Hello anyone//i just got a 78 f150(4x4)reg cab long bed 351-mod 400/auto c6 trans/everything works and works well on the truck//truck completly stock/4x4-works great and is just about is strong has my 07 fx4 crewcab /truck just needs some tlc,and some good clean up and i got a hell of a play toy/the motor 351-mod 400,i have never messed with this type engine and really never heard of this type motor.i have rebuilt my share of (302-and 390big block)=and know about the 351windsor and 351 cleveland but never about 351-mod-400..motor strong runs great supposely rebuilt about 10years ago,but like i said truck fires right up with out haveing to pump the gas (but every time you crank the truck up on the 1st start with cold motor,,see puff of black smoke -but i just thought it would be bad valve seats no big deal-but it only does it when motor cold.my question i thought about putting a new edelbrock 400 satin intake just basic upgrade intake from stock($210) and a new holley 750cfm carb ($285) holly 4-barr-carb looks like a double pumper but its not...and you know replacing water pump-fuel pump sense i will have intake and stuff off the truck..but like i said motor is stock now (351mod-400 with a 2-barr carb)..

so what does anyone think about - what mods i would like to do just help open motor just alittle...

*will it be alright running stock (new) fuel pump with that 750cfm carb and stock single ingtion*motorcraft spark plugs???? thanks-

 

Do you have a 351M (no mod) or a 400? A 750CFM carb is WAY to big for either of them. A puff of black smoke would be gas, not oil from the valve seals.

The 351M and 400 are identical from the outside. The stroke is different. Check your VIN at the link below to find the original engine size:
http://www.medicine.wisc.edu/~mrm/bronco/ftvin.cgi

There is lots of engine info in the 335 series engine forum (351C/351M/400) or at the link below:
http://home.earthlink.net/~bubbaf250/

Check the Read First:FAQ thread at the top of the 73-9 forum for more info.

 

Definately change the intake. I have a beater 79 for plowing snow and I hated that little 2bbl barb. I got a Weiand alum. intake from a 400 for about $50 (used) and pulled an old motorcraft carb out of my junk box. Slapped it all together and that thing screams.

I agree that the 750 is too big. According to Holley's website, the 750 is almost too big for the stock 460. I think you'd be better off with a 650 cfm personally.

Also, headers would help open her up a little, too.

 

Welcome to the site

Let's clarify.

Ford makes two M block engines that are almost identical.

The 351M and the 400.

In 1977 the 400 was destroked into a 351M.

Please don't use the word MOD......

It's either a 351M or 400

The title should have read....."What Performance parts for 400 (or 351M)"

This way we know exactly what the Topic/Thread is about.


as far as Modifications being made to an engine...those questions are best asked in the actual ENGINE FORUM that is related to that engine.


Even though this engine is in a 73-79 truck..the actual engine topic has nothing to do with that truck.

I'll watch for this thread to be moved to the 335 engine forum.

Meanwhile...FTE also has Tech Articles...so have a look at this page.

https://www.ford-trucks.com/article/...00_Engine.html

 

The black smoke at startup likely means your choke is set too rich for cold start. Loosen the slotted head screws on the choke housing and turn it to 'LEAN' direction as indicated. Try one or two index marks in that direction to start. You need to let the engine sit a long time to cool again before trying a new setting.

The 351M and 400 are really Clevelands at heart. They are just taller and use a different intake manifold, and the crank has 3.00 inch diameter journals like a 351W. (the 400 often lends it's crank to the 351W for use in making a stroker)

For carb size, trucks operate usually under 5500 rpm, so a 351 needs a 550-560 cfm carb (351X5500/3456) and the 400 needs a 640-650 (400X5500/3456) cfm carb. No need to go bigger.

Water pump and fuel pump can be done without messing with intake, so you can do them later. Why change them unless they are leaking? When that does happen, you might also replace timing set with an adjustable keyway type, or order a standard set for a 1971 400. (I would go with option #1)

If you know Holleys well, you are fine. If you don't go with an Edelbrock carb. easy to tune and they hold their tune. calibration kits are worth their weight in gold when you buy one. Instructions are quite simple as well.

 

Both a 1978 w/351M and 400,C6 ,49 state engine requires a choke setting of: 3 Rich

 

I always had to two choke settings with my '78 351M. One for summer and one for winter. When it got cold enough that starting was harder, it was time to change setting. Same for when it got warmer. Needed an adjustment to lean. I never did use the index marks, just guessed about 1/8 inch opening or whatever the engine happened to like.

There is a guy on the street behind me with a '72 Galaxie or LTD. I hear him start his car once in a while, and rev the tar out of it to keep it running. Next time I hear him start it, I'm going over with a screwdriver to set his choke! lol