Blocks and internals the same?

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overcomer401965

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I have 2 318's, one from a 74 duster and the other from a 72 demon. Just wondering if they are the same or if one is better that the other. Both are low mileage, below 50,000 anyway. Got to get to know this small block stuff for my son. Im still out in the middle of the ocean, trying to gather as much info before I get home so we can get to work on it.
 
What do you want to do with your 318- there are slight differences. water pumps are different, the 74 should have heavier rods, the heads should be the same. Just depends what your putting it into and what you want to do with it. But the actual internals are identical.
 
It will be street motor that will run the 1/8th everyonce in a while. Probably around 275 hp. The trannny is a 727 soon to be a forward pattern manual, around 2800 stall, rear end will either be 3:55 or 3:91 geared 8 3/4 that came out of my 72 demon Its my sons car and he still has to be able to drive it to school. I have an LD340 intake and was thinking of using J heads ported and gasket matched and everything I know to do to them. Ive done a set of 906's on 400 that ran mid 12's in my 69 charger that still run on pump gas. Headers are 1 5/8" Doug Thorley and will put a complete 3" with flowmasters. I have 650 double pumper List #4777-4 that we will use for now. Thanks any info will be helpful. Oh by the are both cranks cast?
This car was a 31,000 mile 1 owner car when I bought it for my son and still looks almost new.
 
Chances are the crank is cast, but that means nothing to your buildup. The J jeads are a good addition, but I'd suggest if you can swing them, a used set of Magnum heads. They will feed a 318 very well, I would not suggest doing more than a competittion quality valve job..it's very easy to mess up the high velocity these ports have factory. Using a flat top piston will give good squeeze, and a modern detonation resistant chamber, plus seats that will last on todays ether. The heads will need to be re-drilled for the std intake pattern, and you need to run AMC lifters and pushrods that are drilled for oiling, but you get 1.6 rocker ratio, plus the other benefits. That's just a suggestion..The J heads should be cc'd and either the block or heads milled to get a good compression, then make sure the rocker geometry and pushrod length is good. You'll need pushrods..
 
pretty sure going with the J heads. Was already planning on milling th heads to get aobut a 9.5 to one comp and probably using Kieth Black Hypertectic pistons. When He starts using his own money, we will stroke a 360. For right now probably jsut go with a cam just a little bigger than a 340 hp cam, any suggestions would be helpful. Whats the smallest solid lifter cam, if there is one, that can work with this combo?
 
Something like a Mopar Purple 284/.484 and 3.91's will run nice.
 
Comp has a nice solid cam its XS268S .488/.501 lift and 268/274 adv duration- I think you J- heand will work are you thinking 2.02's or just stay with 360 valves?
 
I second the suggestion for Magnum heads, They have a more efficient closed combustion chamber, Better ports with lots of velocity and the 1.6 rockers. You can pick a used set up for around $200.

CarCraft built a 318 using the Magnum heads with no porting, KB flat top pistons, zero decked for 10:1 compression, a Comp Cams 280H cam 230 @.050" 480 lift (512" lift with the mags 1.6 rockers) a Mopar M1 single plane and a 750 cfm carb. It dynoed at 400 horse power on westecks dyno wich is probably closer to 350-375 on anyone elses dyno.
 
It dynoed at 400 horse power on westecks dyno wich is probably closer to 350-375 on anyone elses dyno.
Click to expand...
Maybe it show this 400 number because the engine dyno runs were done with a single crank and water pump pulley and open exhaust in the cell rather than a full set of working pulleys and in chassis exhaust system.
:lol:
I don't know how dynos work in this world. Theres allways going to be a difference in how dyno A performs vs. dyno B. Even in the same town on the same day the results would be slightly different from the same machine.
I allways take it with a grain of salt.

How do you come up with Westechs dyno as generous?
 
Will just stay with the 360 valves for now, when he starts spending his $ on it we can do what ever he can afford. I have 2 projects of my own right now, 65 coronet and a 72 demon that will be my race car. On top of that he wants to change the color of the 74 duster. So just a basic performance build right now, either a 360 or a big block later. I have a few setting around out of the old c bodies I bought up years ago.
 
Cam wise I would stay conservative...Max power is not the goal, good power brakes and drivability is. The next lower XE grind, I think it's the XE256H would be top of my list, followed bythe MP P4452761 (this MUST be degreed when installed), or the Comp HE268 High Energy...The HE cam idles a little rompy, but runs well in a med compression 318. The XE256 will probably idle the best of the 3.

Westechs' dyno is also considered "generous" by me..I've heard of a few engines going elsewhere and not having similar results..Not a punch at Westech, dynos are what they are..Just big, cool tools..Not gospel writers. Kind of like Indy's flow numbers..lol.
 
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