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  1. joseph.signore

    Proper spark plug gap

    1991 5.7 350 magnum with thunderbolt ignition. Alpha one gen one drive. I plan on changing my spark plugs (ACDelco MR43T), but not sure of the proper gap. Thank you in advance, Joe
  2. joseph.signore

    Possible ignition problems

    I have a 1991 5.7 350 magnum with thunderbolt ignition alpha one gen one: I?m having power loss and then stalling issues when the motor gets to normal operating temperature. The engine runs fine after cooling and I suspect the problem is one of the ignition components. I see three but not sure...
  3. joseph.signore

    Thermostat replacement

    Can anyone help me with a thermostat replacement. I have a 1991 5.7 Merc Magnum 350 with thunderbolt ignition and a four barrel carb. The outdrive is Alpha one/gen one I'm reading conflicting threads that claim both 140 and 160. Thank you in advance.
  4. joseph.signore

    Alpha one gen one... new Water pump overheates

    Water pump help 1991 Regal: I recently changed my water pump in my Alpha one /gen one outdrive that cools a mercruiser magnum 350 engine. I installed a new impeller, housing and gaskets. I put everything back together exactly as removed and carefully double checked before reassembling. When I...
  5. joseph.signore

    Cold Start sputtering\w fumes

    My 1991 mercruiser 350 magnum with a 4 barrel quadrjet carburetor started sputtering and lightly smoking (white fumes) only when the engine is started cold. The motor seems to be loaded up and clears and runs fine after I race the throttle or a few minutes of warm up. I?ve cleaned the air...
  6. joseph.signore

    Damaged Prop Help

    Last weekend I had drifted out of the channel and hit the bottom hard. The bottom was mostly sand however my prop has damage to all three blades each blade has a nice ding taken out. The banging noise was so loud I was sure my outdrive had damage but seems to be fine. My boat is a 1991 25.5...
  7. joseph.signore

    Type of oil to use???

    Dose anyone know what the best oil to use? Type and brand for a 1991 Mrec 5.7 350 with 700 hrs. Book says SF or SG. Ive been using Castro SAE API- 30w. I thought SG was for moterbikes. Thanks,
  8. joseph.signore

    Could Bad Timing cause hydro/vaporlock

    I need help please. I have a 1991 Mercruiser 5.7 350 Magnum with Tbolt ignition. I just repaired some issues from water in oil and port cylinders as follows: Replaced both risers, manifolds and gaskets with all Merc parts. Replaced both heads, gaskets and intake gasket. (after finding a...
  9. joseph.signore

    How do I perform a Leak-down Test?

    Dose anyone know how and what tools needed??? I have a 5.7 Merc Alpha.
  10. joseph.signore

    Water in all four port side cylinders and oil

    I need help please... I'm getting raw water in all four of my port side cylinders and water in my oil. I have a 1991 5.7 350 magnum Alpha one mercruiser. I changed my risers, exhust manifolds and checked for blockage out to the stern drive and still have the problem. the moter runs fine with no...
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