So I'm going ahead with my 383 HP rebuild & am trying to figure out a few of the internals but not really sure how to identify exactly what I should use.My goal is primarily street car with maybe a few fun runs down the track for now. If I can build it with the potential of upgrading the top end of the motor later, thats my plan.

I believe the pistons will end up being .040 over flat tops, I plan on using the stock intake & HP exhausts for now & its got a Carter AFB. I can always change the intake, carb & exhaust later if I want & as $$ allows.

So how does one pick a cam profile? I understand what lift & duration are but translating those numbers into real world application I presume needs the experience of swapping out a few cams & knowing what the actual differences are. I was reading an article online from the upcoming Mopar Muscle mag. about a 383 buildup with some comp cam stuff - see article....

http://www.cpgnation.com/forum/testing-testing-mopar-muscle-6684.html

Stock rockers vs. rollers, solid lifters vs, hydraulic, push rods, etc... how much difference does all this make if I'm not planning on bombing down the drag strip every weekend?

any inputs appreciated & if I've not provided enough info up front, my apologies.

Thx!

Before you start, get serious and ask yourself what's the maximum amount you are willing to spend on this engine. Then add 25%, this is your ceiling. I add 25% because when you're waist deep in a project you tend to be willing to spend a little more to get it done.

Then find out the machine shop costs and subtract them from your ceiling cost. Piston selection is critical, ask JohnRR about the perils of putting pistons in a 383. Compression is hard to come by. Your pistons will probably cost more than you think they will.

Also, what kind of gearing do you have now? Tire size? Calculate engine rpm at 60 and 80 mph, using a 1:1 ratio for high gear. How much does the car weigh? Are you going to have to spend money to change any of this stuff?

What do you have left? NOW is the first time to be asking yourself any of those questions. For example: If you have thousands left, it's really easy for me to suggest roller hydraulic lifters, because you can get extremely fast rates of valve opening and closing. But those fast rates will require some pretty hefty spring$ and possibly rocker arm$. Suppose you have medium cash or are scraping a little. You pick a hydraulic flat tappet which uses less hefty springs and can easily use the stock rockers. They are not pretty but work very well for lifts in the 0.520" range which is the outside of what I'd be picking for you.

AT THIS POINT I must warn you that the author of that article is not a Chrysler engine guy. There are too many little things wrong in his statements. He, for exmple, could have picked a better Comp camshaft, the XE275HL, which is nearly the same except it has lobes designed for the Mopar lifter diameter. Also his choice of a pretty big hydraulic cam is guaranteed to make power on the top end so the headlines can scream, "WE MADE 438 HP WITH A FREE 383!" But if he intended for it to be anything other than a dyno mule, it is messed up.

So where does that leave us? Your question is faulty inasmuch as one does not really pick a cam "profile". Cam designers get paid a lot of money to design cam lobes and one cannot tell from looking at cursory data how it will actually work. Very similar lobes in lift and duration at 0.050" can behave smoothly or jump all over the place depending on the second and third derivative of the lifter velocity curve. Computers are really handy in designing a lobe. Probably many of the last 10 years' lobes could NEVER have been developed without computers and the other tools such as the Spintron.

What you do is figure out how much to spend and then pick one or two cam lines that are relatively modern and pick one size smaller than you first think would be good. Remember that a 383 is a short stroke engine and will really lay down on the bottom end with a big cam. You can also call people like Hughes or Porter to get a recommendation. A few years ago Dwayne Porter built a 383 that made surprising power, it was basically stock, so he might have a pretty good feel.

Regarding the trial and error scenario: Few of us have the time, money, or dyno availability to test dozens of cam profiles. AndyF did such a thing on a stroker with stock exhaust manifolds a few years ago and found he could not beat the MP .528 mechanical lifter cam for power with stock manifolds. This is also a cam that I'd consider.

Off the top of my head I'd be looking for something very similar to a Lunati Voodoo 302 cam or equivalent.

R.

A lot of guys on here with 383's seem to like the comp xe268h for a nice mild street/performance cam.

But to properly pick a cam we would need to know your rear end gear ratio, what you want to do with the car, what type of car, transmission type, stock torq converter?, and the specs on the pistons you are using so we can figure out actual CALCULATED compression ratio. 383's are sensitive to over camming.

so the rearend is a 323 ratio 8 3/4" thats in the car currently, the trans is a 727, I dont have a converter yet so thats another question that needs answering. The car is sitting as a roller currently so its pretty well striped, it'll go back complete minus the back seat but everything else will be about stock configuration. It has a full roll bar & frame ties as well.

Running 275/50 - 15's as well. Thanks for the tips on looking at others builds, I'll see if I can search them out on the site, I presume thats what your referring to. I realize its not a simple one step answer & thats why I posted the question. I suppose at some point I'll just make a choice & move forward.

thanks.

I want to know how they got to 10:1+ with "cast flat top pistons" and used 906 heads?
Assuming the "Cast piston" is a Keith Black #162 with a 1.908" compression height and 5cc valve reliefs as a starting point. Because most other "Cast" pistons have no valve reliefs, and sit further down the bore, like the SP-366 that has a 1.848" compression height.
Anyhow, with the KB162 piston, and a "stock" deck height of 9.980", 6.380" rods, and 3.380" stroke, the piston would be 0.024" below the deck.
With a 9.9cc Fel-pro head gasket, the "906" chamber volume would have to be 72cc which is pretty small for a 906 head.
If the blocked was decked 0.024" to "zero deck" the pistons, and they used a 0.020 shim gasket, the head maximum head volume would need to be less than 78cc to get 10:1 compression, and 78cc is still pretty small chamber for a 906 head.
Also, what does "the 906 ports were cleaned up, but not extensively ported" mean? Why not flow the heads and give us the flow numbers?
Then they chose a mild "solid lifter" cam. I guess so they can mess with the valve lash to tune the power curve? Then a victor single plane intake? Why not the RPM intake?
Then the dyno test starts at 3,500 RPM? I guess they think we all drive around with 5.13:1 gears?

Just another reason I let my subscription expire. I'm sure the same article will be in Hot Rod or Car Craft soon after it is published in Mopar Muscle.