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MSD 6AL Installation.....Some Initial Driving Impressions (AS REQUESTED!)

Discussion in 'The Garage' started by Greg72, Mar 21, 2002.

  1. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Well guys I just got back from a short test-drive with my new MSD 6AL box installed and thought you would be interested to hear some initial impressions:

    First off, I like the little plug in modules for the Rev-Limiter. I plugged in the 3000RPM one just for fun and kept the 6000RPM one in my pocket so I could swap it during the test drive. I drove around a while to get the engine warm, and then when I had a open stretch of road I floored it. My factory tach indicated close to 4000RPM before the rev-limiter kicked in.....but that's another issue (See my post about HEI & Factory Tachs in the '69-'72 Forum) Once I hit the limit....the engine just gently stumbled and wouldn't go any faster...no backfiring or abrupt cutout. It was just a gentle reminder that the rev limit had been reached.

    OK enough of that pesky 3000RPM limiter, I plugged in the 6000RPM jobbie, and hit the road again. I punched it from a stop sign and the tires spun more easily than I was expecting....there did seem to be more crispness to the acceleration....and it felt perhaps "smoother"?? The effect is nice....though not an OHMYGODWHATAHUGEIMPROVEMENT kind of add-on.

    Now that I have that done, and installed an "Accurate Tach"....I have a question for you. My engine seems to not pull as hard as I would expect either at the low-end or at the high-end. By around 4000 - 4500RPM it really seems to take it's time building RPMs and accelerating.

    I was wondering what the total ignition advance should be on a big-block motor? I have the specs on the distributor from the P.O. (20* Mechanical Advance at 2800RPM, Vaccuum starts at 11" and has 8* at 14" of vaccuum)....so does that mean a TOTAL of 20 degrees of advance in the distributor? I have read that you could run an engine at about 34-36 degrees of total advance. Currently my distributor is at 10* BTDC....so I think my total advance is only 30 degrees? Could this be causing my lackluster acceleration performance?




    Ready for input...! /forums/images/icons/laugh.gif

    Engine Specs - (for the hardcore guys)
    Displacement: 427 Cu. In.
    396 Block bored .030" & 454 Crank

    Pistons: TRW Forged 9.5:1
    Crank: 10/10
    Rods: Reconditioned w/ ARP Bolts
    Bearings: Mich 77
    Cam: Crower "Beast" Hydraulic Part # 01904
    Grind 292H
    Lobe Center 112 degrees
    Intake Duration 292 degrees
    Exhaust Duration 302 degrees
    Duration @ .050"
    Intake 214 degrees
    Exhaust 224 degrees
    Gross Lift w/ 1.7
    Intake .503"
    Exhaust .529"

    Rockers: 1.7 Ratio Roller Tip Rockers - Comp Cams (Summit Racing #CCA-1411-16)
    Valves: Stainless
    Springs: 502 Springs
    Timing Chain: Roller Timing Chain

    Heads: Decked 0.20
    Port & Polish

    Carb: Edelbrock Q-Jet 850CFM #1910

    Distributor: HEI - Re-Curved
    20 degrees mechanical advance @ 2800 RPM
    Starts @ 11" vacuum
    8 degrees @ 14" vacuum
    Timing set to 10-12 degrees with/ vacuum hose unhooked

    Radiator 5-Core
    Twin Electric Fans
    195 deg thermostat
     
  2. JIM88K5

    JIM88K5 1/2 ton status

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    What gears ya got ?
    Does the carb reach wot with the pedal on the wood.
    With that parts descripton 6000 rpm should come up
    pritty quick. Does it lag through low gears or just in high gear ? How do the plugs look ? (jetting)
    Jim
     
  3. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Jim,

    Ooops!

    3.73's with 35's that measure a true 33" diameter. Not the "greatest" combo, but it shouldn't be like 3.08s either......!!!

    The carb hasn't been optimized....just bolted-on as received from Summit/Edelbrock. I have the "Jet Kit" but have no idea how to start swapping things out.

    It seems pretty "slow" in all the gears.....at least I'm getting a "scratch" out of the tires off the line now.....but I gotta think a Big Block should be ROASTING the tires at-will off the line!!! That's certainly NOT happening to me yet....... /forums/images/icons/mad.gif
     
  4. JIM88K5

    JIM88K5 1/2 ton status

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    I had a 77 C20 camper special with a mild 454.
    It would spin the tires-33 12.5 16.5 w/ 3.73's.
    It didn't boil the tires but it ran sweeeet.
    As long as you've got a free flowing exhast to
    match the rest of your parts & and every thing
    is broken in, (rings seated ect...) it sounds like
    your hidden hp is in the tune up.
    Jim
     
  5. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    Greg-
    I'd just try bumping the timing up a few degrees and taking it for another test drive. Maybe from 10* up to 12* inital to bring that total from 30 up to 32 or so and see if it makes a difference.? Then you can figure out how to adjust the springs or centrifigual weights for the total advance if that is where it runs better and then set the inital back to like 10 if that is where it idles better?.
    with your healthy big block and a cam i'd be thinkin its wanting more timing advance./forums/images/icons/smile.gif
    my 2 cents for ya.
     

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