I am looking for advice on working with a 351M out of a '78 LTD. I have the chance to buy the entire car cheap, and I want the drivetrain to swap into a '65 or '66 F-100 for my daughter's first car.
Swapping is not a serious issue; I converted my own '66 F-100 from a 352 FE with a stick to a 460/C-6 combo using only factory parts. However, are there differences between the car and truck 351Ms? For example, in FE and 385 series engines, the car exhaust manifolds won't work well. What similar differences will I face with putting a car 351M into a truck?
However, my concern is with the drivetrain itself as I have heard the 351M are dog engines from the factory.
What bolt on changes would you recommend to improve the mileage and usability?
What type of cam and gear set, for example.
(By the way, the answers for a '65 will be the same for any truck up to '79. Engine perches, frame, etc are almost identical in the '65 - '79 trucks.)
Thanks for any assistance.

 

turn that 351m into a 400 and you will have a power horse in your hands, you just need to change the crankshaft and pistons, all you need:

Purchase Parts from TMeyer, Inc.

 

Well, my 'dog' of a 351M has 540,000 miles on it, and going strong; I only parked it due to body rust...
It would pull anything for me, and squeal the tires with ease. Oil pressure stays always at 3/4 gauge, whether cold or hot.
100% factory Ford, 1978 vintage. They were made to work, and work they did. You could just cam it and put on headers (which I recommend, since car manifolds may not work anyway) and a 600 cfm carb. If you go with the 400 internals, use a 650 cfm carb (600 will still work fine for all around chores) and cam combo, with a dual plane intake.
Mileage will be dependant on accelerator pedal pressure (LOL)! I haven't seen any mileage difference between the 351 and 400.

 

Thank for the information guys. The drivetrain has only about 70K on it, so I won't be rebuilding it. Are you saying that the stock carb and intake are so bad they have to be replaced for the engine to run well?
That was true for the 460s after '71, that's for sure. The progressive bore carb was pretty poor, but the intake was good. In fact, Edelbrock 's Performer (not RPM) intake is almost an exact duplicate of the dual plane factory 460.
I am not looking for a lot of power, so if the 351M is a decent engine as is, I'll use it. But it seems that you all are not keen on the idea of using the 351M.
What cam and timing set should I use? Are you also saying that the stock cam and timing set are the best? If not, what is the best choice for mileage and overall daily driver type performance? To use the 460 as an example again, the cam timing was retarded 4 degrees in '72, and it lost both power and mileage after that. I put in a straight up timing set with an RV-type cam in my 460, and get 15 MPG at 70 MPH - with a 2.75 rear end, of course. Would the same cam and timing set setup improve a stock 351M?
Also, we have no emissions or smog checks, so I can do what I want to the engine.
Again, I am not interested in extra power, racing or mudding. I want to give my daughter a nice truck for her first car, and this drivetrain seems cheap enough. If it is so bad in stock configuration, though, as it seems to be what you guys are intimating, maybe I better pass?
Thanks for the information.

 

No, the stock carb and intake are not bad at all. In fact, my 351M is one of the smoothest running engines I have owned...
But you asked for 'improvements', so I gave you some ideas. A 4V carb usually gets better mileage because the primaries are smaller than the 2V barrels (if you keep your foot out of the secondaries). But to properly mount a 4V carb you need an intake, and Ford never 'officially' made a 4V intake for a 351M or a 400 (there is an old rumour that Ford had one or more 400 test beds with 4V intakes when the 400 debuted in 1971), so you will need an aftermarket intake. Headers are readily available for the 351M/400 for the '73-79 trucks, so if the older trucks have the same frames and engine compartments, should not be a problem. Once again, not needed, but are an improvement over stock, especially long tube. You can always get truck manifolds from the junkyards out of any 351M/400 pickup.

As for the Edelbrock debate, I am not sure why a company would make an intake that was identical to the factory iron piece, just for a slight weight advantage... Can anyone elaborate on that? I have heard this before...

 

Thanks for the input - appreciate it very much!

As for the intake, I have wondered the same thing, but I know with the FE is is a definite weight savings.

How about the cam and timing set? Any suggestions there? Is the stock one good to go? Any difference between the car and the truck stock cams?

Thanks again!

 

The often given advice is to use an early timing set that is "straight up" vs. the later retarded timing.

The other major fault would be low compression, but if you are not rebuilding, put fixing that on hold.

Car vs. truck cam....don't know. My grandfather had an LTDII with a 351m and it shifted at 3500 WOT, so certainly there is no lumpy cam in the cars...

I would fix the cam timing and put headers on it, with a crossover and some decent mufflers. See how it runs. You do have a new operator here, so excessive power in a '65-66 F100 would not be in anyones interest. Use the money you would have spent on the manifold etc and put a disc brake and dual master set up on it, along with some 15x7 wheels and some decent tires. Being able to stop and turn are big pluses.....

 

For emitions testing leave the stock intake carb then change it afterwards(what i did) but the best dual plane intake for the 400 is the weiand....

 

A couple of trucks ago I had a 78 with the 351M. I built it with an RV cam, with the timing 4 degrees advanced on the cam to bring it to life for towing. Really made a difference. I also put on an Eidelbrock performer with a holley 4 barrel carb. The cam made all the difference in the world with that little bit of advance. Although it killed the top rpm end. But for towing and around town was great

 

Do you mean 4 degrees advanced from the stock retarded cam timing? Or do you mean 4 degrees above zero on the cam marks?
I think retarding the cam timing is better for torque, if I remember correctly... Opposite for higher rpm power.