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Thread: Waking up a 351 with cam and heads

  1. #16
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    C9OZ-6250-A thats the cam for the 69 to 71 351w


    here is a duplicate from howard have to cross reference what JimG posted

    http://www.competitionproducts.com/H.../#.WnhibK6nG00
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  2. #17
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    I would want a cam with about a .500 lift thats about were most SBF heads peak flow
    something like a B cam with a bit more exh duration to make up for wet exh but should be no reversion
    A torqer II intake
    good exh a must


    best exh

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  3. #18
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    MIGHT use someting like the heads here with 170 cc ports and 1.9 valves

    http://www.edelbrock.com/automotive/...r-rpm-sb.shtml

    Also might consider GT40 heads ported
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  4. #19
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    Quote Originally Posted by turbo2256 View Post
    MIGHT use someting like the heads here with 170 cc ports and 1.9 valves
    http://www.edelbrock.com/automotive/...r-rpm-sb.shtml
    Also might consider GT40 heads ported
    I read a comparison article on aluminum heads for 5.0L (302) and the Edelbrock Performer was the best bang for the buck. Not the absolute best in terms of dyno performance but, not too far off. I was surprised how bad the stock GT40 heads were.

    Back to the cam... there seems to be a lot of choices here:
    http://www.lunatipower.com/Category.aspx?id=68
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  5. #20
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    i ported GT40s that out flow the smaller port edelbrocks and others say in the 165 170 180 cc port sizes.
    The 351s need a bit larger ports than the 40s actually but ported well do some low end torq.
    A hydraulic roller would be a good choice link bar lifters are a bit pricey.
    Something around 218 216 @ .050 intake ... 224 ish @.050 exh .500 lift a bit more on exh. advertised duration 260 270 area
    would most likely use a torqer II intake

    My 302 powered car runs a ford B cam with ported DOOE heads flow about the same as ported gt40s pulls 420 FWHP. This engine would do well in a boat although i realize many car engine builds wouldnt.
    exh would need a bit more lift and duration on the
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  6. #21
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    bottom one on this page for flat tappet hyd
    http://www.cranecams.com/212-219.pdf


    top 2 here maybe 3rd one for hyd roller
    http://www.cranecams.com/220-223.pdf

    not necessary this brand but similar cams
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  7. #22
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    I'm sure your GT40 heads do flow well. But, my issues are;

    1) Who would I get to do the porting locally and how can I trust them? 1b) Do they have experience with performance marine motors? (probably not ... in Toronto)
    2) What does it cost for a quality porting job by a well known builder?
    3) What is the cost difference from buying GT40 heads and porting them vs. purchasing an Edelbrock aluminum set ready to go?
    4) How big is the difference in performance between the two heads given it generally takes about 10 HP to go 1 mph faster?

    Given the Edelbrock product is a known commodity and the ported head will be different with each head, I think I'd go with what is proven and I can trust, to spend my money on.
    The only way I'd do GT40 heads ported is if 1) I already owned a set of heads and... 2) I could do the work myself properly (I don't have that skill) or... 3) I had access to a proven engine tech with plenty of experience porting marine engines for my application and...4) There was a significant cost savings or, substantial performance increase with the ported heads....

    But again, heads are not the big unknown. Cams are. What HP/TQ levels do those cams (posted above in links) support?
    Sean Conroy,
    1965 Formula Jr. (hull #2) project

    1972 Greavette Sunflash IV

    "A man can accomplish anything... as long as he doesn't care who gets the credit."

  8. #23
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    i can understand all your concerns. have built engines for many different venues ported a lot of heads and flow tested many competitors. example a set of edelbrock roval port heads that i installed on my 1988 23' 6" Seebold 454 that had the peanut port heads.
    They didnt flow their advertised numbers until i pocket ported them flow was 290 @ .500 lift.
    with no changes to the 400 hour 330 hp short block just installed the heads and tried 3 different intakes.
    a performer RPM, a Air Gap and a Torker II. the RPM and the Air Gap ran about the same as when it had peanut port heads and couldt fell any difference between them. the Torker II on the other hand the boat jumped up on plane and hit the rpm limiter 75 mph so quick my 10 year old son noticed the difference. It was like adding a 100 HP shot of NOS. reproping might have reached over 80MPH

    So air flow is HP a HP factor more so than cam. What is most unknown is what intakes do to air flow when possible have flow tested intakes bolted to a head gives better info on whats going to transpire.
    Cam is more about what RPM the HP/ TQ need to be for the application. Marine , jet boats, street, oval track, towing, strip, etc are all different. towing , off road, marine might be close to being similar.

    Building a 302 would go for ported factory iron for best results except some really high RPM usage as the port volume vs engine size matches up well

    Now building a 351 would recommend aftermarket heads. marine use 165 to 175 CC ports would also favor 1.9/ 1.6 valve sizes . So other things for marine build would be port locations best to remain in stock locations especially on the exh.
    Most of the heads in the above mentioned CC air flow reaches best flow around .500 lift then starts to only increase 5 or 10 cfm if that much. Look for the heads with the best flow rates at the low lift points below .500.
    got to go will talk intakes next
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  9. #24
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    a couple thoughts have come to mind. one is the edelbrock heads have a 1 3/8 x 1 3/8 port i believe this is a bit larger than a stock ford head possibly larger than most SBF gaskets. Is there enought meat on your manifolds to match up.

    the larger heads put the 351W within the same power potential range as a SBC with similar heads. Might look into cams used for marine use in the SBCs and find ford cams with similar grinds. Have read a few test were they built a 351W and a 350 as similar as possible were they produced only a 5 hp difference. have to wounder what cam was used in the 377 scorpion engine.

    Found edelbrok offers marine use coated BBC heads as a while back was suggesting parts for a engine build for a marine shop here. Dont know if its the same mill spec coating used on the SBC Brodix heads though.
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