I got a 1978 F250 with a 351M and a 4-speed tranny . I was wondering how difficult it would be to put in a 460? a 400? What would need to be done.

 

351 to a 400 is a straight swap not alot involved. I just finished putting in a 429 to my 77 1/2 but I had alot of advice from a guy in my area who does it all the time. The easiest method is to check out L&L. They have all the brackets and motor mounts you will need but it is pricy. As far as you 4 spped goes I think that complicates things a bit. I have a automatic so it was simple. Good luck with your research.

 

This swap will not be too hard, I'll assume you're working on a 2wd, you'll need to change motor mount supports (for a ' 73-' 79 460 application), then you will have to get a flywheel, and may be clutch parts for your 460, your present transmission will bolt up to the 460 as is, as the 351M,400, and 460 have the same bolt pattern, the rest is brackets, mounts, exaust etc, which shouldn't be too difficult, if you need a complete 460 setup out of a truck, E-mail me.

 

The 400 should drop right in the place of the 351. The 460 can be squeezed in with some braket changes. You dont have to have L&L brakets but they do help

 

I am in the process of swapping a 400m (which is the same block as your 351m) to a 460 in a 79 F250 4x4. The 460 has cost me at least double what the 400 would have cost. If you are wanting a good motor at a good price go with the 400. If you would like to spend about $1000-$1500 more for the extra 60 CID then go with the 460 and the neccessary parts from L&L or Advanced Adapters. If you have any other questions please e-mail me.

Brent

 

351 to 460 should be a no brainer swap. several things to watch out for. Early 460 were internaly balanced and later were externaly balanced. Parts are not interchangable. You must match flywheel, damper, clutch, etc. There are two different transmission input shaft lengths. one is 3/4" longer 1/2T & 3/4T. It is easy to adjust with a spacer that goes between trans & bellhousing. Long-gate the holes in the motormount pedastel and the motor will fit. The fram may need to be notched 3/4"X6" for the exaust on the passenger side depending if you use stock manifolds.