351M to 351C swap

ok i have a 1979 bronco that has a 351M in it. i just recently found out that there is a crack in the block so time to say bye bye to that motor and go to the next. i have someone that is willing to give me a 351C to put in it for free(lucky right?). i want to know what parts will match up and what will change out. the old motor had a new cam, timing chain, headers, distributor, water pump, and a few others i can't remember changed out in it. i would like to transfer as much as possible so buying the other parts wasn't a complete waste of money. any help or suggestions would be appreciated. Steven

Well the first big thing is the bolt patterns for the transmission are different. 351C would be "small block" and the 351m/400 has the "big block" bolt pattern. Another thing to consider is that the cleveland was made to make power at high rpms, not torque at low rpms like the 351M. Scroll down the page at this link and it has a chart that shows you the interchange on parts for the 351C and the 351M.

http://www.ford-trucks.com/article/idx/0/1...400_Engine.html

As J&S noted, the Cleveland really isn't a truck engine. It's built for high end horsepower not low end torque. Additionally the 351C uses the smallblock bellhousing bolt pattern and engine mount locations so at the very least you'd need an adapter for the tranny and have to do something with the frame mounts (maybe you could adapt 80-96 302 frame mounts or swap 73-79 302 mounts). There *are* C6's with smallblock bolt patterns so you could try finding one of those & swapping in the tailshaft & housing from your 4x4 C6 or get an aftermarket bellhousing.

As far as swapping parts goes, wow, that's a good question /emoticons/[email protected] 2x" width="20" height="20" /> I doubt the distributor will swap since the 351M/400 engines have a taller deck (it's more than an inch taller). With the exception of pushrods (due to deck height differences) all of the Cleveland valvetrain parts will interchange. The heads interchange, the M-blocks have larger combustion chambers so that will drop your compression ratio but you could probably just swap in some domed pistons to get it back, but I don't know if the exhaust port locations are the same so the headers are a question mark. The timing chain will *not* swap over, the 351M/400 chain is larger. Both blocks use the same cast-in timing cover so there's a reasonable chance the water pump will interchange but I'm not for sure.

One things for sure, it'll be in interesting project and a fairly unique truck. Let us know how you make out.

The distributor does interchange along with the water pump / oil pump / front block cover / oil pan / heads / The aussie heads make it a good truck motor /emoticons/[email protected] 2x" width="20" height="20" />

ok so i just found out that there IS a transmission that goes along with the 351C. i should just have to change out the transfer case then right? or will the old one work?

Oh no, no, no. You don't want to swap out that transfer case for anything else. Your 78' has a New Process 205. That's gear driven with a cast iron case. It's fairly close to being indestructible and it's the strongest case you'll ever find short of a Rockwell. The newer ones are chain driven with an aluminum case, if/when the chain fails the whole thing falls to the bottom of the case where it gets caught up in the gears an grenades out the bottom of the case. Ford never put a 351C into a truck so there's no way the C6 coming with it will be setup to mate with a transfer case. this means that regardless of what Xfer case you use you'll need to change the tailshaft & housing. If you have to swap that stuff out *anyways* (and you do) then you're best off keeping the NP205 because any other case you use will only be weaker. Besides, you already have the 205 and 4x4 C6.

Now of course I'm assuming when you say the Cleveland comes with a transmission that it's another C6. It it's a standard then just find the appropriate tailshaft & housing and swap those. However you do it the point is that you want to keep the 205 that came with the Bronco.

73'-76' 4x2 F100's used a 302/FMX combo so that might be a good source of parts like frame mounts, linkages, etc

This really *does* sound like a pretty interesting swap. I'd look into getting a good RV cam for the Cleveland but other than that everything you're looking at is do-able. Do us a favor & let us know how it goes as you proceed. I don't think I'd ever pull one of these swaps myself but considering your circumstances it makes sense and I'm really curious to see how you make out & what it takes to make this swap work.

I can't remember if the Cleveland uses the same cam as the 302/351W. I know the rocker ratio is higher on the Cleveland, hmm.. 1.73? But other than that, the cams may interchange. The reason I'm thinking about this is because there's a bigger selection of aftermarket rv/torque cams for the 302/351W than there are for the 351C. So if a W cam works in there, so much the better. Using 1.6 rockers on the Cleveland would reduce its effective duration and useable lift at the valve, too.

p.s. if your 351C is a 2bbl, it's very similar in performing characteristics to the 351M, other than possibly a slightly hotter camshaft. If it's a 351C 4bbl with those monster boss 302 ports on it, eh, it's going to bog pretty badly in a truck. Those heads start making power above 4000 rpm. If it IS a 4bbl motor, you can order a set of reducing/reshaping plates that fit inside the exhaust ports, which will drastically improve low end torque and driveability.

American Thunder said:

I can't remember if the Cleveland uses the same cam as the 302/351W. I know the rocker ratio is higher on the Cleveland, hmm.. 1.73? But other than that, the cams may interchange. The reason I'm thinking about this is because there's a bigger selection of aftermarket rv/torque cams for the 302/351W than there are for the 351C. So if a W cam works in there, so much the better. Using 1.6 rockers on the Cleveland would reduce its effective duration and useable lift at the valve, too.
p.s. if your 351C is a 2bbl, it's very similar in performing characteristics to the 351M, other than possibly a slightly hotter camshaft. If it's a 351C 4bbl with those monster boss 302 ports on it, eh, it's going to bog pretty badly in a truck. Those heads start making power above 4000 rpm. If it IS a 4bbl motor, you can order a set of reducing/reshaping plates that fit inside the exhaust ports, which will drastically improve low end torque and driveability.

Click to expand...

Why would it bog badly in a truck? How would the the engine know what vehicle its in? I helped a friend put a cleveland in a 79 shortbox stepside 2wd. That engine was ********. Never bogged at all, that thing would fry the tires all day long. If a 302 will move a truck a 351C will be just fine.

Yardape said:

Why would it bog badly in a truck? How would the the engine know what vehicle its in? I helped a friend put a cleveland in a 79 shortbox stepside 2wd. That engine was ********. Never bogged at all, that thing would fry the tires all day long. If a 302 will move a truck a 351C will be just fine.

Click to expand...

Which 351 Cleveland did you install in a 79 stepside? There are 3 variations of the motor. A mild performance 2bbl 351C with the same size ports and valves that the 351M/400 has, a 4bbl 351C with 2.19"x1.78" valves and huge ports, and 4bbl BOSS 351, which has the same heads as the standard 4bbl 351C, but with smaller quench chambers for more compression, and a hotter solid lifter cam.

The 4 bbl Cleveland has intake ports almost the size of tennis balls, and intake valves 2.19 inches wide. The motor bogs in ANY vehicle, unless you rev it, but the heavier the vehicle, obviously, the worse the bog becomes. The reason it bogs is due to the fact that the ports and valves are so enormous, that they **** velocity. When you lose velocity, the carburetor doesnt get a proper vacuum signal, which inhibits the main jets from pulling fuel. (That means low end torque doesnt exist.)

Once the rpm picks up, intake velocity increases, and the motor begins to make power. Sure, it would go like **** in a properly set up truck. (By proper, I mean deep gearing and either manual trans or auto with high stall speed converter) But for any type of pulling or heavy use requiring low speed torque, a 351C 4bbl would pretty much ****. It's not just NOT a truck engine, it's the polar opposite of a truck engine.

The 351C 2bbl, on the other hand, as I mentioned previously, would make as good a truck motor as a 351M, since it has basically the same displacement, bore and stroke, heads and intake. The ports and valves in a 351C 2bbl motor are nice, they're big enough to make power without being so huge that they **** low speed torque.

P.S. I wouldnt put a 302 in a truck either. A 3" stroke has no business being anywhere near a heavy vehicle! Although some of them run ok if set up and tuned just right, it's still not what I'd consider a very desirable motor for a truck, unless it's a seriously built 302, and it's a lightened drag truck.

All I know about the engine is he put a solid lifter cam in it, it was 4bbl but no idea if it was factory 4bbl. It wasnt mine all I did was help install it and then hold on for life when we took it out for a test drive. That thing was insane. I think it had 3.50 gears but I dont remember for sure. The next winter he pulled it out and we put a mildly done 460 in it. Port matched the heads and that was pretty crazy too. The Cleveland is in his 67 Mustang now and it does 12.40's on the quarter

The motor in my Mustang would make my Bronco accelerate like ****, with some 4.56s in the back and a 5000 stall speed, since it doesnt begin to make power until 4500 rpm, but for towing and such, it would eventually blow itself up under the strain of constant screaming. It might be badass for smokeshows, yes, but definitely not a truck motor. /emoticons/[email protected] 2x" width="20" height="20" />

My angry little 302:

http://videos.streetfire.net/video/530-hp-...-mph_194208.htm

I have had many cleveland motors they are a very good motor first one was in a 1973 mach 1 it was the 2 bbl version and would go like **** . The reason they say the 4 bbl will bog is due to the runner size and valve size it doesnt make alot of torque till the higher rpms a stall convertor would help with this but its all on what you want . The 2 bbl heads are way too low on compression but made the torque because of the runner size . they have smaller main journal diameters which make them rev quicker because of the lower resistance ( less surface area ) The australians used this motor up into the late 80,s and thiere adaptation of the heads is one of the best they use the 2 bbl runners and the 4 bbl quench combustion chamber so you get the best of both . I have one of these done right now Im getting ready to sqeeze into a 2002 ranger extended cab . The 351 C and only the C will bolt in where any 289/302/351W was sitting dimensionally the bellhousing and motor mount locations are in the same place . Now when I say bolt in I mean it will bolt into the frame and the tranny the exhaust may be a different story per application . The cams are not interchangeable with the 302/351w but it does use the same cam as the 351M and 400 so any cams for them will work . The rocker arms are 1.73 ratio and are the same as on the 351M/400/429/460 along with the distributor and oil pump . Many many people do not know how to tell them from a 351M or a 400 the easiest way is to look at the motor mount bosses . The C will be inline with the block and there are 2 bolts just like a 302/351W the M and 400 have 3 bolts and not inline with the block other than that and the bell housing pattern if the valve cover sticker is missing you wouldnt have a clue till you took it apart . /emoticons/[email protected] 2x" width="20" height="20" />