I have a rebuild 400(408) that's almost done, just need intake manifold instalation, valve cover gasket (5 years project) with tim piston 9.5:1 0.030 over, rebuilt crank 0.010 under, aussie heads with stainless steel valve, convertion kit for roller rocker, with new spring to match the cam ex256, retainer ,valve lock, edelbrock intake manifold with 600cfm carb, 0* double timing set, new oil pump... well everything new or rebuild.

I can buy a 351c 4 bolt main for 300$ that need a complete rebuild. I can have the block, head and crank from a running engine that's all apart for rebuild.

I allready fit the 400 and tranny in a 1980 mustang then i remove for rebuild. Should i stick with the 400 or sell it and go with the 351c ? With all those years working on weekend on a tight budget.

My plan was to rebuild the 400 (that i know now compare to when a bought it from a guy who couldn't fit ) and edge it in that fox body because nobody did it before. I'm confuse, any help.

 

Only you can make that decision. YOU have to do what your heart tells you. There's and old adage that says "you never know what you had until it's GONE". IMHO ALL that time and work into rebuilding a 400 and your just this close to putting it in!!! and someone offers you a 351C so you can start all over. I dunno man, I would use the 400 and save the cleveland for another project.

 

Weight and size wise the Cleveland would be a better choice. What were you planning on using for a trans ? Unless you have a 400 that has the small bell housing pattern, the trans might be a problem with it's big size too.

 

I have a fmx trans that i allready fit in the mustang. I have the big bell housing 1977 block. Use to have the c-6 but to big so i trade it for a c-4 the guy told me but find out it was a fmx. The trans and the engine(old 351m and fmx trans are in now but the 351m is not running, just for fitting purpose) are in the mustang now. The 400 is on the engine stand. Just waiting for summer now, i live in New-Brunswick, Canada with 5 feet of snow right now!
Popajon your right, never gonna know if the 400 is good in the mustang if i sell it to rebuild a 351c. The TIME and EFFORT i put in that 400 worth it i guess. If i don't like it, just have to sell it and rebuild a 351c. Better fit with the 351c because i can use the original tranny small bell witch i don't have.

 

Tell me about the snow mustang, you got 5 feet we got almost nothing now. Well, if the 400 dosen't work for you and you still want to sell it give me a call. I got first dibs on it guys!!! Either way good luck in your decision.

 

I think the 400 wins compared to 351 cleveland. 4" stroke comared to 3.5" stroke. 4" wins especially in a pump gas motor, low end torque. ran both engines and very pleased. Basically the same engine just taller deck on 400 and a little wider. so if just building for normal rpms, 5500 and down, the 400 wins in my opinion. cleveland is a little screamer in stock form and can't argue either way. but like said before you have a nice 400 sitting in front of your almost done. The 4 bolt main is a good block but not worth dropping what you have.

 

I still have one 4 bolt Cleveland block and a set of closed chamber 4v heads for it around here. Used to have 3 complete 4 bolt 4v motors and more than a few sets of closed chamber 4v heads and one pretty much complete '71 Boss 351 motor that I came across in a small junkyard way back in '79. The whole mustang was still there at the time, hit very hard (if I still remember right) on the right side. It was either orange or yellow ? I should have got the 4 speed too but I didn't have the money back then. I let it go around 3 years back and the other ones have gotten sold off through the years too. I'm keeping what I've got now in hopes of coming across a '71 fastback Mustang or a '72 fastback Torino. Funny, looking back on some of the stuff I passed on through the years. Right before the place where I bought a complete 351c 4v that was for sale with a slight knock for $25 was a kinda rough looking green '70 440 six pack Super Bee 4 speed with a 4 sale sign on it. We stopped and looked. The guy said he couldn't get it running right and the kids had broken the windshield and he'd take $700 for it and I said no and went up and loaded the cleveland and never gave it another thought, that was back in '81.

 

I would say the trans will be your issue. A C6 is a lot bigger than a C4 or an FMX. It's a pity the 400 doesn't have the same pattern as the one on your 351m. just remember all the other stuff you have done for your 400 will bolt onto the 351 ie heads cam etc. so if you do choose to go with the 351 at least you could use all the gear you've just built and justify their existence. By the looks it would go like a cut cat. It will leave you with a 400 short block. A 400 will fit if the 351m fits, so it's back to your gearbox problem. Now this is a really horrible second thought, but pull the big bits out of the 400 (crank, slugs rods), and machine (bore/hone) the 351m to match. Swap all the stuff over and you have your ideal package that you have a real shot at fitting in your mustang.And if you can use that small block bolt pattern, you could obtain an AOD tranny and you would have a 4 speed. How far is your car pulled down? can you do some creative cutting and shutting on your tranny tunnel? Some food for thought, but as per usual, it all comes down to money.

 

was lookin at the AOD tranny idea back awhile. One of the things possible is hughes performance trannys sell a manual shift AOD tranny. No electronics AOD seems to be its problem and the manual tranny is scary simple. run a manual shift c-6 and its different but it the way I like to run for a more performance minded application. electronic problems solved in a AOD with manual valve body. stirring up old ideas. ended up going with a 5 speed manual zf-42 tranny instead. came into a deal and 5 speed wins.

 

Nothing wrong with what you are doing. If you back-track now and get the 351C, just think of how much money you have spent. You will not get it all back if you choose to sell the 400. You will take a loss and then be out more money to build the 351C. For all the hassle and extra bucks, you would be able to buy an adaptor and AOD for the 400. The FMX can be built to handle the 400 power...it is the daddy to the AOD. The only thing the FMX gives away to the C4 is weight and it doesn't have the racing support....but it can handle warmed over street motor easily.

 

X2 on that.

If mine I'd save the 400 for a future truck or project. and go for the Cleveland.

 

Good idea 73XAfalcon. exactly what I would like to do in the future for my old girl, but they are still not cheap. It would be cheaper to machine the 351m block probably than buy an adapter. It always comes back to money. The 351 cleveland awould be heaps easier. BUT as I have said in other forums that 434 kit from TM would be nice but the gearbox would have to be good to handle it. If the 400 is already in there and all the painful stuff done, that could be done at a later date. good to keep options open and dreams alive. From having a steep learning curve on the 400's I can appreciate how he wants to keep it and fit it especially after a lot of blood sweat and tears (and money).

 

There are no problems with transmission choice of a 351M/400....I don't know why everyone thinks there is. The M/400 came with manual trans and the 429 came with a Toploader so bellhousing are available and spacer plates can be bought to bolt a Tremec TKO500/600 to the engines. Also, you can buy bellhousings OR adaptors to bolt T56 and AOD/AODE to the motors. Granted the bellhousings are a bit pricey but those are SFI rated which makes them only slightly more expensive than a SFI Cleveland bellhousing.

As for weight, the 351M/400 is the same weight as a SBC. Period. No chebbie guys complain about the weight of those motors so why do Ford guys whine about the 400? Because it's roughly 25lbs heavier than a 351C?

A 434" stroker Fox body Mustang is a fantastic idea. The motor will be as tall as a 460/Fox swap but you will have just as much room at the front of the motor as you would have with a 302/W/C swap. Also, the 400 swap would be at least 100lbs lighter than a 460 swap and only a little heavier than the 351W/C swaps.

Swapping mid-stream on any project is a costly decision, especially once you have the hard work done like with this project (ie, the motor mounts).

Just my 2cents though.

 

yeah, sorry 73xafalcon. I have tunnel vision over the autos as that is what i have and I will not be changing to a manual anytime soon. A manual 434 would be a weapon!! It was more the original topic started off about autos. I agree, the 400 isn't much bigger than a 351c, but comparitively a fair bit smaller and lighter than a 429-460 just as you've suggested. but from what I've read on a lot of other forums (and you too by the looks of it) the 400's are considered a junker and should be replaced by a 429-460 at the first opportunity of a rebuild. Myself and probably you too by your username suggests a healthy interest and respect for a decent Cleveland that a lot in stateside can't get their head around. A lack of OEM gear in OZ with the big blocks don't help either.

 

Actually, I might own an Aussie XA Falcon but I'm an American and my car is in the US and it is powered by a 400. I've always been a fan of the overlooked 400 and that is why I've followed this guys build. I think it's a cool build with lots of potential. The slushbox isn't a problem and you can put a C4 or AOD behind a 400 for the same price as putting one behind a 429/460. If you have a truck then you can use the E4OD truck tranny with an aftermarket controller just as you would if you put one of these into an old 429 powered car/truck.