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View Full Version : First time out with my Sweet 16. Input please.



John C in PA
05-08-2011, 09:37 PM
I took my 16 (1992, 302 HO) out on the lake today for the first time since I brought it home last October. Conditions were: temp in low 70's, light breeze so the water not flat, 2 persons, full tank (but 1/4 of the gas was at least 2-3 years old).

Comments and Issues:

> the interrupter is still causing me problems and I have to finesse it into gear to keep from stopping the engine. Its been set to specs so does anyone have any thoughts on finer adjustments? I'm thinking some filing of the notch may help as the microswitch wants to drop in but hangs up on the ramp.

>You are all correct-I need to install the ST9 Bennett tabs ASAP. The port side rides lower than the stb side and in a a few tight fast turns the hull seemed a bit skittish.

>I'm wondering if the thermostat is stuck open. After some fairly hard running the temp goes to 160 degrees then when cruising thru the no wake zone the temp dropped to 130 degrees. Opinions guys?

>the prop is a 14.25x23 Viper. Trimmed for top speed the best I could do is 4400 RPM and 55.4 MPH on the gps. I'm thinking a 21" prop will pull the RPM up to 4800. Whose props do you guys like these days? Do you agree with 21" P?

I appreciate any inputs you guys can offer.

John C in PA

mrfixxall
05-08-2011, 11:08 PM
I see you have a 302 ford,,does the boat have a cobra drive also or a volvo??
if its a cobra then those 2 switches have to be adjusted with special omc tools,it cant be done by eyeballing it..

Run the fuel out of the boat first before you try wot runs,old gas will distroy the engone..if it were me i would drain the tank first before you take the boat out and then fill it with premimum fuel then go out and do some speed runs..

thermostat,,those are normal temps,,the engine temps will rise 20-30* at wot.

MOP
05-09-2011, 07:46 AM
Having worked on OMC's for quite a few years I would check the drive cables drag, if it has started to get a little stiff that will cause your shift problem. The 23 is the same prop I ran on the same setup only mine was a 91, I had a mild cam and .030 over bore. My best was 57.9@4,900 the stock HO is 55+ mph setup, to do much better requires $$$.

Phil

John C in PA
05-09-2011, 09:14 AM
The drive is a Cobra and one of the cables is a little stiff (the other is new) but not excessively so. The seller and I tried to adjust the interrupter during the sea trial and you could watch the tip of the microswitch try to fall into the groove but would hang up just barely enough to cause a stall. Jamie tried adjusting the cables for me when he did his work but I don't know if he used his smarts or the OMC tools. When he checks in I'm sure he will clarify this.

Phil, using yesterdays info my calcs show a theoretical top speed of 60.3 MPH and 8.1% slip (pitch only and no correction for cup). At 4800 RPM with a 21P screw, the same formula shows a theoretical top speed of 60.0 MPH. Since its just the 2 of us and no skiers or need to get the revs up faster it looks like this prop is OK.

John C in PA

Sweet little 16
05-09-2011, 10:26 AM
what drive ratio??

John C in PA
05-09-2011, 10:29 AM
1.59 overall

JC

LKSD
05-09-2011, 10:38 AM
The drive is a Cobra and one of the cables is a little stiff (the other is new) but not excessively so. The seller and I tried to adjust the interrupter during the sea trial and you could watch the tip of the microswitch try to fall into the groove but would hang up just barely enough to cause a stall. Jamie tried adjusting the cables for me when he did his work but I don't know if he used his smarts or the OMC tools. When he checks in I'm sure he will clarify this.

Phil, using yesterdays info my calcs show a theoretical top speed of 60.3 MPH and 8.1% slip (pitch only and no correction for cup). At 4800 RPM with a 21P screw, the same formula shows a theoretical top speed of 60.0 MPH. Since its just the 2 of us and no skiers or need to get the revs up faster it looks like this prop is OK.

John C in PA

My smarts are fine ;) , however I used the procedure and tools outlined in the manual to reset the shift cable's basic settings as per your request. :)

Without getting into unneeded in depth details I did inform you that there was corrosion & sediment present in places due to saltwater usage.

I also informed you many times on the phone that I had the unit operating ok out of the water, but that the cable still seemed a little stiff but that some lube may or may not help. I also told you that it may still have an issue under load in the water because what I had done was not necessarily a fix. It was just an adjustment reset.

I recall we had also discussed what had come out of your drive's lube in the fall along with photos and clips sent to you, which looked rather nasty..

As a quick recap. The cable was lubricated as I did tell you it may potentially free up if there was an issue, but no guarantees. I had also informed you that there may be a issue with the drive as the lube was extremely dirty coming out. I also had informed you that running the boat with the cable as far out of adjustment as it was could have potentially caused premature wear or damage.

I know we discussed other options & that I had outlined some potential further invasive steps dealing with this issue including water testing, however you did not want me to get into it further at that time.. Which is not a problem, but my guess is that either there is some corrosion/stiffness that is in the cable yet that is not going to work its way out if you ran the boat a bit, and/or that there is some other corrosion or issue that needs to be dealt with further inside the transom to drive bell housing, or in the drive itself.. :)

I know you were trying to save some bucks & hoping just an adjustment would do the trick, which it does on occasion depending on the boats condition or other underlying issues.

The other issues that we found and discussed however made it slimmer, but still a worthwhile prospect in case the adjustment would have done the trick.. As to diagnose it further would have required the basic settings to be set or confirmed anyway, and they were way out of whack when the boat came in, matter in fact I think some of the stuff was still loose!.

Anyhoo, If you want me to go into it further with you and schedule an appointment give me a shout.. I can re-review the options and some pricing again.. :)

Jamie / Lakeside

Sweet little 16
05-09-2011, 01:01 PM
1.59 overall

JC


you're assuming you can find a 21 with 8 % slip the 23 at 8% is very good but it could be causing some of your handling issues. welcome to the world of prop testing.

John C in PA
05-09-2011, 02:08 PM
SL16, OTOH if I get a 21 with any higher slip than 8% (thinking 9-11%) I'll lose even more top speed. Since I have a port list and the tabs in my garage I won't post about props until I get out with the tabs installed. I've selected props before with good luck. But it is still a bit of an art and a bit of science.
John C in PA

silverghost
05-09-2011, 02:34 PM
John:
From reading Jamie's above post ~
And the condition of your outdrive's lube last fall that he mentioned, along with your hard shifting switch & shift cable issue~
I believe you should seriously look into your outdrive's mechanical issues very soon~~~
Before you do any more serious internal damage to it.
Just my opinion~