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#1
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head swapping
Can someone out there please give me some kind of an idea as to what performance gain could be had by simply swapping the heads on my 360 motor ( "J" heads ) with a set of 340 "X" heads. That being the only change. Surely the better compression and flow would have to do some thing positive for the horse power out put of the motor. Thanks from george
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#2
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The J heads were probably blueprinted at 65cc while the X's were 63cc. The 2.02 will hurt the low a little while helping the high if your J's weren't 2.02's to begin with.
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#3
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heads
Those two heads share the same chamber and ports so the X head will flow only slighly better from what I have seen in articles when both were tested on the flowbench.As for the chamber cc's my stock X heads came in at 70cc's.
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#4
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my dad said it depends on what kind of head you use, the way they flow, the valve sizes etc....
i like my J heads, just wish we would have had them ported more...oh well, i hate being on a budjet... |
#5
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Thanks for the feed back. I should have told a bit more of the story. The 360 engine at the moment is a plus 30 thou bore. The J heads are the 1.88 inlet sized heads. It has a cam that is supposed to be a 340 grind. On top it has a 600 vac sec holley and an edelbrock dual plane manifold. The only two things hindering it a the moment are. (1) the inlet is a small port performer manfold to suit a 318. and (2) it doesn't have pipes on it. Both of these things will be changed in time and with a bit of money. Can any body suggest some thing else that may be helpful with the performance of this motor Thanks from George. All feed back is welcome!
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#6
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If the heads are not ported yet,a good street/strip job would wake up the motor,also a performer RPM or Weiand Stealth intake would be better than the Performer.
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#7
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I'm with jimbo7074 on a porting of the heads. A mild upgrade in cam will boost the performance some more without converter hassles.
In the keeping it simple side.... 1. Open air cleaner 2. Upgrade in ignition. Ethier MoPars Orange box or a MSD or equal ignition box. 3. Dual exhaust with an "H" pipe. Even cheap turbo mufflers will help wake her up. 4. A 650-700 cfm carb. You'll outstrip the 600 quick on a 340. 5.. 2.02's in the "J" head, pocket porting, new springs to match the new cam. (If desired) 6. In keeping the cam small, duration should not be large, according too Comp cams, after about 218 @ .050, a change in converter is recomended, but lift is something you can go crazy on. Which leads to use of 1.6 rockers. But now were getting expensive. Comp has a Dual energy, split pattern cams, and there new Extreme energy cams that are also split. Hughes also has cams custom ground for them by Engle. Enjoy the sites. http://hughesengines.com/www/hughesengines/ http://compcams.com/ |
#8
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On the head cc's: No way the J or the X heads are 63-65 CCs. More like 70 CCs. To compare, the Edelbrock Closed chamber heads are 65CCs. The larger valve heads my hurt you with your current combo. The velocity in the head will drop and you may not get as good of a mix. If you go with the larger valve heads I would make sure to go with the larger port intake as well.
With any of these changes the 600 will be ready for an upgrade. You miught think about a 750 Holley vac sec. |
#9
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blueprint CC's are what Mopar designed them to be, not what they actually are. The same reference has the 273 solid lifter heads at 57! The fast burn 318 heads are 62.6, still smaller than the edelbrocks. They also have the 318 police at 75.1, that sounds big.
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