60/40 stainless impeller

So I have a 60/40 mercury on my boat I did the jet swap and the jet I found used came with the smaller 6 5/8" impeller that was meant for 50/35 engines. I've been running it the 6 5/8 since I had it and figured I'd run it till it was worn. I called outboard jets today and was ordering up the 6 7/8" liner and told them I was wanting to go with the three blade stainless impeller, but they were telling me that mercury has changed the design of the three blade stainless impellers to better suite the four stroke engines they make now and that they no longer run any better in the two strokes than the aluminum impellers. Told me if I wanted stainless to try and find a old stock stainless one that is better on the two stroke engines. Just hoping to see if anyone has compared a older stainless impeller to one of the new ones or knows if this is true that the impellers have changed before I decide to order one or not.

If you look at the outboard jets website, your 93 has 51.8 cubic inches meant for the 50/60hp pump/impeller combination vs. the 98 and up 59 cubic inches meant for the 60hp with the 6 7/8 impeller. What rpms are you seeing at WOT with the 6 5/8?

I'd check with quicksilver ( they make mercury stainless props and impellers) before I'd take outboard jets word on it. They've always said on smaller motors aluminum impellers are better. I know what I've seen EVERY time I've put a stainless in it'll gain better holeshot and normally 1mph on top end. Let us know if you figure anything out.

Give Wooldridge Boats a call and ask Glen. I bought one of his stainless impellers for my 1991 Suzuki PU40 it was a 4 blade and I was very pleased with the performance. Worth a shot!

Lil' Blue Rude said:

I know what I've seen EVERY time I've put a stainless in it'll gain better holeshot and normally 1mph on top end. Let us know if you figure anything out.

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This is exactly what I experienced when going from an aluminum impeller to stainless on my 1994 Johnson 50/35.

I'll try and give quicksilver a call. I'm aware my motor is the 51ci engine, it's the 60hp model. According to outboard jets even back then the 50hp jets although the same AG model had the 6 5/8" impeller and liner where as the 60hp AG model was suppose to come with a 6 7/8" impeller and liner. I'm not sure what my rpms are exactly no tach, I know I should get and plan on it. My motor is a 60hp I've just been running the smaller impeller because that's what the jet I bought came with. I bought my outboard jet lower used because it was only $800 vs around $2000 for a new one. Had I bought new which I didn't do because I couldn't justify the cost of, I would have got one with a 6 7/8" impeller and liner. Just going off of the sound of the engine at WOT it sounds like it's revving a little high, I know get a tach to be able to actually know. I plan on getting a tach so I can compare rpm before swapping around impeller's and liners. I will compare speed as well, but it will be a little subjective as when I make the switch I'm also switching to one of the rock proof UHMW intakes, which I've heard usually hurt top speed 1-2 mph. My hope is that the speed I lose for the UHMW intake I will gain back with the 1/4" larger stainless impeller and wind up with the same speeds but have the tougher intake. I usually don't keep it 100% WOT while running unless I really want some speed to go across a shoal or riffle in a river just because it does seem like the rpm's are a little high.

As for the UHMW intake I will report my thoughts on that as well. Main reason I'm going with it is I tend to have a lot of logs to go over and some spots with riffles that are impossible to go through with out catching some larger rock sticking up a little higher than the rest. The logs are always good at catching the intake as you go over. I'm surprised I haven't done more damage to my intake already. I'd say the one thing that has saved it so far is my motor is older doesn't have power trim and can kick up easily with the tilt assist when the motor isn't locked down. Which I never run it locked down so it can kick up. Thankfully this pic has been the worst outing and didn't do any major harm to the intake, but bent the intake bars up pretty good.

Here is a link to a cheap tach that you could mount on your motor. https://www.ebay.com/itm/New-Digital-Tach-Hour-Meter-Tachometer-Gauge-For-2-Stroke-4-stroke-Gas-Engines-/331223584733?hash=item4d1e76cfdd:g:~awAAOxyi-ZTadfo&vxp=mtr

I'm curious what rpm you're at now and hopefully it will spin a 6 7/8 over 5k, if you want to drag it over here to St Louis you can try it with my aluminum 6 7/8 impeller and foot.

ordered that same tach already shortly after my last post.

mphelle said:

Here is a link to a cheap tach that you could mount on your motor. https://www.ebay.com/itm/New-Digital-Tach-Hour-Meter-Tachometer-Gauge-For-2-Stroke-4-stroke-Gas-Engines-/331223584733?hash=item4d1e76cfdd:g:~awAAOxyi-ZTadfo&vxp=mtr

I'm curious what rpm you're at now and hopefully it will spin a 6 7/8 over 5k, if you want to drag it over here to St Louis you can try it with my aluminum 6 7/8 impeller and foot.

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I'm from stl originally I might take you up on that. Although I already sent the money for the UHMW intake people I found that actually have them really didn't have anything bad to say about them. And ordered a new liner for the UHMW intake as it uses the drop in liner so my current one wouldn't work and outboard jets doesn't make a drop liner in 6 5/8" to be able try and see the difference in intakes using the same size impeller as what I currently have. So I had to go with the 6 7/8" liner. I suspect the motor will turn the 6 7/8" just fine cause if it originally had a jet it would have had that, and it's not a lot bigger only a 1/4". We will see still need to call mercury and ask about weather or not the new stainless impellers are that much different. But next time I'm going to be around stl I can let you know could try running the different impellers and intakes to see how much of difference is made in all them. aluminum intake vs plastic with each impeller, and plastic intake with aluminum impeller vs stainless. Aluminum intake with 6 5/8 impeller vs 6 7/8. I would be curious to see what kind of difference there is between all of them.

Sounds good, I saw that JL8Jeff has a merc 60/45, if it's older than 98 maybe he will weigh in and let you know what impeller he has and what rpm he is seeing at WOT.

hopefully he might chime in as his motor if pre 98 would be pretty much the same. Mine is the mariner variety so it's sporting grey paint rather than black.

I'm not really sure what size impeller my motor has. It looks like a factory jet outboard but the tag is missing. I don't have a tach either so I'm not sure what rpm's I'm turning.

JL8Jeff if you fell like pulling your boot off you can measure the diameter of the liner to know whether or not you have a 6 5/8 or 6 7/8. What year is your mercury if it was a factory 60/40 rather than a 50/35 it should be a 6 7/8 from what I understand. Talking with outboard jets the 60hp got the 6 7/8 and the 50hp although they were same basic power head got the 6 5/8. The 50hp was the same as the 60hp back when mine was made it was just detuned with smaller carbs and a different exhaust tuner. So if mine had been a factory jet it should have had the 6 7/8 as should yours if it's a 60hp powerhead. But in my case I have the 6 5/8 because that's just what I got with the jet unit I bought to swap mine to a jet.

Mine is definitely a factory 60/45 jet I think from 1994. I don't think the motor got a lot of use, it was pretty clean but was hit by a large tree branch during Sandy which cracked the hood and broke some linkage. It might still be the original impeller/liner which are in pretty good shape. I did take the grate bars off to straighten them. I'm putting the boat in the water for the season today so I won't get a chance to pull the foot off any time soon.

well if you ever happen to take the foot off if you can measure the impeller I'd be curious to know what it has. Should be a 6 7/8 being the 60 rather than the 50

I just stuck a measuring tape up inside the foot and the outside of the liner measures 5-7/8 at the bottom. I'm not sure if that helps or not.

Not sure how much the impeller and liner expand as they go up.

While you wait for the tach, measure the OD of the bottom of your liner and take note of it's thickness.

This is a link to a Facebook group I'm on. The new impeller design from Mercury is to get the rpms up on the Fourstroke's, gains about 400 on them and about 1-2 mph. Doesn't help the 2 strokes from what I have read. Since Gw is taking trade-ins for the new ones, you might be able to get a good used one for a better price. Give him a call, won't hurt to check.
https://m.facebook.com/groups/604452952959143?view=permalink&id=1016538915083876

Great info, do you have a link or contact information for those of us that don't use facebook?

mphelle said:

Great info, do you have a link or contact information for those of us that don't use facebook?

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GW Lutrell, (573)689-2647