383 cam selection, I thought that I had it right already

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    Author Topic: 383 cam selection, I thought that I had it right already  (Read 2561 times)

    Offline Kapteenikosmos

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    383 cam selection, I thought that I had it right already
    « on: October 14, 2008 - 08:40:29 AM »
    Ok, seems like my current cam selection is down the drain. My engine is 383 0.30 bored over with KB domed pistons. I haven't checked how deep the pistons are in the hole yet but I will do that during next weekend.

    The heads are 346 open chamber heads with stock sized intake valves and bigger 1.81 inch exhaust valves. I have shaved 0.047 inches off from the heads to raise the compression. The intake will be Eddys performer and the gears are 3.23 and the transmission is automatic. Torque converter will be stock or one with sligtly raised stall speed.

    I will port the heads with mopar perf templates and also probably work on the guide bosses. For the carb I have a chebby  :poopoke: quadrajet out from 400 cid engine (year -68 or something). The quadrajet should provide good mileage without sacrificing too much from the performance.

    My initial choice for the cam, which is also installed in the block atm, was comp cams extreme energy XE256 with 0.50 durations of 212/218 and valve lift of 0.447/0.455

    The original choice for the cam was made by the fact that the car came with the 2.76 gears and I thought that I'm going to use those. Well, I didn't. I bought a yokon limited slip and 3.23 gears.

    I'm starting to feel that the xe256 might be too grannyish cam for the engine with my new gears? I'm planning to use car mostly on the street and I will definately do some road trips with it too, so it can't be too radical.

    If I decide to go for bit larger cam, would Lunati 302 be a good choice? Duration for 0.50 is 220/226 and lift is 0.475/0.494.  I would like to have some indication of "performance" on the idle but not too much.
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    Ville

    1967 six banger Mustang
    1973 Challenger (under restoration)
    1997 Lincoln Mark VIII LSC (daily driver)


    Offline torredcuda

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    Re: 383 cam selection, I thought that I had it right already
    « Reply #1 on: October 14, 2008 - 09:18:53 AM »
    " I haven't checked how deep the pistons are in the hole yet but I will do that during next weekend.

    The heads are 346 open chamber heads with stock sized intake valves and bigger 1.81 inch exhaust valves. I have shaved 0.047 inches off from the heads to raise the compression. "

    Kind of backwards there-if you don`t know where your pistons are why did you go and shave the heads?
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    Jeff
    72 Barracuda 340/4spd  Torred
    70 roadrunner 383/auto  In-Violet
    70 Duster 360/auto drag car  (Petty Blue soon)
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    Offline Chryco Psycho

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    Re: 383 cam selection, I thought that I had it right already
    « Reply #2 on: October 14, 2008 - 09:46:37 AM »
    The Lunati grind will work far better , as long as you have valve reliefs in the top of the piston piston to valve clearance should be Ok but check it
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    Challenger - You`ll wish You Hadn`t

    Offline Kapteenikosmos

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    Re: 383 cam selection, I thought that I had it right already
    « Reply #3 on: October 14, 2008 - 10:59:46 AM »
    Quote from: torredcuda on October 14, 2008 - 09:18:53 AM
    " I haven't checked how deep the pistons are in the hole yet but I will do that during next weekend.

    The heads are 346 open chamber heads with stock sized intake valves and bigger 1.81 inch exhaust valves. I have shaved 0.047 inches off from the heads to raise the compression. "

    Kind of backwards there-if you don`t know where your pistons are why did you go and shave the heads?

    The shaving was based on an assumption that I will zero deck the block which would have led to a static compression bit under 10 (which sounded good at the time). The idea of zero decking the block was tossed  because I cannot get any real quench (whole quench term came to my knowledge way after the machine work was done) with this head & piston selection, which would probably lead into serious knock problems.

    This is my first V8 I'm dealing with and that probably explains some of my amateur "brain farts" on the whole build up. The second one should be much easier to do after I have hitted the rocks couple of times with this one.  :rofl:

    I'll have to think about the lunati cam. I might be able to sell the current cam to my parents who own a 59 dodge royal with 383 out from gt dart.
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    Ville

    1967 six banger Mustang
    1973 Challenger (under restoration)
    1997 Lincoln Mark VIII LSC (daily driver)

    Offline Swedefish66/67

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    Re: 383 cam selection, I thought that I had it right already
    « Reply #4 on: October 14, 2008 - 11:35:03 AM »
    I´ve done a similair build up as you are doing. I did consider to deck the block and shave the heads but that would cause alot of other issues.
    So after asking about the build here at C-C.com, where most of the guys suggested to go with closed chamber heads,
    I went with 915 closed heads instead of the 346:s that way I got a good quench.

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    Offline Kapteenikosmos

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    Re: 383 cam selection, I thought that I had it right already
    « Reply #5 on: October 14, 2008 - 12:04:45 PM »
    My first mistake was to do it in an engineer way " do first, ask questions later". It usually leads into a situation which could be described as climbing into a tree with your butt up first.

    The block I have is from 67 or so and it came with the closed chamber 516 heads which would have probably been much better option than the open chambers I have now if I would have changed the exhaust valves to the 1.81 sizes. But what is done is done so I will proceed with these and see what kind of power I can get out from it.

    What kind of cam did you use on your build Swedefish?
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    Ville

    1967 six banger Mustang
    1973 Challenger (under restoration)
    1997 Lincoln Mark VIII LSC (daily driver)

    Offline bb71challenger

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    Re: 383 cam selection, I thought that I had it right already
    « Reply #6 on: October 14, 2008 - 12:50:30 PM »
    Engle makes some good cams too. Might give a look at the K-56HYD or the K-58HYD. I really enjoyed my engle cam enough that I will get another one next time.
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    1971 Challenger (OO==== ====OO) getting close!
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    *Brett*

    Offline Swedefish66/67

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    Re: 383 cam selection, I thought that I had it right already
    « Reply #7 on: October 14, 2008 - 01:56:10 PM »
    I´m going with a MP purple 284/484 cam, mostley cause Mancini had a package of cam, lifter and pushrods for a nice price.
    Otherwise I would have gone with a Engle stick. Probably with one of those that "bb71challenger" suggested.

    Be sure to check the lenght of the pushrod whenever you change your engine with non stock parts or milling block or heads.
    Don´t ask me how I know. :bricks1: had to buy another set of pushrods.
    Mopar Muscle Mag did a build up as this one but with a more modern cam than the MP.
    And their build was 451 hp on the dyno. I belieave this engine will be really fun in my A-body Fastback.
    I´m still waiting to fire the engine up, have my wifes car to do some rust repair at first.

    I´m in the same boat as you about "do first and ask later", guess I made all of the classic mistakes.
    Hmmm...learning money  :money:
    « Last Edit: October 14, 2008 - 02:23:12 PM by Swedefish66/67 »
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    Offline Supercuda

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    Re: 383 cam selection, I thought that I had it right already
    « Reply #8 on: October 17, 2008 - 08:05:33 PM »
    Education can be expensive. The answer is lift. Get the valve lift over .500", and the .050" duration above 216 degrees, and the engine will be happier. Domed pistons will give a compression ratio near to 11:1, with no trouble at all. The 383 in my '67 'Cuda is built with an Engle cam of 282/299 gross duration, 235/250 duration at .050" lift, and .516/.555 lift, using 1.5:1 rocker arms. Lobe centers on my grind are 108 degrees, and she is a nasty little girl with this thing. Ross pistons with domes to give a 10.75:1 compression ratio with a .039" gasket, 11:1 with a .020" gasket, and Eagle H-beam rods on a cast crank round out the short block. With 346 heads, stock valve sizes, and Magnum exhaust manifolds, the engine produces 450 BHP on pump-premium gasoline, or 470 BHP on E-85. This is with the MOPAR M-1 single-plane intake, and a mildly-modified 0-3310 Holley carburetor. A dual-plane intake would have been more street-friendly, but I was after more than street manners. An Edelbrock Performer RPM or M-1 dual-plane would be excellent, and work up to 7,000 rpm with a 1/2" spacer under the carb. I recommend a 4-hole spacer in phenolic resin. My heads received no actual porting, although I cleaned up any flashing and casting parting lines, and profiled the valve guide bosses. Maybe this will give you some information to work with. Remember that lift is your friend, and that combustion chamber pressures should be high. Shorter duration vs. lift, with a shorter overlap period, will help you achieve this goal.
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