Mercury Mark 40-H - Page 2

Skoontz · 03-20-2008

Used to be the way to make a Johnson 140 run faster was with a Merc prop...Don Henrich hated to hear that, but he sure resplined a bunch of em for us....

I see from one of the pictures the way to make your Merc run is with an OMC tank!

Very pretty motors.

John (Taylor) Gabrowski · 03-20-2008

I had a couple not like that one for racing stock back in the early 1970s. I seen a Merc 40H that had 44 cube liners put in to run the current Merc 44 pistons but he left the head area as was the way if came from the factory and it ran okay. To see that red one here all gussied up and sporting KC6 carbs and what ever else done would make some Mark 55Hs real scared!

How on earth could anyone get them to 49 cubic inch there does not seem the space between pairs of cylinders to ever punch one out that far with liners to increase the bore. Please explain further?

**Mark75H** · 03-20-2008

Quote:

Originally Posted by John Taylor

How on earth could anyone get them to 49 cubic inch there does not seem the space between pairs of cylinders to ever punch one out that far with liners to increase the bore. Please explain further?

I thought the crank throws were on the same centers? Are KG9's and 40H's shorter than 55's?

John (Taylor) Gabrowski · 03-20-2008

As far as I recollect the crankcenters to throw are the same for KG9, Mark 40H, Mark 50, Mark 55, Mark 39H, Mark 55H and Merc 350-400 to 500s too. You can use the same Merc 600-4 series small wrist pin connecting rods in them as well with the newer style flat top pistons for the older 4 bangers and the 44s came with them flat topped already as a newer technology. But how would anyone get them to near 50 cubic inches? The reed block locating pin block side holes would be gone and the liners would have to be on top of each other some how?? But where is the space still, for that?

**Mark75H** · 03-21-2008

The bore for a 49 would be 2.70 vs 2.56 for a 44 ... 0.070" thinner on each side of the reed cage back location pins ... yes, that would be very close to the pin holes, but they would still be there by a thousandth or 2 if the liners didn't need to touch.

My guess is that they just left the pins out and the liners either just touched or just didn't. I don't know of anyone still alive who would know the details

John (Taylor) Gabrowski · 03-22-2008

Some one said that some racers went that far that would make on really oversquare racing Merc with some real power extras to think about.

Would they have used Turner pistons for such an adventure at that time or used what for pistons if not Turners?

49 cube Merc 4 would make for one neat FE or SE engine if such things were legal.

**Mark75H** · 03-22-2008

It might be legal, I'd have to look closely at the restrictions on 44's in 850, there aren't many.

I have no idea who made the big pistons. Might have been from some other motor of the day.

Aeroliner · 03-22-2008

Thought you would enjoy seeing inside. All 4 cylineds used the same basic crank except for the taper. Mark 40-H engines had the smaller taper cranks. The inside of a 40 H was very restrictive and we opened it up quite a bit. The real hard part was taking the heads from a 44 that were power dome and puting them on the engine. Hope you enjoy the photos. We will be posting a video on our website soon you you can hear it. We ran a stock 44 just before this engine and it really hurts you ears. If anyone else is intrested in engine work you can try Doug Kay. His info is on our web page at www.Aeroliner-Boats.com
Alan

Aeroliner · 03-22-2008

As you can see the bore size for the 44 cubic inch mod came right up to the pins so it seems impossible to get 49 cubic inches unless the stroke is changed. Don't think the crankcase will let this happen.

Alan

John (Taylor) Gabrowski · 03-23-2008

I love those pictures, that is really cutting it close to the locating pins alright! Putting on power domed heads must sure envolved some neat welding skills too to get them just right. Nice porting that would make it sing. That motor at 44 cubes must have stung a few when they saw the cowls fly by!

I had 2 KG9s and 2 40Hs and one resleeved Mark 50. One KG9 and one 40H had Hubbell reed valves installed on the intake transfer port areas. The ports too were stock height but squared. Here they allowed the KG9s unaltered as class Ds for hydro but for runabout that was a bit too hard so they allowed the Hubbell reed valved KG9s and 40Hs into D runabout where they enjoyed a but more success with the added breathing. I would run them on that (lightened and bottom revamped) Asburn D Alky runabout I had and could run 2nd or 3rd against 55H stockers with them by sure force of being able to turn that runabout so tight it was a corner catcher against the 55Hs. I got a first for seasons points for a couple of years before I could afford 55Hs just from running 2nd or 3rd all the time consistently in D runabout. There is a picture of that big Asburn banana runabout on the website here under the historical threads with a big CP144 numbered on its sides where it was with a 40H on her and she did cook for her time. I wished I still had her for posterity sakes.

Please keep up the pictures and the write ups on the work, it is all a pleasure to see all that.

03-20-2008	#12
John (Taylor) Gabrowski CANADIAN PRAIRIES REGION Join Date: Dec 2004 Location: Winnippeg Posts: 1,555	Some put liners to 44 inch Mark 40H blocks alright I had a couple not like that one for racing stock back in the early 1970s. I seen a Merc 40H that had 44 cube liners put in to run the current Merc 44 pistons but he left the head area as was the way if came from the factory and it ran okay. To see that red one here all gussied up and sporting KC6 carbs and what ever else done would make some Mark 55Hs real scared! How on earth could anyone get them to 49 cubic inch there does not seem the space between pairs of cylinders to ever punch one out that far with liners to increase the bore. Please explain further?

03-20-2008	#14
John (Taylor) Gabrowski CANADIAN PRAIRIES REGION Join Date: Dec 2004 Location: Winnippeg Posts: 1,555	Mark 40h - Punched Out Real Big? As far as I recollect the crankcenters to throw are the same for KG9, Mark 40H, Mark 50, Mark 55, Mark 39H, Mark 55H and Merc 350-400 to 500s too. You can use the same Merc 600-4 series small wrist pin connecting rods in them as well with the newer style flat top pistons for the older 4 bangers and the 44s came with them flat topped already as a newer technology. But how would anyone get them to near 50 cubic inches? The reed block locating pin block side holes would be gone and the liners would have to be on top of each other some how?? But where is the space still, for that?

03-21-2008	#15
Mark75H Sam Cullis Join Date: Nov 2004 Location: Annapolis, MD USA Posts: 3,295	The bore for a 49 would be 2.70 vs 2.56 for a 44 ... 0.070" thinner on each side of the reed cage back location pins ... yes, that would be very close to the pin holes, but they would still be there by a thousandth or 2 if the liners didn't need to touch. My guess is that they just left the pins out and the liners either just touched or just didn't. I don't know of anyone still alive who would know the details __________________ Since 1925, about 150 different racing outboards have been made

03-22-2008	#16
John (Taylor) Gabrowski CANADIAN PRAIRIES REGION Join Date: Dec 2004 Location: Winnippeg Posts: 1,555	Has anyone really got that far and what were the results? Some one said that some racers went that far that would make on really oversquare racing Merc with some real power extras to think about. Would they have used Turner pistons for such an adventure at that time or used what for pistons if not Turners? 49 cube Merc 4 would make for one neat FE or SE engine if such things were legal.

03-22-2008	#17
Mark75H Sam Cullis Join Date: Nov 2004 Location: Annapolis, MD USA Posts: 3,295	It might be legal, I'd have to look closely at the restrictions on 44's in 850, there aren't many. I have no idea who made the big pistons. Might have been from some other motor of the day. __________________ Since 1925, about 150 different racing outboards have been made

03-20-2008	#11
Skoontz - Join Date: Apr 2006 Location: Encinitas, California Posts: 510	Used to be the way to make a Johnson 140 run faster was with a Merc prop...Don Henrich hated to hear that, but he sure resplined a bunch of em for us.... I see from one of the pictures the way to make your Merc run is with an OMC tank! Very pretty motors.

03-22-2008	#18
Aeroliner Team Member Join Date: Mar 2008 Location: Lake Charle, Louisiana Posts: 264	Inside the red wild one Thought you would enjoy seeing inside. All 4 cylineds used the same basic crank except for the taper. Mark 40-H engines had the smaller taper cranks. The inside of a 40 H was very restrictive and we opened it up quite a bit. The real hard part was taking the heads from a 44 that were power dome and puting them on the engine. Hope you enjoy the photos. We will be posting a video on our website soon you you can hear it. We ran a stock 44 just before this engine and it really hurts you ears. If anyone else is intrested in engine work you can try Doug Kay. His info is on our web page at www.Aeroliner-Boats.com Alan Attached Images

03-22-2008	#19
Aeroliner Team Member Join Date: Mar 2008 Location: Lake Charle, Louisiana Posts: 264	49 cubic inch seems impossible. As you can see the bore size for the 44 cubic inch mod came right up to the pins so it seems impossible to get 49 cubic inches unless the stroke is changed. Don't think the crankcase will let this happen. Alan

03-23-2008	#20
John (Taylor) Gabrowski CANADIAN PRAIRIES REGION Join Date: Dec 2004 Location: Winnippeg Posts: 1,555	I really enjoyed my KG9s and 40Hs back in the late 60s and early 1970s I love those pictures, that is really cutting it close to the locating pins alright! Putting on power domed heads must sure envolved some neat welding skills too to get them just right. Nice porting that would make it sing. That motor at 44 cubes must have stung a few when they saw the cowls fly by! I had 2 KG9s and 2 40Hs and one resleeved Mark 50. One KG9 and one 40H had Hubbell reed valves installed on the intake transfer port areas. The ports too were stock height but squared. Here they allowed the KG9s unaltered as class Ds for hydro but for runabout that was a bit too hard so they allowed the Hubbell reed valved KG9s and 40Hs into D runabout where they enjoyed a but more success with the added breathing. I would run them on that (lightened and bottom revamped) Asburn D Alky runabout I had and could run 2nd or 3rd against 55H stockers with them by sure force of being able to turn that runabout so tight it was a corner catcher against the 55Hs. I got a first for seasons points for a couple of years before I could afford 55Hs just from running 2nd or 3rd all the time consistently in D runabout. There is a picture of that big Asburn banana runabout on the website here under the historical threads with a big CP144 numbered on its sides where it was with a 40H on her and she did cook for her time. I wished I still had her for posterity sakes. Please keep up the pictures and the write ups on the work, it is all a pleasure to see all that.

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