Is my car running what it should? Engine build thoughts?

Discussion in 'High Performance Modifications' started by Jhboy10, Sep 14, 2020.

  1. Jhboy10

    Jhboy10 New Member

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    Hey y'all,
    Second time posting here I hope this is the right place, I thought I'd see what you're opinions are on my times and what I could do to get faster. I tried to keep it mild enough to drive 100 miles round trip to work a couple times a week. Y'all think I went too mild?

    1973 Z28
    4 bolt 350 with Eagle cast 383 kit
    Promaxx series one 185 heads 2.02 1.60
    According to my calculations 9.75 to 1
    Crane cams Z-274-2 473/486 lift 224/230 @50
    Gm Corvette 327 holley intake cast iron
    Holley 670 street avenger
    Headmen 1 5/8 headers
    2.5 summit exhaust with x pipe
    Turbo 400 with 2500 stall converter
    3.42 gears posi
    255/60r15 MT Street S/S drag radials

    Best time is 13.91 @ 97 with a 2.000 60'
     
    Last edited: Sep 15, 2020
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  2. 1980RS

    1980RS Veteran Member

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    Before I give you my thoughts on this, what is your goal for the car?
     
  3. Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

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    A few thoughts

    1. That car should be breaking into the 12’s . Dyno tuning is in order.
    2. That intake manifold has to go. It’s heavy, and frankly wasn’t that good when it was new. An Edelbrock RPM is the obvious choice
    3 The headers are borderline, I’d probably be running either a Tri-Y or a 1.75” primary.
    4. The carb is on the small side. Building from scratch I’d go 750, but the dyno will tell you more
     
    Last edited: Sep 15, 2020
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  4. xten

    xten Veteran Member

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    Stick or auto? What trans?
     
  5. Jhboy10

    Jhboy10 New Member

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    I wanna be able to have a little fun on the street and go to Fast Friday and run for fun. Keeping it daily able is important too. Seeing what I can improve without making major changes.
     
  6. Jhboy10

    Jhboy10 New Member

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    Turbo 400 with a 2500 Hughes Converter
     
  7. Z28zz383

    Z28zz383 Veteran Member

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    Are you "dead" hooking off the line? (no spin?)
     
  8. Jhboy10

    Jhboy10 New Member

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    Yes sir, no wheelspin that I can tell.
     
  9. Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

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    The combo isn't bad for what you want. Replace that intake manifold with a newer design unit made from aluminum, and get the car on a dyno to set up the timing curve and carb mixtures at speed.
    I find the vast majority of cars like this are simply not tuned properly. Setting the idle A/F mixture and initial timing is just the beginning of the tune, and it's where most people stop.
     
  10. 1980RS

    1980RS Veteran Member

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    So what I would start with is just a good old RPM Performer intake over the factory one. The cam you have is fine and I would get rid of the 670 Holley and put a 750 double pumper as that should wake the 383 up a bit. Make sure you put at least 36° of total timing in it also as I just tuned a guys 496 and the shop only had 30° in it, we added the extra 6 degrees and it really helped the car a lot. If you have 11:1 or higher compression then 32 would be in order. Might want to invest in some slicks for the car as 383's make a lot of torque and cam blow the tires off the line pretty easy.
     

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