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  1. Scott06

    Engine fogging

    No issue With carb at all.
  2. Scott06

    MerCruiser 4.3lx shortblock compatibility?

    Missed that. Then yes rebuild the junk yard 4.3 vortec... unless it has good compression. if so might get away with just changing head gaskets and core plugs
  3. Scott06

    MerCruiser 4.3lx shortblock compatibility?

    You can re jet your weber carb for the vortec heads. The weber carb is essentially the same as the edlebrock 1409. There are a few threads here where guys lay out the jetting needed to work on a vortec 4.3 If there is nothing wrong with your current short block take the donors heads to a shop...
  4. Scott06

    1986 Mercruiser 470/170hp/3.7L Carb backfire, low vacuum, other weird issues

    Ok if cooling system holds pressure head gasket is ok, look elsewhere for low compression rings or valves. Rule out dwell and timing.
  5. Scott06

    1986 Mercruiser 470/170hp/3.7L Carb backfire, low vacuum, other weird issues

    You said the AF side of the cooling system did not hold pressure, correct? if so there is a leak somewhere could be heat exch. Would do a poor mans leakdown test or rent a leakdown tester to see if valves are leaking by and verify dwell timing and Scott recommended. Hard to say from the...
  6. Scott06

    1986 Mercruiser 470/170hp/3.7L Carb backfire, low vacuum, other weird issues

    Find out if you have a valve leaking past seat that would be my inclination with low compression and backfire
  7. Scott06

    1986 Mercruiser 470/170hp/3.7L Carb backfire, low vacuum, other weird issues

    cyl 2 is basically dead cylinder or close to it 3 &4 are not far behind. Videos looked fine based on what you saw with pressure test I would guess head gasket. Since you could loose cooling system pressure other places besides head gasket Get #2 up to tdc with valves closed put compressed air...
  8. Scott06

    MerCruiser 4.3lx shortblock compatibility?

    Yes but you can likely prop around one or two steps in outdrive ratio like I did. What I surmised from my repower is each ratio step is approx 2" in prop pitch. This allows the boat builder to keep all different hull and power train configurations basically working within the 15"-23" 'normal'...
  9. Scott06

    1986 Mercruiser 470/170hp/3.7L Carb backfire, low vacuum, other weird issues

    Yes take the plugs out and ground the coil wire (take dist end off the cap) and ground. Spin it on starter. You want to look for even movement on every valve. Intakes and exhaust may have different lift amounts but all intakes and all exhaust should move about the same. The clips on the rockers...
  10. Scott06

    MerCruiser 4.3lx shortblock compatibility?

    Yes probably. I kept my V6 drive (1.81) with the 5.0 (stock except for intake and Edlebrock 1409) that should have by the factory had a 1.62 drive. I had to go up from a 19" pitch to 21" pitch. If I knew then what I know now I would have done a 5.7 instead of a 5.0. Boat was not offered with a...
  11. Scott06

    1986 Mercruiser 470/170hp/3.7L Carb backfire, low vacuum, other weird issues

    That temp is too high , likely you have blown a head gasket as 3.7 s are very sensitive to over heat due to open deck block design. do a compression test , if ok have you checked ignition timing? replace impeller make sure heat exch is clean. Do you have milk in oil ?
  12. Scott06

    MerCruiser 4.3lx shortblock compatibility?

    Have to agree with Scott. While a vortec head intake and carb swap will gain 20-30 hp if you have a 22 ft boat just get a 5.7. I did a 4.3 to V8 swap. Since the front and back of the 4.3/5.0/5.7 blocks are the same, you can keep a lot of your accessories and piece it together easily. Certainly...
  13. Scott06

    Fuel Pump Wiring

    https://www.justanswer.com/boat/5y7cc-wirer-electric-fuel-pump-installed.html this is a link to the merc wiring diagram shows how the OEM two terminal switch (6) is wiring into the harness and splice from starter terminal to fuel pump (7).
  14. Scott06

    Fuel Pump Wiring

    You need to add a new switch that is the oil gauge sender with one wire on it. If you look at parts 41,42,43 in this diagram they use a 1/8" npt T to put the sender (41) and oil pressure switch (42) into the oil system. You can reuse your sender and get a 1/8" T and pipe nipples to attach...
  15. Scott06

    Working During Winter

    Why not just pull the drain plugs after every time you use it? In mine this takes 10 min... You could do a tub if it were big enough and you had the refractometer to check and top up AF strength. Would need a huge tub I think the marinas that winterize this way use a couple 100 gallons of PG...
  16. Scott06

    Dieseling after shut off and loud noise when trim is higher in shallow water

    Agreed trim it back down a hair and the rattling should stop
  17. Scott06

    Dieseling after shut off and loud noise when trim is higher in shallow water

    Our dock is in shallow water (27") so every time I go in or out we are at max up on the trailer button. Important to keep rpms at a min doing this Would pull your drive check gimbal bearing, U joints, and engine alignment. Check bellows for cracking or splits. Also a good time to do the water...
  18. Scott06

    Mercruiser overheating

    Take the elbow off and see if the passages are clear. I think you may also be able to take a cap off each end of yours. As along as water can flow it is ok
  19. Scott06

    Mercruiser overheating

    In freshwater they outlast the boat. Have had boats 40+ years old with original exhaust manfiolds in perfect working condition
  20. Scott06

    Mercruiser overheating

    I would bet the passages in your thermostat housing are plugged. The one "after the thermostat" -I assume you mean the hose that feeds water to manifold? that should be flowing some water at all times to cool the exhaust even when the thermostat is not open. Or do you have a separate feed to...
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