deck height of 360 pistons??

[Toadmanor]

I'm rebuilding my 360 and want to get some OS pistons before I tear it apart. I have rebuilding specs but can't find the compression height: the distance from the pin to the top of the piston. does it use the same piston as the 390 or are these pistons unique?
Thanks
Michael

[FE427TP]

early pistons were 360 specific, but later on ford got more cost conservative and used 390 4v pistons to get the low truck compression ratio, you'll probably need to go custom if you want anything much over 8:1 compression

[Toadmanor]

THANKS Fe: since this is a 70, it's probably the late motor with the 390 pistons (hooray!!) I can either deck the block or chop the heads for more, The heads are 70 cc.~ Did the early ones use the longer 352 rods? These should be better but I have no idea of their HP capability I'm going to compare chevvy pistons in that they are cheeeeeep!
Michael

[FE427TP]

all 360's use the small rods as far as I know

[Toadmanor]

Thanks FE, Somehow with the shorter stroke, the pistons have to get to the top of the same block though, Either the pin sits higher or the rod is longer--else the piston would be down in the hole a bit!

[Toadmanor]

Uh--I mean lower in the piston sorry

[FE427TP]

If I understand your post right your saying that even though the 390 piston is used the piston still has to make it to the top of the bore with the shorter stroke and longer rod....

If that's right well it's kinda wrong, the pickup engines all had a piston well below the deck, hence the 390 piston being low is what they used for the low compression. Also as far as I know the main difference between the original 360 pistons and the 390 pistons used in 360's is. The 3.5" stroke 352/360 piston still used a full skirt that didn't need cut back to clear the crank counterweights at the bottom of the stroke, but the 390 piston did need cut back. (my assumption) Hence when they wanted to save money they used one kind of piston (the cut back 390 piston) for the 390's (high compression) and 360's

Originally posted by Toadmanor
Thanks FE, Somehow with the shorter stroke, the pistons have to get to the top of the same block though, Either the pin sits higher or the rod is longer--else the piston would be down in the hole a bit!

[Toadmanor]

Hi again FE: the stroke of the 360 is 3.50, the 390 is 3.78" with a difference of .280" If the piston was THAT far down the hole, it wouldn't have almost ANY compression! in 58, the Edsel with the 360 had 10.5 Cr just like the 390, The 353" rod is .062" longer which still doesn't make up the difference-- Must be a different piston if not a special 360 rod.
I probably have a compression height list somewhere, just hoping I could get the info without spending the day digging!

[FE427TP]

no, half of that. Half of the stroke is gained on the bottom of the stroke, and half of it on the top. So the piston would only be .140 deeper. If the 390 was .280 higher than the 360 on the top of the stroke it would be .280 deeper on the bottom of the stroke too for a .560" longer stroke, but it's only .140 higher on top and .140 lower on bottom for .280, but it's really late for me right now so if none of that made sense sorry. and the 360's had 8:1 compression or less, it seems like they even went down to 7.4:1 at one point...

[Toadmanor]

Hi again FE: True some 360's DID have low compression but also the Edsel also used the 360 motor in 58 with 10.5 CR and 303 Hp@4600 with one 4bbl which is in line with the 352 of the same era. I doubt that motor has different pistons or rods than the trucks. The original heads on My F-250 Camper special are 70 cc's so have a very low compression which I haven't computed The pistons appear to have the same tops as the typical 390. I haven't pulled them yet so I havent measured their compression height.