Grandpa's Super 10 KG-7 Hurricane

[kaifeiji]

Hello everyone,
I recently joined this group and have purusing all of your posts, searching for information on a Super 10 Mercury Hurricane. It has a lot of sentimental value to me because my grandfather told me stories about his racing adventures with the exact same engine. He ended up pursuing a career in building, racing and repairing outboards. After he passed away, I was priviledged enough to acquire the Mercury Hurricane that he had for so many years.
I just purchased my first boat, (it's a 12' aluminum Delhi Woodstream), and am anxious to get it on the water w/ the Mercury on the back.
However, I don't think the engine has been run in over 40 years. The person who my grandpa acquired it from said that he bought it new, ran it once, determined that it was too much power for his flat bottom boat, and hung it on the wall in his shop for 30 plus years.
Around 10 years ago, my grandpa installed new points and condensors, spark plugs and wires, and was in the process of replacing the water impeller. He passed away before he got it running.
My question is where should I start w/ this engine? I planned on purchasing a repair manual and was thinking of rebuilding the carb and resealing the lower unit. Besides that, is there anything else that I should do? Any advice or help would be very much appreciated.
Thank you very much for your time and for reading something that was not intended to be so long-winded.
~Steve

[mercguy]

Hello everyone,
I recently joined this group and have purusing all of your posts, searching for information on a Super 10 Mercury Hurricane. It has a lot of sentimental value to me because my grandfather told me stories about his racing adventures with the exact same engine. He ended up pursuing a career in building, racing and repairing outboards. After he passed away, I was priviledged enough to acquire the Mercury Hurricane that he had for so many years.
I just purchased my first boat, (it's a 12' aluminum Delhi Woodstream), and am anxious to get it on the water w/ the Mercury on the back.
However, I don't think the engine has been run in over 40 years. The person who my grandpa acquired it from said that he bought it new, ran it once, determined that it was too much power for his flat bottom boat, and hung it on the wall in his shop for 30 plus years.
Around 10 years ago, my grandpa installed new points and condensors, spark plugs and wires, and was in the process of replacing the water impeller. He passed away before he got it running.
My question is where should I start w/ this engine? I planned on purchasing a repair manual and was thinking of rebuilding the carb and resealing the lower unit. Besides that, is there anything else that I should do? Any advice or help would be very much appreciated.
Thank you very much for your time and for reading something that was not intended to be so long-winded.
~Steve

Steve, sounds like you are on the right track! First, do a quick compression check to make sure the motor is still "ok" inside. Replace the water pump impeller FOR SURE and you might have to replaced both coils, as they dry out and crack over a long period of time. Let me know if I can help in anyway, I still have ALOT of 2cyl 20cube stuff left, like your KG7.......

[Bill Huson]

And carry a wood hammer . . .

A good size wood hammer, no kidding. Back when I was a wee pup (1950 sumpin) I had a KG-7 and I recall many pull start recoil hang-ups. Smacking the top with a chunk of 2X4 usually freed the recoil up. And twice the little flat head allen screw in the center of the recoil vibrated loose and went bye-bye.

Other than that minor annoyance, my KG-7 rocked! I had it on a 14' fairly light plywood runabout, had it jacked with cedar shingle strips until the prop would start to break loose inna turn, and the local marine poo-leece couldn't catch me! Moved up to brand spanky new Mk 25 after a boat racer gave me a wad of cash for my KG-7. The Mk 25 was only a shade faster.

[Mark 72@E]

My 2 cents

In addition to asking for help here, also head on over to the Antique Outboard Motor Club at:

http://www.aomci.org

and see if someone will take you under their wing who is knowledgeable about this engine. You'll also quickly learn what parts and supplies are available. Someone there can lead you to who sells the exact color green spray paint used on your Mercury, just to give you one example. It will save you time and trouble and will save the engine some pain.

Many a novice has removed the "cylinder head" on an old Mercury expecting to see the tops of the pistons, only to discover that the "cylinder head" is actually a plate for the cooling system. But in the process they break one or more of the water jacket bolts and then make it worse by removing the frozen studs improperly leaving gaping holes.

Also using improper tools to remove the flywheel can crack it. And you can't walk into your local Mercury dealer for a replacement.

Both of these can be avoided by following the proper service manual (not a generic manual that covers every model ever built) as you mentioned and by using the right tools.

AOMCI also conducts regional meets all across the country where collectors display their restored engines. Check the AOMCI webiste to see if there are any in your area. There's nothing better than learning from someone who has restored the same engine as you have. And these guys love to talk about old outboards!

[kaifeiji]

Hey guys, thanks a lot for all of the information.

Daren-thanks for the heads up; if I find that I need parts of any kind, I'll write you a PM. Thanks for your willingness to help.

Bill-I'll be sure to carry a large 2x4 with me . In regards to racing, my grandpa shared many stories of beating boats with 25 horse engines, using only his Merc. Hurricane. He put it on an 8' plywood boat that he made himself and was clocked, (literally with a stop watch), at 42 mph, (he weighed all of 110 lbs back then and I'm sure the boat was pretty light). While I'm definitely not shooting for anything that fast, I'd be more than happy if the boat stayed on a nice plane.

Marc-Thanks for the info on classic outboards; I'll be sure to check out their site. It sounds like they have a wealth of knowledge concerning the intricacies of these motors. Where can I get a service manual specific to the KG7? The only one that I've found goes for $50 and covers lots of models.

Thanks again for all of your help.

Best regards,
~Steve

[mercguy]

Hey guys, thanks a lot for all of the information.

Daren-thanks for the heads up; if I find that I need parts of any kind, I'll write you a PM. Thanks for your willingness to help.

Bill-I'll be sure to carry a large 2x4 with me . In regards to racing, my grandpa shared many stories of beating boats with 25 horse engines, using only his Merc. Hurricane. He put it on an 8' plywood boat that he made himself and was clocked, (literally with a stop watch), at 42 mph, (he weighed all of 110 lbs back then and I'm sure the boat was pretty light). While I'm definitely not shooting for anything that fast, I'd be more than happy if the boat stayed on a nice plane.

Marc-Thanks for the info on classic outboards; I'll be sure to check out their site. It sounds like they have a wealth of knowledge concerning the intricacies of these motors. Where can I get a service manual specific to the KG7? The only one that I've found goes for $50 and covers lots of models.

Thanks again for all of your help.

Best regards,
~Steve

Steve, is your KG7 an "H" model or a "Q" version? Here is my KG7H.....

[Bill Huson]

Steve . . .

After 50 years my memory is a tad fuzzy, but I'm sure the KG-7 was a 20 cu in block (actually 19 point sumpin) and tuned to ~10 hp via smaller carb throat than the MK 20/MK 25.

Back in the good ol' days, my 14' boat didn't weigh squat, and I was a skinny swamp rat who tipped the scales at less than 100 pounds. The KG-7 pushed my rig close to 40, and the new MK 25 was only a couple miles faster until I cleaned up the carb throat and filed on the ports and prop -> honking rig!

The guy who bought my KG-7 (*sniff* hated to part with it) was very happy since I had already figured out that one set of points needed to be set at .012 thou and the other at .016 thou for max speed. I never had any trouble pulling the flywheel like Mark 72@E said, but I musta had it off more'n a dozen times to fiddle with the ignition so the flywheel was used to the abuse.

[kaifeiji]

WoW!! That's a beautiful Merc!! You must have spent a lot of time and money restoring it to that condition; very impressive. It looks like you have the Quicksilver lower unit; wouldn't that make it a "Q"? I'm pretty sure mine is the "H" model, as it doesn't have the Quicksilver lower unit.

Bill-did you port the intake and exhaust ports? I thought about cleaning up the reed cage, (if I must pull the engine apart to reseal it), and intake/exhaust ports. I've ported quiet a few cylinder heads for various vehicles but I'm hesitant to go to crazy with the grinder on a two-stroke. To do so would dramatically change the power curve, and not necessarily in a good way. On a small block Chevy or Ford head, if you make a port too big, oh well, there are millions more. With this engine, that's a different story. I don't think a little cleaning up of the ports and cage would hurt anything though. If you think about it, making a little more than 10 hp out of 20 ci isn't really very impressive, considering that two stroke dirt bikes of the same cc are making upwards of 70. Technology has advanced a bit since 1950 I guess.

Is it possible to use the Mark 25/28 carb on the KG7 for more air/fuel? Do you know if they bolt up to the KG7 powerhead? As far as the exhaust goes, I've seen something that attaches to the exhaust port and looks like a big megaphone. However, I'm sure that would have to be fabricated; finding those would probably be pretty difficult and pricey.

[dwhitford]

The Mark 28 carb bolts to the crankcase with wider stud spacing than the spacing on a KG-7 and hence will not fit on a KG-7. It would take major metal surgery to adapt the Mark 28 carb to a KG-7, including enlarging the port in the crankcase behind the carb throat. It can be done, but it's a major task without significant benefit.

[79-0-DMH-Ron]

My two cents

I was wondering which Hurricane you have. At the begining of this post you mentioned that you have a super 10 Mercury Hurricane. Toward the end of hurricane run right before the Mark 20 was introduced, Mercury produced A super 10 Mercury Hurricane with a shifting Lower unit. This was the same lower unit that was produced on the mark 20. This was basically the same moter as the Mark 20. the Previous Hurricanes and Lightnings Kg4 and Kg7 were direct drive.

From what you have told us about this moter it has very little time on it. If it is in good condition i would not tear into it and start porting it. I race D Modified Hydro so i can appreciate you wanting to extract as much power from that moter as possible but I think that you will be suprised as to how much power that Little moter actually produces stock. Porting the moter will make it not idle very well and will take its every day driveability away. The Moters are very responsive right out of the box. When Kiekofer(sp?) Produced those moters he wanted to blow the competition away so he rated all of his moters at a certain rpm which was below the actual peak power of the moter. That little 10 was more like close to 20.

[dwhitford]

The "gearshift" Super 10 was the KH-7: same powerhead as the KG-7 but with what was the preview of the Mark 20 driveshaft housing and gearcase introduced in 1953 with the Mark 20. The KH-7 in 1952 was called the Super 10 Cruiser.. The KG-7 was the first of the Merc "10-hp" engines with an 8-port reed cage and made an honest 16 hp.

[79-0-DMH-Ron]

cont'd

My father has a Classic outboard shop and i have done quite a few restorations on Kg4's Kg7's and Mark 20's and 25's. Like merc guy said i would run a compression test on the moter. If it has over 110 psi and both cylinders are within 10% of one another then i would start with a tune up and get the old timer running. get the flywheel off and clean the stater plate. once the stater is clean check the top Crank shaft seal for leaks by spraying the seal with WD 40 on the seal and looking for bubbles. IF the seal is blown replace it other wise you will be running with low crank case pressure and it will not idle correctly as well as possibly hurt the moter if run to long. If the seal is in good condition clean the points with 600 grit wet dry sand paper. Next set the points at 18 tho. check the Coils for cracks if they are cracked they will need to be replaced. Next clean the carb and check the float level. Once you are done with the carb remove the lower unit and check or replace the water pump.
If you need Parts or have a question my dad is a wealth of knowledge. If you email me i can get you his contact information. ron.wright@erac.com
Hope this helps
Ron

[mercguy]

H vs> Q

WoW!! That's a beautiful Merc!! You must have spent a lot of time and money restoring it to that condition; very impressive. It looks like you have the Quicksilver lower unit; wouldn't that make it a "Q"? I'm pretty sure mine is the "H" model, as it doesn't have the Quicksilver lower unit.

Bill-did you port the intake and exhaust ports? I thought about cleaning up the reed cage, (if I must pull the engine apart to reseal it), and intake/exhaust ports. I've ported quiet a few cylinder heads for various vehicles but I'm hesitant to go to crazy with the grinder on a two-stroke. To do so would dramatically change the power curve, and not necessarily in a good way. On a small block Chevy or Ford head, if you make a port too big, oh well, there are millions more. With this engine, that's a different story. I don't think a little cleaning up of the ports and cage would hurt anything though. If you think about it, making a little more than 10 hp out of 20 ci isn't really very impressive, considering that two stroke dirt bikes of the same cc are making upwards of 70. Technology has advanced a bit since 1950 I guess.

Is it possible to use the Mark 25/28 carb on the KG7 for more air/fuel? Do you know if they bolt up to the KG7 powerhead? As far as the exhaust goes, I've seen something that attaches to the exhaust port and looks like a big megaphone. However, I'm sure that would have to be fabricated; finding those would probably be pretty difficult and pricey.

if you do not have a racing quicksilver lower unit, then your motor is neither a "Q" or an "H" model, but a "fishin" style motor. The Q motors had Quicksilver towers and lower units for racing and were the first version produced by Merc. The Q motor is about 2" longer than the next version, the "H" motor. Like Ron said DO NOT modify the ports or reedcage, as they are plenty good enough as is for a "stock" closed up motor. Maybe if you have "open exhaust" (megaphone), then porting "could" help slightly, but only on top speed. You can use a MK25 carb, but the AJ32A carb on the KG7 is fine for use. You cannot use a cqarb from the MK28 without having to machine the carb opning on the front case bigger, as the MK28 has a KA carb, which has a 1" opening.

[mercguy]

My father has a Classic outboard shop and i have done quite a few restorations on Kg4's Kg7's and Mark 20's and 25's. Like merc guy said i would run a compression test on the moter. If it has over 110 psi and both cylinders are within 10% of one another then i would start with a tune up and get the old timer running. get the flywheel off and clean the stater plate. once the stater is clean check the top Crank shaft seal for leaks by spraying the seal with WD 40 on the seal and looking for bubbles. IF the seal is blown replace it other wise you will be running with low crank case pressure and it will not idle correctly as well as possibly hurt the moter if run to long. If the seal is in good condition clean the points with 600 grit wet dry sand paper. Next set the points at 18 tho. check the Coils for cracks if they are cracked they will need to be replaced. Next clean the carb and check the float level. Once you are done with the carb remove the lower unit and check or replace the water pump.
If you need Parts or have a question my dad is a wealth of knowledge. If you email me i can get you his contact information. ron.wright@erac.com
Hope this helps
Ron

Ron, you have been holding out on me!!!!

How's the D motor?

[79-0-DMH-Ron]

My D

Daren,
Still working on the D. I have been really busy at work so i haven't had the time to finish it off. I am at work now as a matter of fact. I am building a Mk 58 style block this time so i had to start from scratch. I hope to be stabing the crank on tuesday of next week and geting it broke in the following weekend if time permitts. We will see how she runs soon enough.
Talk to you later
Ron

[mercguy]

take a break Ron!!!!!

Daren,
Still working on the D. I have been really busy at work so i haven't had the time to finish it off. I am at work now as a matter of fact. I am building a Mk 58 style block this time so i had to start from scratch. I hope to be stabing the crank on tuesday of next week and geting it broke in the following weekend if time permitts. We will see how she runs soon enough.
Talk to you later
Ron

all work, no play, makes Ron a ..............you know the rest!!! How is the progress on the new Dmod boat Ron? If you guys have never seen Ron's equipment, it is top notch stuff and very clean and pretty!!! Hey Ron, any chance you have a "spare" MK58 block in good shape??? Looks like next year will have to be when I get to run my new DMH with ya Maybe we could do some testing together in the "off season" and give me some of your "speed secrets" Word is that Bill Clinton is testing his new Darneille FEH at Salt Springs today, then him and the Bird crew are headed back East tommorrow for the Pro/Mod and Stock Nat's with a packed trailer full of boats and loaded on the top of his motorhome.something like 8 boats?????

[Bill Huson]

Steve RE ports . . .

I sorta *cleaned* up the ports on the KG-7 but didn't remove enough material to alter the port timing. Now the carb throat and reed cage intake was flowed and polished but not to a super shine. Methinks #400 grit, time to quit on those parts.

I can't recall the carb interchangability betwixt KG-7 and 20/25 motors, but I believe that was the power control used by Mercury, smaller carb = 10 hp, bigger on same cubic inch block = 20/25 hp.

More KG-7 tales . . . I had it trimmed for WOT speed and had to twist it WOT (tiller steer), dash up to the bow and knock her down on plane and dash back to the helm. FUN! The only boat on the river that could even come close to staying with me was a 16' Raveau with V-4 Johnson. Then I got a few nicks in the prop and filed the blades down and balanced it - sort off (teeter-totter balance). The Raveau was hosed in my wake! heeheehee . . .

[dwhitford]

The KG-7 reed cage was milled, and hence less "roomy" than the sand-cast reed cage on the Mark 20. Many racers (including myself) felt that that the sand-cast reed cage flowed air better and opted to replace KG-4 and KG-7 milled reed cages with the sand-cast cages from Mark 20s.