Dpad, you may try posting your seat question in the "Fiberglass & Paint" forum or even the "Restorations & Upgrades" forum for more responses.

well we found the problem the hard way, after doing all that was stated one thing was over looked the oil bypass valve we found the oil leak was the also the front of the pan.

So it was the oil by pass not allowing the oil to go into the cooler and we where cooking the oil in the motor the reason i never picked up on this was the motor never ran hot temp wise and the oil temp gauge was not working correctly, on the last run sat we idle out takes about 12 mins to hit the end of the harbor, I throttle up and off we went at 3k things where great motor sounded great all the gauges where on the money. Then i felt it and heard it a loud thump pulled power off we open the hatch and the motor turned off, There was a smell of burnt oil and smoke coming out thbreatherer caps.

I pulled the dip stick and burnt my fingers it was so hot and the oil which was fresh was brown and smelled burnt nuts. I pulled the filtertler and a load of metal spun the main bearing. So now the motor is off to a marine racing engine builder to see how bad it is. might go 30 and super charge it what are the pros and cons of super charging

I wouldn't feel too bad, from your initial description it sounded like the motor had already croaked, you just witnessed the funeral this weekend.

You will be much happier when you get this back from a REPUTABLE builder who rigs this motor properly and sends you out set up properly. As far as supercharging, what kind of boat is this and what speeds are you hoping to achieve?

You kept running the boat, even though it wasn't right....and now you want to add a supercharger? The supercharger will help show a problem that you are ignoring even quicker :D

Hopefully you learned a lesson ins boating. If a car has a problem, you can sometimes get away with still using it every day, rolling around being easy on it. Now take that car with a problem, and tow a heavy trailer up a hill all day at 3500 rpm, you won't make it far....and that is the load a boat puts on a engine.

Get it right, put some time on it, learn from it without the supercharger.

its a 1979 super boat 24ft the boat was custom built at super boat in 79 for poker runs meaning its a little heavier then you would think it should be it handles 2/3 ft chop really well long island sound back in the early days it had a 427 solid lifters and dry exhaust had a Volvo single prop then would do about 60

that motor is long gone now the boat has Volvo 290 drive with D8 dual props we are going to D9 in the summer

with the motor that was in it we tapped about 65 with ease i like to be in that range max out about 70/75

like to cruiz at 35 to 40 at 3k

Adding that 5 mph is going to be expensive. Nevermind the motor mods, when you start hovering around 70mph you really need to seriously consider hydraulic steering. I don't even know where you would get such a critter for an old Volvo. I would forget all about the supercharger and start looking at a healthy NA motor. Since your crank is junk anyway you might as well stroke it out to a 540. Put a decent set of heads on it with a good roller cam and this motor is going to have more than enough steam to hit 70. A call to Bob Madara can get you on the road to a healthy build that will achieve what you want without the added complexity of supercharging. Be warned though, there is no cheap way to get reliable speed out of a boat. Everything needs to be quality - parts, the combination, machining, assembly, and rigging. Cheap on any aspect and you will experience failure all over again.

Good call thanks 65 to 70 in a 24 ft boat is fast enough on the water ill stay with the 750 double pumper the intake we are using is off the original 427 motor which i understand is a OEM vet intake from 79 what type of head setup would you suggest and cam timing and duration now that we are going 30 over to a 540

Um, 0.030 over will just take you to around 509 CI. You will need to add a 4.25 stroker crank to achieve 540 CI. If you do that, kiss that 750 cfm Holley goodbye, along with the 1960's era intake manifold. Even on a 502, the 750 will be too small - you run the risk of leaning it out and melting it down. I'm running a Holley 800 on a 489 (stroked 454), and I should probably be running something larger, like a 950 HP.

Stick with the 509, you will be happier.

So, do I get a gold star for correctly diagnosing your problem? ;)

Help me to understand please, if he is carbed too small, that will be an intake side restriction, but if jetted properly won't make it lean unless there is something more here that I am missing. I do agree that a 750 is way to small for a 540, probably even too small for the 502 he had