496 stroker bbc compression
+ Reply to Thread
Results 1 to 6 of 6

Thread:
496 stroker bbc compression

  1. #1
    Junior Member
    Join Date
    Jan 2014
    Location
    clermont ky
    Posts
    2

    Default 496 stroker bbc compression

    I have a 81 Nordic 20 with a berkley jet. I have built several car engines but this is my first marine. My engine is a 4 bolt main 60 over 454 stroked to 496 with scat forged crank, rods and wiesco +30cc pistons all balanced. With my 292 heads I'm now afraid I will have to much compression for my boat. What do you think? Also i don't have a cam yet. Im worried about reversion with my basset water injected through transom headers, air gap single plane intake and a 750 holley Msd distributor and Msd box.

    Thanks

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    Senior Member hihosilver's Avatar
    Join Date
    Mar 2009
    Location
    bullhead city
    Posts
    500

    Default

    running similar stroker 30 over closed chamber almost .600 lift , bassett headers, a little over 10 to 1 comp. 91 octane with no issues

  4. #3
    Junior Member
    Join Date
    Jan 2014
    Location
    clermont ky
    Posts
    2

    Default

    With my closed chamber heads I think I will be around 12 to 1

  5. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  6. #4
    Senior Member H20MOFO's Avatar
    Join Date
    Dec 2007
    Posts
    4,288

    Default

    As far as the cam......I am told as long as you keep the headers dry to at least 2k r's....you should be fine as far as reversion.
    Another Hot Boat refugee

  7. #5
    Senior Member bc18's Avatar
    Join Date
    Jul 2008
    Posts
    950

    Default

    Quote Originally Posted by BigRed77 View Post
    With my closed chamber heads I think I will be around 12 to 1
    Youll need to run good fuel.

    i wouldn't go over 250 on the duration at .050
    Last edited by bc18; 09-13-2015 at 03:38 PM.

  8. #6
    Muffler City Old as Dirt's Avatar
    Join Date
    May 2015
    Location
    Monroe, Wa.
    Posts
    489

    Default 12:1 496

    High compression isn't a problem.. just have to run good fuel and keep the timing under control(right close to 36* total).. big HP is fun.. and with the weight of your 20' boat.. the more the better..

    H20MOFO is right.. get a spring loaded valve inline with the water cooled headers that only allows water into the headers after 2K rpm.. spring pressure is key.. play with it, as rpms increase, so does the water pressure at the pump.. so you'll need to dial that in..

    Like to also say... a BBC with close to 500CI.. needs a bigger carb than a 750DP Holley.. go bigger... a 2-circuit 950-1050CFM Holley would be my choice...depending on the cam and the rpm you plan to run it at.. going to run mine to 7400rpm MAX..

    I am running the same basic 496 combo, right around 650HP.. stroked MKIV 454 with 088 GenV heads(open chamber rectangular ports) w/2.25" intake valves and 39cc SRP Forged Pistons..

    12.07:1 and it lives on 100LL Avgas... pretty blue fuel @ 6.00 a gallon... might look into E-85 @ 2.78 a gallon... cheaper but burns 30% more fuel than the blue stuff... so will have a shorter cruise capacity, just have to carry more fuel with you when you take it out.. any way you look at it.. it needs higher octane than pump Premium to keep it happy..

    Cam is 271/282 @ .050" Duration Comp Solid Roller w/.680" lift, easy on the valve train.. AR306-10..
    Single Plane Team G manifold and an 1150 Holley Dominator... dry "Rewarder" headers.. have fun!
    Last edited by Old as Dirt; 09-14-2015 at 12:32 PM.

+ Reply to Thread

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