351M Ideas

cjperry81 · Jun 12, 2008

I just got a hold of a 351M out of a 77 PU off of a friend of a friend who was practically giving it away. I want to put it in my 66 coupe. I was wondering what some of my trans choices would be. I currently have the Straight 6 200 in it with a C4 auto. What type of manual trans for this 351 would be an affordable option? Also I was wondering if there is anything I need to watch out for when installing this engine. I know that people on here always advise the Windsor over the Cleveland just because there is a touch more clearance between the shock towers and the engine. If anyone could give me some tips i would really appreciate it.

CP

bnickel · Jun 12, 2008

ok first of all, the 351m is a dog of a motor and not worth the scrap iron it's made out of, second it won't physically fit between the towers of a 65-66, it's too wide. a 351c will barely fit and it's much narrower than a 351m, the 351m is almost as wide as a 460. also the only trans that will work behind the 351m is the big block C6, the same one used behind the 429/460 and it won't fit in the trans tunnel of the 65-66.

the 400 is a much better motor than the 351m and even if you were getting one of those for free, i'd tell you the exact same thing, it won't fit, the only way you'd be able to fit either would be to rip the towers out and use a mustang II front end and that's just plain spending money in the wrong place to get rid of the six popper.

you're better off getting a 302 and stroking it or even a 351w which you can also stroke to over 400 inches but even that's a tight fit and you have to special headers for it. same thing goes for the 351c and it's even tighter of a fit than a 351w and is physically the biggest engine that will fit between the towers of a 65-66.

rbohm · Jun 12, 2008

the only thing the 351m is good for is using the block to build a 400.

D.Hearne · Jun 12, 2008

Take heed of these guys advice, they're speaking the truth. Even if it would fit, it's not much of a motor.

68coupe351 · Jun 22, 2008

throw it away!

havi · Jun 22, 2008

www.tmeyerinc.com can build that motor into a 500+ hp 500+ ft. lb. motor. typically it gets stroked into a 434cu in. engine. You can use Aussie heads or CHI heads, intakes for a Cleveland will fit with spacers. I'll throw a picture on here of a 400 in an old car. You decide if it fits or not.

Only transmission you can use is one with the big block bell pattern (C6) unless you find this bellhousing for a C4: part number D5OP-7976-BA

Just for the sake of arguement.

Cory281 · Jun 22, 2008

That dog of a motor is made for trucks, not cars. My brother put it in his 79 F250 and it pulls great, he also has a 01 F250 V10 and says they are about the same. His 01 has stock tires and the 79 has 35s on it. I've driven it and rode in and would have to say it's a pretty good motor if it's build right.

I'm not sure what exactly he had done, but it dynoed at close to 400hp and over 400 torque. He has out pulled his friends 99 Cummins before.

D.Hearne · Jun 22, 2008

If he dynoed at 400 hp, it's no where near anything like a stock 351M. It's been stroked and poked, cammed up, carbed up, everything's been changed. I've driven a stock 77 F250 Hi-boy with a stock 351M, and it was slow as ****, fuel mileage was 8 mpg (on a good day) Wouldn't pull itself out of a pot hole.

havi · Jun 22, 2008

In all honesty, to make it fit and perform, it will cost money. In about the same amount, you could put a crossflow intake onyour 200
http://www.fordsix.com/tech/engine/crossflow/crossflow.php

The 400 came in cars starting in 1971, and were smogged starting in 1972, and then destroked to a 351 in 1975. Reversing this back into a 1971 400, would be a cheap way to go, if you do all the work....only a 400 crank, and pistons are needed, and I suppose the "straight up" timing set. But fitting it still requires a bit of ingenuity, for starters the motor mounts are totally different. i get the impression affordable means you don't want to spend alot, so I'd suggest keeping the 200 and maybe the crossflow set up and a big pair of earplugs so you don't hear that it is still a I6. My .02

D.Hearne · Jun 22, 2008

The 400 won't fit between the shock towers of a 66. Nor will it in a 67. Even if you did get it in a 67-70, spark plug access is nil.

Cory281 · Jun 22, 2008

It's a 351M thats now a 400. I just called him and it actually dynoed at 360hp with over 400 torque. It has a carter 650 carb a different manifold(can't remember what brand) and just the factory heads and exhaust manifolds, they have been slightly ported, but nothing extreme. It has a custom cam, but like the heads nothing extreme.

It cost him about $2,000-2,500 for it all to be rebuilt. He gets about 12mpg around town.

Cory281 · Jun 22, 2008

And I'm not trying to say that this guy should use this motor for his car, I wouldn't personally. I would go with a 302 or a 351w. All I'm saying is a 400m is for a truck, and if it's built right it's a good motor.

bnickel · Jun 23, 2008

yeah it's a great truck motor and also good if you have a big old 70's LTD or something but it's not a good idea to put one in a mustang because you'll need special motor mounts, a big block c6, and custom headers because i don't know of any factory manifolds that will work with the 400 and not contact the shock towers, at least in a pre 71 mustang anyway, the 71-73 has a larger engine compartment that will swallow a 400 rather easily

rbohm · Jun 23, 2008

havi said:
In all honesty, to make it fit and perform, it will cost money. In about the same amount, you could put a crossflow intake onyour 200
http://www.fordsix.com/tech/engine/crossflow/crossflow.php

adapting the crossflow to the 200 is old school, time consuming, and somewhat expensive. better would be to buy the new aluminum head for the small six;

http://classicinlines.com/products.asp?cat=31

the overall cost will be about the same, and you wont have to adapt the head to the block.

havi · Jun 23, 2008

rbohm said:
adapting the crossflow to the 200 is old school, time consuming, and somewhat expensive. better would be to buy the new aluminum head for the small six;

http://classicinlines.com/products.asp?cat=31

the overall cost will be about the same, and you wont have to adapt the head to the block.

time to update my links....thanks.

Cory281 · Jan 17, 2009

Kinda of a late reply. But a C6 is a auto right? Because my brothers truck that I have been talking about is a 4 speed manual. I'm not sure what tranny it is. When he bought the truck it had a 429, he took out the 429 because the block was cracked and put back in the original 351m that was in the truck from the factory and used the same 4 spd tranny.

Anyway I just thought you guys would maybe want to know. Or maybe I'm just retarded and a C6 is a standard?

D.Hearne · Jan 17, 2009

The C-6 is a bigger, tougher 3 speed automatic. Your brother's truck had either a granny gear 4 speed truck transmission or a Toploader 4 speed. Can't tell you which as none of the 1/2-3/4-1 ton pickups came with 429's. There were 429 truck motors beginning in 1978-79 in the meduim duty line (F600-900)

Edster · Jan 17, 2009

Don't waste your time and money trying to get that engine to fit.

Cory281 · Jan 17, 2009

Yeah I agree, I personally wouldn't spend the money or time for a 400m in a Mustang. There are a lot of better choices that would be a lot easier. Straight from the factory the truck had a 351m or a 400m, with a 4 speed manual. It's a 78 F-250 and one of the past owners installed the 429 that my brother took out and put back in a 351m.

Anyway I was curious about the tranny. Thanks for clearing that up D. Hearne, you seem to know your stuff.

D.Hearne · Jan 17, 2009

78 F250 would have a Granny gear 4 speed. Basically a 3 speed with a deep reduction 1st gear. It's not a performance transmission

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