360 to 390 conversion

[fireguywtc]

Yes the headers are the same. Externally, the 360 and 390 are exacly the same.

[hotrodfeguy]

Yes the 390 2V car and 360 truck is the same piston. The CR is 9:5 on the 390 2V due to the longer stroke(3.78")short rod. Now in a 360 configuration the stroke is shorter(3.5")long rod. The blocks are the same bewteen the two, enjoy FORDS

PS: Lift cam issue with is the keeper retainer hitting the top of the guide boss in the head, roughly around .530 lift. Take them to your local machine shop have them cut down for positive seals and your valve lift becomes a not so much of an issue, besides I like positive seals on the intake side myself. It keeps oil from getting pulled down the intake side. I also run the exhaust naked :0) but that's me.

[stephen44]

- listen to Barry !

[onetuford]

Good advice from Barry_R. I guess nobody ever asked you what your budget was and if you really wanted to do it right. Are you still doing the project?

[hotrodfeguy]

Barry is right but with unknown status of what he has now its kinda up in the air. My engine was a rebuild 360 and was in great shape to start I just swapped rods and crank and light hone. Didn't even do the bearings And used a cam I got from you witch I love BTW Would recommend it to anyone 390 truck just dont know what it was anymore It was a dual pattern and around a .520 lift but was RV type I think it was around 5 year old grind now.

[bluemoose]

Barry addressed exactly what I was looking for but didn't have the terminology to ask. The project will continue, just has been back burnered until I can get back into the garage. Got a lot of other irons in the fire right now. Hope to get the block off to the machine shop next month. It's awful tough without a truck!

[Barry_R]

To do the 390 you need crank, rods, and pistons as noted. Some of the old 360 slugs can work - but you should not really try that unless you're on a zero dollar "deliverance" budget.

The pistons have been travelling up & down those cylinders, stopping at the same place for decades. The ridge you feel is where the rings stopped every time. If you just hang new parts in there the new rings are going to catch that ridge or worn area even if you shine on it with a bottle hone and at best bounce losing seal, compression and power - at worst they'll skip and break either the ring or the piston. You should bore and hone the engine and get new pistons that fit. The differnece in cost is going to be a couple/few hundred dollars total at the maximum. How does that compare to the cost of redoing the entire job if you're not "lucky" or happy with the results?

[fordsnjeeps]

my buddys selling his 390 out of his 66 tbird w/c6, will it bolt up to my 71 f250 with a 4spd and 360?

[Tikinorton]

Hey I'm gonna rebuild my 360 and I was wondering if you would get more power by converting it to a 390 or putting in a 360 stroker kit?

[colnago]

my buddys selling his 390 out of his 66 tbird w/c6, will it bolt up to my 71 f250 with a 4spd and 360?

A qualified "yes." The tranny housings are the same between a 360 and 390. You may have to change engine mounts between car/truck (not sure on this, so don't quote as fact). I think someone said that compression is different between car/truck engines. You might have to change front/intermediate driveshafts, if there is a different length between C6 and manual trannies (if you change trannies; not an issue if you keep your tranny). There's a "plug" at the rear of the driveshaft for manual trannies that is not there for auto. Not sure if there's a difference in flywheels between auto and manual (auto uses a "flexplate"). Small differences, but the physical fitment should be the same.

Joseph

[MadJoe]

Hey I'm gonna rebuild my 360 and I was wondering if you would get more power by converting it to a 390 or putting in a 360 stroker kit?

The 360 stroker kit will definitely give you more power since a 390 is essentially a lightly stroked 360 (not really, but the most significant difference between the two is the stroke).

-Joe

[My427stang]

Hey I'm gonna rebuild my 360 and I was wondering if you would get more power by converting it to a 390 or putting in a 360 stroker kit?

If the truck is worth the cost and will likely be kept a while, I would wholeheartedly go with a 4.25 stroke kit in the 360. You end up at 445 cid with a .030 over build and it will be nothing short of amazing compared to a low compression 360. Even if you cannot afford a big dollar top end, the short block will be all modern and new parts and will allow later improvement up top. It isn't cheap though

If the truck is just a toy and not a big dollar build, I would look at L2291 390 pistons, 390 rods and a 390 crank, square the decks to the mains with a .010 cut and you'll have a great little zero deck 390 at about 9.5:1 compression. Really hard to beat with a mild cam and a good intake and headers.

If it's really a budget build, the 360 pistons can likely be reused, cut the ridge, get a 390 crank and rods, and run it. You'll still gain noticeable torque from the compression and stroke and have better quench so it will be less fussy of fuel

There's the range of cool...if you decide to keep the 360 stuff, all you can really do is rebuild it and make it run clean, the pistons are so deep in the hole it is to expensive to modify it much to make any power at stock bore and stroke. That being said, you "could" buy a set of 700 dollar custom Racetech pistons and rings that get you to zero deck and 9.5:1 compression, then run your existing parts, but it's a sort of expensive way to not get a whole lot.

[Manny]

If the truck is worth the cost and will likely be kept a while, I would wholeheartedly go with a 4.25 stroke kit in the 360. You end up at 445 cid with a .030 over build and it will be nothing short of amazing compared to a low compression 360. Even if you cannot afford a big dollar top end, the short block will be all modern and new parts and will allow later improvement up top. It isn't cheap though

If the truck is just a toy and not a big dollar build, I would look at L2291 390 pistons, 390 rods and a 390 crank, square the decks to the mains with a .010 cut and you'll have a great little zero deck 390 at about 9.5:1 compression. Really hard to beat with a mild cam and a good intake and headers.

If it's really a budget build, the 360 pistons can likely be reused, cut the ridge, get a 390 crank and rods, and run it. You'll still gain noticeable torque from the compression and stroke and have better quench so it will be less fussy of fuel

There's the range of cool...if you decide to keep the 360 stuff, all you can really do is rebuild it and make it run clean, the pistons are so deep in the hole it is to expensive to modify it much to make any power at stock bore and stroke. That being said, you "could" buy a set of 700 dollar custom Racetech pistons and rings that get you to zero deck and 9.5:1 compression, then run your existing parts, but it's a sort of expensive way to not get a whole lot.

Impressive on the FE knowledge there! Built several and deliberated on the 410/445. Then a $400.00 DOVE 429 showed up to work with my already owned zf5. My427stang is making me feel guilty now..........

[Manny]

stupid double post!!!!

[My427stang]

If the truck is worth the cost and will likely be kept a while, I would wholeheartedly go with a 4.25 stroke kit in the 360. You end up at 445 cid with a .030 over build and it will be nothing short of amazing compared to a low compression 360. Even if you cannot afford a big dollar top end, the short block will be all modern and new parts and will allow later improvement up top. It isn't cheap though

If the truck is just a toy and not a big dollar build, I would look at L2291 390 pistons, 390 rods and a 390 crank, square the decks to the mains with a .010 cut and you'll have a great little zero deck 390 at about 9.5:1 compression. Really hard to beat with a mild cam and a good intake and headers.

If it's really a budget build, the 360 pistons can likely be reused, cut the ridge, get a 390 crank and rods, and run it. You'll still gain noticeable torque from the compression and stroke and have better quench so it will be less fussy of fuel

There's the range of cool...if you decide to keep the 360 stuff, all you can really do is rebuild it and make it run clean, the pistons are so deep in the hole it is to expensive to modify it much to make any power at stock bore and stroke. That being said, you "could" buy a set of 700 dollar custom Racetech pistons and rings that get you to zero deck and 9.5:1 compression, then run your existing parts, but it's a sort of expensive way to not get a whole lot.

Impressive on the FE knowledge there! Built several fe's, and deliberated on the 410/445. Then a $400.00 DOVE 429 showed up to work with my already owned zf5. My427stang is making me feel guilty now..........

Hard to beat a D0VE 429, if I didn't have FE parts laying around I would build a big 385 series for my F100. The heads are better and the engines are cheaper. However, now my advice is not 445, it's 545 cid or even 557 cid!