Need Cam Advice- 331CID w/Big Alum Heads

Discussion in 'Engine Topic' started by Christopher McBurney, Feb 12, 2021.

  1. Christopher McBurney

    Christopher McBurney New Member

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    Building a 327 for a client, he is supplying parts. 331cid (30 over, 9.8:1), 205cc Assault aluminum heads (2.02/1.6)(244cfm @.500)(chinese castings assembled and machined in Iowa), dual plane aluminum intake, 650 Holley, 4 speed stick, 68 Corvette. These heads were a great value at $750 and have pretty big 205cc ports (remember he is dictating parts). Im a little worried that velocity may suffer with these big flow heads and low end could be sluggish, luckily its a stick. What cam do you guys recommend? I had my eye on the Lunati Voodoo 268/276 (227/233, .489/.505) fast ramp, low overlap cam. I have this cam in my 468 Olds and its a terrific cam...but thats a big motor with mountains of torque. Is it too big for this combo considering these heads are probably a bit too big for our build? Should I consider the typical L79 cam (224/224, .465/.465) or would I be leaving too much HP on the table. My desktop dyno says 394HP for this aluminum headed 9.8:1 with the Lunati Voodoo. Not looking for any more and am willing to give up a bit if it helps low end torque. At high rpm Im sure it will rage, but want to select a cam that helps us down low too. Not opposed to using Rhodes lifters on our HFT cam either. Advice?
     
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  2. 1980RS

    1980RS Veteran Member

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    Naw you'll be ok with the heads but I would do a decent valve job on them before the install, the ones I have seen did not impress me in that area otherwise they were ok. The ports on the ones my buddy got poured 195cc's if that helps. If you need a little more response than use a 750 with an A/D booster. For a cam is this a street car, street and strip or a drag car?
     
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  3. Christopher McBurney

    Christopher McBurney New Member

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    Its just a street car.
     
  4. 1980RS

    1980RS Veteran Member

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    Ok if that's the case I would opt for a cam with a 114° LCA for good street manners and a good crisp throttle. All your other specs look good for a cam choice.
     
  5. Lowend

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

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    What are we running for rear gears?
     
  6. flht99b

    flht99b Veteran Member

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    I've run that Lunati Voodoo cam in my ex- 71 Z28 the last few years. 355", 10.6 comp, Dart 180 aluminum heads, Forged Wiseco 2VR flat tops, Holley 300-36 intake, Holley 3310-2, MSD Pro Billet HEI, Hooker headers. New owner was holding onto dash and seat 1st thru 3rd gear during test ride. Pulls hard right to 6500rpm. Got 17mpg during the 2019 HRPT long haul over 1987 miles. My car had 28" rear tires with 4.10 gear and TKO 600 trans. 13" vacuum at 800rpm idle so PB friendly. I would suggest other than Lunati lifters, they tend to bleed down if car sits for 2 or more days. 355 building now for ? car will use the Voodoo 101207104 cam ground to a 112 LSA. The 101207103 at 112 LSA should work well in a 331.
     
  7. 1320feet

    1320feet Veteran Member

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    I would leave the cam selection up to your client. Keeps you from getting blamed for a sluggish combo.
     
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  8. DesmoEd

    DesmoEd Veteran Member

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    With only 331 cubes and those huge heads I'd rethink the torque approach and go for rpm instead.

    Get the CR up and stick a healthy cam in it along with a light flywheel and lots of rear gear.
    May need more carb as well. A peaky quick revving sb that howls up top in a light 68 vette would make a fun package.
     
  9. G72Zed

    G72Zed Veteran Member

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    Looked through your build/specs, all looks good. But, to make 9.8CR with a 327 +.030 you need 76.7 cc @ TDC. If the heads actually poor 64cc, a HG of 9.1cc (ex:FP-1003) and 5cc valve reliefs and crevice volume of 1cc puts you @ 9.55 cr. (79.1cc @ TDC) this assumes a true Zero deck block. And in the 3.250 short stroke "big" runner head world, the SCR is your friend.

    Call Lunati and ask for the min-max SCR for that exact cam, it's a light weight Vette with a stick, and the Aluminum heads "need" more CR to make the same power as their Iron counter parts, don't short change yourself or the engine.

    Here's another thing, if the heads have a "good" port and valve job, and flow as advertised, the engine will "see" around 240 CFM, and with that cubic inch, the peak HP will be attained @ approx. 6,200 rpm, just what this UDH designed ramp cam likes.

    Port velocity will be what it is, VE% will fall were it may. If it's a "true" dual plane with no notch or open/semi open spacers used, your small on the carb. Look at a '750' sized instead.
     
  10. Lowend

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

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