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  1. #1
    LTX Member


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    Bob
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    Default Stock iron heads - flow numbers?

    I've been kicking around the idea of adding some 1.6 rockers to my (stock motor) '95 roady. I'll be replacing the valve springs either way.
    Did some hunting for flow numbers of stock iron heads and found some discrepancies in the info, was hoping someone could verify the data I found. Mainly concerned with the flow (rise or lack thereof) between .400 and .500 lift.
    Also if anybody added 1.6s to their stocker b body and has dragstrip numbers to share, that would be great.

    1st data set: lift/intake/exhaust
    .100 69.8/53.9
    .200 138.5/112.5
    .300 195.9/148.0
    .400 231.0/159.0
    .500 232.2/161.6
    .600 236.1/165.8

    If these numbers are relatively correct, there would be no point in going to 1.6 rockers or a cam with more than mid .400s lift. FWIW I saw several flow charts for stock alum. heads that were also 'flat' from .400 lift up.

    And then there's these numbers...

    2nd data set: lift/intake/exhaust
    .100 55.0/48.0
    .200 119.0/91.0
    .300 179.0/128.0
    .400 214.0/140.0
    .500 230.0/147.0

    3rd data set:
    .100 58.0/57.0
    .200 117.0/107.0
    .300 174.0/135.0
    .400 207.0/146.0
    .500 221.0/150.0

    If sets 2&3 are 'accurate' then there should be some advantage to pushing the valve lift closer to .500 ...

    Anyways, feedback would be appreciated.
    Thanks

  2. #2
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    Default

    IDK what the iron heads flow stock. Reported better than "stock" aluminum though.

    New valve springs, especially if yours are original, will allow the motor to rev higher. 1:6 RR will add a little HP also

    Crane 10309-1 spring kit is a plug & play good replacement for iron heads. Crane Gold "narrow body" SA RR are also good and require no trimming of the valve cover baffles...although that mod in itself is easy to do if you want Comp Pro Magnum RR

    what would help make more power is to get a mail order tune when you do the springs & RR. Typically people swap to a 160 T stat also so the tune can have a little more timing in it and fan temps are programmed to come on at a lower temp.

    iron heads have pressed in studs
    96 BBB 383/T56

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  4. #3
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    Default

    Already have the ability to tune it myself - not to say I know what the hell I am doing though
    Running a 180 stat currently but have set the fans to come on a bit earlier, temps are definitely more stable than the stock setting.
    Ran 93 octane for a while. Managed to bump up timing quite a bit (2 degrees at a time) w/o seeing any knock but the car runs the same et/mph on 87 octane with 29 deg. total (knock free) as it does on 93 octane with 29/32/34 total.
    Was taking some data logs at the dragstrip and could see small map fluctuations with a slight dropping trend in the upper rpm range (loses about 5 kpa from 4k to 5400 where the shifts complete). Maybe valve float, maybe exhaust restriction, maybe normal - I dunno but for no more hassle than swapping springs I might find out. At 170k miles it is cheap insurance, no idea if the springs are original or not -only had the car 5 years now...
    Haven't settled on springs yet but am leaning towards edelbrock 5703s (just toss the damper) for the short term. Not ready to dump a bunch of money into this thing just yet, it's also my daily driver.
    I was bracket racing it all last season, typically running 14.9-15.0 @ 90.5 mph with ~2000' DA. "Race" weight with driver is 4450#
    Best finish to date was runner up (1st place loser) at the BOP nats in October.

  5. #4
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    Shaun
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    Default

    @NightTrain66

    Sent from my SM-N950U using Tapatalk
    2009 G8 GXP #871 - Stock and faster than my LT1

    1994 Z28 T56 - Le2 H/C, SBE, Hooker lt's, some rod ended suspension stuff, and a whole lotta tetanus

    The wrench for LTConvert's 94 Z28- Ellwein 383/LE Trickflows/ P600B/ CPT Pro Race/Pro Torque 3200

  6. #5
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    Default

    edelbrock 5703 spring has 1.700" install spec so get a bag of shims

    Howards also is another option
    96 BBB 383/T56

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