make a 50hp out of a 40hp

[MKEPHART]

would like convert my 40hp merc to 50 hp merc. just purchased a 40 elpto and want to power-up. As far as i can tell, i need to buy bigger jets and remove my reed stops and replace it with the "retainers". any thing else I need to know? any adjustments necessary? Can I go with the 60hp jetting specs and make it a 60hp-or ir the exhust to restrictive for that? thankx, Mitch

 

[WillyBWright]

Re: make a 50hp out of a 40hp

Sorry Mitch, I'm afraid you're WAY off base. Rejetting only leans or richens the mixture. Rejetting will only result in a LOSS of power as you will be running either too rich or too lean. If you want a 50Hp, BUY a 50 Hp. If you want a 60Hp, BUY a 60 Hp. Playing with these things like that only gets you a ruined 40Hp. Rejetting is not the answer. Changing the exhaust is not the answer. There are a lot of factors that go into getting the same horsepower from the same block. Fidget with just one and you upset the balance, you'll never get the full effect unless you do all of it, and there's a good possibility of trashing the powerhead if you do just one thing slightly wrong. I'm afraid this far outdated notion of just changing one or two things to change the horsepower dates back to the 1950s. Time marches on. Outboards are WAY more complicated than that now. If your boat is rated for 40Hp, run the 40Hp AS IS. You'll get more satisfactory results playing with props than carbs.

 

[jimalsk]

Re: make a 50hp out of a 40hp

Willy is right Mitch. The bore size may be different. The stroke may be different. The porting may be different. The previous owner of my 75 put carbs off of a 90 on it,they are jetted the same but that doesn"t make my 75 a 90. A 40 is a 40 and a 50 is a 50.

 

[Clams Canino]

Re: make a 50hp out of a 40hp

If you go through the *entire* parts listing and find those are the ONLY differences then you are prolly good to go. Way back in 70/71 they used a reed stop to make the 135 a 115. It was just reed stops and jetting. <br /><br />Make sure the block and intake is the same part number 1st too. Reed stops *will* clip the top end, this might not be as wacky as it sounds, Merc did it before.<br /><br />-W<br /><br /><br />-W

 

[MKEPHART]

Re: make a 50hp out of a 40hp

nope, bore and stroke are all the same on merc 40/50/60. the only parts that differ on a 40 and 50 is the jet size and the forty has a reed stop. the is also true for the 60, except the exhust is different.

 

[MKEPHART]

Re: make a 50hp out of a 40hp

block and intake are the same part number. I was hoping to hear from flyboymark who posted on clams canino boysen reed message thread and said he did this upgrade. But I do apprecuale all comments here. I bought the motor new, dirt cheep, and was just hoping for an easy upgrade.

 

[phatmanmike]

Re: make a 50hp out of a 40hp

easiest way to make that 40 into a 50 is do this:<br /><br />1. take off hood<br />2. put on 50hp hood<br />3. go boating

 

[Clams Canino]

Re: make a 50hp out of a 40hp

Heh.... we've made a few 150/140 inlines into 90/115 inlines with stickers to combat "HP ratings" for hulls. Never went the other way though.<br /><br />But seriously, it would not surprise me if intake restriction in the carbs or reeds etc wasn't the whole difference. It's not the most common thing, but like I said they did it once for sure that I know of.<br /><br />-W

 

[vetstudent]

Re: make a 50hp out of a 40hp

Hate to just chime in but I have a 97 40hp merc tracker... Are you guys saying that I could have a 50 or 60 hp motor that's just being "restricted"? I have no intention on doing modifications... just curious.<br /><br />Brent

 

[b20]

Re: make a 50hp out of a 40hp

too many variables.timing, carbs,exhausts.if it come out the factory a 40 leave it a 40.as all the rest says : Mr mercury done some good work to make them engines reliable at what they are.don't go messin' with 'em!

 

[FlyBoyMark]

Re: make a 50hp out of a 40hp

I have a Mercury 2001 40 HP converted to 50 HP....this is what you need: 3-50 hp carbs, YOU MUST change the oil injection pump to 50-60 HP model and remove the reed stops and final, put in a little plastic "t" thats bigger in the oil line. There are NO OTHER DIFFERENCES and tune up specs are the same. Part numbers are as follows for 2000-2003 models, carbs could be different on 2004 model. YOU NEED MANUAL to do this job.<br />Carbs: top;WME-68-1 mercury #3301-824902t16<br /> middle;WME-68-2 mercury #3301-824902t17<br /> bottom;WME-68-3 mercury #3301-824902t18<br />oil pump: 818902a<br />t-connector: 22-818993<br />3 special washers to replace reed stops: 812879002<br /><br />40-50-60 HP power heads are identicle except for carbs, reed stops and on 60 HP, some port milling. You must change the oil pump because the 50 HP uses more gas and the 40 HP oil pump does not put out enough oil. Hole shot torq will remain the same, top speed will be faster and you will have to repitch 1" to 3" more depending on boat and load.<br />Cost of parts discounted is about $375.00 + tax, might need to add induction manifold gasket set to this...<br />For my specific application, I picked up about 5 MPH from 39 MPH to 44 MPH GPS and 16" prop to 19 " prop. <br />Curious..wadja pay for the 40 HP? Bought mine @ Outdoor World for $2,500.00 in the box, ELO 15" shaft. Put in Mercury trim kit for $475.00

 

[FlyBoyMark]

Re: make a 50hp out of a 40hp

I forgot...while you have it appart...polish reed block assembly and put in Boysen reeds...<br /><br />= 150-200 more rpm, better idle and better hole shot.<br />Sincerely,<br />

 

[WillyBWright]

Re: make a 50hp out of a 40hp

The difference in the carbs is the diameter of the venturi. If you decide to get the 50Hp carbs, you'll notice that they have a larger diameter than the 40s. The additional air that passes thru gives you more ponies.<br /><br />If you do decide to convert that to more horsepower, also get the appropriate stickers for the hood. The horsepower should ALWAYS be correctly represented to avoid a mess of potential problems down the road. Like potential lawsuits. It's a sad fact that you can never be too careful regarding outboard motors in our lawsuit-happy society. Cover your bases and don't exceed your boat's rated maximum horsepower. In other words, cover your A$$.

 

[b20]

Re: make a 50hp out of a 40hp

and when you've spent all that money to get all the bit and time to install them,it would have been cheaper to sell the 40 and buy a brand new,out-of-the-box 50.

 

[FlyBoyMark]

Re: make a 50hp out of a 40hp

B20..Not so...I got $3,450.00 including Boysen reeds tied up in my NOW 50 HP with trim, at the time it would have cost me $4,100.00 to buy a 50 hp. Total conversion time was about 3 hours.....I did spend an additional 3 hours polishing the manifold for the Boysen reeds. I'd say a $650.00($750.00 without reeds) savings is pretty good considering the class of engine!

 

[MKEPHART]

Re: make a 50hp out of a 40hp

Thankx for the info. flyboy. I paid $1875.00 for the 40 elpto 20". I was in a flood and sold without a warrenty. I didnt catch the oil pump diff.,thats an important one. are u sure on the carbs,If i look at the p/n's for the two carbs(40 and 50) the only diff is the jets and linkage p/n's

 

[FlyBoyMark]

Re: make a 50hp out of a 40hp

MKE...Yes.. the carbs ARE a little bigger. The carbs ARE different numbers. The Mercury exploded views and parts list are a little tricky.<br />The 50 HP operates at higher manifold pressures at WOT but at same rpms as 40 HP and the same for the 60 HP which has even bigger carbs. Putting 60 HP carbs on the 40 or 50 HP will do nothing. The block on 60 HP motor has additonal port milling done to improve the mass air flow even better. Basicly, the three motors all use the same inductiion manifold and reeds. Linkages are the same unless you have a manual model. You willuse the old linkages on the new carbs.

 

[Clams Canino]

Re: make a 50hp out of a 40hp

Originally posted by WillyBWright:<br /> If you do decide to convert that to more horsepower, also get the appropriate stickers for the hood. The horsepower should ALWAYS be correctly represented to avoid a mess of potential problems down the road. Like potential lawsuits. It's a sad fact that you can never be too careful regarding outboard motors in our lawsuit-happy society. Cover your bases and don't exceed your boat's rated maximum horsepower. In other words, cover your A$$.

Willy, In this *one* case I could not dissagree more. If you in fact exceed the rated HP of your hull with modifications, the **last** thing you wanna do is advertise that - EXACTLY because of the lawsuit issue should you ever run over some blathering idiot snorkleing in the center travel lane. <br /><br />To think that anyone that matters could even begin tell the difference is giving the general public (and the lawyers in particular) WAY too much credit. you really think anyone that counts has the knowledge or ability to measure your venturi diamater?? Pa-leeeese! No one will ever EVER know a thing if you keep your yap shut and "forget" you ever changed a single part.<br /><br />Conversely.... if your mods don't overpower your hull.... there's no need to worry at all, therefore no need to re-sticker. <br /><br />-W

 

[WillyBWright]

Re: make a 50hp out of a 40hp

I'm against overpowering boats. Nuff said about that. But it sounds like he was considering a larger horsepower but got a 40 because of a great price. I figure his boat is okay.<br /><br />The main reason for restickering is for down the road. When the motor comes off that boat someday. That motor shouldn't end-up on a boat rated for a 40. A boat should never be overpowered and a motor should always be appropraitely represented. Keeps you outa trouble in so many ways. And the rest of us safer.

 

[FlyBoyMark]

Re: make a 50hp out of a 40hp

WARNIG! WARNING...PLEASURE POLICE OUT IN FORCE!<br /> <br />We've been over this hundreds of times in other post.<br />The coast Guard Plate is a GUIDE and NOT law unless the state you are in has legislated that guide as law. IN FLORIDA, as an example, you may do what ever you want AND if the insurance company insures it and you have been honest with what you have done, they MUST pay in THIS STATE for claims. AGAIN this varies state to state. There is nothing wrong with "increasing horse power" but there is something wrong with "over powering". An example of increasing Hp to me is a 25 HP on a 12 aluminum boat. "Over powering.." is putting a 40 HP on it. But then again I know a lot of guys that fill thier britches when they go faster than 18 MPH in a boat Then there are some 12' boats I would feeel comfortable putting 60 HP on it. These projects are NOT for beginners OR individuals that have NO experince with high performance boats.<br />With another point of view, I am accustomed to driving 80 MPH+ bass boats where I live...going less than 50 MPH is like a crawl to me.