Thread: is it a big block?

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I've recently pulled my engine in my 81 F-250 to put a different engine in. i noticed that the engine i pulled is bigger in size than the other engine and won't bolt up. Is my original engine a big block?

where would the block numbers be

Just to show my ignorance You mean to say Ford dosen't have the engine code numbers on the block like GM ????

You can tell how many Fords I've worked on.

numbers on the valve cover sticker are 5F575AP

I'm not sure if it is the stock engine. My VIN says its a 351W and the guy I got it from said it's a 351M

Check the block numbers.It probaly is a 351m,some one pulled out the 351w,and put it in its place and got rid of it.

My "new" engine is supposed to be a 351W but the old one is wider both where it bolts up to the tranny and in overall size

i don't know if it makes a difference or nopt, but the old engine is a 2 bbl

i've seen 460s with 2bbls and small 200 l6s with 2bbls.... ok check on the block where the starter mounts there should be a flat spot with some numbers.... read off that code

could also be a cleavland ( I havent messed with them in so long) I think that the bolt pattern is the same on the clevland as is the modified the quikest way to tell the difference is infront of the intake where the flat space is for the gasket to seal the intake to the top of the block in between the heads on a cleavland the intake sets about 1/4 inch off the timing chain housing and the modified sets about 1 1/2 off the housing it will have a half inch thick web that runs from the intake valley( the flat spot) to the timing chain housing gasket surface.

The wider spaced bolts on the back of the block shows the old engine to be a 351M or a 400. 351C uses the same bell as 302/351W. Could also be a 460, hard to tell from what you've written. Pics would help. Doesn't really matter, there's no way the Windsor is gonna fit that tranny, it's back to the boneyard for one that will fit.
I hope you got the flex plate with your Windsor, there are different balances on these things, hard to find the right one. Been there, done that!

the thing with the flex plate true, true, true. and another thing with the windsor that you could run up on in 81 I belive they cahnged the spacing for all the assesories on the front of the engine. The altenator, water pump and etc,, mis spaced off of the timing cover and eaven thought the everything else on the motor may be pre 81 if the timing cover is post 81 it will throw off the belt line up for the ballancer pulley. The fix is the get a spacer with this in mind, or change the ballacer which may not be as good an option if it is a match to this engine (if you run into this problem who knows at this piont if it matches or not) or the fool proof way is to get another timing cover that maches. 81 and up is spaced further out than pre 81 timing covers (found all this out the hard way.

wow sorry about the bad spelling and the mis placed words there fellas, any questions about the mess i made of exsplaining all of that just e-mail me. I'll try to do better next time

Another mid-year change to Windsors in '81 is the starter. The register hole in the trans is a different size, and the ring gear is farther back.
"Parts off a red one won't fit a blue one!"