89 OMC Cobra 4.3L RPMs???

[89 VIP Valiant]

Hello all, just took my 19' 89 VIP Valiant on the water for the first time this year, and the boat ran great. I was watching my RPMs at WOT, and noticed that it didn't want to go over 4000. I believe I had read previously that it should run up to 4400-4600. What does everyone think about this?

A few more specs on the boat that may or may not matter. I am running trim tabs, my boat has a 19 pitch prop, and the trim indicator does not work, but during my run yesterday I had it trimmed up as high as I could withouth it throwing a large mist of water. I assume when i see it throwing that big mist of water I am getting a little high. Also, I can't remember what the timing is set at, but I did put it at maybe a degree advanced (at most) above what the manual called for.

Any input? If it sounds low, any ideas on remedying the problem?

 

[HT32BSX115]

Re: 89 OMC Cobra 4.3L RPMs???

Howdy,


Well, there is a sticky "up above" that addresses an engine that will not reach maximum rpm.


Before you start troubleshooting the engine you should ensure that your tach and speedometer is accurate. That would mean that you should use a known tach and GPS.

Tachometers are well known for being inaccurate at high RPM....

Also, if you haven't done a tune up in recent times, now might be a good time to do it to include points, plugs, wiring, timing, filters etc..... slightly retarded (can we still say that?) timing will absolutely lower max rpm....

I used to have a OMC 460 in my boat. When I got it, it would only turn about 4200......down from 5000 before. Turns out the camshaft had several flat lobes....


Good luck,


Rick

 

[89 VIP Valiant]

Re: 89 OMC Cobra 4.3L RPMs???

Thanks Rick, my engine only has about 15 hours on it, so I assume the cam is good. I did put in new plugs, points and condenser, yet my wires look to be several years old. Probably wouldn't hurt to replace, but I wouldn't think that would cause that, do you? Coil is pretty old, any thoughts there? Carb is also only about 15 hours on the rebuild. Boat is very responsive, so I guess I hadn't really thought about the ignition system have a bad spot in it.

I do believe my speedo to be correct, have tracked it with a gps, though I have not used a remote tach; which may be a good thought. I will check out the sticky, thanks Rick!