinder head. Assuming it has a POWER CRATER bowl design, make the piston top flush with the top of the sleeve and then the head gasket will give you about .060" running clearance. THE COMPRESSION WILL BE WHATEVER IT WILL BE DEPENDING ON THE BOWL VOLUME. Years ago, I removed .170" from the outer edge of the piston tops on a set of M&W SP46 pistons. It had 240 psi of cranking compression and ran well with 103 octane fuel. Ignition timing will probably be around 25 degree BTDC at full throttle, but dyno tuning is the best. Cold spark plugs like AC Delco 43's is what I always use.
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