455 cam choice and rpm

Discussion in 'Street/strip 400/430/455' started by Buickpwrdolds, May 21, 2020.

  1. Buickpwrdolds

    Buickpwrdolds Well-Known Member

    Just want thoughts from bigger brains than mine before I spend big. I have:
    75-76 block, chamfered main feed holes, radiused 90* turns near pump
    Std bore, Wiseco 22cc forgings
    Stock rods, resize w/ arp hardware
    Crank turned and assembly will be balanced
    Big valve 430 castings from a fellow member
    1 7/8 headers
    Most likely will go b4b if not just for my back.
    I calculate static at 9.7:1 with my deck height and gasket. I'm looking for a 425-450ish hp motor I can cruise around without having TOO much fuss, but I also don't mind knowing it's not stock if that makes sense. I've been eying the ta 284-88h, as it seems it should make good torque, and pull to up around 51-5200. I also figure this combo should, provided the machinist hits the marks, be safe to turn around 5500, so that seems like a good match. Does my thinking make sense on this?
    If no, what rpm should I be sure to keep it under, and/or which direction should I go cam wise?
     
  2. johnriv67

    johnriv67 Well-Known Member

    Based on that head flow, I’m thinking you could go for an even bigger cam. Worst case scenario you deck the block or cylinder heads or pick a thinner headgasket.
     
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  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    The TA 284/88H will put you at 7.55 Dynamic compression with 9.7:1 static.

    The TA 290/94H will be 7.23 DCR

    Go with the smaller cam.

    425-450 HP, it will depend on the heads.
     
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  4. johnriv67

    johnriv67 Well-Known Member

    If you up the compression, I’d say bigger cam.
     
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  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    What gears out back?
     
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  6. Buickpwrdolds

    Buickpwrdolds Well-Known Member

    I have cometic gaskets already so that's as thin as it gets for the late block, so 9.7 is where we're locked in at. Heads are said to flow 251/187 I believe.
    3.50 gear and a 275 tire Larry. The th400 will be gone through, and probably get a converter from TSP at some point.
     
  7. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    275/60R-15, or 275/50R-15? One is 28" tall, the other is 26". The taller tire will give you less gear (~3.32), the shorter one, a bit more (~3.58)
     
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  8. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    Spend good money on the right converter. Do it before you swap the new motor in. Have you measured the deck height?
     
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  9. Buickpwrdolds

    Buickpwrdolds Well-Known Member

    275-60/15, my bad. Gear change isn't impossible, especially being a 9 inch.

    Got .085-.087" to the stock 75-76 pistons which should be 1.935 pin height iirc. Have not measure with new pistons but they are 1.980.
     
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    OK, so you'll have about 3.32 effective gear ratio. Get one of Jim's 9.5" converters.
     
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  11. Buickpwrdolds

    Buickpwrdolds Well-Known Member

    Plan was to match converter and gear if need be to the motor, so good to hear I'm at least headed the right direction. Just wanted to be sure I'm not too optimistic about rpm and the likes.
     
  12. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    To answer your rpm questions I would build it on the tight side to keep oil pressure up. .002 on the rods and .0025 on the mains. Make sure the oil pump is perfect and 5500 will be fine. The wisecos are kind of heavy so i wouldn't go past 6k. With the right converter it'll run good. 450 hp is optimistic with a mostly stock build though.
     
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  13. Buickpwrdolds

    Buickpwrdolds Well-Known Member

    Unless the machinist misses his marks that's what I should have. The timing cover looks really good so I was just planning on getting a standard volume pump set up perfect and uing the adjustable regulator. Perhaps I've been reading too many magazines on the number, just seems to be several running good times with less compression on small valve heads so I got a little optimistic :rolleyes:
     
  14. 70 GMuscle

    70 GMuscle Plan B

    What about the 288-94.
    They call the sleeper grind.
    230-240@ .050
    504/504 lift.
    114 lobe centers.
    Idle nice and rip.
    Never know who you may pull up next to. Might have to take em down, lol.
    Lot of fast stock cars out there now and our Buick’s need to showem who’s boss.
     
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  15. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    It will all depend on the head flow.
     
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  16. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    TA 288/94H will be 7.18 DCR with 9.7:1 Static. The smaller cam (TA284/88H) gives you 7.55 DCR.
     
  17. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    I think another point of compression will help big time for the goals.
     
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  18. Buickpwrdolds

    Buickpwrdolds Well-Known Member

    Larry heads are quoted to me as flowing 251 cfm intake and 185 cfm exhaust. I can't prove it as I don't have them yet but they are supposed to have been in the 11's on the previous engine.

    It's worth noting that if I get 400 or a tick over out of it I will be happy with it, just been reading about similar builds making good numbers (perhaps a little fisherman storytelling) got me wondering if I was on it with cam selection etc
     
    Last edited: May 21, 2020
  19. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    251 can make some power. The question is at what lift? I would assume thats the peak number at max lift it was tested, probably .600. Your cam is .475 lift, so you will not see 251 cfm.. obviously you can swap a higher lift cam but you'll need more compression to make that work. The other option would a custom roller cam with a high lift and short duration.

    I would either add some compression or run a small cam and focus on the mid range.
     
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  20. Buickpwrdolds

    Buickpwrdolds Well-Known Member

    You may well be correct on that as I don't have numbers for specific lifts. These are the 109's that Ol Blue just had for sale on the board, off a 470 from Steve Reynolds's 70 gs. Porting was done by TA. I've not been here long enough to know anything about the car or the engine other than that.
     

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