I finished my 351M build-up about six months ago and thought I would pass on what I learned from the experience.

The main thing I learned was that if you can't get headers for your application there isn't any point in building an engine. If the air can't get out in an efficent manner, the air you put in won't mean poo.

The car was a Ford LTD that I bought from an old lady for 100 bucks. The 351M had 130,000 miles on it and it felt like it was struggling to make 100hp. At first I thought there was something seriously wrong with the motor because it felt so weak. After doing some research on the 351M motor I found out it came from the factory that way. I guess that 1978 wasn't exactely Detroit's heydey for engine design.

I have had experience working on chebbies and a couple of 351W so I was somewhat disapointed when I saw there was a limited supply of performance parts available for a 351M. Once I got done with the motor it had the following equipment on it.

408cid
flat tops
Edelbrock power package(I think Edelbrock uses the term "power" a little to loosely) dual plane intake, 600 cfm, 2172 cam
no headers, just stock manifolds

It turned out to be a mediocre set-up. With the money I spent I expected to get more torque and power than I got.

Talking to some of the old time hot rodders around town after I did the build, they suggested I go to the local drag strip on test and tune night and walk around the pits. What I saw on the dragsters is what to use to make a car go fast. After doing that I was lucky enough to come across a 68 F100 with 48,000 miles on it. I doled out the 2000 bones and had a nice new project to start on. I replaced the 240 I6 with a 302 then started the build. The build is done now, and I'm getting more power now out of a 302 than I ever dreamed about getting out of my 408. I learned that the parts you put on have to match in order to make peak power. This setup I learned was a good one: This is on my 302

Holley carb
Edelbrock Intake
MSD ignition
Crane cam 272 Energizer
with headman headers

My Ltd got rearended by a cement truck, but the engine survived. I going to rebuild it with better parts, with parts that compliment each other. Also cam selection is critical. The wrong cam can kill a motor, (E2172 )

Just my two cents

Sanders

 

did you ever do anything with the rear gears in the LTD? the rear gears are the single most important factor determining how fast a vehicle will accelerate. you can build the engine to the moon but if you don't re-gear, it won't move. right about the cam and being matched to the other components. the intake, cam, compression ratio, stall and gear are the main players.

 

I had doubts about that Edelbrock cam, the first time that I looked at the specs, but I thought that my Edelbrock catalog had a misprint. It turns out it wasn't a misprint. I don't understand how Edelbrock can sell such a P.O.S. and call it a Performance cam.

It is a shame that you didn't use a Crane or Comp Cams cam instead of Edelbrock, but not having headers didn't help either.

Now all you need is a good vehicle to put it in.

 

I did do some research on the gears, it had a 2.75 gear. It wasn't very quick off the line but it had a sky high top end. The thing would do well over 100mph. Another problem is the old bomb had a FMX tranny. A rock solid tranny, but it sucked up alot of my power. Also I don't think a stall converter would have helped that much.

It was a 8.8 rear so changing the gears would have been expensive, that is a little beyond my scope of expertise. I change 9 inches all day long but I don't much care for the 8.8.

Sanders

Danlee I just took a glance at your gallery, that's a mean looking truck and an even meaner looking motor. Pretty impressive hp numbers you got there.

 

I'm not convinced that headers is a necessity for any engine build, to a point anyway, as in you didn't build a race engine here. I'm not going to dispute the advantages or disadvantages of them, but I've heard from alot of other 400/351 builders (mainly 4x4 owners) and a good portion of them just see headers as more of a pain than any real benefit. I think you might have had other issues with your build not necessarily exhaust issues. Using highway gears in a rearend don't help that "weak" feeling, that's for sure

 

I will admit there were other issues, but efficent airflow is always better. As far as offroaders go, I also have a 77 F150 with 39 inch boggers and a 460 Lincoln motor. The main thing with headers that I have encounter is that you run into a ground clearance issuse. When going through a mudhole that has a log lurking in it. Headers can bend, and cause a leak. Not a good thing when going through Gulf coast swamps, exhaust manifolds usually are more resistant to engine abuse.

Nevertheless, I enjoy hearing any opinions people have, whether they be pros or cons.

Sanders

 

Yep, me too How did you get that 460 in your F-150? I have a '79 F-350 4x4 with the 400, and I've often debated rebuilding that, or putting in a 460. I know that there are adapter kits out there, but they seem a little expensive

 

I am using 3.25:1 gears in my 9" posi rear. They are good on the highway, but for the track, I should be using 3.80:1 or 3.90:1. I have yet to run it in the 1/4 mile, but I am planning to do that soon.

 

Sanders,

That is interesting you experienced such poor performance. I have a *similar* build...400 bored to 408, except with Aussie heads and factory style 427P .030 pistons, and the Edelbrock "Plus" cam, lifters, dual plane intake, and 600 CFM squarebore, also in a 78 LTD. It is definitely not "quick" off the line, but it does meet its intended mission - a luxury cruiser. I too am running factory exhaust manifolds, as I cannot fine aftermarket headers that fit. My aftermarket headers flow into dual catless Flowmasters, so that probably helps a lot. The car will spin the tires if you hold the brakes as you give the engine a little RPM...so a stall converter would likely help a lot for off the line performance, but I really built the car to be a torque monster and have plenty of highway passing power. I live in ATL where everyone drives 70-90 MPH on the highway, so that was important. I have the stock rear end, and on the highway, this thing gets up and goes. I am sure it would do well over 100MPH, but I have no need to do that, especially in a car that is this big with sloppy '78 pimp steering.

I guess the key in this discussion is to build the engine and choose a cam for the purpose you want to use it for: IF you want an off the line tire roaster, put in a nasty cam (I say that in a good way) with a lope at idle, change the rear end, and add a stall converter. If you want a daily driver with a nice idle and tons of torque for passing and being able to just "putt putt putt" around town all day at 1000 RPM, go with the Edelbrock Performer Plus kit, which is really mild.

Just my .02.

DiMora

 

I have a 3.70 that is going in my F100, in place of the 2.75 I pulled out. Combined with the 2400 stall I have, I think I'm going to have a strong truck at the track.

53fatfndr, as far as the 460 swap it was real easy. I made the motor mount towers out of some metal I found behind the barn. And somehow the Lincoln motor had the same bolt pattern as the truck tranny so it bolted right to my tranny with a little amount of fiddling. It isn't the prettiest setup in the world but it get's the job done. It's a mudding truck though so it's not supposed to look pretty.

Sanders

 

53fatfnd, also if your interested I just added a picture of my mud truck to my gallery.

Sanders

 

we used 390 mustang engine mounts to drop a 460 where an M was in a 79 F150. the 390 mounts have two mounting holes that line up with two of the 460 engine bolts. the studs on the mounts dropped right into the holes in the ears on the frame.

 

The best way to put a 460 in a truck is to find a donor truck with all you need. The motor mount perches bolt to the frame and really are about all that needs to be changed unless you have transmission match problems.

Sanders, as you have probably gathered, the main problem with your build was the cam, and the rear end gearing. If you'd had even a 3.25 rear end, and used a Comp 255 or 265 DEH cam, I bet you'd have had much better results.

As far as exhaust breathing, in the fabled Hot Rod build that is frequently mentioned around here, they hogged out the stock manifolds and got good results.