OK So I have a repower question.
I have a 18ft 1986 sea swirl spyder sport 178 with a Chevy 350, its a medium V hull, the hour meter was unplugged at 320 hours long before I bought it 2 years ago. when I started it up there was a lot of blow by and it eats oil. ~1qt @ 48 hours, guessing ~2 hrs a weekend for 6-8 months (summer season), do to a miss hap at the lake and bad guidance I'm now on my old prop (backup/spare) and I think I'm way under propped. Currently running 3 blade 14.5x19 (~50mph topped out), was running a 4 blade 15.0x21 (~65 Mph topped out, still spun to red line and pulled till the motor cant pull anymore, need a 15.0x23? maybe?) due to the lower pitch I was running it a bit higher more often for the speeds, so that could definitely explain the increase oil consumption, but that still seems like a lot to me.
So I'm really leaning towards a repower with another 350 but out of a 1996-2000 this way I can reuse a lots my current parts ( exhaust, oil pan, starter, fly wheel, starter, alternator ) and gain fuel injection, programmable ignition, starter, ECU, Vortec heads and more power . I know the motor will need new head gaskets and different freeze plugs
questions:
1) has anyone done this?
2) if i rebuild the motor, at this point why not do a 383 stroker? I know the OMC is power limited but if I pick up power under the curve and ease into peak... can the cobra take it?
3) Cam selection, 350 truck motor uses a close cam, but the peaks are moved up a 200-300rpm higher then a marine cam. is there a good hydraulic roller cam replacement? or reuse it out of current motor ( if its good)? If possible I'd ditch the tappet and go roller, needle bearings, 1.6:1 rocker, and high rev springs with head work ( porting, polishing, polished combustion chamber) so i can spin to 7-9k if needed
4) ECU tuning, so it looks like only tuner cat can retune the "black box" for easy retunes I should get a PCM411 (LSx computer), thoughts?
5)383 + EFi or 350 + CF blower+ EFI?
6) convert to closed loop or open loop cooling? its all cast iron, and fresh water. closed loop is a cost adder, its currently open loop.
7) addition of oil squirters, all of my high performance euro and diesel engines have them to help pull heat away from the piston and reduce the chance of knock. most marine engines are 60-75%+ load so it sounds like a good idea.... so not adding them seem silly with all that unlimited cool potential. however drag motors use scrapers and other meant to keep oil off the rotating assembly and reciprocating assembly ( added weight), but then again this is not once of those types of motors
i don't see a need to keep the carb, and smog system.
I have a 18ft 1986 sea swirl spyder sport 178 with a Chevy 350, its a medium V hull, the hour meter was unplugged at 320 hours long before I bought it 2 years ago. when I started it up there was a lot of blow by and it eats oil. ~1qt @ 48 hours, guessing ~2 hrs a weekend for 6-8 months (summer season), do to a miss hap at the lake and bad guidance I'm now on my old prop (backup/spare) and I think I'm way under propped. Currently running 3 blade 14.5x19 (~50mph topped out), was running a 4 blade 15.0x21 (~65 Mph topped out, still spun to red line and pulled till the motor cant pull anymore, need a 15.0x23? maybe?) due to the lower pitch I was running it a bit higher more often for the speeds, so that could definitely explain the increase oil consumption, but that still seems like a lot to me.
So I'm really leaning towards a repower with another 350 but out of a 1996-2000 this way I can reuse a lots my current parts ( exhaust, oil pan, starter, fly wheel, starter, alternator ) and gain fuel injection, programmable ignition, starter, ECU, Vortec heads and more power . I know the motor will need new head gaskets and different freeze plugs
questions:
1) has anyone done this?
2) if i rebuild the motor, at this point why not do a 383 stroker? I know the OMC is power limited but if I pick up power under the curve and ease into peak... can the cobra take it?
3) Cam selection, 350 truck motor uses a close cam, but the peaks are moved up a 200-300rpm higher then a marine cam. is there a good hydraulic roller cam replacement? or reuse it out of current motor ( if its good)? If possible I'd ditch the tappet and go roller, needle bearings, 1.6:1 rocker, and high rev springs with head work ( porting, polishing, polished combustion chamber) so i can spin to 7-9k if needed
4) ECU tuning, so it looks like only tuner cat can retune the "black box" for easy retunes I should get a PCM411 (LSx computer), thoughts?
5)383 + EFi or 350 + CF blower+ EFI?
6) convert to closed loop or open loop cooling? its all cast iron, and fresh water. closed loop is a cost adder, its currently open loop.
7) addition of oil squirters, all of my high performance euro and diesel engines have them to help pull heat away from the piston and reduce the chance of knock. most marine engines are 60-75%+ load so it sounds like a good idea.... so not adding them seem silly with all that unlimited cool potential. however drag motors use scrapers and other meant to keep oil off the rotating assembly and reciprocating assembly ( added weight), but then again this is not once of those types of motors
i don't see a need to keep the carb, and smog system.
