Classic Black Max Mods Questions

**skialot2** · 05-31-2023, 11:53 PM

Hi everyone. I just bought a classic 1989 Checkmate Spectra 171 to restore. It came with a 1976 2.0 Liter 175 Black Max outboard that has 2 bad pistons. I have a 1992 2.0 Liter Black Max 135 that runs great. It already has a Bob's machine shop exhaust tuner, offshore exhaust outlet and solid motor mounts. I want to take the carbs off the 175 and put them on the 135. Will that turn my 135 into a 175? Or are there other things I would need to do? Both motors have the same bore and stroke. They use the same reed part number. But the 175 has vertical reeds and the 135 has horizontal reeds. Any advice or tuning tricks would be appreciated.

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**derekfl** · 06-01-2023, 02:22 AM

The 76 175 is no more powerful than the 92 135. In 76 they were rated at the crankshaft. Mid 80’s they were rated at the prop. There is nothing on that 175 motor that will improve the 135. Run the 135 and put the 175 aside. Look for a 2.5 powerhead. Inspect both motors for salt damage. The steering arm and 4 motor mount bolts are big tells on how rebuildable your motors are. These are 30 and 50 year old motors. A lot of bolts in these guys may never come out. I scrapped an 81 175 that had good compression. It was so salted up I snapped most of the head bolts. Get a set of torches before trying to get the 175 apart. And stop using the term Black Max.

**FMP** · 06-01-2023, 12:08 PM

Black Max ... ?

**pcrussell50** · 06-01-2023, 04:17 PM

Originally Posted by derekfl

...And stop using the term Black Max.

LOL, yes. That is one of those things that separates the newbies from the OG around here.

This thread is a good fun read: =>What exactly is a Black Max?<=

-Peter

**derekfl** · 06-01-2023, 05:26 PM

This thread has some good info. This was when I asked about the early V6 motors. I learned a lot. Bought 6. Sold 1-1/2. Scrapped 2. Still have 1-1/2 left. And learned a LOT. Like how to tell if a motor is too salted up to be salvageable. https://www.screamandfly.com/showthr...ith-these-days

**FMP** · 06-01-2023, 06:23 PM

IDK, but since when they appeared never heard anything about not using the label. Probably not the first thing you say, HP usually being first but still cool over here when we see one. Particularly an early one.

**skialot2** · 06-01-2023, 11:01 PM

Hi. Thanks for the reply. Maybe I should clarify I am not new to boating or Mercury's. They went from powerhead to propshaft horsepower in 1984 or 85. About the same time the 175 went from 2.0L to 2.4L. There is some power loss going from powerhead to propshaft HP. But it is not 40 HP. More like 15. Thats when the 150 was rebranded the 135. I should be able to get some more power just by changing the carbs. The 135 and the 150 use the exact same powerhead down to the part number. Just different carbs. The 175 was a fresh water motor. All head bolts came out without any problems. I already took the powerhead off the 135. Took the mid section apart and pulled the exhaust plate to install bobs exhaust tuner pulled the can and installed the offshore outlet. And installed the solid mounts. And why should I stop using the term Black Max? It is written on the side of my motors. See my pictures. A Black Max is basically any old school carbed V6 Mercury from 1976 - late 90s- early 2000s. Except for a few specialty models like the 2.4 Bridgeport (I had one back in the day) or Mod VP. Optimax's are not Black max's. 4 Cylinders and inline's are not either.

**Baker343** · 06-01-2023, 11:26 PM

From what I know the 135 had smaller venturi carbs to choke them down. I think your 92 135 is a top guided motor that would benefit from the addition of 150 to 200 carbs with larger venturi. I would check your 175 carbs to make sure they don't have foam floats. BTW Your 175 made a lot of light boats scream back in the day. The change in carbs will make your 135 a 150. The 175 had a much larger cut out exhaust chest and larger exhaust dump or tuner which benefitted lighter hulls. We ran these on our roundy round races because we were limited to 2L. With no Mods other than 26cc heads and freshened up they would run around 79-81 on light Mod-vp hulls.

**derekfl** · 06-02-2023, 08:17 AM

actually they put max on the side of 3 and 4 cyls shortly after they started it with the V6. it started out meaning the "new" V6. then it became a marketing tool. check your exhaust cover. the 81 175 i parted out had the shallow one. the only "fat back" (to borrow a johnrude term) exhaust covers i have seen are on 200's. i have a spare or two if you want one. with the exhaust work you have done your motor should be closer to 200 with some carb upgrading. i would think the horiz reed 135 would be more powerful than the vert 175 powerhead everything else being the same. the one nice thing with early 175's is they were significantly lighter than later motors. mainly the mid and 2 piston trim setup. as long as it is rebuildable. with that if you can find an XR4 150 lower you can get that motor under 350 lbs.

**pcrussell50** · 06-02-2023, 01:57 PM

Originally Posted by skialot2

And why should I stop using the term Black Max?

I stopped using it because that was the advice and the custom from the legends who built this board, back when I joined. When I was a newbie, they were the cool kids, and they still are in my view, even though they are more silent these days, and I want to be like them. So I don't use "Black Max" as a helpful descriptor... Even though I own three of them.

-Peter

**skialot2** · 06-02-2023, 09:00 PM

Then how do you describe the difference between a Black Max or an Optimax or a Verado or a SeaPro or a ProXS or a Fourstroke? Did you join back when Black Max was all there was?

**skialot2** · 06-02-2023, 09:26 PM

I have never saw a 3 or 4 cylinder with a black max on it. People use to call my 1989 4 cyl 115 a Black Max all the time. I would correct them and say it can't be a Black Max it's only a 4 cylinder. I would say it's a Mini Max. I would love one of your exhaust covers if you think it would give my 135 more power. I put the carbs from my 1976 175 on it already. But I haven't started it yet. I am replacing the stringers and floor in the checkmate. It's not on the boat yet. I also just picked up an empty old school CLE gearcase. 4 slot. In like new condition. I also have a old 8" Detweiller hydro jack for it.

**pcrussell50** · 06-02-2023, 09:46 PM

Originally Posted by skialot2

Then how do you describe the difference between a Black Max or an Optimax or a Verado or a SeaPro or a ProXS or a Fourstroke? Did you join back when Black Max was all there was?

When I’m talking about my “Black Maxes”, I use the term “2.0/150” or “2.4/200” as the case may be since I have both. In the 2.5 era I use “2.5/200” or whatever.

-Peter