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  1. 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...
  2. 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"
  3. 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...
  4. 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
  5. 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...
  6. 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
  7. Scott06

    Mercruiser 4.3LH backfiring & weird timing

    If its backfiring it is intake valve . can put air pressure in cylinder at tdc on compression stroke and see where it comes out most important to find out what happened and why is it running lean and tulipped valves detonation etc. if your timing was too far advanced could be detonation. Pull...
  8. Scott06

    Annual Mercruiser Maintenance

    Some of them look to be boiler plate. steering linakage look for play between steering arm and pin inside boat. play between steering cylinder and steering arm. I had two odd ball ones over the years - nut holding steering cable to steering cylinder mechanism got loose, also had at the helm...
  9. Scott06

    GM EST Distributor Kit and Mercruiser Shift Interrupt Switch

    Never seen the Delco set up that way. not sure why if it is working as it should -what the advantage would be? Can only think the stumble via the 12 v supply to that input on the module is controlled/timed through the module vs grounding out for as long as the shift plate/interrupt switch is...
  10. Scott06

    7.4 carb with Thunderbolt V - Cant get into base timing

    You can set your idle speed to 650 or so on the water and in gear, close enough. There is no test per see for the module. TBV is a great system until you need a module as they are NLA or $$$$. Most take it out and go back in with a Delco EST if they need a module. Since you have voltage drop...
  11. Scott06

    2011 4.3 Alpha MerCruiser winterizing question

    to the OP I think this has a video of your same set up being winterized. Would also agrees the single point drain system can clog and potentially not drain. Personally I would remove it and go back to multiple drain plugs if you have to disconnect all the lines and probe them to be safe...
  12. Scott06

    7.4 carb with Thunderbolt V - Cant get into base timing

    Are you starting the engine with the timing lead grounded or grounding it after starting? Procedure says to ground it then start engine. If your total advance is in the ballpark I would use that to back into a base timing setting. If you are loosing voltage could be in the engine harness...
  13. Scott06

    496 HO Failure

    Unless you can tell where the nuts and bolts sound is coming from he is looking at a tear down to fully diagnose. Would also think a rod bearing is the culprit or lifter/cam lobe that ran dry In the end it was run low on oil under load so you can tear into the engine to see what part of it is...
  14. Scott06

    Annual Mercruiser Maintenance

    In addition to above If those are closed cooling would check the freeze point before bedding it down for the winter, and also assume there is a change interval for the AF
  15. Scott06

    Boat choice

    That's another direct drive (engine in the center of boat) vs V drive (engine in rear of boat) Direct drive is design for skiing. I assume you are trying to find a way to get wake boarding without having to win the lottery. Here are a couple of videos doing just that that may be helpful in...
  16. Scott06

    Cold riser vs Warm riser

    A warm manifold set up will have two hoses constantly feeding cold water the risers snd two hoses feeding water from the thermostat when open to the bottom of the manifolds. This just keeps the manifolds at engine temp to keep condensation out of them. Either set up works fine if the engine is...
  17. Scott06

    Unidentified wire

    If you havent hit wot with either you dont know what they are capable of . This is the classic tradeoff on how you want to use your boat. If top speed is more important to you use the 3 blade. If you want better holeshot especiallyif loaded with people 4 blade is probably better as mentioned U...
  18. Scott06

    Unidentified wire

    Your oil pressure is fine as a rule of thumb 10 psi per 1000 rpm is perfect so at idle 25 is great You didn’t mention what is wot rpm for both props . You said at 3/4” throttle What are both props running at wot
  19. Scott06

    Oil in bellows questions…

    you can use the ball joint press The yoke is probably ok but I usually use OEM parts. The speedi sleeve willing to bet if you search here on iboat you will find the size . also you can find info about repositioning the seal about .030" rather or less deep into the housing so it rides on a...
  20. Scott06

    Oil in bellows questions…

    If you keep the original bearings no you do not need to reshim
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