how to make a 360 to a 390

[1982 flareside]

My friend bought an 68' Mercury Cougar with a 289 auto. He is trading me the 289 with automatic with 120,000 miles on the engine. For an 360 with like 350,000 miles on the engine. He want to make it a 390 for more period correct engine. So how to make a 360 in to a 390.

[sideoilerfe]

... For an 360 with like 350,000 miles on the engine. He want to make it a 390 for more period correct engine...

It's the same period. They are the same engine except the crank, rods and pistons. He needs a 390 rotating assembly.

[1982 flareside]

Sorry for confusing you i mean for a cougar they came with 390s.

[fordman]

crank rods and pistons. plus bearigns and rings plus a whole gasket kit. redo the heads and get the cam you want.

[crewdcab]

pistons are acutally the same, as the 360 and 390 have the same bore. He only needs crank(2U) and rods.

[sideoilerfe]

pistons are acutally the same, as the 360 and 390 have the same bore. He only needs crank(2U) and rods.

No, pistons are different. The 352/360 rods are longer so the 360 pistons have different pin height. The factory 360 pistons also had a full skirt.

[crewdcab]

explain to me why 360 pistons will say 390 on the skirt then

[crewdcab]

I just did some piston research from my interchange manual. I stand corrected. Pistons are different.

[hazelnut]

Ive heard on a engine post a coulple weeks ago that stock 360 (short skirt)pistons are the same as 390 car pistons,and the post went on to say that if you put 390 crank and rods in a 360 that you would have about 9.6 compression,with 72 cc heads. I dont know if this is true or not but i would like to know myself as im also making a 360 into a 390. A 360 has 6.540"long rods and a 3.50 stroke, a 390 has 6.488" short rods and a 3.78 stroke,the 360 rods are .052 longer but the 390 has a .28" longer stroke,the difference being .228",I dont know what the pin hight differene is or if there is a differance but i know every time ive pulled the head off a 360 the piston dosent come to the top of the bore at TDC but a 390 will. i think im going to e-mail keith black and ask about the pin height. then we can answer this age old question of do you have to change pistons from a 360 to a 390 Opps it took me to long to post this

[sideoilerfe]

[hazelnut]

thank you for posting that,you should post that on 1971ford (ryan) engine post because someone has told him that 360 pistons will work in his 390 build. "building my 360/390 for towing" i belive is the tread.