First, I can't emphasize enough that you should read that thread on oiling and follow everything in it. It'll mean your motor will live much longer.

On building the engine, it's nothing like a street car engine. The loads on a marine engine are constant and non-stop. Think NASCAR with the addition of continual loading & unloading of the driveline. Any and every thing you can afford to do to bulletproof things will make your engine live. At a bare minimum I'd use an SRP piston. TRW's and pistons like them just won't last they way you'd want them to. KB's and other hyper-casts are a waste of money here. Prep and blueprint makes a world of difference. Clearances are critical. Depending on your cooling system, your cylinder clearances are going to be 1.5 to 3 thousandths larger- or possibly more. Valve clearance is critical too. Street clearances will cause your exhausts to hang and hit the pistons. That's a bad thing. Stainless valves are the minimum. On cams, it depends on your exhaust. Do a search on "reversion" This is a phenomenon that pulls water back into your exhaust ports due to cam overlap. if your exhaust mixes water too close to the heads, you need a fairly mild cam. If you want horsepower, you need dry tails or at least tails that mix very far out. in case you didn't catch it, reversion is a motor-killer. Cold water on hot exhaust valve heads causes them to pop off and put holes in your pistons. Don't get crazy with heads. Big rectangular ports that flow big on top have lousy mid lift velocities, especially at low and mid rpm. Your boat won't be much fun if you have to change the plugs every time you hit a no-wake zone. Also, if you're realistic, you'll recognize that you spend your time at max RPM a very small amount of the time you're out boating. You need that midrange- don't give it away thinking you'll be going mega-fast all the time. I've seen motors that dyno'ed big that didn't have enough low-mid to pull the boat on plane.

:D
If it aint broke dont fix it!!!! If its fast and has no issues thats the best kind!!:D

i know but the hot rodder in me is wanting more and few bolt-ons for now can't be all bad. besides as i found out in this thread its gonna take rebuilding soon(as she does puff "chevy smoke" first start of the day) before any serious upgrades are made. i do see your point:cool:

chris

thats kinda the answer i was looking for clearences, reversion and all that type stuff that is boat related. i have built engines for years for all my toys but this is all new different principles apply. thanks for help:cool: the oil cooler thread was eye opening

luke

Just keep in mind you're building a completely different type of engine. Take a look in the general tech thread at some of the recent oil pressure discussions. There have been alot on HV, HP HV/HP vs. stock oil pumps and the upsides/downsides.

On your engine- if it were mine, I'd bore the block 30 over and put SRP flat-tops in it with the JE rings. If you compare, you can get SCAT rods with good bolts and bused small ends for about what it'll cost you to rebuild your stock rods- that's the way I'd go. I just bought Manley's on Ebay for under $400 a set so watch there too. Since you're probably aiming at about 550 horse and a broad torque curve in the 575 range and a max RPM of about 5600 or so, I'd stay close to stock bearing clearances on the mains & rods and a blueprinted standard-volume pump. That should gove you 60 PSI running. On top, I'd do a bowl cleanup on your heads and install manley severe duty's in them. On cam, I'd talk to Bob Madara (RMBUILDER on the board) and have him grind to your application. It won't cost you more and will probably save you a few bucks. The can he gives you will probably look very similar to a Crane 731, but it'll be better. Morel roller lifters are a necessity. Bob will send you the right springs. Roller rockers are a must. I like the Comp Cams stainless for the RPM range were talking about. Depending on your hull, you may want to stick with a good dual-plane. A light boat could be tolerant of a single-plane a bit more. Top it with a Holley HP 950. Buy it from Nickerson and they'll send it to you tuned, tweaked and jetted- ready to bolt on. On exhaust, you're going to be hard-pressed to be the Stainless Marine for price/performance. Eickerts are excellent as well but more expensive. If you can find a nice set of Gils you'd be OK there too. On ignition, you probably have something you're comfortable with but I'd look at either the marine versions of the MSD 6 and the Crane Hi6.

yeah 550 is about the number. i think i will keep the mefi, of course with the correct injectors fuel map etc. its a little bit expensive to keep but if i want a cheap sport this ain't the place to be. i will start my search for engine hard parts and get ready to pull her this winter. i am going to upgrade oil cooling system before summer is out...

Yeah, I missed the MPI. Can't help you on that one- I'm a carburetor guy. There's lots of tips to be had on injection- I'm sure someone will weigh in.

well mpi i got handled except for the marine aspect of it. so those 502mag heads will do the job with some work that will save some money.

Those heads should be 088 or 990 castings- both will do very well with some mild bowl work and a 3-angle valve job. Make sure to magnaflux them- they can develop cracks between the valve seats.

all right moving on, what about installing livorsi depth gauge shoot thru style. is this a do it yourself thing ( no laughing if its real easy)




:cool: