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Old 10-26-2003, 03:30 PM   #1 (permalink)
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351M / 400 Crank Swap

I read in one of the ford muscle article about taking a 400 crank and putting it into a 351M. Is this really just converting to a 400? Do I need to use the 400 rods with the swap or re-use the 351M rods? What if any other mods should I do to get the max grunt out of the 351M? My use for the motor is in a stock racing class on a oval track. The motor currently twists about 5,000 rpm's. Any help that i could get on stroking and grunting this 351M would be greatly appreciated.
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Old 12-01-2003, 12:48 AM   #2 (permalink)
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351M / 400 Crank Swap

Well, basically you'd be just converting it into a 400. I think it would be more simple and less costly to just get a complete 400 and bolt it in.
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Old 02-13-2004, 04:28 PM   #3 (permalink)
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351M / 400 Crank Swap

Hi.. You need a 400 crank & 400 pistons.. you can use your 351 rods.. All else is the same >>>Jim>>>>fordsemi
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Old 04-16-2004, 11:40 AM   #4 (permalink)
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351M / 400 Crank Swap

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Old 04-16-2004, 11:52 AM   #5 (permalink)
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351M / 400 Crank Swap

What you need to do is I take it you are talking about a 351 windsor block? If so get a 400 midi crank, get the main bearing journals ground to the same size as the windsor crank. Then grind the webs down so as to get the crank to physically fit into the block and rotate. You will have to re-balance the crankshaft with mallory metal or "heavy metal" to off set the weight you have removed. (Still with me) You can then use 6 inch Carillo or similar chev con rods and increase the bore size to 4 and 1/8th (or 4 and a 1/4 if you can get a SVO block.) This will give you a very srong torquey donk the will be between 383 cubes and 454 cubes depending on bore size. And believe me this is a gem of an idea for cheap horse power and more importantly torque. Don't muck around with anything else just do this and you'll think all your Christmas's have come at once!
CheeRS, Skid.
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Old 01-16-2005, 04:45 PM   #6 (permalink)
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351M / 400 Crank Swap

Basically the 351M is a 400 with a 351 W crank
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Old 01-17-2005, 12:52 AM   #7 (permalink)
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351M / 400 Crank Swap

Bless you Skid!


Good eye der, converting a 351m into a 400, if they check the casting numbers they will know right away, but if they don't you'll have a mule in horse's game and we all know that mules out work horses. Now get out there and kick some butt!

Increasing the bore size will make about 408 cubic inches, you shouldn't have anyproblems with the 2V heads to make 400 hores and 400 plus foot pounds of torque. The 5000 rpm range is perfect for the 400 cube Modified block and crank.

Make sure your gearing is right, and that you get a good ignition aftermark if possible. The 650 cfm holley work well on this combination. Edelbrocks website shows the 400m with good numbers in the 330-350 hp range with 385 foot pounds of torque. Just make a good cam selection. Call the boys at Cam research, they can set you up with a good cam.

Mac

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Old 01-22-2005, 10:59 PM   #8 (permalink)
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351M / 400 Crank Swap

i am grinding a 351M crank to fit in a W351 4 bolt block. Cutting .125 off throws to clear lower cylinder walls. block will be 4.125 bore. planning on being a 454 small block. if it runs good will ad a T76 garrett turbo. going in 95 stang/ Pony hasn't run in awhile hope to make it get up and go

a 351M is a 400,the 351W crank has a 3.500 stroke the 400/351M is 4.000 stroke 351M stroke is 1/2 inch longer than a 351W mains and rod journals are the same 2.310 on the rods and 3.000 on the mains

cut .200 of counter weights 351M crank will fit in 351W block w/ a little grinding on block besides clearancing for the rods. just finished grinding one last night and tried it out in the block turns good/ now got to fit everything. find got to find the right rod for the extra 1/2 inch stroke

<font size=-1>[ This Message was edited by: crankshaft on 1/25/05 7:28am ]</font>
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Old 01-23-2005, 10:34 PM   #9 (permalink)
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351M / 400 Crank Swap

Don't think you can offset grind a 351M crank to a 4.24 stroke.
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Old 01-24-2005, 09:35 PM   #10 (permalink)
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351M / 400 Crank Swap

Quote:
On 2005-01-22 21:59, crankshaft wrote:
a 351M is a 400,the 351W crank has a 3.500 stroke the 400/351M is 4.000 stroke 351M stroke is 1/2 inch longer than a 351W mains and rod journals are the same 2.310 on the rods and 3.000 on the mains
If I read that right, you are saying that the 351M and 400 are both 4.000" stroke, correct? WRONG. 351M 3.5" stroke. 400 4.000" stroke, both use 4.002" bore but the 400 uses different pistons...same rods as 351M (6.58&amp;quot

the 351W and 351M have exactly the same bore/stroke dimensions. The W has shorter rods and a much shorter deck (9.5" vs. 10.22&amp;quot The main journals are both 3" dia.

Also, if you are using a 351M crank in a 351W block, it will be 363 cubic inches. Use a 400 (4.000" stroke) crank and it'll be 415". I don't think I'd trust a ground-down cast crank in a turbocharged motor. Been there, done that....learned a few expensive lessons along the way!

<font size=-1>[ This Message was edited by: mavman on 1/25/05 8:37am ]</font>

<font size=-1>[ This Message was edited by: mavman on 1/25/05 8:40am ]</font>
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Old 01-25-2005, 01:16 AM   #11 (permalink)
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351M / 400 Crank Swap

Yep - you can grind a perfect 400 crank offset by .12 if going down to a 2.1 rod journal. Not a 351M crank. Sounds like a call for custom rod with a mondo length. Good luck with that. You must have your own equipment because normal folks can't afford to balance a thing like that.
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Old 01-28-2005, 10:23 PM   #12 (permalink)
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351M / 400 Crank Swap

oops i stand corrected on the 351M you are right it is a 3.5 stroke miss read my federal moguel bible on cranks.

yes sir i do have my own equipment have a machine shop of sorts i use in my diesel repair business. behind my house

just trying out different combinations to see what will work or not. in order to put some good strokers together for the average guy on the street that can't afford the high dollar engines. Money isn't a big thing i just like playing around with little engines. a labor of love is what my wife tells me. got a 300 berco grinder hc1dp hone WVN VB 120 this is a neat toy bore holes then deck blocks with out removing the block well enough of this

got on this site to find valuable info like what i read hope to be corrected more often to keep my witts up thanks

old men need toys too

<font size=-1>[ This Message was edited by: crankshaft on 1/29/05 9:24am ]</font>
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Old 01-27-2008, 04:23 AM   #13 (permalink)
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Re: 351M / 400 Crank Swap

There are some other things that you do need to do, but it is some what just that. it could explain it all to you, but it would be eaiser for you to just click on this link and read it all for your self. hope this helps you out tdmuir


351M/400 Performance Build Up
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Old 11-06-2014, 09:13 AM   #14 (permalink)
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Re: 351M / 400 Crank Swap

Quote:
Originally Posted by tdmuir View Post
I read in one of the ford muscle article about taking a 400 crank and putting it into a 351M. Is this really just converting to a 400? Do I need to use the 400 rods with the swap or re-use the 351M rods? What if any other mods should I do to get the max grunt out of the 351M? My use for the motor is in a stock racing class on a oval track. The motor currently twists about 5,000 rpm's. Any help that i could get on stroking and grunting this 351M would be greatly appreciated.
It's all the same except the piston connecting-rods and the crankshaft. The pistons are actually the exact same as well as the cam and push rods.
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Old 11-06-2014, 10:30 AM   #15 (permalink)
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Re: 351M / 400 Crank Swap

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Originally Posted by OleBlueFord79 View Post
It's all the same except the piston connecting-rods and the crankshaft. The pistons are actually the exact same as well as the cam and push rods.
Welcome to the Forums Wow - a 3rd-time zombie thread from 2005! That's not problem, but the info is. OleBlue, that's a bit confusing, but if you are saying the 351M and 400 pistons are the same - that is not true. If you meant something else, please clarify.

A previous post was correct, that the rods are the same, but the pistons and crank are not. To make-up for the different throw (stroke) of the two cranks, while using the same rods, the pistons are different. See the comparison of the Silvolite 1160 and 1167 pistons below.

David

The 400 piston had a compression height of 1.63" to get correct total height with a 4" stroke crank and 6.58" rods:


When the 400 was later de-stroked to 351, the shorter 3.5" stroke and same 6.58" rods required a taller 1.92" CH piston to make-up the difference:
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