Head choice for a hemi

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by SpeedDemon, Nov 13, 2017.

  1. SpeedDemon

    SpeedDemon New Member

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    Hey guys
    Building a blown hemi this winter. Parts I've acquired so far are Brad cast block(unsure of bore), Bryant 4.150 crank, PSI 206B. I think it's suppose to be around 512 ci. Looking for a nice set of heads. Is it possible to have too big of valves for an engine this size? Engine is going in a old Plymouth, so it won't be light or aerodynamic. Probably 3200 lbs. Hoping to go mid 6s. Any suggestions on head choices? There are a lot of great deals on a lot of different heads out there, and wanted to get something nice, unrestricted and modern, but didn't know if there's a point where the heads flow too much air. Will bigger valves help make same power with less boost? Less restrictive? I have no class rules to follow, just trying to build a fast car. Also, never built anything like this before, so any help/suggestions I can get is greatly appreciated.
    Thanks
     
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  2. jay70cuda

    jay70cuda Member

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    If I were building one today. My top choice would be mbe, he’s on top of it. Next would be nre. Not far behind. After that aj, Brad are kinda the same. All are great choices. But there were some current outlaw heads on here a few days ago. Can’t go wrong there. Always try and build way more than you think you need. Easier to back it down by lowering shifts or dropping timing then trying to stand on it harder and wishing you had More.
     
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  3. Mike Canter

    Mike Canter Top Dragster

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    I agree 100% with jay70cuda. With a PSI screw blower you want the biggest valves your class allows. If you have a Roots blower then smaller valves to keep the velocity up.
     
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  4. SpeedDemon

    SpeedDemon New Member

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    This was my thinking too.
    Again, not knowing anything about the capability of this blower, I was unsure on head choice and just how "big" I could actually go without having an adverse effect on power or tuning. I have seen int. valve sizes from 2.400-2.550. Now I know I can safely persue the bigger sized valve options with no worry.
    Thanks Jay and Mike for your experienced input.

    Btw, thanks to all on this great site. I've learned a lot from you all in a short amount of time. Thanks for sharing your knowledge.
    Lance
     
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