360 to 390
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New User
Joined: Apr 2004
Posts: 6
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From: newalla
360 to 390
One question i have is the pistons. Do the 360 and the 390 share the same pistons? I know the rods and crank are different. Also, besides just the extra 30 cubic inches what are there any other advantages going to the 390? Are the (1969) 360 heads good heads to beef up without going to the expense of aftermarket heads? Thanks to everone on this forum for all the good info. Wish Would have had access when I was younger, wouldnt have to have learned most things the hard way.
Elder User
Joined: Jul 2002
Posts: 510
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From: Charlotte
Yes, you will need 390 pistons. I believe the full skirt (?) dished pistons is what you will want. More compression. As far as difference, I don't have the numbers in front of me, but slap a mild cam in it, 4 barrel intake (stock or go a bit further and use the Edelbrock Performer RPM, not just the performer) headers and a 600-700 cfm carb. As far as the heads, you will do real well keeping the same heads and having hardened seats put in and have the heads worked for better flow. Aftermarket heads are WAY Expensive and unless you are ready to drop 1500.00 on aluminum, stay stock. MY 2 cents anyway.
Posting Guru
Joined: Nov 2003
Posts: 1,888
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From: Iowa
flat top pistons would have more compression than the dished pistons, the dished pistons hurt compression, and yes you need skirted pistons for a 390. i think most 390's came with dished pistons for the valves.
Postmaster
Joined: Nov 2002
Posts: 3,447
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From: Littleton, CO
Wait a second here. The 390 pistons will not have a full skirt on them, those were the early year 360's, they are pretty much one big round piston that looks like a can. The skirted pistons from the 390 will have the two "legs" that drop down. A full skirt piston will not work with the 390 crank and rods, the rods are too wide. Most of your 390 pistons are flat tops with valve reliefs cut in them, dished pistons are just that, they have a dish cut into them as well as the reliefs. Your dished pistons will lower compression. The flat tops with the valve reliefs will not be an issue unless you do to an exteme lift cam. Your heads are another item. If you are using the 69 heads, you will want to have them rebuilt with some hardened valve seats. The 360 and 390 shared the same heads so there are no performance issues. FWIW, you can use skirted 360 pistons on the 390 build, but you will have to check deck height as they have a taller "compression height" and may rise above the deck.
Welcome aboard! --Mike
Welcome aboard! --Mike
