88b King Kobra 460 Ford or GM

"Did the OMC 460 KC ever come

"Did the OMC 460 KC ever come with a GM? I am a first time boat owner, 1988 Reinell 18'-19' closed bow run-about. It appears to be powered by a GM motor. GM is stamped the intake manifold and the distributor is in the rear of the motor. Since most of the OMC KC 460's came with a Ford 7.5L BB, I would assume my boat would be the Chevy counterpart, 7.4L BB. However, a) that seems a bit of overkill for my boat model and size and b), I was told a small block has a four bolt pattern and a big block has an eight bolt pattern on the value covers and mine has a 4 bolt pattern (in the middle of the covers).

Does anyone know what came standard that year in a OMC KC setup or if there is a definitive way to tell what motor I have?

I am having some “bogging down” issues between 2000 and 3500 RPM (depending on the weight of the boat). Fully loaded (family and gear) I can’t get over 2400 RPMs and can’t get the boat on plane. By myself, I can get up on plane but then it bogs down at a higher RPM, 3000-3500. If I try to power through it, it will stall. If I come way off the power, most of the time I can prevent it from stalling and continue to travel. Below 2000 RPM, I can travel for long periods of time (I have only done 25 minutes-and that was only to limp back to the trailer) with no stumbles of bogging down.

I have only changed the fuel filter, which it was partly filled (1/5-1/8) with water. I intend to do some basic “ruling out” tests (compression, spark, maybe fuel pressure if I can rig something up) today and will report back. I have seen repeated suggestion of hooking up a different tank. Is that an actual separate tank or can I jerry-rig a larger gas can. Any other easy to do out of water tests before I haul it off to the repair shop or change out the fuel pump?

Oh, one last notable mention. This first time this happened was directly after I removed an aftermarket speaker setup under the dash. I hit some rough waters 2-4 wind chop, and they were hanging down. This was a mid trip “quick fix”. Is it possible either something else (under the dash) came loose or I mistakenly cut the wrong wires? All electrical items seem to be functioning correctly.

Steve"

"Compression checks out, 145 p

"Compression checks out, 145 psi in #8 and 150-155 in all others.

Spark to all the cylinders too.

Thoughts?

Any thoughts on how to determine what engine I have?"

"Can you find a plate on the r

"Can you find a plate on the rocker cover that has the engine model # and serial #? The 460 was used from 87 to 90 however in 90 they changed the drive to NEW King Cobra that had a cone clutch shift instead of dog clutch. Also in 1990 was the first year they started using the 7.4 as the replacement to the 460. Anyway in 88 they also had a 350 KC so maybe that's what you have?

You could have fuel starvation, you should have an anti-syphon valve at the tank where the engine fuel line attaches, it's basically a spring loaded check valve and the fuel pump has to overcome the spring tension to suck the fuel out of the tank, this could be partially plugged or the pick up tube in the tank could be dirty and plugged? Also the air vent line for the tank needs to be clear so you don't develop a vacumm in the tank, this is why some suggest hooking up a small tank in front of the filter to eliminate all these things."

"Bob,

Thanks for the reply

"Bob,

Thanks for the reply. Sounds like a 350. The only thing I see on the value/rocker covers is a US Pat No label with a bunch of numbers. Nothing that indicate the engine size or model. There is one section I can not see to good because there is a fresh water cooling system covering it up. I was going to do some cross referencing on some of the other parts to see if I can't narrow it down. I am definitely a little more concerned about how it is currently running.

I will try to find a small tank or test and clean the items you mentioned tomorrow. Some of that sounds highly plausible since this all started shortly after getting beat up in 2-4 wind blown chop on Lake Tahoe for over an hour. Thanks again.

Steve"

"Steve...if the boat is out of

"Steve...if the boat is out of the water look on the sterndrive (port side) also for a model # and ser # plate, we can cross reference the drive to see what engine it's attached to."

"Maybe this little pic will he

"Maybe this little pic will help you locate it

"

"The plate had the below liste

"The plate had the below listed on it,

Model # 985271
Engine 5.0L
Serial # T0570562

Looks like a 307. Reading up on the 307, I came across a High Performance version rated at 245 hp. I wonder if there is a way to find out which version I have.

Going out side do try some more tests and cleaning of the fuel system."

"ok the 985271 verifies it&#39

"ok the 985271 verifies it's from a 1988 5.0, pretty sure it will be a 305 and if it's a 4 bbl the book has it rated at 185 HP"

"It's a Rochester 2 Jet &#

"It's a Rochester 2 Jet (2bbl), 17059060. Is upgrading to a 4bbl a good and relatively inexpensive way to get some more horsepower/performance?

Everything you mentioned earlier looked pretty good, so I went down to the local marine shop to order a fuel pump. The guy behind the counter suggested to bypass the anti-siphon check valve and test the boat under load before I spend the money on the fuel pump. I will try that tomorrow afternoon.

Steve"

"Well it up and running, mostl

"Well it up and running, mostly. Seems a bit sluggish and won't go over 35 MPH or 3400 RPMs. I bypassed the anti-siphon value with no improvement. Then I found an incorrectly sized and type of paper mess carburetor filter installed. It was partly twisted and crushed. I also found one pretty loose top carb bolt. After removing the carb filter, tightening the bolt and spraying some carb cleaner down the barrels, I got the above results. At least the starvation issue is gone and it runs. It needs some adjusting and fine tuning though.

Thanks for all the help Bob. This should be able to get the family back on the water while the weather is still nice.

Steve"

"Good work Steve...thanks for

"Good work Steve...thanks for letting us know what you found, happy boating!"

"Back to 95-98% and took the f

"Back to 95-98% and took the family out on Lake Couer D' Alene, ID. Seems I was only running on six cylinders. I crossed up two of the plug wires after the compression check. I am back to jumping up onto plane and a top speed of 45MPH @ 43-4400 RMPs.

Steve"