Mercury Mark 40-H

[John (Taylor) Gabrowski]

I wonder what would have been if Merc / Mariner would have released the 3 carb 3 Holer 650 racing technology to the pleasure boating ski / fish crowd instead of the lemon 2 carb 3 Holer they did that tanked? That picture of your 650 tells a progressive and enlightened way of doing things that worked!

Nice thing about going away from standard Merc cranks surround reed valves and reed blocks on Merc 44s is that it does not matter anymore whether your throttle butterfy being horizontally or verticaly opened once you enter into pyramidal reed block systems that dumps straight into the base of the crank throw area. From Rogers' 4 carb picture carb linkage simplification comes to be evident for horizonatl butterfly opening carbs and just as easily configurable for 4 staggered (in-out) carbs with vertically opening butterflys, same idea just different orientation. You see the same thing adapted to the Quincy Flatheads using 2 carbs. Lots of variations and possibilities.

Why I like Tillotoson carbs be they the KAs, KCs or HRs is that they are simple, parts are very plentiful, inexpensive, very reliable and can all be made fully high speed needle adjustable even though some of them were original to their engines with scew in fixed jets or like HRs you can setup as self pumping or use a separte fuel pumps like those required for KAs or KCs. How does one beat a used KA, KC or HR carb for $20.00 bux or less and the total rebuild kit diaphrams and all for $13.00 right off the shelf retail? That is great economics for the sport.

The available reeds systems speak for themselves in terms of flexability. Some of the old tricks developed in Modifieds back in the 1970s are being adopted in aftermarket reed and reed technology here today, like venting the reed stops so that their is no air pressure barrier as the reed opens up against the stop as it opens and closes. Better still there are now reed stop less reed blocks that use the properties of reed materials (length, width, thickness and composition) to give reed opening and tunning properties. The technology has come a long way and again not expensive, very reliable and very adaptable. Snap off a composite reed instead of a metal one and your engine looses power instead of metal fragements from reeds fragmenting and breaking up that engine you built.

There is a lot going for Tim's 444 inspiration in his engine for the rest of us to get involved in.

[Mark75H]

Originally Posted by John Taylor

I wonder what would have been if Merc / Mariner would have released the 3 carb 3 Holer 650 racing technology to the pleasure boating ski / fish crowd instead of the lemon 2 carb 3 Holer they did that tanked?

They did. Sold 1,000 units ... about the same reputation. The weak component was the crossflow scavenging, not the intake path

[RogerH]

John,
I think Mercury loaned a few of the 3-carb motors to fishermen to try. Word came back that they shook the fish off their stringers when they went through that pesky mid-range vibration point.
I know that only happened when they forgot to put the stringer in the boat before heading to the next fish'n hole. I also heard that the minners couldn't swim after the ride to the fish'n hole using the XS motors.
Sorry, just had to have some fun. Too bad this motor didn't get blessed by APBA. It was pretty stout.
Roger

[Mark75H]

John, I'm having a hard time finding $20 HR's, they seem to be the most popular Tilly. Even the bigger pumpers seem to go for less than the HR's that I find.

If you see some somewhere for $20 please point them out to me.

[John (Taylor) Gabrowski]

Up here there are snowmo sled recyclers that don't shred those old snowmo sleds until all that is left is the track and rotted out tunnel. I will see what there is for an inexpensive pool to tap and there are a lot of those pools up here never mind individuals getting rid of old sled parts outside of any re-cycler. I will see how I can help out more than just myself.

I have come to write off the 2 carb 3 Holer Mercs and Mariners. From scavenging intake design they were barely liveable under 5,000 rpm but over that they ran the middle cylinder lean but passable but the top cylinder you got head and piston heat erosion big time. You could not richen your air/fuel way out of in terms of fuel cooling. They didn't care how much more lube you mixed with your gas, if petroleum based made the problem hotter and worse because it burns. Synthetic oils don't burn it that didn't matter either, heat erosion stayed. It seemed to be a cooling problem you could not change with more water volume or of directed cooling water at the top cylinder the same as the bottom enjoyed. Some blamed it on the top cylinder needing its own cooling from cylinder heat generated but also from the top bearing loading underneath that heavy flywheel (flywheel engergized ignitions) where the top bearing could not shed its heat from operation fast enough to the rest of the motor contributing the problem to the top cylinder's heat stresses which further up the block kept getting worse. Even with a belt drive ignition systems of early Merc 2 carb 3 Holers making a lighter flex plate laminate flywheel less and 1/4 of the weight didn't help the housing section where the top bearing sat you could not touch from the searing heat. Some Merc factory reps suggested that there needed to be deep cylinder separation in the water jacket of the Merc casting to isolate combustion chambers more from each other but that made casting more complex. I tried drilling between cylinders (an old Quincy Alky Deflecor method) to separate them more as well as dimpled the blazes out of the water jacket side of the combustion chamber to increase surface area for water jacket cooling water. None of it worked so it had to be inherent in the overall engine design that under high and then higher racing rpms caused heat concentration it could not shed or spread out to the rest of the enine efficiently and great rid of easily through air / fuel cooling or the water jacket cooling systems. I even tried other cooling tricks found on Merc Alky Deflectors like deep probe cooling water relief pipes that were multiple and deep next to the exhaust port structures on the water jacket side with no success.

In the end I took great pleasure in getting rid of them to recyclers when I could not even give them away for spare parts to anyone else after burning up too many of them to finally giving up without any solutions. Were they one big waste of time.

[John (Taylor) Gabrowski]

Sam:

I heard about that too but could not find any 3 carb Merc or Mariner 3 Holers here so they may have been a USA distributed product mainly with very few ever getting up here. You have no idea how many times I found 2 carb Merc / Mariner 3 Holer engines for sale here for parts for next to nothing and even give away. I finally gave up. If they didn't have smashed lower units they were top cylinder burnt already or well on their way to it.

Did I even mention relieving exhaust housing cast in directional steps for gas flow equalization and exhaust tuning? Leveled those out. Made a kind of OMC Mod 50 humped exhaust housing to enlarge exhaust chamber area leading to a dump pipe, a megaphone yet for extra extraction and no luck either. The extremes we went to, to find out they were unworkable lemons!

[Aeroliner]

In going through the boxes of parts I bought I found a bunch of new Mercury Quicksilver housings. Some time ago there was a discussion about the paint on the housings. Well packed in the box was the original mercury shipping invoice for three new housings. I have taken a photo of one of the three. Also in the box was a new 25XS housing and two 44XS housings all of which are as cast using the lost foam technique.

Alan

[Mark75H]

What is the date on the invoice? After the 25ss came out, there would be no surprise that they would be painted black.

[Aeroliner]

Hi Sam,
The date was October 1976.

Alan

[Aeroliner]

In going through the original 20-H parts manuals that I have I found that it appears to have been the first release. It is dated May 1954. The first revision appears to have happened in January 1956 and the last revision November 1964. Does anyone know if there were other revisions. Of intrest the last revision shows the replacement foot with the long skeg and all the conversion parts. Looking at the price list back then, this will make you sick! A conversinon gear set (29513A1) which included the gears, drive pin, tab washer, drive shaft seal, cone and water pump cartridge seals and the cartridge ring seal cost $36.45. Anyone have a set forsale, I will pay full retail, only kidding.

Alan