I read up on all I could find in the forums about doing this swap. I already have a 351m block, and will be putting 351c heads on it with a performer cam. I dont feel i need to make it a 400, but your input on that would be welcome. I currently own a 1986 f150 4x4 with a 300i6, and a 4spd w/granny transmission. The current engine is going through oil both from burning and leaking, and I would like something with a bit more HP as well as the torque. My primary question is about the current tranny in my truck, most people I have asked or read opinions of say the current tranny will handle the 351m just fine. But I'm mainly concerned with is will the big block bellhousing I have fit on it, and specificly what tranny I have or how I could find out. Also, any tips or relaying experiences on doing this swap would be appreciated, especially about the motor mounts.

 

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Is your clutch cable or hydraulic? Make sure you pick up the right 7.5L bellhousing. Not sure about the mounts, I have a LTD with 400, 351W and 429/460 all options on same crossmember. I think Ford kept the mounts in the same position for ALL engines, possibly someone can confirm/deny this for you. If so, get f150-400 mounts and correct bellhousing and drop in.

IMO, if you are buying new parts, spring for the extra 49 cubes. The only difference between a 351M and 400 is the crank and pistons. With a 4.00 in. stroke, the 400 is Ford's longest factory stroke engine. Spring for an aluminum intake and Barry Grant 4bbl. I thought carbs were all about the same, but when I couldn't get my Holly right, I rode up to BG, they helped me pick the right carb and give me a helpline number that I have yet to use. I am running a 625 Road Demon Jr. b/c with the 400, after 4500, you are just overworking the engine.

Do you have the heads? If not, I used GT40X heads from Ford Racing. The FRPP website will tell you where to drill and fill the coolant passages for the differences in cooling system plumbing. These aluminum heads solve the compression problem common in the 335 family. With my al heads, mild comp cam, and 4bbl, my 73 LTD will lift both front tires and never pass 4grand. Best of all, I picked up 4 MPG getting the right 4bbl over the stock 2bbl.

 

I've already got an edelbrock 400 aluminum intake and a 4bbl carb, I'd like to build the engine somewhat but dont want to go overboard, just a decent upgrade for a small amount of cash. so far all the parts have been given to me as a repayment of sorts, I just have to purchase any internal upgrades and any machine work to the block etc. I made sure to match the bell housing to my hydralic clutch, but that reminds me to ask another question, how do i determine which clutch assembly I will need to get? The clutch for the 351m is larger than the one for my i6 but the transmission isnt changing. I'm sure you can tell I'm a bit of a novice but I have solid help putting this stuff together, I just want to make sure I've got all the bases covered before I tear apart my truck, I would like to take a weekend off and have a new engine in my truck =)

 

Look up part numbers for a 82 F-250 truck with 400. The splie count is the same, so you should be able to just drop it in and go. The spline count looks like this 10TX1 1/16. Meaning 10Teeth with a 1 1/16 inch diameter shaft with 10 teeth made on it.

Just wondering, what will you be doing with the 4.6L bellhousing? I have a 351W to put in my ranger, but the only bellhousing I could get was cable, the salvage yards concider removing the bellhousing disassembling the transmission, and want me to buy the whole unit.

 

well, if all goes well I'm hoping to have the engines switched late may. in which case I dont have any plans for the old housing, if you want to pm me your address i'll check into what it takes to send it to you. but it may be a while before its available