360-390 question
Thread Starter
|
Senior User
Joined: Nov 2003
Posts: 221
Likes: 0
From: eugene
360-390 question
I was looking to turn my 360 into a 390, and i was checking out cranks and rods for the 390, rods are kinda expensive, unless someone can help me here, but I saw a post by rusty70f100 saying
"You can also use 1.680" compression height 390 pistons with the 360 rods and 390 crank. This will result in about 9.5 compression, which is about perfect. However, the 360 rods are not as strong as 390 rods, so dont plan on building a whole lot of high end HP, or it might chuck a rod. If you're going this route plan on a 5500rpm redline, and build it up for torque."
What does the 1.680" mean, can somebody direct me into the right direction here, im not sure that i quiet understand. Sorry for the stupid question, i just really want to know... also what is the difference with that setup compared to an all stock setup of a 390. anyother ideas would help me with my build too. I have dual exhaust already on stock headers... Im probably going to leave stock, i have a 4v intake and an edelbrock performer carb. Im going to get my heads redone and make sure they make them for unleaded fuel... I was a couple more horses out of it. So i was thinking for a bigger cam... I want a lil over 300 or right around there. thanks a bunch.
"You can also use 1.680" compression height 390 pistons with the 360 rods and 390 crank. This will result in about 9.5 compression, which is about perfect. However, the 360 rods are not as strong as 390 rods, so dont plan on building a whole lot of high end HP, or it might chuck a rod. If you're going this route plan on a 5500rpm redline, and build it up for torque."
What does the 1.680" mean, can somebody direct me into the right direction here, im not sure that i quiet understand. Sorry for the stupid question, i just really want to know... also what is the difference with that setup compared to an all stock setup of a 390. anyother ideas would help me with my build too. I have dual exhaust already on stock headers... Im probably going to leave stock, i have a 4v intake and an edelbrock performer carb. Im going to get my heads redone and make sure they make them for unleaded fuel... I was a couple more horses out of it. So i was thinking for a bigger cam... I want a lil over 300 or right around there. thanks a bunch.
Post Fiend
Joined: Feb 2001
Posts: 6,624
Likes: 8
From: Missouri
1.68" is the distance from the centerline of the wristpin to the top of the piston. This determines how far it will stick up above the top of the rod. The FE has a deck height of 10.17" The 390 crank throw is 1.892" The 390 rod is 6.488" and I think the 360 rod is 6.54" but it may be 6.58". I can't remember.
Crank throw + Rod length + Piston heigt should not equal more than 10.17.
Any junkyard or machine shop should have 390 rods on hand. They sell H-beam rods now for the 390 that run just over $400 ready to go. The 360 rods will work fine if you don't get too crazy.
Crank throw + Rod length + Piston heigt should not equal more than 10.17.
Any junkyard or machine shop should have 390 rods on hand. They sell H-beam rods now for the 390 that run just over $400 ready to go. The 360 rods will work fine if you don't get too crazy.
Postmaster
Joined: Nov 2002
Posts: 3,447
Likes: 1
From: Littleton, CO
The 360 rods are longer than 390 rods, so you need a short compression height on the piston as to not increase cylinder compression too much. You may also want to consider some aftermarket headers, the stock exhaust logs choke the motor out quite a bit.
--Mike
--Mike
