Hi Gregg,
Depending on your prop pitch....According to my OMC King Cobra Owner's--Operator's Manual you should see about 4400-4800 RPM at WOT (wide open throttle) Everybody I talk to says you want to be at the high RPM(4800) ..... My brother told me that he routinely saw 5000 RPM (maybe that's what flattened the cam......but he ran it that way from 1987 to about 2004 or so. I bought it in 2005)
At 5000 RPM(and a 19p prop re-pitched to 20) he clocked it at 60 mph(with a radar gun).
I have everything but the engine.....including the bell housing, exhaust manifolds/risers, shift plate/esa plus a new (old stock) shift assist module. I also have the OMC kit for adding a heater (which consists of a different thermostat housing and instructions to add fittings, hoses to add a cabin heater or a water heater using engine heat)
(I did sell the coupler though) Speaking of couplers, you should try to find one for a spare because if you spin a coupler on either side you'll be done. You also have to remove the engine to replace it. No other way. Also if you don't have a service manual you should get one. I ended up having to buy a reprint. (it was about $100!!) I also have the 7.5 Parts Catalog.
Is yours fresh water (closed) cooled? That makes your exhaust manifolds last a LOT longer.
There was really not a lot wrong with the Cobras........except OMC being out of business (the early ones had lower shift cable problems which was finally fixed with a new improved cable.... You can identify it by it's red color) you might want to do a little reading........ if you haven't seen this:
http://www.hastings.org/~stuart/cobra/This guy has REALLY done his homework. (If you don't plan to do any of the maintenance you should give this to your mechanic. He should already know about it!!! If he doesn't, you might want to find a OMC mechanic that does!! If the lower shift cable is not adjusted correctly you can seriously damage the drive)
Speaking of damage. If you have anyone change the oil in your Cobras, be absolutely sure that they fill them in strict accordance with the service manual. (that means NEVER filling them exclusively from the bottom (like a Mercruiser) THAT WILL trap an air bubble in the drives causing you to oil- starve the upper gears and bearings. It will destroy the drive in less than 30 min!
If you are where it gets cold, (and you're not closed cooled) be absolutely sure you drain the block, and manifolds or you will crack everything!
I would also go the extra step of putting the drives in a large tub of 50/50 water antifreeze mix and running the engines until the temp comes up to operating temp to circulate AF everywhere. My Mercruiser 454 Bravo is closed cooled but the raw water pump, and plumbing that includes the power steering and eng oil coolers are on the raw water side as is the heat exchanger and exhaust elbows. I started up the engine and ran it on muffs until it was at operating temp to change the oil. Then I took about 3 gallons of 50/50 in a pail and put the hose to the muffs in it & ran the engine until it sucked all the mix thru the cooling system. This way any residual water in the engine will have AF in it and shouldn't freeze.
I'm pretty anal about all this stuff, I know. I read about a LOT of people even up here in the NW that break blocks, manifolds, oil coolers, etc every year because they didn't get all the water out of the blocks/manifolds. It's a pain but the alternative is engine/manifold replacement.
You may may already know all of this stuff, if so, please ignore all my ramblings
!!
I haven't really figured out what to do with all this stuff. I figured I would just put it all on ebay or craigslist and part it all out over the winter.
Hope you had a good thanksgiving! Merry Christmas!
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