Can anyone tell me what the stock horsepower for a 1978 351w is? I have searched every where and have came up short.

 

2v or 4v carb?..either and or i'd say around 180-200 at the rear wheels...zap!

 

Chilton's shows (for cars) 135@3200 with the 2v carb at the rear of the trans. The other 2v carb version had 149@3200. Sorry, I have no data for pickups but I feel sure they will be about the same.

 

during that era, everything was choked-down due to smog regs and lack of knowledge on how to make clean power. I bet the power ratings noted are quite close...and sad for a 351.

 

Any ideas on how much extra horsepower I will get from boreing my 351w 30 over. I had it rebuilt and added an accel 200 series ignition.

 

One more question, on average how much horsepower do headers add.

 

I am fairly sure that Ford did not put a 351 Windsor in a 78 ford f150 (someone may have put it in after though). At that time they used the 351 Modified, which is the same as the 400, and similar to the 351 Cleveland. You can tell easiest by looking at the intake manifold - the 351W has the thermostat housing coming out the front of the intake, and the 351M had the thermostat coming out of the top of the block in front of the intake manifold.
You need to know which engine it is before ordering any parts for it, as they are very different.
Either way, a duel exhaust, headers, a 4 barrel intake and about 600 cfm 4 barrel carb would wake it up.
Overboring the engine will not make much more power - 5 to 10HP.

 

163hp. i have been looking for awhile also. actually i was looking for torque specs on google and this thread came up. so im sorry for reviving a 5yr old thread but it was never answered correctly. also they WERE put in the f150s. i had a 78 f150 custom 2wd manual and it was a 351W. the difference is the windsor was supposedly a small block and cleveland and modified were big blocks i think. but they put out the same hp. torque specs would be most likely higher in the big blocks. look at wikipedia for all the engine ratings. it is the only place i could find them.

 

just boring out .030 and adding a better ignition won't do much on the horsepower side...

If you have a 351M you can throw all sorts of performance parts at it, when you can find them, and it will do nothing but make your wallet thinner. They are gutless engines which do a better job anchoring a boat then moving a truck.

If you have a 351W, you have a great base to make gobs and I mean GOBS of power. Keep the trucks stock rods and crank, throw on cheap forged pistons with higher compression. Add a good set of used aftermarket used heads, intake, and cam and that engine can easily be touching 5-600hp.

 

The 351M-400 is not a big block, it is a small block engine. During the late 60's and most of the 70's ford had 2 different lines of small block engines. There was the windsors like the 260, 289, 302 and the tall deck version the 351W. Then there was the clevelands which consisted of the 351C and the tall deck versions, the 351M and the 400. Both engine families shared the same bore spacing at 4.38" and head bolt pattern, therefor the heads are interchangable between the two, after the water passages in the block are modified to accept the other style heads.

Now, the old '69 and '70 BOSS 302 (the real ones) was actually a hybrid of both engine lines. It was a 302 windsor block with 4 bolt mains and a steel crank with 4V cleveland heads. That engine was such a screamer ford designed a new engine to go under these awesome heads and thus the 351C was born. Ford later brought out smaller 2v heads for the cleveland line to make it a little more streetable. Then around '74 ford took the hybrid concept one step further and dropped a 351w crank into a 400 block and the 351M was born. Now the story behind it was ford had production problems with the 351w blocks at the time and demand for a 351 was high during the mid 70's so since the 400 block and the 351w block shared the same bore spacing and same main journal diameter, it was a logical move to drop a windsor crank into a 400 block, so all a 351M is its a 400 with a 351w crank. For some unknown reason ford decided to use the big block 429/460 bellhousing pattern on the 351M/400 small block engines, hence the mistaken thought that they are big blocks.

From around '74 to about '79/'80 when you ordered a ford with a 351 in it, you got what you got, there was no choosing which version. They put in whatever version they had at the time. Now most trucks/large cars got the M's while medium sized cars got W's. There are exceptions to that rule, I had a '78 t-bird with a 351M in it (the 77-79 birds were much smaller than the 74-76 land yachts that had 460's in them)

For your own knowledge most all ford small blocks from 289 and up have the same bore diameter, the stroke is what changed.

289= 4.00x2.87
302= 4.00x3.00
351= 4.00x3.50
400= 4.00x4.00

 

i know ive heard of them getting over 500hp. but i found out that my 86 chevy 305ci 2bbl was about 160-165hp and my 78 f150 was pretty close in power to that. but i was looking for the torque numbers and going by the closest hp rating given for a 351W, i would guess about 290Lb-Ft. so 163hp and 290Lb-Ft is probably what they were rated. mine was geared very low, no idea what it was tho but 1st went to about 5mph, 2nd to 15, 3rd to 35 and 4th to about 90. my uncle bought it in oklahoma back in the 80s. it was being used as a logging truck. only 2wd so it must have been pretty smoothe trails. my uncle gave it to my grandfather when he went into the military. my grandfather used it to tow his camping trailer which i think was 29 ft long. and it had no problems. engine was rebuilt at 100k, it was given to me in 2001 with 285k on it. still had plenty of pulling power but was definitely not a speed demon. raced a 91 nissan kingcab truck with 3 people in the nissan. he smoked me the whole way. pretty crappy that a 2.4L truck smoked a 5.8L truck but i know i could have pushed or pulled his truck all over in a contest.

 

351m's aren't that bad. Decent cam an ed performer intake with a 4 barrel carb while removing most of the asinine pollution controls and your making decent power. Very similar to the engine in my car.

 

Interesting discussion.I have a 1978 f150 with a 351m and an automatic. I would like to rebuild this engine and restore this truck. I bought it new in 1977 in Nevada so it has less smog equipment than if I had bought it in Calif..Should I put in a 4 barrel intake and carb and a new crank to make it a 400 ? Are the heads good enough for this change ?What are your best ideas to get the most for my money out of this rebuild. An extra 100H.P. would be nice. I don,t need a rocket, Just some simple changes. Thanks all.

 

like i said above a decent cam an Ed performer intake a 4 barrel carb set of headers modern ignition and your up over 250 hp at least. You have 2v Cleveland heads and they'll perform alright. You could go with 4v heads but then the intakes are hard to find and a bit pricey. if you want a 400 just grab a rebuildable core and build it and swap it in. Same deal cam modern intake ignition headers.. over 300 easy..

 

ehhhh....

My 78 has a 400m .040 with a edelbrock intake, cam, cleaned up heads, roller rockers, long tubes, etc. etc. and it is a boat anchor. For about the same price we spent on that engine, we could have a solid 393(stroker crank, 302 pistons, 351 rods) setup making much more power and torque. Granted the 400m does still have the same factory compression(low 8's)...

There is a reason the 351-400M engines never had a performance market....

I've messed with lots of the ford engines, and by far the worst I have came across is the 351-400M. Best IMO is the 351windsor, 385 series, 2.3 turbo motors, 302(weak blocks), Cleavland(only because parts are rare and expensive), blah blah blah... and dead last 351-400m.