351m Crankswap?
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Elder User
Joined: Apr 2010
Posts: 518
Likes: 0
From: Mount pleasant, michigan
I did try a search but there wasnt anything that was real close. So i dont have a garage where i can pull the motor out, ive changed the oil pan gasket before in it, so is it as easy as unbolt the rod caps and mains and drop the 351m crank, and then bolt in the 400 crank and its good to go? or do i need to swap anything else?
Hotshot
Joined: Feb 2004
Posts: 11,697
Likes: 3
From: Marengo, Iowa
You will have to pull the engine, you can't get the flywheel/flexplate out without splitting the engine from the trans. I believe you also need to change the pistons, as since the stroke is different, so is the pin center. If not the piston, then the rod.
Senior User
Joined: Aug 2007
Posts: 115
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400m pistons have same comp.height as 351 cleveland but they run the same rods .So make your 351m a 400 find your 400 crank stock rods w/351c pistons but I think the wrist pin is differant . You can probably get a crank threw your local parts store I sure Auto Zone carry's them and I've found piston and ring sets on ebay for around 150
Lead Driver
Joined: Mar 2004
Posts: 8,922
Likes: 153
TMI sells zero deck 400 pistons, The rods are the same but I'd get them resized with new bolts.
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Laughing Gas
Joined: Feb 2004
Posts: 1,013
Likes: 2
as some have already said you must use 400 pistons.rods are same.i have made both 351m and 400 through the years.
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Junior User
Joined: May 2010
Posts: 98
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From: Kentucky
The blocks and rods are the same. The only significant diffs are the crank and pistons. If you use clevland pistons, then you must have the rods resized for the larger wrist pin. Hope this helps.
New User
Joined: Jun 2010
Posts: 12
Likes: 0
The piston diameter is the same, but the piston height is different. The 351m uses the rods from a 400, but a 351c crank. The 400 block has increased deck height that the piston compensates for. The 400 gets it higher compression from a longer stroke. Basically the 351m is a de-stroked 400, hence the different crank, and taller piston. I believe the difference is somewhere about .31 ...I have all my notes about the build to a 400 from a 351m , will post them tomorrow when I get to work. You can change the crank and pistons and the engine will run...but it is recommended that you change the cam as well for the proper performance that the engine is capable of giving.
Regards,
Will R. Everett, WA.
Regards,
Will R. Everett, WA.