97’ 330DA 7.4 has me baffled

Discussion in 'Gas Engines/Drives/Transmissions/Props' started by Climate East, Oct 9, 2019.

  1. Climate East

    Climate East New Member

    23
    May 14, 2018
    Greenville NC
    1997 330 DA
    1999 280 BR
    7.4L V-drives
    Had to replace my intake manifold due to a rusted hole in the exhaust crossover. I believe this is a common issue. Put it all back together and it fired right up. The issue is that the Rpm’s are surging at idle. 650-1400 then somewhere in between. Rev engine and it would have a very noticeable miss. Thought maybe a vacuum leak and of course the new manifold has a recessed square plug that I can’t get out to hook a gauge up to to test for that. I decided to to look at my carb gaskets which are the quadrings and replaced them. Same results. I noticed the carb wasn’t giving equal amounts of gas on both sides and the air idle screws made no difference. I said the hell with it and replaced it. It’s an Edelbrock 1410. Installed seemed to run good and went to adjust the timing but no marks on damper, just a line for TDC. I did verify that it is TDC. Installed some timing tape to the damper and did the whole base timing procedure by mercruiser and it seemed to be perfect. Rev the boat to higher Rpm’s with no missing or hesitation. Rapped things up and was going to put it in the water the following day to test under load. I keep this on a trailer in my yard. Went out to it the following day cranked it and it started to act up again. Pulling my hair out. Anyone know an easy way to get that plug out of the manifold? No trusted mechanics close by otherwise I wouldn’t be wasting my time on this. Any help appreciated.
     
  2. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    1/2" extension on a breaker bar should fit it.
     
  3. Climate East

    Climate East New Member

    23
    May 14, 2018
    Greenville NC
    1997 330 DA
    1999 280 BR
    7.4L V-drives
    It’s smaller than a 3/8” drive
     
  4. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Grind down a 3/8" extension until it fits.
     
  5. Climate East

    Climate East New Member

    23
    May 14, 2018
    Greenville NC
    1997 330 DA
    1999 280 BR
    7.4L V-drives
    That’s what I will do. Really curious why this engine is acting up.
    Thx
     
  6. Thornton69

    Thornton69 Active Member

    455
    Sep 15, 2014
    Northern BC
    1981 245 SDC
    1984 18' Valco sled
    5.7 260 Merc/ Bravo 2
    Evanrude 115/80 jet
    Did you confirm the ports on both of the manifolds were the same? (Oval or rectangular)
     
  7. Climate East

    Climate East New Member

    23
    May 14, 2018
    Greenville NC
    1997 330 DA
    1999 280 BR
    7.4L V-drives
    Yes, exact replacement.
     

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