Wanted: 25ss Carb - KC16A

[ZUL8TR]

Wetback

Nice hydro. I raced that very Kelly hydro in the 1970's in APBA Region 5 in the 25ssh and 20ssh clases. I got the plans from Hal Kelly when he was at a race in south Fla that I attended when a teanager. Still have the hydro and the Merc 25ss and the Yamato Y80 for the 20ssh class. I did very well once I got it balanced, prop, engine adjusted and set up. When you get yours running with the right prop and set up to run about 7000-7200 rpm you can expect 60- 64 mph.

If you need any hydro mods and set up tips or other questions about the hydro and Merc 25ss engine I would be happy to help. I have been into that engine many times as well as knowing the hydro very well.

Do you have a prop? What do you have in pitch and diameter? I ran a 7.25" diameter x 12" pitch with cup Pinner 2 blade.

I notice in the pic that the transom was constructed per the plans. That is to low for the 25ss engine. I had to mod it to about 15.5" vertical and then adjusted up with shims depending on race conditions to get competitive speeds in the 60's.

How much does the hull weigh with steering, throttle, etc less the engine. Mine weighed 125lbs.

What length are the air traps?

[David_L6]

Doug,

Other than on original 25SS engines, I've only seen two KC16s ever and they were on my 44. Maybe use something else to get it running while you're looking for "hen's teeth"?

[dndsam]

ZUL8TR,

I have a compete, fully restored 25ss with fiber reeds now and am restoring another that will have a open stack on it. This is the one I am looking for the carb for. Once complete, I will use this one on my boat and let my dad use my current 25ss on his 10ft hydro.

I am currently running gps 55mph with my boat now. I am running a 3 blade Dewald, 6-3/4 x 12-1/2, cupped. I do not feel it turns up enough RPM's, but do not have a tach to know what it is for sure. I have a tiny tach, but too short to read while running. I also have a 2 blade Ron Hill 7-1/8 x 12, Pop Smith style prop that I plan on testing this weekend. Both props are cupped. I have ran the 2 blade and it turns the revs up, but my gps was dead so I was not sure of the speed. I should know more this weekend.

I have an additional 1" stick for my transom now that I run with to shim it up. I believe I can go another 1/4-3/8" max. I am not sure of the total weight of the boat, but the air traps are 60" from the back of the sponson, going all the way less 1/2" from the transom.

Any tips and tricks would be appreciated. I think 60mph is a realistic speed, but sqeaking 5 more mph might be a lofty expectation.

David,
I know there are options other than the KC16A, I am just trying to make this complete. I do appreciate your thoughts and insight. I have a KC16A carb that was on the motor, but the faceplate mounting stud on the right side(red box) was ground off so a plexiglass cover could swing over instead of using the faceplate and bracket, which was prone to breaking. Below is a pic of the one I have. If anyone has any ideas how I can fix this, I will be able to end my search.

[trident]

Kc16a

Get a KC15A, restamp it to read 16, some were done this way Factory OEM, and swap the internals... if you have a broken 16, you have the essential internal parts (hint: idle tube)

Align everything correctly, set float height correctly and stop obsessing one digit. Restamp it like the factory did! Put that one on your open stack motor, which is no longer stock anyway and go.

Jerry

[ZUL8TR]

Tips on set up

ZUL8TR,

I have a compete, fully restored 25ss with fiber reeds now and am restoring another that will have a open stack on it. This is the one I am looking for the carb for. Once complete, I will use this one on my boat and let my dad use my current 25ss on his 10ft hydro.

I am currently running gps 55mph with my boat now. I am running a 3 blade Dewald, 6-3/4 x 12-1/2, cupped. I do not feel it turns up enough RPM's, but do not have a tach to know what it is for sure. I have a tiny tach, but too short to read while running. I also have a 2 blade Ron Hill 7-1/8 x 12, Pop Smith style prop that I plan on testing this weekend. Both props are cupped. I have ran the 2 blade and it turns the revs up, but my gps was dead so I was not sure of the speed. I should know more this weekend.

I have an additional 1" stick for my transom now that I run with to shim it up. I believe I can go another 1/4-3/8" max. I am not sure of the total weight of the boat, but the air traps are 60" from the back of the sponson, going all the way less 1/2" from the transom.

Any tips and tricks would be appreciated. I think 60mph is a realistic speed, but sqeaking 5 more mph might be a lofty expectation.

You can get the 5+ mph if you get the revs, prop and setup right. I am presently running my 1973 25ss engine (one I raced back in the 1970's) on a pickle Karelsen hydro and am at the 62 mph range at 7000 rpm with the 7.25 x 12" Pinner prop. Pitch measured at 2" from center at the center of that arc. Don't know where Dewald measures his.

Some questions and thoughts:

1) What is the vertical height of the transom (no shims)? Can easily be measured with a carpenters square with the long edge along the bottom and the short leg vertical and read the outer (rear) top edge of the motor board.

2) What is the present distance of the center rear of the prop shaft below the bottom? Need to be about 3/4" to get the revs from your 12.5" pitch Dewald. The prop shaft needs to be parallel with the rear boat bottom.

3) What timing do you have the mag set at? Need an inductive timing light to do this. Factory is 38 degrees BTDC. I had to mark the flywheel with the degrees from TDC tic mark on the flywheel and install a stationary pointer on the crank case. For top speed 38 for accelleration 40 to 41 but be careful with this higher setting as pistons will runn hotter. Good for short course running.

4) Do you still have the fixed jet in the carb? Is it the 0.061" jet? I raced and presently run with that jet and that is what came from the factory. Tried adjustable and had poor success.

5) Does you boat at speed ride with the sponsons clear of the water? See 7) below.

6) Did you use Fir or Okume plywood? Fir is much heavier and hard to get a 125 lb hull.

7) Good on the long traps. Do they fade to zero height at the rear? If you can't get the boat to float the sponsons at speed you should consider making the traps trail to zero height at the rear and go all the way to the rear edge. That will provide higher angle of attack. I ran that way with the Wetback.

8) Do you have the gas tank as per the plans under the front cowl? If yes to much weight forward, consider moving to the rear at the transom or hang off the motor.

9) What type turn fin do you use? Is it at the left sponson back? Needs to be there.

10) What crankshaft endplay did you set? 0.010" is needed for this engine.

11) What sealer did you seal the crankcase to block with?

12) My playing with props including a 3 blade Dewald the 25ss runs better with the 2 blade tulip type props on my Karelsen. I would expect the 2 blade designs run better on the Wetback 10 degree transom as I raced with them .

13) What brand and style plastic reeds? What open height are they set at?

14) What fuel type and oil are you running? Hope no E fuel, not good for the motor. I run 87 octane E free at 16:1 oil mix.

15) What plugs are you using? I use NGK BP8HN-10. When racing I used Champ L61Y projecting instead of the surface gap Champ L78V standard on the 25ss. The L61Y are NLA and the NGK are the closest I can find to the L61Y, they work well at 0.040" gap.

That's it for now.

[dndsam]

Jerry, you are probably right. The fortunate thing is I am in no hurry so when the motor is complete, it will be decision time.

ZUL8TR,

Lots of questions I do not have answers for but here is what I know.

1. Vertical height of transom is 14-1/2" with no stick, so I am there at 15-1/2" with stick

2. Will find out this weekend.

3. I have no idea on the timing setting, not sure how to to that. I left it as it was when I got it.

4 and 14. Fixed jet, .063 for 87 octane E fuel. Dallas/Fort Worth does not have any stations that I know of without it, unfortunately. Pennzoil synthetic blend 25:1.

5. http://www.texaschapteraomci.com/wp-...1-2013-013.jpg

6. I am not sure of the construction of the boat. It was started by the Snell Brothers, then finished out by the late George Jacobs in Sherman, Texas. The decking on the top is door skins. Very thin with a Ceconite nose.

7. Traps do fade to the rear and end about 1/2" from the transom.

8. Gas Tank is a Dick Fickett steering bar tank.

9. The fin is mounted to the bottom midway aft, off center to the left.

10. Not sure.

11. Permatex High Tack Gasket Sealant.

12. 2 blade to trial this weekend.

13. Chris Carson drag reeds

14. see #4

15. NGK BP8HS

Thank you for all of your advice and questions. If need be, we can take this to email or PM.

[ZUL8TR]

tips

Jerry, you are probably right. The fortunate thing is I am in no hurry so when the motor is complete, it will be decision time.

ZUL8TR,

Lots of questions I do not have answers for but here is what I know.

1. Vertical height of transom is 14-1/2" with no stick, so I am there at 15-1/2" with stick

2. Will find out this weekend.

3. I have no idea on the timing setting, not sure how to to that. I left it as it was when I got it.

4 and 14. Fixed jet, .063 for 87 octane E fuel. Dallas/Fort Worth does not have any stations that I know of without it, unfortunately. Pennzoil synthetic blend 25:1.

5. http://www.texaschapteraomci.com/wp-...1-2013-013.jpg

6. I am not sure of the construction of the boat. It was started by the Snell Brothers, then finished out by the late George Jacobs in Sherman, Texas. The decking on the top is door skins. Very thin with a Ceconite nose.

7. Traps do fade to the rear and end about 1/2" from the transom.

8. Gas Tank is a Dick Fickett steering bar tank.

9. The fin is mounted to the bottom midway aft, off center to the left.

10. Not sure.

11. Permatex High Tack Gasket Sealant.

12. 2 blade to trial this weekend.

13. Chris Carson drag reeds

14. see #4

15. NGK BP8HS

Thank you for all of your advice and questions. If need be, we can take this to email or PM.

1. Shoot for prop shaft center at 3/4" below bottom and level prop shaft with bottom

3. email me at psushinsky@cfl.rr.com for how to do

4. Generally the ethanol requires a richer mix, have you checked the plugs for color? any carbon build up on piston crown? If you ever get non e fuel run 0.061" jet. The 25:1 is the recommended mix.

5 rides nice and clear
8. good on the tank

9 need that fin off the left sponson. The Wetback has a large lightening hole in the frame on the inside that needs to be filled to support the fin. Does your front cowl come off for acess?

11. next time you open it up use either Locktite 518 or Permatex gasket maker they are both anerobic sealers and set without air in presence of metal and only a very very thin coat is needed on both halves. If sealent to thick it will make the center bored holes for the reed cage and crank bearings fit loose. The factory center bored these areas with the case bolted to block and no sealer.

15 Those plugs are fine, next time you need plugs get the NGK BP8HN-10, (NGK part # 4838), the main difference is a 0.040" gap and a special center electrode. The CD ignition can easily run the larger gap and the surface gap plugs these engines came with use a 0.051" gap.

Good luck testing.

[Fihn176R]

Kc16a

I have about 60 to 70 KA and K

[Fihn176R]

Kc16a

Sorry, Wrong button. I have about 60 to 70 KC and KA carbs, but no 16, I found some 15's. If you need a 15 give me a call. 5416652920.
Tim

[ZUL8TR]

Tiny tach

ZUL8TR,

..................I am currently running gps 55mph with my boat now. I am running a 3 blade Dewald, 6-3/4 x 12-1/2, cupped. I do not feel it turns up enough RPM's, but do not have a tach to know what it is for sure. I have a tiny tach, but too short to read while running. .......................

What model Tiny tach do you have? I have the old TT226R-1C (bought it 4 years ago) they now have a new style for gas engines. Wires were also to short for my cockpit so I just added about 20" to the red lead by a simple crimp splice plus tape (could use heat shrink) using 18ga solid core with outer cover, also extended the ground lead with a crimp splice. Works just great on the 25ss CD ignition. One thing that TT tech dept told me was to wrap the red lead 3 times around each plug wire for correct rpm reading with the 1C on this 2 cylindere engine. Did that after first test with one plug wire wrapped when rpms were 1/2 what they should be?

Once you get the red lead around both plug wires cut off any extra red so you do not pick up any stray signals.

[blueskyracer]

very nice boat.. That was my first boat build in 1969

[dndsam]

Bump.

Still looking for a Mercury KC16A carburetor. Any leads would be appreciated.

[ZUL8TR]

Kc16a

Indeed rare and bird to come by In my searching at AOMCI meets and on the web since my last post I have not seen one without a 25ss behind it. Maybe it's time to consider the options expressed above so you can at least use it and maybe in the furture find a 16A?

Have you corrected the wire lengths on the tiny tach so you can mount it on the dash and installed the red wire 3 wraps on both plugs as I posted above? If so does it work and what rpm are you getting with your the best prop? BTW I find with my Wetback the 2 blades 7.3" x 13.3" works best for me running with prop shaft level to bottom and shaft end 5/8" below bottom. Pulling about 7200 rpm @ 63mph. I tried a 3 blade Dewald he made for a fellow boater with a 25ss on a hydro and it was not as good as the 2 blade.

[G Stillwill]

I think thAt the KC16A also came on some of the Merc 800's not sure what years though.

[trident]

Kc16a

George, might you be confusing the KC16A with the KA16A, the 1962 Merc 800carbs?

Those KA16A's are unusual in that they were factory milled out to 1 1/16" venturi, even though the casting says 1" on the float bowl bottom...

KC16A was a race carb only, supplied OEM on the 22 cu. in. 25SS only. They came factory equipped with full butterflies, something that service carbs never had.

Jerry