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Thread: 220cc heads on a 10:1 327 not tuneable? Possible detonation

  1. #1
    Junior Member APPRENTICE
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    220cc heads on a 10:1 327 not tuneable? Possible detonation

    My origonal plan was to run a 6 psi supercharger on this fresh built engine but that is not going to happen so now I have 2 problems with this setup

    Thing #1 .506 cam with 1.6 ratio rockers = .540 lift

    Thing #2 220cc motown lite heads

    I have a plan to sell the heads w/ rockers then get the stock camel backs modified with studs/guide plates, undercut valves and titanium retainers, 1.5 ratio rockers.

    I just got the engine set in / broke in and id like to see if I can get it smoothed out / streetable atleast till late spring before I have to pull it to swap the heads because the distubutor hits the firewall so underhood head swap is no option.

    Im using forged flat top 4 relief pistons so comp ratio should be around 10:1, 3200 rpm stall converter, 2:73 one wheel peel(for now) rear end, new 600 cfm edelbrock carb w/ 50cfm k&n stack, all msd ignition, long tube headers with h-pipe.

    Inital timing is set at 16` + 18`mechanical = 34` total

    My problem is besides the expected super weak bottom end power when I do actualy get the tire to rip the engine sounds like it wants to unleash 450 horspower but it has like a nasty power robbing rev limiting effect from 4000-7000rpm under load im not to framiliar with detonation but my only guess is it has to be.

    Things ive done that had no effect:

    Tried various advance rate springs-

    92 octane fuel-

    checked fuel pressure (6psi)-

    tried various step up springs in the carb-

    drilled the 3/32 holes in the primarys to close them enough to get a idle mixture signal but they still have to remain open to far

    I noticed after about 15 minutes of terrorizing the neghborhood at 7 grand it goes away a little bit but its still there enough to ruin my day and after I shut it down I notice white smoke fuel vapor evaporates out of the carb for a good 15 minutes.

    Next time out i will make a video so you can hear/see what it does

    Anyone got tips to get this unmatched combo acting decent?

    I have a 2 piece timing chain cover and the timing gear set that came with the bushing to advance / retard the cam so that might be something to mess with

  2. #2
    Senior Member MASTER BUILDER
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    There is 3 things that i don't like
    2.73 gears
    600 edelbrock carb
    220cc heads

    heads r to big for your application unless u r turning 7500 rpm+ and u will kill your bottom end especially with 2.73 gears also i have never had any luck with trying to tune edelbrock carbs they r great for low end mods but just dogs for any performance...u have everything set up like a 1/4 mile car except them gears and carb...which kill u as far as i am concerned...my son has a 84 mustang with a 351 windsor with headers,dual plane intake 650 cfm holley with a auto with a 3000 stall verter with 2.79 gears that car is a dog and runs way to slow for that combo and he has his setup more the 1/4 but the gears which kill him just like u...my son is putting in 4.11 and i know his car will be a beast after that........if u put in some decent gears your torque will work better and your cam will to.......but them big heads won't

  3. #3
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    I found a guy that claims to have experience in this situation getting this combination to have a streetable powerband with the oversized heads and he thinks my main problem is "lean misfire".

    He suggested I richen my air fuel ratio, retard my inital timing as much as possible and use required bushing to get 34` total, increase my valve lash as much as possible and advance my cam 6-8 degrees. He said this should work out with my 3200 stall and a 3:42 gear to match my tires / th350 tranny with higher shift points.

    Anyone see a problem with this info?

    My cam card suggests .025 valve lash hot anyone know how loose I should go here?

  4. #4
    Senior Member MASTER BUILDER
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    I don't think u r addressing the problem but you go ahead and listen to him.........34 degrees with 92 octane is good, u shouldn't have a problem there.............6-8 degrees advancing the cam without seeing your cam card that could make it even more of a dog..normally advancing the valve timing will increase your cylinder pressure with both valve opening earlier and will increase bottom end and mids but will also decrease top end power loss of rpm's in top end power..well u might not have pv clearance( as advancing your cam u will change your pv clearance) and all that is going to do is compound with your problem.......... valve lash is recommended by the manufacture for a reason. as far as more lash i see what he is thinking but not going to do u any good( if i remember right loose valve lash loose is suppose to give u more bottom end or torque or tighter valve lash is suppose to give u more top end hp...correct me if i am wrong)..the heads r to big the gears r to small and the carb is not right for the application......then do your tuning but u know about advice its free.....if u had a 210cc head the motor would be way more repondsive

  5. #5
    Senior Member RACING JUNKIE
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    Do yourself a favor and toss the carb, edlebrock carbs are boat anchors you'll never get it right trust me.
    Get yourself a 750 Holley double pumper, some 373 gears 411's would be better. I agree with the above that your heads are way to big for your low compression no gear having car, they are killing your bottom end. Big breathing heads and high lift cams and highway gears dont mix.
    I wouldnt recomend monkeying with all that other stuff your friend suggested now I'm not saying that it would'nt help but NOTHING will help that car like some gears (373's or taller) and a good Holley carb will.

    Goodluck >< Cp
    ***IN GOD WE TRUST***

  6. #6
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    http://detroit.craigslist.org/pts/520421258.html

    For anyone living in the southeast michigan area

  7. #7
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    update

    Im gonna keep the heads and get a more proper cam, my compression ratio is 9.85:1 and below are the specs of the cam I believe I need

    Cam Style: Hydraulic flat tappet
    Basic Operating RPM Range: 3,000-6,200
    Intake Duration at 050 inch Lift: 234
    Exhaust Duration at 050 inch Lift: 234
    Duration at 050 inch Lift: 234 int./234 exh.
    Advertised Intake Duration: 292
    Advertised Exhaust Duration: 292
    Advertised Duration: 292 int./292 exh.
    Intake Valve Lift with Factory Rocker Arm Ratio: 0.488 in.
    Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.488 in.
    Valve Lift with Factory Rocker Arm Ratio: 0.488 int./0.488 exh. lift
    Lobe Separation (degrees): 114

    With the 1.6 rockers and bigger heads I think this this should put me in the 4000-7000 area

    Any disagreements?

  8. #8
    Senior Member MASTER BUILDER
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    Re: update

    Quote Originally Posted by caprice327
    Im gonna keep the heads and get a more proper cam, my compression ratio is 9.85:1 and below are the specs of the cam I believe I need

    Cam Style: Hydraulic flat tappet
    Basic Operating RPM Range: 3,000-6,200
    Intake Duration at 050 inch Lift: 234
    Exhaust Duration at 050 inch Lift: 234
    Duration at 050 inch Lift: 234 int./234 exh.
    Advertised Intake Duration: 292
    Advertised Exhaust Duration: 292
    Advertised Duration: 292 int./292 exh.
    Intake Valve Lift with Factory Rocker Arm Ratio: 0.488 in.
    Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.488 in.
    Valve Lift with Factory Rocker Arm Ratio: 0.488 int./0.488 exh. lift
    Lobe Separation (degrees): 114

    With the 1.6 rockers and bigger heads I think this this should put me in the 4000-7000 area

    Any disagreements?
    The camshaft is only good to 6200 rpm u need 7500 rpm to make power out of these heads also your compression is to small for this to work right.....u need something like 270 duration with 650 lift with at least 12.5 cr with higher gears and then this combo will work probably

  9. #9
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    :roll: Yes the cam itself is good to 6200 but when you factor in the 1.6 rockers and the oversized heads that moves up quite a bit and would probly preform well with a 100 shot of nos for my 12 second pump gas daily driver.

    As I stated in the first post im no longer running the blower and I am definetly not going to run domed pistons and race fuel to mach the 265 @ 50 duration cam thats already in it.


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