Register

If this is your first visit, please click the Sign Up now button to begin the process of creating your account so you can begin posting on our forums! The Sign Up process will only take up about a minute of two of your time.

Follow us on Facebook Follow us on Twitter
Page 1 of 2 12 LastLast
Results 1 to 10 of 12
  1. #1
    jmz
    jmz is offline
    Registered
    Join Date
    Jan 2011
    Posts
    44

    Cam Specs on a standard 502 GM Marine engine?

    I am in the process of a repower on a Donzi 22. I went with the 502 crate (marine) from 1800runsnew.

    I called and asked them what the cam specs are and their response was that G.M. keeps those specs close to their chest and that they did not know the specs. ...sounds like B.S. to me but that is as far as I got.

    Does anyone know what the cam specs should be? ...standard 502. I am trying to order a distributor from DUI and they ask for the cam specs so they can set the advance up properly.

    Thanks,
    Jay

  2. #2
    Back in another old BAJA VIP Member Baja226sport's Avatar
    My Boats:
    2011 16ft Tracker Grizzly 40hp....Fast!, Baja 280
    Join Date
    Mar 2003
    Location
    PA/MD
    Posts
    1,884
    ENGINE MODEL

    454 MAGNUM

    502 MAGNUM

    8.2L


    Lobe Lift + .020 (0.051)

    Exhaust

    .342 (8.687)

    Intake

    .342 (8.687)


    Duration at .050 In. (1.27 mm)

    Cam Lift

    Exhaust

    227

    Intake

    211

    Journal Diameter

    1.94282-1.9492 (49.485-49.509)

    Journal Out Of Round

    .001 (0.025) Maximum

    Camshaft Runout

    .002 (0.051) Maximum

    Timing Chain Deflection

    3.375 (9.5) from taut position [total .75 (19)]

  3. #3
    Back in another old BAJA VIP Member Baja226sport's Avatar
    My Boats:
    2011 16ft Tracker Grizzly 40hp....Fast!, Baja 280
    Join Date
    Mar 2003
    Location
    PA/MD
    Posts
    1,884
    Found that @ Perfprotech.com

    Do a little looking on yahoo or google. It is not hard info to find. No secret. It would be mercruiser info not gm you would be looking for.

  4. #4
    Gold Member Gold Member 1BIGJIM's Avatar
    My Boats:
    Pachanga Twin 502s Bob Mandra Cams
    Join Date
    Jun 2004
    Location
    Omaha, Nebraska. Boat on the Mighty Mo! Longest river in the USA!
    Posts
    1,616
    GEN 6 Billet Roller Cam

    Mercruiser 454 502 Mag Roller
    Merc# 431-850478 / GM#12551622
    .004 300*/ 300*
    .006 288*/288*
    .050” 225*/225*
    .200” 125*/125*
    Lift .483”/. 483”
    ICL 109*
    LSA 115.5*

    I also purchased two brand new engines from 1800runsnew
    Took them apart to put in RMBUILDER cams, and did some headwork.
    Best of everything, no problems whats so ever.

  5. #5
    Registered
    My Boats:
    42' Sundancer from 2004 formerly known as Big azz cruiser from 2004. Still looking for the right new 38-42 ft. v-bottom!
    Join Date
    Apr 2009
    Location
    Denmark and hopefully some place nice
    Posts
    1,852
    Quote Originally Posted by 1BIGJIM View Post
    GEN 6 Billet Roller Cam

    Mercruiser 454 502 Mag Roller
    Merc# 431-850478 / GM#12551622
    .004 300*/ 300*
    .006 288*/288*
    .050 225*/225*
    .200 125*/125*
    Lift .483/. 483
    ICL 109*
    LSA 115.5*

    I also purchased two brand new engines from 1800runsnew
    Took them apart to put in RMBUILDER cams, and did some headwork.
    Best of everything, no problems whats so ever.
    What kind of gains did you see with the Bob cam? Did you do anything else? Different springs, lifters, valves, rocker ratio ect.?

  6. #6
    Gold Member Gold Member 1BIGJIM's Avatar
    My Boats:
    Pachanga Twin 502s Bob Mandra Cams
    Join Date
    Jun 2004
    Location
    Omaha, Nebraska. Boat on the Mighty Mo! Longest river in the USA!
    Posts
    1,616
    Yes, I had to change the springs to match the cams.
    As always, great idle, they pull to 5,000rpms no problem.
    The other reason I wanted new cams, was to get a fuel pump lobe.

    If I had to do it all over again, I would have saved the money for $4.00 a gallon gas.

  7. #7
    Registered
    My Boats:
    42' Sundancer from 2004 formerly known as Big azz cruiser from 2004. Still looking for the right new 38-42 ft. v-bottom!
    Join Date
    Apr 2009
    Location
    Denmark and hopefully some place nice
    Posts
    1,852
    Quote Originally Posted by 1BIGJIM View Post
    Yes, I had to change the springs to match the cams.
    As always, great idle, they pull to 5,000rpms no problem.
    The other reason I wanted new cams, was to get a fuel pump lobe.

    If I had to do it all over again, I would have saved the money for $4.00 a gallon gas.
    4$? C'mon. You should try boating around here. 9$ a gal.

  8. #8
    Gold Member Gold Member 1BIGJIM's Avatar
    My Boats:
    Pachanga Twin 502s Bob Mandra Cams
    Join Date
    Jun 2004
    Location
    Omaha, Nebraska. Boat on the Mighty Mo! Longest river in the USA!
    Posts
    1,616
    Quote Originally Posted by A.O. Razor View Post
    4$? C'mon. You should try boating around here. 9$ a gal.
    I would have to get rid of the first mate.

  9. #9
    Registered
    My Boats:
    1992 Rinker 236 SSV Solid Yellow Hull 625hp
    Join Date
    Dec 2007
    Location
    Detroit River/ lake Erie
    Posts
    774
    Quote Originally Posted by 1BIGJIM View Post
    GEN 6 Billet Roller Cam

    Mercruiser 454 502 Mag Roller
    Merc# 431-850478 / GM#12551622
    .004 300*/ 300*
    .006 288*/288*
    .050” 225*/225*
    .200” 125*/125*
    Lift .483”/. 483”
    ICL 109*
    LSA 115.5*

    I also purchased two brand new engines from 1800runsnew
    Took them apart to put in RMBUILDER cams, and did some headwork.
    Best of everything, no problems whats so ever.
    This is the right spec numbers for the new GM base 502 new engine only
    Last edited by Rockfish71; 02-14-2012 at 07:45 AM.

  10. #10
    jmz
    jmz is offline
    Registered
    Join Date
    Jan 2011
    Posts
    44
    Thanks All.

    My plan is to run it for a season and then consider going for a cam change too.


Page 1 of 2 12 LastLast

Posting Permissions

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


OSO Directory
All times are GMT -5. The time now is 10:12 PM.
Powered by vBulletin® Version 4.2.0
Copyright © 2014 vBulletin Solutions, Inc. All rights reserved.
Search Engine Optimization by vBSEO 3.6.1
Original Poster In Postbit provided by Original Poster In Postbit v1.0.0 (Free) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd. Runs best on HiVelocity Hosting.
Copyright 2011 OffShoreOnly. All rights reserved.