72 F250 4x4 360 to 390 swap clutch issue

[mwdaug72]

Hello all, total newb so I will keep this short and read up in my spare time. I have had a 72 F250 4x4 forced on me since 2000. It belongs to my buddy and we blew the 360 motor on the way home from riding dirt bikes and it has been sitting at my work and home ever since. Buddy bought a new 390 crate motor in early 2000s and we just recently built it. NP435 trans shifted ok so thought was to leave it alone and get new clutch kit before we drop the motor in. This is a beater truck. So we need a new flywheel too? What is the right way to do this? I will get to reading and hopefully learn something.
Mike
72 F250 4x4

[1972hiboy]

So a long block was purchased 15 yrs ago and never ran and you just dressed it to do the engine swap? If that is the case I would think twice. You may get a array of opinions but my understanding is a fresh engine is supposed to be broken in relatively soon after its assembled. Un-ran engines dont sit in storage well. Most of its assembly lube is now in the pan instead of where its needed, If it were me. personally, I'd tear that engine down for a re-lubing and inspection for corrosion, I would also get a new clutch kit and flywheel but you can keep the smaller 360 clutch or step up the the bigger size that was an option for the 390. I forget the size but one is a 9inch diameter and one is a 10 inch? its been awhile. but you can figure that our when you get the engine out. I know this must sound like a bummer but you want the best possibility for success, and with a pushrod engine that has to break in a camshaft to its lifters, its crucial to make sure proper lubrication is there for the initial run-in. Then again this is just one persons

P.S welcome to the site

[mwdaug72]

There might be some things I would be worried about if it were mine, but it isnt mine. Cam and pistons have been in it a few years, heads and the rest just went together with help of one of my old-timer buddies who knows a little bit from his days of working for a tow company. They built a bunch of 390's. I will figure out the clutch thing and see what happens.

[Lee]

Hi,

I would also be concerned running an engine after it has sat "un-ran" for those years.

A friend of mine installed an engine in his truck under the same circumstances as you describe. The engine ran great up to about 2800 rpm. Then if developed what appeared to be a "miss". After much trouble-shooting: plugs, wires, coil, etc. the problem ended up being a few valve springs.

Since the engine had sat for years not being rotated over, some of the valve springs had sat compressed all of this time and lost their tension. They operated just fine until the rpms went to high that the springs could not close the valve fast enough from their loss of tension.

Take care.
Lee

[Canonman67]

You can order a new flywheel for about $100 shipped to your door so I would go ahead and do it. It's cheap enough to not take the chance that you'll have to take it apart again to replace it. I have no opinion on the motor except to say spin the oil pump and pump oil into the galleys and mains before you try to start it.

[colnago]

You can order a new flywheel for about $100 shipped to your door so I would go ahead and do it. It's cheap enough to not take the chance that you'll have to take it apart again to replace it. I have no opinion on the motor except to say spin the oil pump and pump oil into the galleys and mains before you try to start it.

From what I've read, spin the pump until you get oil in the top of the heads, then manually turn the engine 90 degrees. Turn the pump more, then turn the engine 90 degrees again. Keep doing this until you turn the engine 360, then go from there. This makes sure that oil is pumped through the engine, and to all the bearings that need it prior to firing it up. This is my plan for my rebuild.

Joseph