502 bbc
Page 1 of 2 1 2 LastLast
Results 1 to 14 of 26

Thread:
502 bbc

  1. #1
    Senior Member HKROB's Avatar
    Join Date
    Feb 2008
    Posts
    620

    Default 502 bbc

    I have a bbc 502 in my 21' shockwave its a SLUG what can I do to get more power out my 502.I do have some parts on hand I could use.I would like 600+hp.

    Specs
    21' shockwave skier
    marine power 502-425hp
    stock exhaust
    weiand stealth intake
    demon 750 vac sec
    dominator 12s pump A-cut @4800rpm & 58 mph

    Parts I have
    Edelbrock vic jr rec port
    comp roller rockers 1.7 ratio
    Edelbrock oval port heads 290cc 100cc chambers
    Edelbrock victor oval port
    demon 850 dp
    Quick reply to this message Reply  

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    E-7 Sheepdog (ret) SmokinLowriderSS's Avatar
    Join Date
    Dec 2007
    Location
    Newton Ks.
    Posts
    6,834

    Default

    The rockers won't get you anything of consequence.

    I'd consider the heads (depending on what they'd do to the compression ratio (not too high), the oval port manifold (although, at a 502, I'd almost consider strapping the rect. port one on, kinda borderline size spot IMO). A better exhaust (tubular headers like my Lightnings) and a cam improvement.

    My 454 already had an RPM Air Gap and cam change when I put Lightnings on the stock heads. Gained 200RPM/50HP, no other changes (that was over log manifolds tho). My old exhaust was a choke-point.
    Now my heads are.

    If you were to have to buy heads, IMO you'd get more from a porting job by a pro for the same or less $$$ than buying the edelbrock heads, since you already have them, I'd try them.
    Just had factory iron ported, enlarged valves, reduced stem size (dropped a good deal of valve weight), installed exh. seats (one was cracked). Can't hardly wait to bolt them back on. $1800 ballpark and all the parts I selected.
    Quick reply to this message Reply  

  4. #3
    21 Daytona Outlaw's Avatar
    Join Date
    Dec 2007
    Location
    Artesia, N.M.
    Posts
    5,291

    Default

    pick up a copy of the April issue of Powerboat.

    Bob Teague has a tech section on engines, he has a detailed
    response to this question, it lists part #s and everything.
    Quick reply to this message Reply  

  5. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  6. #4
    steelcomp was here
    Join Date
    Dec 2007
    Location
    n/e TN
    Posts
    26,280

    Default

    The parts you have aren't bad, but you just need the right cam to bring them together. Kind of depends on the level of performance you're looking for.
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.
    Quick reply to this message Reply  

  7. #5
    Senior Member
    Join Date
    Feb 2008
    Location
    Avondale,AZ.
    Posts
    302

    Default

    Dump the 750 vac carb, they will not typically fully open at jetboat rpms, next the stealth intake, sell it to a car guy, a Performer rpm air gap is best with a stock or mild cam. Above that a Merlin single plane is IT!!! Cam is next change, with a log exhaust or center risers a Comp hydraulic of 288 or 292 works well. If you have a hyd roller or want somthing more specific, call me during business hours. TIMINATOR 623-877-8553
    MODESTY IS A CRUTCH FOR THE INCOMPETENT!
    Quick reply to this message Reply  

  8. #6
    steelcomp was here
    Join Date
    Dec 2007
    Location
    n/e TN
    Posts
    26,280

    Default

    Quote Originally Posted by TIMINATOR View Post
    Dump the 750 vac carb, they will not typically fully open at jetboat rpms, next the stealth intake, sell it to a car guy, a Performer rpm air gap is best with a stock or mild cam. Above that a Merlin single plane is IT!!! Cam is next change, with a log exhaust or center risers a Comp hydraulic of 288 or 292 works well. If you have a hyd roller or want somthing more specific, call me during business hours. TIMINATOR 623-877-8553
    The Demon 850 is a good choice for moderate performance. Don't bother with a dual plane intake on a jet. Either of the Victors will work for what you're doing, but the oval may be a better choice. Again, depends on what you want. The Victor Jr will hurt you some below 3000, but there's no real load on a jet down there. The oval will be strong in the 2500-5500range, but with 500ci, it may start to suffer on top much over 5500, which is fine... you're not going there, anyway. Some small mods to the heads would go a long way toward your 600hp goal. You can settle for an off the shelf grind, but I'd recommend getting the right cam for your specific application. The difference will be night and day, and probably the only way you'll get the 600hp you're looking for. I'd say some sort of exhaust upgrade will be a must.
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.
    Quick reply to this message Reply  

  9. #7
    Senior Member HKROB's Avatar
    Join Date
    Feb 2008
    Posts
    620

    Default

    Quote Originally Posted by steelcomp View Post
    The Demon 850 is a good choice for moderate performance. Don't bother with a dual plane intake on a jet. Either of the Victors will work for what you're doing, but the oval may be a better choice. Again, depends on what you want. The Victor Jr will hurt you some below 3000, but there's no real load on a jet down there. The oval will be strong in the 2500-5500range, but with 500ci, it may start to suffer on top much over 5500, which is fine... you're not going there, anyway. Some small mods to the heads would go a long way toward your 600hp goal. You can settle for an off the shelf grind, but I'd recommend getting the right cam for your specific application. The difference will be night and day, and probably the only way you'll get the 600hp you're looking for. I'd say some sort of exhaust upgrade will be a must.
    Would I get better results with Edelbrock oval ports or the Rec port heads with some port work.Is there anything that can be done to the Edelbrock heads to get better performance.I will be getting a cam form Clay smith or chris strab once the heads are ready.Also looking for a used set of lightning headers.
    Quick reply to this message Reply  

  10. #8
    steelcomp was here
    Join Date
    Dec 2007
    Location
    n/e TN
    Posts
    26,280

    Default

    Quote Originally Posted by HKROB View Post
    Would I get better results with Edelbrock oval ports or the Rec port heads with some port work.Is there anything that can be done to the Edelbrock heads to get better performance.I will be getting a cam form Clay smith or chris strab once the heads are ready.Also looking for a used set of lightning headers.
    Those Edelbrock heads will work, but might need a little work to get you to 600hp. A set of 310cc Canfields would be a better choice, or the small AFR's if you have the budget. You cana run either of those out of the box and your target HP will be no problem. When you decide, you'll need to get some flow numbers and have as much information available as possible on your build. Then contact Chris and he'll get you set up with the right grind per your application.
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.
    Quick reply to this message Reply  

  11. #9
    Resident Ford Nut Sleeper CP's Avatar
    Join Date
    Dec 2007
    Location
    San Diego County
    Posts
    10,072

    Default

    Just for a heads up; this is an engine I helped a friend with a few yrs back:



    The heads were Brodix Oval ports, I'll see if I can find the flow numbers for it.

    Sleeper CP

    "Dark Sarcasm"
    Going fast is only half the fun ... what you make go
    fast is the other half.
    " A Government big enough to give you everything you want is big enough to take away everything you have"
    Quick reply to this message Reply  

  12. #10
    Senior Member hotbo's Avatar
    Join Date
    Feb 2008
    Location
    lake Ouachita AR
    Posts
    4,677

    Default

    looks very nice,but the one thing i see is the heads on that build were brodix far superior to edelbrock anyday.


    i think with the parts you have it will run good.good luck,travis
    Quick reply to this message Reply  

  13. #11
    Resident Ford Nut Sleeper CP's Avatar
    Join Date
    Dec 2007
    Location
    San Diego County
    Posts
    10,072

    Default

    Here are the spec's on the Brodix heads:



    This was with light porting the Cam was a Crower Hyd. roller .650/.656 lift with 260/268 dur @ .050 and a 114* lobe sep. The engine had 9.2:1 comp.

    at the lift of .600 they were flowing 310 cfm the engine made 650 HP so with 650HP at 310 CfM's the engine was making 2.1 HP per Cfm. That is pretty efficient.

    Sleeper CP

    Big Inch Ford Lover/ sometime Chevy parts gatherer

    "Dark Sarcasm"
    Going fast is only half the fun ... what you make go
    fast is the other half.
    " A Government big enough to give you everything you want is big enough to take away everything you have"
    Quick reply to this message Reply  

  14. #12
    Member
    Join Date
    Mar 2008
    Posts
    42

    Default

    This topics is close to home for me just having a 505 built last summer by Timm, and am interested in reading about options for more power. While I am happy with the motor and speed gains, power/speed is like a drug, when you get some you want more. My boat is not a race type deal, just something to haul the family and friends and "rip" around every now and then.
    Quick reply to this message Reply  

  15. #13
    Senior Member HKROB's Avatar
    Join Date
    Feb 2008
    Posts
    620

    Default

    Still not sure what I am going to do.My 502 is bone stock with 130 hrs on it. I think I will just leave it alone and install my spare 468 (575hp) That should get me to my 70 mph goal.
    Quick reply to this message Reply  

  16. #14
    Member
    Join Date
    Mar 2008
    Posts
    84

    Default

    Those Brodix heads flowed 318 on the intake and the Edelbrock rectangle ports flow 320 out of the box on the intake so they are pretty close in flow except the Brodix heads were ovals. That cam would be pretty nasty for a jet boat application. That motor made good numbers for a 502.

    I'm helping a buddy put together a 454 to 496 stroker package for his 25ft i/o and would like to see 700 hp with a vortec making 6lbs of boost. I don't expect that motor to spin past 5400 rpms

    I would definitely go with a demon 850 with annular boosters. I installed one of these on my buddies cobra jet motor in his jet and we actually saw improved fuel economy as well as better performance.
    Last edited by thmper321; 03-31-2008 at 03:07 PM.
    Quick reply to this message Reply  

Page 1 of 2 1 2 LastLast

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Please select your insurance company (Optional)

Log-in

Digg This Thread

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •  
 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95