Is there any way to get a little more HP out of a NS40C?

[deezy]

I have a jewel of a motor, but a few more horses would really be handy. Is there any way to convert my NS40C into a 50hp or just get a bit more out of it? I really appreciate any help Thanks

Randy from Louisiana

 

[Sea Rider]

Welcome to Iboats,

A 40C and a 50 are two different CC powerheads, can't be upgraded. What type of boating like doing, cruising at speed lightly loaded, family oriented ?

Happy Boating

 

[deezy]

No Title

Thank you for the welcome to Iboats as well as replying. It pushes my little camp around at about 5.5 MPH. I know its not a speed machine i am working with, but I was hoping to get a little bit more power to help with manuevering her around as well as gaining a MPH or 2.
Thanks

 

[Sea Rider]

To take the max HP out of that nice 40 C you need to install an Induction Tach, go for a wot spin as usually loaded and check max wot rpm achieved. 40C wot revs are 5200-5800 rpm. If with current delivered factory prop, definitely will need a prop maximization tu pull revs up and push much better that heavy combo. Would suggest buying a Hardline hour tach model [FONT=&quot]HR-8061-2, check Iboats, Amazon. It's not good for OB to swap props blindy before testing actual one with tach.

Happy Boating[/FONT]

 

[deezy]

I will give it a try and see what she does just ordered the tach. I have a new stainless prop on it may have to get it reworked or do you suggest a certain pitch/cup prop for this type of load?

Thanks

 

[deezy]

this is the current prop that I have on her "Solas Sature Boat Propeller 13 Pitch 5331-111-13 "

 

[Sea Rider]

Tach must be set to match 2P (2 sparks per revolution) or won't read accurate. Should read once engine is fired around 900-1050 idle rpm. Can install it on tiller near thottle grip or at medium lower cowl, for this one leave sufficient internal cable for cowl removal ease when in need to remove it.

Go for a wot run on flat calm no wind water cond as currently loaded, check max wot revs achieved and check if inside 5200-5800 min-max factory wot range. Depending on your reading can maximize a less prop pitch to pull wot revs higher. Once there doen't mean that you must run that combo at full wot, can run it throughout the throttle of your prefference.

It's very important to check timing advance if well set to get the most out of a healthy engine along a maximized prop, how mechanically inclined are you ? How heavy is that camp ? Depending on the wot reading, could modify actual SS prop at a prop shop but to a certain limitation. Report your wot numbers to work from there.

Happy Boating

 

[deezy]

Ok we will be taking it out camping for the 4th of july. I will do some test runs while out and report them back. I am pretty good with wrenches I work offshore on an oil platform (where I am now) as well as do all my own repairs to vehicles and boats. I do well with the proper guidance on things i know nothing about so i really appreciate your help with optimizing the power and efficiency of my unit. The motor is in very good shape very clean and runs smooth. Not sure on the weight but I will try to put it on a scale before the trip. Where about should the timing advance be? from what i find BTDC 25

 

[Sea Rider]

Have found after installing some Tohatsu outboards, they were not performing as expected, were factory delivered with carb and timing advance out of correct sync, which made all the boating fun difference. This is a simple procedure to check if carb/timing advance are spot on for best top acceleration.

Carb sync : move gear lever to forward position, with left hand rise butterfly pawl fully up (left of carb) with right hand throttle grip fully back and forth towards max and check if a slight banging roller to cam can be heard and if roller stays at the max height it can go while having butterfly widely open to 180 deg. If not will need to make a throttle/carb sync adjustment by means of A stopper. Confirm if adjusted spot on. If so, pass to next sync.

Timing advance sync : Same procedure as of carb sync, while maintaining roller fully up check if timing advance marks on plate stops at 25 deg at middle of both mating crankcase surfaces while standing looking at front of them, as in pic . If with less than 25? will need to shorten as needed the synch bar that's attached to timing plate till 25? is achieved. 25 HP and 40C share same 25? timing advance.



If carb/timing advance is found ok or needs to be properly adjusted will go from there for a prop maximization. If any point is not clear, just report back.

Happy Boating

 

[deezy]

You are a wealth of knowledge and your help is very appreciated, Thanks! When I get home from work next week i will go through these things as I have printed this conversation. I will report all findings and adjustments back. Thanks again.

Randy

 

[Sea Rider]

Hi Randy,

Hope you had a wonderful 4th of July and were able to check what suggested. In order to have spot on timing advance sync, will need to check these 2 pics which corresponds to the upper and lower throttle mechanism. Pics explains by itself. Although both pics are not from a 40C, mechanically applies.

Upper Throttle :
If Ball Joint (1) is worn out will give excessive side play to Cap C (2) when rod is moved sideways. Old ones are bronze color, newer are chrome plated which are better, wears less. To remove Ball Joint just unscrew it CCW with wrench. If both 1 and 2 are found to give excessive side play change both. Grease when assembling new, If found ok grease old ones too.



If 1 is ok and 2 has too much lateral play, place a plastic tie & wrap around yellow line, pull hard so to strangle Cap C tight to Joint, this will help remove side play only if Cap C is flexible. If already hardened won't do the trick. When replacing Ball Joint, apply grease before is pushed down to lock Joint.

Lower Throttle :
Remove washer and clip pin from Cable Pin (2) remove Rod Joint (3) Check if (2) is severely scratched at middle portion (black line), will see lines, if scratches are light, not deep, sand it with sand paper till all lines are removed, if not, lines will abrade middle Rod Joint and will give excessive play to Link Rod. If (2) & (3) are found excessively worn giving too much up, down play when throttling, change both.






Check while moving rod up & down next to supporters (1) if there's too much side play, if so change both, check that throttle rod doesn't have lines same as cable pin, if so, sand same till all lines are removed, if not will abrade new supporter faster at middle. Grease cable pin and middle rod joint prior assembly, same for both supporters.

Happy Boating

 

[deezy]

Thanks Sea Rider We sure did have a great 4th. We camped for 4 days in the lil camp on a sand bar in the atchafalaya river. It was great! I did get to check a few things out. I couldn't get a weight due to the scale at the closest truck stop broken. I did install the hardline tach and my RPM's at WOT were 5320. Which is between the recommended so if I were to do prop work I would need to go from a 13 pitch to a 12?? to bring my RPM's up a bit higher for gains?? It ran really good though. I am just seeing your last reply so I haven't checked into these ball joint points or lower throttle shafts, but If my memory is correct the ball joint is in good shape no real slack in it. I didnt get to check the timing like I wanted, couldnt find my ol mans light in his mess of a shop, but I will continue to look for it and check when I find it.

Randy

 

[Sea Rider]

Hi Randy,

With that wot rpm achieved you're at the lugging side, if remember right wot rpm for a 40C is 5850. You need 530 + revs to reach 5850. How heavy is that set up as usualy loaded ? Impossible to gain + 530 revs going for a 12 pitch . Will need at least going to a 3 blade11 pitch. Check at a proip shop if possible to test an 11 without having to pay for it.

Happy Boating

 

[deezy]

I will try to weight it again when I go back home from offshore the scale was broken when i tried. I know it's heavy thats for sure. I figured i would have to go down with pitch tho. I will check and see my speeds in the bayou close by the prop shop with my prop and then see with his the current and conditions will be about the same at all times. Thanks

 

[Sea Rider]

Deezy,

Don't need the exact weight of your set up, was just a reference. Before buying a new prop or have it re pitched if possible , check at which lower leg height is water flow passing at full power. OB must sit at 90? , check if flow skims under small upper water def plate or above anticav plate. Can you play with OB height or sits full on transom ?

Happy Boating

 

[deezy]

Not sure what lower leg height you speak of? I will have to double check, but i believe the motor sits pretty level. I will look again also to see if I could raise it an 1" or so. it is sitting full on the transom, but i may be able to adjust it some I built a fully closed in alluminum transom that i might have a little wiggle room just have to drill new holes. I believe the cav plate is under water a lil bit while WOT its kinda hard to tell with the pontoons and all.

 

[Sea Rider]

Deezy,

Trim OB to 90?, this is the ideal leg height when middle water flow passes (yellow line) at fast displacement speed. Check if flow passe above yellow line, how much under towards larger lower anticav plate, report findings.. Height must be dialed spot on before passing to a prop maximazation.





Happy Boating