HP 500 EFI head gasket failure
#31
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From: Merritt Island, FL
#33
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#34
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From: park hill OK
Great to see you back up and running! I’m one of the few others that also have a 342 with factory 500EFIs, it’s a nice running boat with those motors. I’m approaching the first valvetrain service, this has convinced me to go full shot with heads off and new headgaskets.
#36
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From: park hill OK
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I’m at 74-76mph on gps. 74 right now with 30P B1 props at 4,600 RPMs. I have the original 28P B1 props that had been cut down a bit, those were 76 at about 5,000 RPM. The 28’s would blow out easily getting on plane, 30’s are much better. I also get really good cruise speed and good efficiency with the 30’s. 2,750 RPMs is 40mph at 1.6 mpg, which is where most of my runtime is. Lab finishing the 30’s is the plan - at some point, lol.
How about you? I’m very curious about the extension boxes.
#38
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From: park hill OK
Yeah, that’s got me thinking pull the motors when it’s time. I was going to just do the springs, retainers, etc and fresh rockers without pulling the heads because both engines still have all of the factory cable seals and I didn’t want to break them. But fresh headgaskets would give me way more confidence after seeing your situation.
I’m at 74-76mph on gps. 74 right now with 30P B1 props at 4,600 RPMs. I have the original 28P B1 props that had been cut down a bit, those were 76 at about 5,000 RPM. The 28’s would blow out easily getting on plane, 30’s are much better. I also get really good cruise speed and good efficiency with the 30’s. 2,750 RPMs is 40mph at 1.6 mpg, which is where most of my runtime is. Lab finishing the 30’s is the plan - at some point, lol.
How about you? I’m very curious about the extension boxes.
I’m at 74-76mph on gps. 74 right now with 30P B1 props at 4,600 RPMs. I have the original 28P B1 props that had been cut down a bit, those were 76 at about 5,000 RPM. The 28’s would blow out easily getting on plane, 30’s are much better. I also get really good cruise speed and good efficiency with the 30’s. 2,750 RPMs is 40mph at 1.6 mpg, which is where most of my runtime is. Lab finishing the 30’s is the plan - at some point, lol.
How about you? I’m very curious about the extension boxes.
#39
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From: park hill OK
I am also no genny and no AC, but everything else including a 50lb box anchor setup in my modified anchor locker. Shes a bit porky, but definitely rides nice on my wakeboat, mini yacht infested lake lol.
#40
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I have the cut down 28s, when they were fresh back from the lab I was at 80gps @5200, the props held very well. I am always gentle with the sticks when planing, cause of the bravo1 drives. I caught a log last year and dinged up both props, I fixed them myself cause I didnt want to spend another 1000.00 plus 2 weekends out. It hasnt run past 76 since. I was considering 30s after I do rebuilds on the engines. I cant cruise under 3000 and 3400 seems like the sweet spot at 50mph. I rarely take it to full throttle anymore mostly because of the hours.
I’m also no AC/genny.
Enjoy it and have a great season!



