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140 mercruiser top speed question

zack4285 said:
KGHOST Question 1985 Hydra Sport 150 Marnier , Quick Silver Control Box Advanced Idle Button wont push in, Did you say you can fix , I have Taken it off and looks like a red button not pushing something up
Click to expand...
Take a picture of control and send me a private message
 
CONTRARY TO WHAT I THINK I KNOW..... ? I had the timing INCORRECTLY SET by my MISTAKE. Somehow I Remembered it specifying 3* and it actually specifies 6*. JUST THE MOVE FROM 3 (incorrect by my misremembering) to 6 gave it a much better idle and several mph. NOW I NEED TO RE-SET the timing per book spec for elevation. CLEARLY YOU DID NOT READ MY ENTIRE POST. SO SEEING AS YOU THINK I AM IGNORANT, mr. ghost, I need to now set the timing to SPEC FOR elevation. Where exactly did ANYONE get some rediculous idea that SOMETHING was out of spec? Any idea at all? I bet you will be proven wrong when timing is set to spec for elevation. which will be in the 9* range respectively. Not chasing speed, get that out of your head, just simply ASKING WHAT TOP SPEED OTHERS SEE with a 140 sterndrive and 18' vessel. thats it. READ THE ORIGINAL POST. You will quickly realize I am not chasing speed. justasking to compare numbers.
 
So back to the original post before ghost man and whoever else totally keyboard warriored it into submission, so, now, for the million dollar question, is there a few folks here thathave a 140/3.0l/181 powering a 17/18/19' v hull vessel and what kind of numbers are you able to see, speed, load, rpm, and if you know what timing you are set at static and full advance and operating rpm, just asking to compare, no idea how this went to "your a speed demon and need a v8 and what your doing is a waste of time" No idea how it made that translation. someone must not know how to read pure and simple english apparently.
 
if a few folks would give a speed/rpm/prop/boat configuration/cargo post that was all my question was, my lurking here I knew everyone would automatically assume that my boat was poorly performing and ask the details so I just included them initially, thanks to all who have helped, if you have no interest in contributing anything other than buy a bigger motor, don't bother. just move on to the next thread and save us both some time.
 
Most 18 ft 4 cyl boats run between 35-45 mph depending hull design, boat weight.
Prop pitch is unimportant as it sets wide open, fully trimmed out max specified Rpm. Which is how they all are designed.
Also the X demension location plays a huge factor in boat speed. Two identical boats with only the X demension being different can cause well over a 5 mph difference.
X demention is the hight at which the transom hole is located. 1/2 inch of hight difference is a big difference in boat performance...so this is another factor rarely diacussed..

Getting what others with "similar" set up leaves out a lot of factors.

I have personally lake tested well over 500 4 cyl powered boats mostly point ignitions with everything set to spec, ranging from 16-19 ft long.
They are what they are....and thats it!
Again just my OPINION...
 
The main reason for this question was NOTHING TO DO with CHASING SPEED. 3 boats were given to me one with a cracked head but good 181cid and a really really old outdrive one with a good head but cracked manifold and cracked block and one with a very very low hour frozen broke 305 cid and a really low time outdrive. I took all the best parts and made one running boat that is very solid. HOWEVER, the manifold and controls were compatible with a mercarb and I had a mercarb but it ran really rich, due to restricted airbleeds which I eventually found and it then went from really really rich to just really rich. by chain of events I had several mechanic friends that would go fishing with me and half said it was lean half said it was rich..... now finding parts for mercarb is not easy.

I ran into a gentleman from AZ that had lots of documents, experience, part numbers, and training with sterndrive outfits and low and behold he provided me SEVERAL mercarb powerjet part numbers that were ALL leaner than what I was able to find. I had a 90 (barely would come to 3000 rpm sooooo rich) a 84 (would come to about 3400 and tich and blubbery) a 74 (4000+ but blubbery and not clean) so that told me I was going in the right direction, and found several other power jets I got from ebay way smaller, like down to 61.

I started some more jetting and this spring got to a lean condition on top with the leanest power jet and a 1.35 main. I stopped immediately dismantled carb and went back to 1.45 main and 65 power jet.... lets face it, better safe than sorry, I know its a little rich there. step it down again and see if I can improve it and get it to its best performance for IT, not swapping to v8, just getting my project boat pretty close and asking for mutual feedback of performance levels to be expected with a properly running 140 (181 cid) sterndrive, I leaned it out one step on the main for the next outing (this weekend hopefully) as it was rich on top still and I now need to uncover it and bring timing to spec for elevation, If it is still blubbery on top and rich, I need to find some 150 and 155 jets and step the power jet down one step and the main up, because with 165s its rich everywhere.

I am not chasing speed, just asking for a mutual idea of performance to tune/shoot/attain since I am resurrecting a basket case project hobby. I need a project, a hobby, I am a tinkerer. I found another boat I may sell this one once its perfect and start over with the next free boat, also with a 181 inline 4cyl.
 
ok simple, of your over 500 tests, one significant aspect is what was the boat carrying??? just you, you and another? several others? fuel? gear? If I totally unload my boat, and one tank of fuel, no trolling motor, no kicker motor, no down rigger, no cooler, no extra battery, no extra downrigger balls, it picks up several mph.... another aspect, folks, lets get a few details.
 
honestly, I had my boat up to 85+ one time, pulling it down the hiway behind my big block powered f350. so if I need the boat to go faster, I can always just hook it to my pickup.
 
farmerrick53 said:
if a few folks would give a speed/rpm/prop/boat configuration/cargo post that was all my question was, my lurking here I knew everyone would automatically assume that my boat was poorly performing and ask the details so I just included them initially, thanks to all who have helped, if you have no interest in contributing anything other than buy a bigger motor, don't bother. just move on to the next thread and save us both some time.
Click to expand...
That was answered in posts 6 & 18 .

lighten up francis ….
 
went out today jetted it to a 1.40 main and 65 powerjet and brought timing to 9* which would be 6* static + 2* for 5000 feet plus 1* more for another 2500' and it picked up 200 rpm at top speed from 4100 to 4300 rpm and 1 mph just to bring the timing from 5* to 9* and IT does run way better, and smoother. I started looking and have 4 10# downrigger balls and a 6# rigger ball 2 riggers a electric minn kota a honda 10hp a extra bat for minnkota a cooler... all that I roughly calculated to be 400# respectively (that honda is heavy) so I am not disappointed with the performance at all. I need to unload it and take it for a test with just me and nothing else and I bet it will make a few more mph, so I am pretty spot on for my tuning now, At sea level I bet i would get 40 mph and that just impresses me. I'm not chasing speed i'm just chasing tuning to get it running right.
 
here we are a month later and I got timing set on point, power jet is a 65 and main jet is 1.30 and it seems to run about perfect. no more blubbery on top, and 4200 rpm and 30 mph with 3 of us, gear, lots of weight, some chop on the water and a 15 prop at 7500 feet elevation. I think its good. I might take it out and run it flat out by myself un loaded just to see but tuning it to run proper was a huge gain and I am sure it is using a lot less gas by not blubbering on top too.
 
I don't think there are very many others here that run on lakes at high elevation, or with those 3.0 4 bangers. Congratulations on getting the performance you wanted.
 
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