89' 2.3L OMC WOT not reaching RPM's

[stylze76]

I have a quick question. I have an 89 Sunbird Corsica with the 2.3L OMC Cobra. Manual says WOT should be 5200-5600 RPM's but I'm lucky I can get it up to 4500. I have the recommended prop so I would think it should get there. Any ideas or suggestions? I was toying with going with a 4 blade 15 pitch rather than the stock 3 blade at 17.

Also one more question. I can't pull a darn thing with it. Maybe a single person tube but no skiers or 2 person tubes. Won't do it. Way to bogged down and goes way slow. Anything I can do to help that or does it just come down to a different boat?

 

[MikDee]

Check your Distributor, take off the cap, grab the rotor, and see if it moves 1/4 turn either way by hand, then springs back? If not, you need to take off the points breaker plate, and clean, and or repair the mechanical advance weights, & springs underneath.

 

[achris]

If the prop is too big (not reaching recommended max revs at WOT) then yes, you are going to have serious trouble trying to pull anything.The first question I have is 'has the engine ever reached the right revs?" So, is this a new problem, or an old one that has been ongoing since new???

 

[stylze76]

@MikeDee I've never had it off. I'll have to check that. Thank you.

@achris I've had the boat for 3 years. The first year I was new to boating so to be honest I was just having fun being out on the water so I didn't really dig into anything. The second year my tow vehicle broke so I didn't even get it in the water. This year I'm actually looking into things and this is one of the things that has bothered me. I am almost positive its never gotten up to ideal WOT rpm's.

 

[Maclin]

How big is this boat? Those engines need RPM, so even in a good state of tune, if it is in a 17 or 18 footer a 17p may be too much pitch. As others mentioned, give it a good tuneup first to try to get the top RPM's, and go from there.

 

[stylze76]

It's only a 17ft boat.

 

[Maclin]

Stylze, just for reference, I have a 16 foot open bow vee hull with a 90hp, it has a 17p stainless 3 blade and it is a little underpropped unless it is loaded or towing skiers. With just me in it she really rips out of the hole, has almost 40mph top speed.

 

[Maclin]

Sorry Styzle, I had this post and another one mixed up, my outboard boat is not all that good for comparison.

 

[jerryjerry05]

If the dizzy's advancing?
The compressions good?
The coils not getting too hot?
The outdrive the right one? Pics?
Then the prop's the problem.
Go down in pitch again.
Trying a 4 blade is probably asking too much from a motor of that size.
I think the HP isn't much more than 120

 

[Bulbash]

I have exactly same setup. Currently running 13 1/2 x 15 pitch prop. WOT is at roughly 5500rpm... I found 17 pitch was a little too much, my WOT was at 5300rpm... Hope it helps.

 

[stylze76]

Check your Distributor, take off the cap, grab the rotor, and see if it moves 1/4 turn either way by hand, then springs back? If not, you need to take off the points breaker plate, and clean, and or repair the mechanical advance weights, & springs underneath.

The rotor doesn't turn very far a all. Maybe A 1/2 inch at the most either way and does not spring back very well at all. It won't turn very far even with some force. I assume from what you told me to check that this is a bad thing?

 

[MikDee]

The rotor doesn't turn very far a all. Maybe A 1/2 inch at the most either way and does not spring back very well at all. It won't turn very far even with some force. I assume from what you told me to check that this is a bad thing?

Yes, You can take off the breaker points plate (2 screws in sideways) I believe, then you'll see 2 weights, and 2 springs, they maybe rusty, or gunked up? take it all apart, it's easy, clean it all up with brake cleaner, the lightly oil it, and put it back together making sure it slides easily, and springs back.