I reviewed the VIN and discovered that I do NOT have the original 351 in my 81. VIN code is for a Windsor, but I'm seeing Modified/Clevland heads and fuel pump. Is there any easy way to tell what C6 id behind it (SB/BB) and has anyone done a Cleveland swap into an early 80's PU? Trying to double check everything before I start doing upgrades and rebuilds. Planning on taking care of the turn signal issues and brake issues (hopefully) this weekend.

~Critter

 

351M/400 uses the BB bellhousing. 351W/351C both used the SB pattern.

 

Are you sure you decoded it correctly? I thought the 351w wasn't available in trucks until 83 or 84.

 

I thought it was 82, but could be mistaken.

 

Ford used the same letter, "G" IIRC, to denote an M in 80/81 and a W in 82 and on. And 81 was the last year for the M, of which I have two, both with M's. And I've owned two 82's, both with W's. All had the same code for the engine.

 

It most likely is the original engine. Find a 400, build it up and put it in there.

 

While I agree fully with Dave about the 400, and in fact that's exactly what I'm doing, a properly built 351M gives excellent power. At one point I had two of the M's in two 1981 trucks. Dad's truck came with the M and never, ever had reasonable power. And, it got 10.5 MPG on the highway, in town, everywhere. Rusty's M has been warmed up with an RV cam and Edelbrock intake and 4bbl carb, and would run circles around Dad's and get 14 MPG doing it. So I really like M's and think you will if you either rebuild yours or go for a 400.

And, by the way, the difference between the two is scant - the 400 crank has 1/2" longer stroke and the piston pins are set 1/2" lower to compensate. The heads, intake, rods, pan, valve covers, and everything else are identical. So do like I'm going to do - call it a stroked 351M.

 

Wouldn't the piston pins be set 1/4" lower to match a 1/2" increase in stroke, Gary?

 

Yep. .250 x 2 would equal the .500 difference in stroke.

 

Yes, you two are right - the piston pins are down 1/4" because the crank throw is only that much longer than the 351's. But, when it spins full-circle the effect is a 1/2" longer stroke.

 

Plans are on a 400 build, but using the block already in there. The data I have from LMC on decoding VINs said a different letter for the 351M. Also doing an emissions delete, since most of them are already gone. Also planning a 6-spd manual trans. Going to have to junkyard a lot of the cab parts. I was hoping that there was an easy way to verify if it's a 351 or 400. But I have to do the rear main anyway, so I'll check the crank then.

 

What Lima pattern gearbox has 6 speeds?

 

Go see Dad's Engine thread for a discussion on the cranks. But if your engine will turn over pull the plugs and stick a straw in one cylinder and measure the stroke.

 

If you do have a 6 speed that will fit the engine be careful, you will probably need the transfer case also. I know on the diesel six speeds they have a different output shaft so they need the transfer case that goes with them. And none of this has a place for a mechanical speedo so there is no place to hook your speedo up.

They broke what they had going before. Any Ford transfer case will mate with any 4x4 Ford tranny, until they came out with the 6 speed.

 

Moot point, since the ZF6 didn't come along till well after the demise of the Lima bellhousing pattern......