I'll admit I know little about these. most of my old ford trucks had 390's or 300's in them. My 79 f250 supercab 4x4 (married 203 with C6) has a 351M that knocks. Found a (ad says) 400M bolted to a C6, for a great price. I get a little confused while searching here. Will this 400M bolt to my tranny, and what about engine mounts? Looks to me from searching here that the 351M and 400M are basically the same critter, the stroke is different, is that correct?
Thanks.

 

Yup, the 351M/400 are the same engine. The 351M is just a destroked 400. Only the 351M carries the "M" though, the 400 does not. And yes the 400 will mate up just fine.

 

every thing like block, heads, manifold, etc. is the same

 

Thanks ya'll. Found out it's a 76 model. was rebuilt and stuck in a 56 Ford car. Ran good, no smoke, no knock. That was a year and a half ago, and according to the guy who's selling it.

 

Just verify that it is a 400 first. PPL probably try to pull the same mess with these as they do with the 360/390. Because they are visually interchangeable, the only real way to see if it is a 400 is to measure the stroke.

Not sure if it makes a difference in your case, but it's always nice to know that what you are buying is really what they say it is.

 

Couldn't agree more. Its amazing how many 360's are claimed to be 390s, and also how many 351Ms are claimed to be a 351C. It's so bad I think when most people here a truck has a Cleveland or a 390 they just assume its a 351M or 360.

I was in the same boat with me 351M. No oil pressure and no compression on cylinder 7. I was going to do a super budget 460 swap just to be me back on the road but ended up doing a performance rebuild. I would seriously looking to the 460 swap but thats just me. My family has been burnt by those Ms more times that I can count on both hands and for us the 385 swap puts an end to engine problems. This is just my opinion and I can assure you plenty of people will say the Ms are great engines, but I seriously have no idea how anyone can say this.
My dad has a 79 F250 that he bought from the original owner in 1984. It was on it's second 351M, the first was replaced by Ford and the second was already done for. He installed a $75 junk yard 429 with home made exhaust and accessory brackets. The only thing he bought was L&L mounts. Runs great to this day and didn't cost much at all. Two brand new from Ford 351Ms lasted 5 years total. Then a junk yard 429 lasts 25 years with no issues at all. I have about 10 more stories just like this that I can tell on those Ms.

 

I think you will be hapy with the 400 if it actually is a 400 not a 351M. If it ends up being a 351m I would change the crank and pistons to make it a 400. If it is all stock a simple change of the timing chain and camshaft will turn it into a little beast. I love the 400 in my 79 Bronco.

 

I had looked into the 460 swap, have had several over the years. I'm looking for cheap, and plug and play right now. This is just going to be a feed store/hunting/fence building rig for now. $350 seems a good price, if it actually is in as good a shape as it's supposed to be.

 

Been a long time but it seems to me that the 351/400 m 429/460 are in the #385 which shared the same valvetrain layout (not the same VT just style, semihemi) and bellhousing. Don't be to quick to give-up on the 400 though. With the right parts and heads it is capable of 1 and 1/2 hp per cu. Look-up Jon Kaase.

 

look and see what jon kaase can do with his. then look to tmeyer to see what YOU can do to make yours a little beast. completely stock, you can swap the timing gear, that is the the chain and both sprockets to aftermarket kits (not stock replacement at the auto parts store, some kinda performance make), and make it more than a hot enough street motor. the cams on the 400 and 351M were retarded 6 degrees. a new timing set can correct this and put you around 300 horses and 375 torque.

 

They aren't the same at all. The 351m/400 is 335 series. You can actually get those heads to go on a 302 but a water passage has to be drilled. They call that a Clevor (cross between a 351c (also 335 series) and a Windsor. The distributor from a 351m will fit a 460 though. A 429/460 is not a semi hemi. A boss 429 Mustang was a semi hemi but these are so rare its not worth mentioning, they basically don't even exist to the common man.

Does anyone else not have oil pressure problems with the 351m/400? My 351m had no oil pressure, neither did my dads or any of my uncles trucks over the years and he's had a bunch! Off the top of my head I can think of 4 that he's had to do main and rod bearings and a hi volume oil pump. Some of them are still going to this day. My dad tried it and was not so lucky.
From what I've heard this is because these engines send oil to the cam shaft before the crank, therefore the crank runs without pressure on start up for a longer time then say a 302 or 351w which sends oil to the crank then cam. But the 429/460 oil the same way and they don't have near the oil pressure problems of the 351m/400. Or is it just every 351m/400 that I come in contact with that has this problem and no one else? I am seriously dumbfounded that there is this many people out there that like these things!

 

we like em cause we know what they are capable of... and there are ways to get around the oiling issues.

 

Maybe you just had bad luck with them, lol. I don't know how many miles are on the 400 in my Bronco, probably don't wanna know, lol. Its stock except for dual exhaust, Edelbrock SP2P Intake, 600cfm Holley. I beat the living crap out of it and she still runs like a champ. Like 460/5 said there are ways to get past the oil pressure problems. In the front side of the block on driverside there is a port you can tap into run a line and t-into where the oil pressure sending unit goes to give extra oil to the rear main. All sorts of other things you can do also. They are torque houses waiting to be unleashed. There are starting to be more aftermarket parts for them to where you can make them down right nasty.

 

I have a 79 400 4WD completely stock except for dual exhaust. Over 100K miles and used to plow snow ever since new. Had it California smog tested yesterday and results were amazing. Idle: HC 250 max, meas 9, CO 2.0 max meas 0.00. 2500 RPM HC 200 max meas 40, CO max 2.0 meas 0.01.

Maintain 'em right and they should last a LONG time. Or maybe I'm just lucky. Either way, no complaints at all.

 

A small detail that an old local engine builder showed me when my bracket motor was being machined. There's a oil gallery plug that goes in around the cam housing under the timing chain assembly that too many people, sounds like even some builders at ford, install too deep, and restricts oil pressure straight off the pump. Small detail, and a big impact.