Engine break-in/Tach question...

Discussion in 'High Performance Modifications' started by 71RS350, Feb 29, 2012.

  1. 71RS350

    71RS350 Moderator Staff Member Gold Member

    May 10, 2004
    hey guys...I just about got my engine back together after doing head/cam swap....and my car doesnt have factory tach....i thinking about buying temporary cheap sunpro tach..to make sure i keep it at 2000 rpms during cam break-in.....how hard is it to temporary wire up a tach? just for the 30 min cam break-in....

  2. muscl car

    muscl car Veteran Member Lifetime Gold Member

    Jul 8, 2001
    san bernardino calif
    red- 12 volt switched power

    white - 12volt dash lights

    green - (-) neg side of the coil or connected to tach input on HEI distributor


    you can just find a (+)12v switched hot wire or tap into your fuse box to a switched 12v source and attach the tach's red wire to it . next take the green wire and attach it to the coils (-) side or HEI tach pick up then find a suitable ground location and attach the black ground wire from the tach to this ground source and you're ready to use the tach

    now if you're going to break in the motor during night time and need the tach illuminated then you can take the white wire from the tach and wire it to the same location your red wire is terminated to

    now if you want to make wiring easy you can also use "test leads" wires with alligator clips on either end to make wiring the tach in easier and quicker .i've also have used the (+) pos side of the coil or HEI (+) 12v connection to get a quick power source for the tachs red wire

    hope this helps ya .....:):)

    Last edited: Feb 29, 2012
  3. 70 gsconvt

    70 gsconvt Veteran Member

    Sep 30, 2009
    Wadsworth, OH
    And go to any GM dealer and get a bottle of their break-in fluid. Good stuff.
  4. 71RS350

    71RS350 Moderator Staff Member Gold Member

    May 10, 2004

    Thanks!...seems pretty simple...think got some test lead wires laying around mite use that as quick temp setup....:confused: :crazy:
  5. COPO

    COPO Veteran Member Lifetime Gold Member

    Sep 15, 1999
    Toronto Maple Leafs
    You want to rev it to 3000 every couple of min.
    Per Crane: http://cranecams.com/uploads/breakin/548e.pdf

    7. Start the engine and immediately bring to 3,000 rpm. Timing should be adjusted, as closely as possible, to reduce excessive heat or load during break-in. Get the engine running fairly smoothly and vary the engine speed from 1500-3000 RPM in a slow, to moderate, acceleration/deceleration cycle. During this time, be sure to check for any leaks and check out any unusual noises. If something doesn't sound right, shut the engine off and check out the source of the noise. Upon restart, resume the high idle speed cycling. Continue the varying “break-in” speed for 20 - 30 minutes. This is necessary to provide proper lifter rotation to properly mate each lifter to its lobe. Should the engine need to be shut down for any reason, upon re-start it should be immediately brought back to 3000 rpm and the break-in continued for a total run time of 20 - 30 minutes.

    8. Let the engine cool, and then drain the crankcase and properly dispose of the oil and oil filter. Refill the crankcase with a premium petroleum-based oil, not a synthetic oil. At this point the initial “breakin” is complete. You can drive the vehicle in your normal manner. We recommend changing the oil and filter after 500 miles. You might want to put another 5000 miles on the cam before switching to a synthetic, if that is your preference.
  6. 71RS350

    71RS350 Moderator Staff Member Gold Member

    May 10, 2004
    Thanks COPO...will do...got comp cams break-in oil to do the break-in with for 30 mins then after cools change oil and filter..... i'm using Valvoline Oil with high zinc for flat tappet engines for final....

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