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ap 46 pistons |
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jvin44
Silver Level Joined: 04 Mar 2015 Location: Elsie, MI Points: 53 |
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Posted: 27 Mar 2017 at 8:40am |
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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mattb
Orange Level Joined: 11 Jan 2011 Points: 348 |
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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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Big Orange
Silver Level Joined: 11 Sep 2009 Points: 313 |
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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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Big Orange
Silver Level Joined: 11 Sep 2009 Points: 313 |
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That's with Sp 46 M&W kit .
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jvin44
Silver Level Joined: 04 Mar 2015 Location: Elsie, MI Points: 53 |
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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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DrAllis
Orange Level Access Joined: 12 Sep 2009 Points: 20548 |
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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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