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  1. Scott06

    1990 vs 1992 4.3 block swap

    Try a OEM merc impeller and housing. Its been a few years since I had a gen 1 but I found they last twice as long as the sierra ones. Not a huge data set but on both the gen one and gen two drives the OEM impellers last a very long time. Definitely the gen 2 design is better but I think you will...
  2. Scott06

    1990 vs 1992 4.3 block swap

    Whose impellers are you using ? Muffs can sometime be tough to get in a spot where it flows fully
  3. Scott06

    7.4 carb with Thunderbolt V - Cant get into base timing

    Only two things to check on throttle cable adjustment does it positively close the throttle against the speed screw, and does the throttle open wide …
  4. Scott06

    No Spark on 1988 4.3 ltr. engine

    From seeing his posts dont think english is his first language but seems to have worked on engines etc. and has some knowledge base. He is saying test the coil with an ohm meter before you replace it. You can find a bunch of you tubes on how to test primary and secondary side (thats what he...
  5. Scott06

    Am I just nuts???????

    Then may be worth doing it. I also collect old cars and love to work on my daily drivers ( which have a lot of miles). I might suggest and old tin starcraft vs trihull as they are relatively indestructible. Might be better channeled into older cars, like things that will be classics in 10...
  6. Scott06

    Am I just nuts???????

    Yes you are nuts I wouldn't invest the time in this boat. Unless you love it or have some sentimental attachment to it I cant see it be worth the effort.
  7. Scott06

    New boat with merc 5.7

    There is a man overboard switch on some models usually a red toggle switch on the shifter. It cuts ignition of when the key is in run and the switch is tripped. I think during start the ignition system is feed off the starter lug during cranking. On my boat if the MOB switch is tripped the...
  8. Scott06

    7.4 carb with Thunderbolt V - Cant get into base timing

    That's what I was gonna say something is wrong the throttle cable should push it back against the idle speed screw. the few mercs that use a throttle return spring (357 Alpha does) it is there as a back up - really the throttle cable should be adjusted such that it pulls it back against the...
  9. Scott06

    Mercruiser 4.3LH backfiring & weird timing

    Yes and around the circumference of piston looks pitted ? Not sure if that is detonation marks? center piston says 030 on it which normally would imply a 030 overbore on rebuild but other pistons have no such marks
  10. Scott06

    7.4 carb with Thunderbolt V - Cant get into base timing

    It really is not an issue that matters. You don't use the boat in base mode. Set the mix and speed on the water in gear. I usually do it in my hoist or tied to the dock. Or replace the module ...your call
  11. Scott06

    New boat with merc 5.7

    You can google homemade spark gap tester and find a bunch of ways to coble one. If you have a system that works for you stick with it, I'll try the timing light next time. Just really stuck out at me on a inexpensive tool how different the spark looked on a poorly performing system vs when I...
  12. Scott06

    New boat with merc 5.7

    Yes has its place too but I had a outboard where you could see a spark on the plug, this was an old 2 stroke with little gap on the plugs. Was hard to start and would bog at mid range rpm then catch eventually at higher rpm. Both coils were DOA... the difference between old and new coils on the...
  13. Scott06

    New boat with merc 5.7

    As Nola mentioned a couple teaspoons. I use an empty small food container to dribble it in a teaspoon or so at a time, you can keep it running this way if it is fuel starved but has a good spark. Not to beat a dead horse but did I mention using a spark gap tester. One of the best tools for...
  14. Scott06

    496 HO Failure

    Handle the diagnosis as you see fit, just make sure the owner can and does check his oil level before going out. If the oil wasn't so low I would also think more diagnosis is warranted. I personally wouldn't want put my name behind anything less than a full tear down given the lack of lube. As...
  15. Scott06

    7.4 carb with Thunderbolt V - Cant get into base timing

    I wouldn't worry about the base timing if it works 32 is a reasonable total advance for your engine. In the old days when they would put the advance degrees on the module I cant recall if a 7.4 was 32 or 36. I suspect now that you aren't loosing voltage it probably runs fine. If it does leave it...
  16. Scott06

    New boat with merc 5.7

    Hook up a small gas tank to fuel line or use an outboard tank to test. Or dump fresh gas down carb should stay running if you dribble fuel down it if you have spark and its fuel related Use a $10 spark gap tester to asses spark strength should be blue or white and jump at least 3/8"
  17. Scott06

    No Spark on 1988 4.3 ltr. engine

    No on bench testing of the module. There is a thunderbolt igntion diagnostic flow chart in the stickies at top of mercruiser section to diagnose no spark in TB system. I think first thing is measure 12 v at coil ….if you have 10.4 youre loosing voltage . Make sure batt is good and fully charged...
  18. Scott06

    GM EST Distributor Kit and Mercruiser Shift Interrupt Switch

    no rev limiter and no knock sensor A lot of folks in the perfomnace crowd use it because it has no rev limiter
  19. Scott06

    New boat with merc 5.7

    There are more drain points on a 5.7 than a 3.0. You can use af in block but drain it first. Personally I leave mine dry and drained but that debate is like a which oil is best discussion. Do you have a serial number for the engine so we know what version of the 5.7 you are working on? Would...
  20. Scott06

    GM EST Distributor Kit and Mercruiser Shift Interrupt Switch

    This is the Delco EST the OP was talking about . Its a good OEM quality system that is more cost effective than replacing a Thunderbolt module (unless you can find one used). https://marineenginedepot.com/distributor-kit-57l350ci-74l454ci-gm-delco-voyager-est
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