TOPIC: 85 HP White Merc with Black cowl

eauclaire.craigslist.org/search/bpo

Decent deal on that! If it pulls over with good compression, likely with some servicing it'll be a runner again.

Controls can be hard to find (unique wiring harness) but in a pinch the internal harness can be upgraded to newer-style that will work with the more commonly-found external harness. Sometimes the old FGS external harnesses come up on eBay.

These can be easily boosted with a set of 100hp carbs and can be built to 100hp specs with the replacement of the exhaust tuner plate and upgrade to the reed valves' stops (requires splitting the crankcase for that one).

Excuse me for sidetracking you Ed but is there any weight difference between the 85 and the 100HP ? I'm dreaming of a white 100HP but since I've got nothing now I can search wider if there is any advantage to be gained by souping up the 85. Thanks in advance

No, the motors are virtually identical, same bore & stroke, etc.

What makes the 100hp are carbs with larger throats, the special exhaust tuning plate, and the reed stops which are larger in the 1000 and allow the reeds to open more for higher airflow.

Basically, the 85hp is a detuned 100. And they run very well with just the addition of 100hp carbs, since the carbs on the 850 have teeny throats. Merc did a similar thing on their later-60's 900 & 950 Sixes.

I ran an 1964 85hp Anniversary Special with 100hp carbs back in the early 80's on my '69 Fiberform 14' deep-vee runabout. And I'll tell ya it really ripped!

I built that motor from a basket case, but can't recall if I threw a tuner plate in it, or messed with the reed stops. Don't think I knew about the stops, anyway. Got that info from my good buddy Doc Frankenmerc.

Anyway, dunno how much hp it really was making, but it'd go around 44 with a ski prop and rip me out of the water on a single ski. Had it up to 50 on the lake one time with an old speed prop, and was it screaming!

So I reckon it was pumping pretty good hp, far above the original 85.

You'd have to put one on a dyno to see how much it actually made, with only 100hp carbs. I have a feeling the carbs made way more difference than the other "tuning" items.

So yeah, if you run across an 850-6 there's no reason to pass it by, it's an excellent-performing engine with tons of potential. Also a great classic look in Cloud White with the black & chrome cowling.

BTW both the 85 & 100hp '64 25th Anniversary motors were painted Phantom Black. Very cool if you could find one of those with the original racing flags on the faceplate.

Cheers..........ed

hmmmm - I have a prime condition 1963 850 I6 (Thanks Bill!!!) sitting right next to a 1965 1000 with a lower unit currently in pieces and most of the non-block upper in a "box-o-parts" as they were using two 1000's to get one running. Since I might need to scavenge the wiring harness off of the 1000 for the 850, maybe I will borrow the carbs too!!

How does the reverse carb swap work out - 850s on a 1000? I think the 1000 will be fine once it put it together and give it a little TLC. Makes me hesitant to part it out too much knowing that I will just need to source more parts for it. There is a very good chance that the 1000 will be going on a pontoon up at the cottage next spring. Depends on what my dad buys for a pontoon, and what it is powered by. How hard is it to find a decent set of 1000 carbs? Can you go bigger - 1150 or bigger - on the 850?

Ed - send me a pm with your email and I will send you some pics of the 850 and the 1000 and what I have and what I need. Maybe you can give me some guidance versus swapping parts versus sourcing. I will need to pull the cowling on the 850 so you can see what is missing for the harness. I really need to get a gameplan together. The 850 should be in running order with the exception of the harness. Can't say the same for the 1000

That's really good to know Ed. THANKS. Looks like I asked a good question I've seen more 85's than 100's for sale up here and that may be the ticket for me. The only thing I do know is I want a white and black one. I'll probably catch it for saying this but "most" of the "best" G-3's look great with them. Fire at will. LOL.

If you are looking for a universal Merc wiring harness, here is one for sale in Charlotte Craigslist:

charlotte.craigslist.org/bpd/5693834404.html

Take a look at the plug on your motor, I think it'll be the same as this set of Old School controls on eBay:



Note that there was a big design change from 1964 to 1965 and some parts might not interchange. The mid-section design and powerhead base pattern are different. Lower units won't interchange without modifications.

Stuff like the wrap-around cowl, ignition, carbs, etc will fit but some engine internals are different, too.

You might want to post some pics in this thread, then the rest of the Merc Gurus can have the opportunity to chime in......ed

BTW Doc Frankenmerc can probably help you with internal harness needs, he has a couple of parts kicking around (or was that a couple of Thousand, I forget!!!).

Thanks Ed! I will make a point of posting something in Merc Outpost. I just saw the opportunity to ask you at the time.

63LStriton wrote:

How does the reverse carb swap work out - 850s on a 1000? I think the 1000 will be fine once it put it together and give it a little TLC. Makes me hesitant to part it out too much knowing that I will just need to source more parts for it. There is a very good chance that the 1000 will be going on a pontoon up at the cottage next spring. Depends on what my dad buys for a pontoon, and what it is powered by. How hard is it to find a decent set of 1000 carbs? Can you go bigger - 1150 or bigger - on the 850?

The 100hp makes better power at the top end because of the larger carbs & reed stops. 85hp carbs on a 100hp would restrict airflow because of the "bottleneck" and mostly the top-end would be affected.

It'd still run good, with lots of low-end torque, actually would be perfect for a pontoon boat 'cause you're not interested in top speed (or, depending on the boat, whether it's gonna plane or not).

Would definitely use less fuel due to the smaller carb throats and smaller main jets.

You can't use later carbs on the older 90 c.i. blocks because the bolt pattern is radically different. But you're only gonna flow so much air thru the engine, anyway.

So carbs larger than 100hp aren't gonna help unless you do radical changes to the powerhead to increase airflow, which would make it suitable for racing only and pretty much too cranky to use on a "normal" boat.

BTW, as I recall the 65hp carbs have the same throat size as the 100hp, so probably you could adapt 3 of those to an older Six.

Some good parts sources are Craigslist, Fiberglassics, John's Old Mercury site or eBay. Sometimes you'll find a good deal on eBay, but a lot of the sellers must think their old outboard parts are gold-plated!

Doc Frankenmerc might have some spares kicking around, so give him a holler when you start looking for stuff.

Cheers.........ed

Speaking of "25th" anniversary Phantom Black Towers of power, check out this beautiful one for sale in the Chicago area:

chicago.craigslist.org/sox/boa/5726151851.html

$350 is a Steal! It even has controls and 2 tanks! And the faceplate is in very good shape except for what looks like a small dent.

I'd snap it up immediately if it were here in the PNW.