i have a 400 in my 79 f150 4wd, it has rattlin mains and needs a clutch, i also have a good 351m came out of this truck, im wondering should i put the known good 351m back in when i do clutch, or will the main and rod bearings work from the 351m in the 400?

 

100 views no answer? Wow

 

Everything in a 351m and a 400 is the same except the crank and pistons.

You can put the old 351m back in, that would probably be the easiest.

Pulling the bearings out of the 351m and installing them in the 400? No, only if you are under enemy fire and that is the only way to reach safety.

If your 400 is worn out, you can put new bearing shells in there, but don't expect to run it long before you get the rattle and knock again.

If you put the 351m shells in there, expect it to rattle and knock or spin a bearing pretty much right away.

 

i think the mains are not rattling. probably the piston clearance is huge and at btm dead center, pistons rattling around. which means overhaul. just guessing! if 351m is decent would install and work on 400 and give it decent chance at a good life and build properly. good luck. what is your oil psi at idle if any at all.

 

Just stock guage shoes midway all time, already pulled it today, droppin 351 in morning bought new clutch also, the 400 at idle and when on gas no noise, but hold steady at 55 rattled bad, i figured mains

 

good luck and keep us updated on the upgrades. always got time for a ford story upgrade.

 

Well i just done a 78 460 upgrade with c6, now bought this 79 4speed, plan on sinkin lil cash in the 400, i wanna make it talk cause everyone 460 bound lol