TOPIC: 1967 mercury950ss

Hi All! I have recently acquired a ‘67 Larson All American with a ‘67 merc950ss on it. Neither have seen the water since ‘09. Both have been garaged most of their lives. Both are in extremely good condition. All of the controls for the motor are free and functional; steering, starter, elec. choke. The lower unit has been drained, refilled and there is no visible leaking (wetness) anywhere around the unit/drive area. The owner stated that the impeller had been replaced but may open it up and check it regardless. I’ve replaced the primer bulb and any other rotted fuel lines exterior of the motor. All lines interior appear serviceable. I’ve pulled the plugs, fogged the cylinders and cranked the motor on the starter to distribute oil. All cylinders have good compression and the rotating assy spins beautifully. At this point im going to make a heavy oil/fuel mix and give ‘er hell.
I’m really expecting the fuel pumps/carb diaphragms to be the weak link and am looking for info regarding replacement parts/overhaul kits. I have seen some YouTube stuff on old marine motor start up and have read some of the forum material in the same. I promise ill try and not be a giant pain in the ass……but I figured I’d rely on expert knowledge before i wasted too much time fishing about.

Welcome to Fiberglassics ! I have not worked on outboards much.... yet. But I was told once that the water impeller should be replaced every 5 years whether the motor is used or not ? The experts can tell you more.
There is an Mercury outboard section below. You will most likely get more replies there.
Enjoy your restoration journey, and ask anything you want, as much as you want !

Wowee Zowee!!!
What a beauty!!!
And it still has the crankcase factory seal and the distributor factory seal!!
What are the compressions?
If the carburetors flood when you pressure up the system with the primer bulb, you will probably want to replace the possibly original float needles & seats (Sierra Marine # 18-7057)
There are other parts (floats, some gaskets, etc) that might need replacing, so don't order parts until you know what all you need. www.marineengine.com and follow the prompts to 1960 & up Mercury.
Scroll down the list of models, and your serial number will be listed under the 950 (6 cylinder).
Definitely replace the impeller, and due to its design plan on replacing it every (2) years for maximum water pressure.
Mercury Marine # 47-89984T4.
With an older used impeller, you might not get good pressure up to the top cylinder - primarily during idling, or low RPM cruising.
This can cause overheat and scoring in the higher cylinders.
Lots of advice will be available when you move your discussion to the Mercury Outpost Forum down the list of this sight's forums.
Good luck in your project, and looking forward to following your progress.
doc

Thanks, doc. Strong advice and valuable information. Have not yet done a gauged pressure check…..all 6 pushed enough air for me not to be able to keep a finger over the plug port and an aged battery spun the crank easily with no plugs in but was worthless with the plugs installed. Not sure how much more I’ll dig in to it this fall/winter….need to deox the hull/deck and various small items on the trailer. Looking forward to sharing progress/stories with the fiberclassics community. Again, appreciate the input. I’ll just say it right now…….I’ll probably look at the photo of your garage every hour……for the rest of the winter!!! Truly gorgeous collection.
Michael.

Michael - Everything the Doc said! Impellers are cheap so it's good insurance to replace it. Here's some really good deals on eBay, be sure you make sure it's either an OEM Merc part or a Sierra Marine aftermarket (Sierra Marine makes good parts). Many of the El Cheapo impellers are made in China, and no Chinesium impeller will EVER touch any outboard I ever work on!!

https://www. ebay .com/sch/i.html?_fsrp=1&_from=R40&_nkw=47-89984T4&_sacat=0&rt=nc&Brand=MerCruiser|Sierra|Mercury&_oaa=1&_dcat=177688

Just take the spaces out of the link, this site parses eBay links for some reason.

Here's your motor's listing at marineengine.com :

www.marineengine.com/parts/mercury-outboard-parts/950-6-cyl/1869776-thru-2318585

Fuel pump info:

www.marineengine.com/parts/mercury-outboard-parts/950-6-cyl/1869776-thru-2318585/fuel-pump-and-fuel-line-assembly

You'll need 2 ea of #3 (diaphragm kit) for your fuel pumps. Good idea to guarantee their reliability.

Your ignition is fully electronic and the old "horseshoe" style trigger (in the distributor) is actually quite durable, so I wouldn't be surprised at all if the ignition sparks, unless there's a problem with the CDI box. And even that can be upgraded with a more common, newer Merc CDI ign box so Never Fear!

That's a really clean motor and rare to see one in such nice original condition. IIRC the 950-SS was a 1-year-only engine.

HTH and enjoy your "new" rig.............ed

p.s. I've had the pleasure of many Pilgrimages to the Doc's lair. It's quite an experience and one you'll never forget! Beautiful color on those 2 hot-rod boats, BTW!

Fuel pump diaphragm kit on Amazon on sale for $7.79 each with 1-day Prime shipping:

www.amazon.com/Sierra-International-18-7804-Mercury-Outboard/dp/B0009TRVE0

Hard to beat that price! Unless the fuel pump check valves are "hammered", they can be cleaned and reinstalled with new gaskets from the diaphragm kit.

Thanks Ed! I truly appreciate all of the advice/parts info. I did check spark on all plugs while I was “investigating” the motor and she fires on all 6. I’m fortunate to have the original owners son as a neighbor on the lake……he’s a wealth of knowledge re: the usage and care of the boat/motor. He says they used the rig rugularly for the first few years after purchase in ‘67 and it was used only sporadically after that. Always garaged, always maintained. He gave me the whole rig under the condition that I would “give his dads boat a good home”. That didn’t seem quite right. Knowing he was a whiskey guy, I “donated” 6 bottles of my favorites…..he said that was way too much…..I disagreed. And here we are.
Thanks again, Michael

Shot in the dark……Mercury black dark!!! …..anyway….. two things……and I know this is a cop out…..but I’m a firm believer in knowing your place….. wondering if a) Dr. Frankenmerc does service work, and b) where his lair is located!!
It’s not that I don’t love working on my own stuff……that’s why I own all this vintage crap…..I’m not a collector….I’m a owner/operator. It’s just that I don’t want to damage anything beyond repair the first time I work on it. I’m a car/sailboat/house/motorcycle repair expert …..basically a mechanic with no two stroke outboard marine experience what so ever and I don’t want to trash what I feel is a genuine heirloom barn find by throwing naïveté at it point blank. If we’re being honest.
Input always welcomed and appreciated.

I have closed my shop due to health limitations, but continue to answer questions to assist.
I'm located in the western area of Washington state.
If you send me a PM, I'll respond, but I no longer post my contact info.
doc

Good eve, Doc!
So.......the usual can of worms has been cracked open on my '67 950ss. Rebuilt the fuel pumps and pressurized the fuel system via primer bulb to see fuel pissing out of every factory crimped end on every fuel line under the cowling!! Given the supple condition of the lines themselves, was a little surprised that the connections were the weak link. Oh well, a resto is a resto, right? Have decided (based on parts avail/unavail)to build my own lines. Feel as tho i need to try and maintain OEM volume/flow as much as possible?? For access removed starter/soleniod and what im assuming is the coil? Not fun. During this process have discovered that the main wiring harness is 50/50 trash. Was fully willing to cut back to clean wire, splice in and try to keep the OEM merc plug etc intact.......but just not an option. The choke wire and the main power feed are losing casing at an alarming rate dangerously close to the plug. The harness, for safety reasons, needs replaced. In your opinion is the a/m unit avail from marineengines a decent product or should i be looking somewhere else for a harness?? Also.......and this is embarrassing.......where do i find a good shop level manual for this thing?
Swimming in the deep end.......
Michael.

I prefer the after-market CDI-electronics components, and use them exclusively.
The internal harness part number from CDI is 414-2770
You will have to fabricate a retaining piece since the 950ss used the (4) screws through the side of the engine pan, where this harness is specifically designed to replace the harness on the 1973 thru early 1979 inline-6 harness,
Another option, that avoids the cost of the replacement internal harness is to drill a hole in the front of the engine pan, insert a grommet, and hard wire in your external harness.
I have attached pictures of the manual I use all the time for this era Merc.
doc