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  1. Lou C

    Compression test results 4.3L V6 2005 what do You think?

    Question: When you did the comp test was the engine warmed up and throttle valve all the way open? If not the results might not be as accurate as they could be. Also, I’m not convinced that the difference you saw is really enough to be concerned about on a 16 year old engine. I would definitely...
  2. Lou C

    4.3 OMC Cobra and or...

    I know people focus on top speed but the closer your WOT rpm gets to the actual redline the less strain on the engine every time it pulls the boat up on plane. Like a trailer tow gear ratio for your truck. My boat I feel is on the big side for a 4.3, 20’9’.
  3. Lou C

    4.3 OMC Cobra and or...

    Normal redline is 5,000. I had mine out in the bay today and it easily pulled 5,000. This is with a 15.5x15 prop. It limits my top speed but reduces the strain on my old 4.3. Fake cat is to keep birds from turning it into their bathroom.
  4. Lou C

    Compression test results 4.3L V6 2005 what do You think?

    If perhaps water is getting to that cyl from a leaky exhaust manifold to elbow gasket the exhaust valve in that cyl might not be sealing 100% due to rust. Might want to do a leak down test. If it shows leakage past the valves esp the exhaust valve I’d remove the exhaust manifold to take a look...
  5. Lou C

    97 four winns motor replacement

    It depends on if the 97 is a Vortec engine which has different cyl heads and different intake manifold (8 bolts to hold it down vs 12 for the pre Vortec). You have to check what you have. The 94 for sure is not a Vortec. It might be possible to use the cyl heads from the 97 on the 94 block if...
  6. Lou C

    1987 5.7 omc outdrive

    they are from a commercial site that sells parts, which then makes it against iboats policy. do a search, hint...the place is located in Ontario Canada.
  7. Lou C

    1987 5.7 omc outdrive

    taking that apart is like taking apart an automotive differential, you have be able to set preloads and rolling torque, there's more to it than you might think. Unless you have to tools and experience you might end up with another blown up drive. there are vids on a few sites that show what's...
  8. Lou C

    Power Steering Pump Test

    interesting I wondered if you can test a power steering/actuator & cylinder while off the boat? the old style ones with the seperate control valve and cylinder, can be rebuilt apparently because the same units were used in US cars back in the 60s and 70s, people are still using these on classic...
  9. Lou C

    1987 5.7 omc outdrive

    While your upper may look ok don’t forget that the bits of the failed gears are spread through the whole drive because the lube supply is share with the upper & lower. I would try and see if there is a local shop that could do it, it might be tough because of parts & special tools availability...
  10. Lou C

    4.3 Starter mount area cracked

    maintaining your exhaust is your #1 top maintenance job in salt water. My old engine is on its 4th exhaust system since I've owned it (bought in 2002). Replaced orignals in 2004, again in 2011 and again in 2017. No hydrolocks due to bad exhaust. Even with 3 sets of batwings!
  11. Lou C

    4.3 OMC Cobra and or...

    while the 9.3 or so comp ratio of the old 4.3s is low compared to modern designs we must keep in mind certain other factors it does not use a quench design, due to the use of GM full dished pistons this limits the amount of spark advance that it could tolerate before detonation becomes an issue...
  12. Lou C

    Stickies on Winterizing 3.0 cobra

    You will get mixed opinions on that, it depends on your storage environment. If you are in a dry climate it is not so critical but in a damp climate like I'm in, I always fog the boat because its stored outside. My collection of small engines I store inside so I don't fog those. Here with the...
  13. Lou C

    1987 5.7 omc outdrive

    Yep there are 2 ways to do that. If none of the shops near you will work on OMC Cobras that’s an option that’s worth pursuing. Go on to SEI’s website and read up on their Cobra conversion kit
  14. Lou C

    1987 5.7 omc outdrive

    nope that is the older style Aquatic drive system, the style that would work for the Cobra is the Volvo SX, 1994-2005 or so. The reason why is that OMC and Volvo went into a joint venture in 1993/4 and the OMC Cobra was redsigned to use cone clutch shifting. These were sold as the Cobra (up to...
  15. Lou C

    Stickies on Winterizing 3.0 cobra

    with AF, I also think its a good idea to test it at the lowest temp you might get if possible. I found that with my freezer set at zero, both the -50 and the -60 solidify, whereas the -100 definitetly will not nor does the Sierra no tox PG stuff I will mix up. So go by your local conditions, if...
  16. Lou C

    4.3 OMC Cobra and or...

    PS for my year (1988) they listed the timing spec at 1* BTDC for regular gas and 6* for premium gas this is why I used at least 89 octane. I guess they felt these were prone to detonation because in fact the centrifugal advance distributor is specified for only 12* at 3200 rpm. So 6 base + 12...
  17. Lou C

    Stickies on Winterizing 3.0 cobra

    If you can go on eBay and search for an original OMC Cobra owners/operators manual it explains exactly how to do it. These steps are also listed on a commercial website but I’m not allowed to post it here. The main points: Block drain and poke hole Manifold drain and poke hole Disco big hose at...
  18. Lou C

    4.3 OMC Cobra and or...

    My boat was specified to have the 15x17 but the WOT rpm was still lower than I wanted so I went with a 15.5x15, which lowers my top speed but reduces the load on the engine as I always felt that the 4.3 was a bit on the small side for my boat (20’9”). I can get 5,000 wide open. When I repower...
  19. Lou C

    Stickies on Winterizing 3.0 cobra

    If you are going to use that method, I suggest loosening a drain plug take a sample and put it in the freezer to make sure it won't freeze. I do think the antifreeze helps because when I start my engin up in the spring I do not get rusty water coming out of the exhaust.
  20. Lou C

    Fuel leak

    www.Holley.com
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