yesrej

im looking to get some more top speed. i have a small block 350 with a omc king cobra drive. right now the boat runs 53-56. im looking into doing some motor work. im thinking of using no more then $3000. im not sure of what work i should do for top end or if this is enough cash to use. i mean with using 3k in motor work how much more mph am i looking at? if anyone could help with this, that would be great.

yesrej

the boat is a 1990 four winns liberator. 270 hp. im not sure if a want to go with a blower and no i dont have very much room.

olysan

For 3K you should be able to put a stroker crank in it, new cam and heads, and you'll be pushin 400hp. Plus you'll love the torque. Get Dennis Moore's book about marine small blocks.

Caincando1

Are you sure its a GM350 and not a ford351W? I don't recall OMC using GM's but I'm not forsure.

Dennis Moore

You have the best intake manifold (GM high rise cast iron) and a carburetor that will support 475 horsepower (Quadrajet) already on the engine. The ignition system is fine (replacing it will waste your money).

The heads are fine and the camshaft is a roller lifter design. Install a better roller camshaft and keep the stock lifters (212 intake and 218 exhaust duration @ .050 on a 110 degree LSA, Comp Cams).

To install a stroker crankshaft (a good idea) you will need an expensive, custom made, flywheel for the one piece rear main seal crankshaft (look into the price of the flywheel before deciding on the stroker kit).

If you decide that the stroker price exceeds your budget (installation is really an engine rebuild with new pistons, rings, bearings and balancer) install some GM Vortec heads and a matching spread bore intake manifold instead.

The camshaft is the key to a performance increase on the small block Chevy.

Dennis Moore

rmbuilder

Dennis,
Doesnt the option of an internally balanced stroker kit eliminate the necessity for the custom flywheel?
Bob

MIKEHTMSR24

by that I mean will the drive hold up?????

yesrej

thank you very much for your help guys. youve come up with some great ideas. yes i am sure it is a gm 350. omc used the gm 350 in the early 90s. and i think the drive should hold some more power. i ve heard of people running close to 500 hp with a king cobra drive.

jaroot

i've been here a few times in a few iterations... and i had at one time what Mr. Moore put out there but i wanted more...

Pro-Action 64 CC Iron lightning cylinder heads.. all i can say... 200 CC are PLENTY with the 264 HR.. 180 better if not future upgrades are planned

XM270 HR Comp Roller

.015 steel shim head gasket nets you 9.4:1 from a merc/omc stock 9.1:1 motor and 64 cc chambers and .015 head gaskets.


Right now with an edelbrock perf. rpm airgap, 600 holley, XM264HR and 220 pro actions i am in the 380 crank hp range and i have the XM276 HR in the toolbox for future installation... which should net me in the 410 range with a 750 cfm carb. i require this much cam because of my intake and cylinder head volumes... this is one reason i bumped my compression ratio a bit.. i do run 93 octane and 36 degrees total advance by 2800 out of my MSD... no issues cept around 75 - 76 mph in my little boat 80 on teh way...

all depends on what you want for HP...