Hi, I am buying a gorgeous 1968 F100 but unfortunately it has the 6 cylinder engine in it (300??? I think) Anyways... what is the biggest Ford Engine that will easily fit without much modification? Thanks for the help!
Rusty

 

460 will go only thing is you have to change frame perches for the 460 and get the block mounts, i believe its a 3 piece mount system, also any other v8 ford will fit in it granted you change the frame perches to a v8 setup, only 3 different ones i believe, the ones for a six cyl. and the common v8 ones and ones to put a 460 in it,

 

Any of the small blocks, 351C, 351W, 302, or 6 bolt 289 will bolt to your tranny and save you the hassle of swapping that but don't knock the six they are great motors and they can be built to make modest amounts of power, but if you want a racer an engine swap is in order.
-Johnboy

 

Rusty, The 460 is an easy fit for your engine bay. It was used before 79 so there are factory engine perches that are direct bolt on. The 385 series engine has a different bell pattern so you will need to bring a bell or auto tranny with the engine. The V8s use a larger radiator but that shouldn't be a problem either.

You might want to drive the truck for a while and get to know it before ripping into it.

John

 

i think theres more of us runin big blocks then anything else here! very popular swap and its pretty easy to do also. so pick your favorite ford engine and stuff it in there,im shure some one here has probably done the same thing and will ofer there help

 

I'll swap you a set of V8 (289, 302,351) frame perches for your 6 cyl ones

 

I know you are talking about going with a big engine. A former owner before me converted my 1968 360 with a 3-on-the-tree manual transmission to a 302 with a three-on-the-tree manual transmission.

When I found my truck on a local free internet classified site I had to fix a few things (like the column linkages) but I get a full week of driving to and from work on a tank of gas, and some, (something your 6 will probably give you too). Remember something else, if you have a manual transmission in your truck you might have to try to find all of your manual transmission parts (and who knows what else) to do the conversion too. I don't know what differences there are between the six cylinder engines and the big block trucks.

I know when I converted a 1967 Mustang from a 200 6 cylinder to a 289-4V back in the 80s there were all kinds of differences in the two I wasn't expecting to see. A donor truck might be something to look for or shop your local U-pull-it wrecking yards. You can do some "stare-and-compare" work of your own at the wrecking yard or look to see if anyone has posted a "six cylinder to big block" conversion post on this site for tips on what you'll run into and what you'll need before you dive into it.

 

My 67 was a 6 cylinder with 3 speed and the previous owner swapped it out for a 400M with C6 transmission. I love it!! Plenty of power and a lot lighter block for handling purposes, You might consider it. They made the 400 from 1971 until 1982 I believe, so there should be plenty of them out there. Just put a 4 barrel intake and carb on it.

 

i put a 300 6 cyl in my 68 f250 4x4,used same motor mounts,originally a 390 truck.we just used different holes in frame to move perches

 

Hey Guys, great info on this thread. Quick question - I have 68 with the straight 6, I love it but its shot, rear seal and a rod and it just needs a rebuild or replace. I wanted to know if I could swap in a modern 6 from an 80's/90's model. Will it fit and do the mounts match? I would love something with EFI.

 

An EFI 300 (4.9L) out of a 80 - 96 F-Series truck will be a direct, bolt-in replacement for your 240 or 300... except for the EFI wiring, of course.

 

The 4.9L (fuel injected 300) came out in 1987 and was produced through 1996. 1987 up to about '93 or so had Speed Density engine processor control. Around '94 through '96 had the much better Mass Air engine processor control. --Mass Air is much more receptive to changes in camshaft, air induction components and improved exhaust changes than Speed Density equipped vehicles.