1987 43 OMC timing and idle problems

"I have several questions for

"I have several questions for a 1987 stingray super sport with a complete all new rebuilt engine and new block. What should the timing be set at on a 1987 4.3 V-6 2bbl and horsepower? 175 0r 190? 190 is on the back of the boat but doesn't say horsepower. Also, seems to be a little switch problem (is 2 of them on some notches, black ones on top of engine for engageing gear) when I try to put in gear (mainly forward). The engine runs rough and in neutral, sometimes still rough unless I jiggle throttle a little. How to adjust that or fix? Sometimes sticks and will not go no faster than idle speed unless I take out of gear, put into reverse, then forward then is ok. But cannot figure out the hesitation taking off, it as if the motor dies like not enough fuel until enging has some rpm's, then will shoot like a rocket. Anymore info on anything on the engine or boat is a big help as I have no manual! Thanks to all."

"Steve...the 2bbl were 175 hp

"Steve...the 2bbl were 175 hp and the 4bbl were 205 hp. The switches you are talking about are the ESA (Electronic Shift Assist) switches interupt and overstroke. The way the ESA works is it pulses the coil when activated to cause the engine to stumble/drop rpms and it becomes much easier to take it out of gear. This is only meant to be for a second. It almost sounds like yours may still be engaging. Go to the link below and read the write up that Stuart Hasting's did, very thorough in easy to understand words and it includes many pictures right out of the OMC manual (which you should get anyway)

http://www.hastings.org/~stuart/cobra/"

"Thanks Bob! I got the online

"Thanks Bob! I got the online manual and is great. I suggest it to everyone as it is very easy to understand. Got my boat running good. Main thing was set the points correct, they were too closed up and set the timing up 2 degrees being I am running 93 octane. Idles smooth at 500rpm, more power and very good on gas, 1/2 tank for a whole day of some riding and trolling for fish!

I do have one question about a prop. The easiest way to tell you is my boat takes off like a rocket about 1/2 throttle with 3 people and fully loaded for a day on the lake, (boat is 18' 7") when running say 2,000 rpm, going 20 mph, 3,500. 35 mph, RPM'S match speed. Use a gps speedometer and is correct with the speedometer in the boat. I would like more speed without the rpm's being it takes off so fast and do not pull skiers, what would you do? Or, will it be hard on the engine to switch to a more pitch prop? Thanks and happy boating!
Steve Wilson"

"Steve....you don't say wh

"Steve....you don't say what your RPM's are at top speed, full throttle, WOT or what size your prop is. The RPM's should fall within the factory suggested range for your engine, I think yours is in the 4400 - 4800 range (from memory). To give you a little more speed at lower RPM's you will have to go up in pitch. General rule of thumb, for every inch of pitch you go up you will lose approx 200 RPM and you will lose a bit of your hole shot. It's all about compromise. If you go too high in pitch you will cause the engine to lug and if you go too low then the RPM's go beyond the recommended range."

"Hi Bob, thanks! Prop says a

"Hi Bob, thanks! Prop says a 14 1/2 X 19 (part # on prop 389924). I ran full throttle for about 15-20 seconds and was right at 4600. Almost made it to 46 MPH. Had it trimmed to do the best. So been staying when cruising about 3500 or 35 mph not wanting to keep the engine reved too much. If I go up 1 pitch, what speed do you think? Or what's best, leave it as is?"

"Steve...checked the manual an

"Steve...checked the manual and the 2 bbl range is 4200-4600 and the 4 bbl is 4400-4800. So you are reaching the upper limit of yours at 4600. I wouldn't run there much especially on an older engine. In your case it wouldn't hurt to go up 2 inches of pitch to a 21". This will bring your RPM's down approx 400, reduce your hole shot a bit and increase your speed a bit. You may be able to achieve the same 35 mph @ 3100/3200 rpm so you should actually see a little better efficiency for your application and even save a few fuel $$."

"Thanks again Bob. Got me a 21

"Thanks again Bob. Got me a 21" pitch on the way. Found a new OMC stainless steel one for $100.00 on ebay! Will slap it on when it gets here and head to lake to try it out. Being the one on it now does good, thought I better just stick with the factory OMC prop. At least will have me an extra spare prop. Will let you what how it turns out. Thanks for all the help. Steve"