Can I bolt a 390 clutch to a 360 flywheel? I have a 1972 truck that originally came with the 360 motor. It has been rebuilt as a 390. However I believe it still has the 360 flywheel and clutch/pressure plate. I would like to bolt in a 390 clutch/pressure plate but the pressure plate bolt holes don't line up.

Do I need to get a 390 flywheel or can I have a machine shop drill the 360 flywheel to accept the 390 clutch/pressure plate?

Also, if I bolt on a different flywheel to this motor does the flywheel need to be balanced with the motor?

Thanks for any advice.

JD

 

I have changed from a 360 in my 71 F350 to a 390 using the 360 flywheel after having it drilled out to accept the 11.5 inch pressure plate. The 360 had a 11 inch clutch and the 390 came with an 11.5 inch. I wanted the bigger clutch for the F350 as I will be pulling a heavy trailer. What size of clutch do you want? the balance is the same as far as I know for both engines, 360/390.

 

The 360 flywheel will work on the 390. I used the flywheel from my 360 when I swapped to the 390. I used the clutch frim it to. I have had over 3500 lbs in the bed with no issues with the clutch while trying to get the truck moving.

 

Thanks for the response.

I think I am going to go down to my local machine shop, Monday, and have my 360 flywheel drilled to accept the 390 clutch. I'm sure I would probably be OK with the 360 clutch, but I think I want to beef it up a bit.

By the way my shop manual says the 390 clutch is 11.5". However the Borg-Warner (Brute Force by Zoom) clutch I purchased is 12". Not sure why the discrepancy.

 

JD, Before you go out and redrill, try fitting the unit to the wheel. There are different size clutches, but you may be able to use the holes that you have.

John

 

Just wanted to update this thread.

I found out that most machine shops shy away from drilling a flywheel. They need special equipment in order to insure "nuts-on-centeredness" of the holes.

I went to a Ford wrecking yard and looked at several "390" flywheels. They all were drilled to accept the 11" clutch. The guy told me that the 390's came with the 11" clutch. He then directed me to a 390 HD (heavy duty) flywheel. This flywheel was drilled for a 12" clutch and pressure plate.

My Ford shop manual says the 360 had a 11" clutch and the 390 had an 11.5" clutch. This is confusing and doesn't seem to agree with what I've been told.

If anybody can shed any light on the this clutch size issue - good luck.

I finally decided to just go with the 11" clutch behind the 390 motor.

The clutch salesperson talked me into going to a diaphram style over the 3-finger type. Is this a good move?

Thanks again.