Finish on 20H Conversion LU

[RogerH]

What was the finish from the factory on the 20H Conversion LU??? I've never seen a gold one. Have seen quite a few painted silver ones. Have seen an equal amount that are "natural" (as cast). The one I just got has "factory" ZO primer but not a hint of color anywhere. What's right?? Were they different if you bought just the kit vs buying a converted 20H from Mercury? Did they just sell them as kits?

I'd love to see a post with a correct 20H Conversion picture if you have one. Thanks

Roger

[anzaniwest]

I bought the "Conversion Kit" back in the early 60's and they were pained matt silver. It came with rewind brackets, throttle cable attachment, filler block, exhust elbow, copper 'O' rings, gaskets, toilet bowl, and 16:21 grears.

APBA did not have a rule for the filler block, so we fitted and potted with Devcon and hit a few local races. We caused a bit of a contoversy at the Divisionals at inspection. Anyway, APBA and Mercury (same people in those days) cleared up the rule.

[Mark75H]

I'm sure that 57 out of 60 that I've seen were natural aluminum. The other 3 had everything painted gold or black ... certainly not original

[Gstillwill]

Here is two just as they came out of the box in 1960 no paint just natural finish on all the cast parts. I think a few of the later kits came with the tower painted white for some reason but white was a big color with Mercury then. As was blck and white pictures back then.:D

[Ron Hill]

AS I was going to bed last night I read this post. Seems the only kit to hit California in 1959 went on Ernie Dawe's 20-H. Ernie won his qualifer at the Seattle Nationals 1959, but didn't do well in the finals...I recall his kit having no paint..everthing was new aluminum casting...(The Hedlund's had no paint on their gearcases also, , and I thought they had to be GOLD, but was told them came with no paint and didn't have to be painted.....The next one I saw was for Monty Gibson's 20-H, that was 1960. It also had no paint...I think the silver paint has been used to cover the black exhaust down in the "TOILET TUBES" as we called them...

I vote was cast aluminum...as cast...no paint...

Ted May's "Toilet Bowl" was painted gold, but Ted painted everything gold and put gold glitter in the paint...homemade metal flake....

[Gstillwill]

The painted gear foot rule has always been in place and is still in the Mod inspection manual as the 20H popper is a leagle AMOD motor. It doesnt state what color just that it has to be painted when on a 20-H.

[Bob Rusnak]

Purchased a 20 H conversion kit new some where in 1969-1971, can't really be shure of the year? It came painted white..Bob N-96

[RogerH]

Thanks for the input. I'm not surprised that a large number responded in support of the natural (as cast) finish. I can also believe that Mercury might have shipped some with paint (probably that "dirty" white) later in the run. That's what confused me, as my "bowl" most definitely has Merc's primer on it. I think I will be media blasting mine back to natural.

Interesting that the rules state the gear case has to be painted on the 20H.

Regards - Roger

[Mark75H]

The gear case has always been sold painted unless you bought an empty case


I am not surprised at this late date to find a Merc piece painted with the primer that Merc sold for bare aluminum. Painting top coat color paint on bare was just not thought of

[RogerH]

Sam, I was aware that the gear cases were painted gold, but was surprised that the APBA rules would require them to be painted. A lot of people like to polish the case (and LU) for appearance enhancements. Is there an actual performance gain over a polished case vs a painted case? If someone shaved or altered a gear case they could always repaint it in an attempt to hide that change. Measuring would have to be done to distinguish G / NG cases, whether the case was painted or polished. So why require the paint? I'm assuming the the polishing is cosmetic in nature and not significantly changing the case dimensions.

[Mark75H]

There may or may not be a difference in performance, but the must be painted rule nullifys worrying about it and the expense of testing to determine one or the other

Requiring paint is a simplification

[dancrabt]

I know we purchased some equipment back in the mid 70's from a gent in Wisconsin and all 3 20H conversions where painted gold from top to bottom and he said they came that way.

[Gene East]

Quincy Welding converted quite a few 20-H housings to fuel tanks. Every one I saw came without paint!

[Aeroliner]

Here are some photos of my last 20-H conversion. Well I must say I used the white fuel lines but all the rest is there. Almost all came as cast but the very last kits had some white parts. There were 3 kits. One was the tower housing and recoil mounts, the second was the carb and fuel pump plus a conversion for the pressure tank and the third was the gear kit. I have the original instructions for all three kits. Also my brother and I bought the first kit that arrived at the Mercury New Jersey factory branch. Currently I have 7 conversions and a few green and golds.

[Aeroliner]

The conversion kit did not include a lower unit. The replacement B lower unit was a long skeg and all came painted black. I will get a photo of one of two I bought thats still on one of my 7 conversions. OldRacerBU on hydroracer.

Alan

[Aeroliner]

Hope this photo helps

[Mark75H]

Excellent pictures and commentary :)

[Peter Crowley]

Maybe we are getting a little confused... The "gold" painted lowerunits that we are now used to seeing on the MK20H engines are supposed to look like someone had an original (green & gold) MK20H engine and then, when the conversion kit came out, they converted it. That is where you get the gold painted powerhead, clamp brackets and lowerunit.
Another thing- the early lowerunit housings were sandcast and were finished in a polished appearance. These were on all the Q engines and had the bronze bushing tail cone. The later diecast units appeared to be natural diecast finish. They all had to meet the minimum dimensions at inspection. If yours was slightly undersized- you would paint it to make it pass! Over the years some of these lowerunits were painted many times and stripped almost as many times.
When I got my first MK20H, it was against my fathers wishes! He hated the sound of them and if I was going to get one to run on my AU, then I would have to buy it myself! I got the conversion parts from Buddy Tomlinson and actually ran one of my 1:1 A lowerunits until I could afford the gears....

[Mark75H]

Merc put out a notice that as of Jan 1 1954, production Quickies would be diecast.

[Aeroliner]

My brother David has just completed the restoration of three 20-H engines. Shown in the photo is the clasic Green and Gold, a 20-H conversion and a Quincy modified 20-H to run on alky. The tower housing on the alky is still in its original paint. All three are numbers matching 20-H engines and in running condition. The conversion is nearly correct except for the two white fuel hoses that came with the carb and pump kit. Hope the photos will help folks doing restorations. Lower units were short skeg unless you ordered a replacement housing which came in the basic C configuration with the long skeg. Copleted 16:21 housings fully assembled were usually phantom black.

Alan

[Mark75H]

Lower units were short skeg unless you ordered a replacement housing in the basic C configuration with the long skeg.

Alan do you have some documentation of this or just hearsay? I did some research a few years back and determined that most of the last 1,000 serial numbered 20H's have a long skeg; only a few of the first 3,000 have the long skeg ... this appeared to be a pretty consistent pattern. The sense I get is that they ran out of short skegs at the same time they were making 30H lowers and switched production over to the short skeg rather than making more short skegs just for the 20's in 1956.

It is true that after 1956 any replacement 20H housings were long skeg.

Somewhere buried in the Merc service bulletins and APBA Propellor magazines there has to be documentation one way or the other of the change over date where you were allowed to retrofit the long skeg housing onto any 20H. That kind of stuff was and still is very strict in APBA.

[Aeroliner]

Hi Roger,
I bought a new 20-H in October 1955 and it still had the short foot. I bought two complete lower units for my B's in 1960 which were long skeg with 16:21 gears and came with instructions on how to cut them to the short skeg. If I remember correctly some time in 1956 they started using the long skeg. The three production years for 20-H were 1954, 1955 and 1956. The last 20-H's had a tower housing that looked like the 30-H with the single exhaust spout, very much like the 25SS unit. My old Mercury data shows that in the June 1957 the revision of the parts catalogue has both of the items shown. Hopes this helps a little Roger.

Alan

[Aeroliner]

Roger,
Here are a few units that are freshly refurbished. Note the black short skeg unit which is reshaped per the Mercury instructions. This allowed it to be used in class A with 1:1 gears. See the unit in the top row second from right which is a cut unit.
Alan

[A/B Speedliner]

While going thru our pile of rubble I found an original white fuel line still connected to the pump and the connector. The pump had all of the original fittings. I installed these parts on the 20H conversion so now the only thing missing is the white fuel hose the runs from the pump to the carb.

I am working on another conversion 20H that I hope to sell to help finance our other projects.

David

[Aeroliner]

David and I went to a garage sale this weekend and found an original cloud white conversion tower never used. We also got a few other things shown on the rack. Now we have a photo of what Mercury painted their last conversions. All early were as cast and late were white. Sam hope you like the photo.

Alan

[RogerH]

Damn!

You guys have all the luck AND great garage sales!! My wife doesn't come home with stuff like that!
Roger

[Aeroliner]

Roger,
A little training for your wife might help you with parts. Have to tell you though that if David's and my wife understood what we are doing we would be out of luck.

Alan

[Aeroliner]

Roger,
In the pile of things there was a brand new 20-H block and crankcase.

Alan

[X-racer]

Maybe we are getting a little confused... The "gold" painted lowerunits that we are now used to seeing on the MK20H engines are supposed to look like someone had an original (green & gold) MK20H engine and then, when the conversion kit came out, they converted it. That is where you get the gold painted powerhead, clamp brackets and lowerunit.
Another thing- the early lowerunit housings were sandcast and were finished in a polished appearance. These were on all the Q engines and had the bronze bushing tail cone. The later diecast units appeared to be natural diecast finish. They all had to meet the minimum dimensions at inspection. If yours was slightly undersized- you would paint it to make it pass! Over the years some of these lowerunits were painted many times and stripped almost as many times.
When I got my first MK20H, it was against my fathers wishes! He hated the sound of them and if I was going to get one to run on my AU, then I would have to buy it myself! I got the conversion parts from Buddy Tomlinson and actually ran one of my 1:1 A lowerunits until I could afford the gears....

As I recall, the MK-20H came out around the mid 50's (1954 if I'm not mistaken). My father was a Merc dealer at the time and I remember the lower units were painted gold like the rest of the motor and were definitely diecast with needle bearing tail cones. I think the "natural" die/sand cast lower units utilizing solid bronze bushings in the tail cones were used prior to 20H production possibly on the KG-4H or the KG-7H.

[Aeroliner]

Having bought a new 20-H in 1955 and still owning it I can tell you that the lower unit was gold and sand cast with the small holes for the water intake. Also having a KG-4H I know that the original engines had painted tower housings and lower units. I still have a brand new KG Q tower housing never used and it is painted silver as was the foot. The 20-H was the first engine to use the needle bearing in the tail cone while the older units had the solid cone with the brass bushings. When the short skeg became NLA the C foot was allowed for the B and C application. These were die cast with the single large water intake hole. It was permissable to cut the skeg to the short style and use it in class A. Today almost everyone polishes the lower unit. When I bought the B deep foot complete it always came black and when I bought cases sometimes they were in primer and other times in black.

Currently were are making a number of parts for the racing lower units. Look at our website aeroliner-boats.com.

Alan

[Mark75H]

I am certain a small number of deep skeg 20H's came from the factory as new.

Some 20Hs produced early in the run may have had sand cast housings, but by January 1 1954 all new Quickies were diecast.

20H's were a 1954 model year motor, but not all were sold the first year. Some lingered on at distributor's warehouses and dealer showrooms for years and people bought new unused 20H's that had been made in 1953/54 as 1954 model year motors quite a while after 1954.

[Aeroliner]

Hi Sam,
I beleive you are correct. If you go to the 20-H parts catalogue dated June 1967 they show the 20-H tower housing with the single water outlet like the 30 and 55 H engines. It also shows the long skeg. I beleive very few engines were made with the single exhaust hole.

Alan

[MTECHMARINE]

Never seen one - in 40 years of racing. Ron Lietha in MN has one on a prototype MK25H, I saw it at Tomahawk. Anyone else ever see this??

[Aeroliner]

Diging through the boxes in my garage attic that have the remaining parts from my Mercury dealership I found just about a completly new A/B lower unit in parts. The case has a few scratches on it but it's an original black case from Mercury, drive shaft, prop shaft, gears, water pump cartridge, cone and carrier, bearing, seals and so on are all there. The only thing missing is the GB bearings in the cone which I must have used for something ease. They should have been installed in the assembly so I guess I pressed them out for somthing. Might have been years ago when I started making cones and carriers. Hope you enjoy the photos.
Alan

[MTECHMARINE]

Here is one unmolested original 56 with the long skeg.

54865

[ampsjunkie]

Alan do you have some documentation of this or just hearsay? I did some research a few years back and determined that most of the last 1,000 serial numbered 20H's have a long skeg; only a few of the first 3,000 have the long skeg ... this appeared to be a pretty consistent pattern. The sense I get is that they ran out of short skegs at the same time they were making 30H lowers and switched production over to the short skeg rather than making more short skegs just for the 20's in 1956.

It is true that after 1956 any replacement 20H housings were long skeg.

Somewhere buried in the Merc service bulletins and APBA Propellor magazines there has to be documentation one way or the other of the change over date where you were allowed to retrofit the long skeg housing onto any 20H. That kind of stuff was and still is very strict in APBA.

I know this thread is old but take a look on page 28 they mention February ,29th 1956 as the change over date.http://www.boatsport.org/magpdf/ss565.pdf

[Ron Hill]

How many 20-h's were built? And how many had long skegs???

[Mark75H]

There were 4,000. As original equipment, approximately 1,000 had the long skeg.

[A/B Speedliner]

I have S/N 789594 a late engine purchased from Jon Woods estate still with the factor seal and all with original paint on the short skeg gear case. So I wonder were the deep skeg cases used intermittently in production?

David

[Mark75H]

I have S/N 789594 a late engine purchased from Jon Woods estate still with the factor seal and all with original paint on the short skeg gear case. So I wonder were the deep skeg cases used intermittently in production?

David

1,018 from the end of production, at the very tail of the last 3/4 of production - exactly as I would predict, a small skeg motor

[Ron Hill]

There were 4,000. As original equipment, approximately 1,000 had the long skeg.

No wonder we had boat racers in the old days. Now days we try to build a class with 10 motors from Japan....and less Sidewinders.

How does a 20-H housing differ from the Mark 30-H??? Does the 30-H have a larger needles bearing in the driveshaft??? Seems me dad changed a 20-H housing to fit it on a 30-H...

[Aeroliner]

If I remember correctly the deep skeg housing were the same basic design. The big differences was in the completed assembly. The 30-H had a stronger drive shaft which was later adapted to the 20-H. Early 20-H shafts when run on a conversion tended to fail in the upper ball bearing area. Broke a bunch years gone by. Note that the production run had about 4,000 engines but there were additional engines built for development.
Here is some data from the OldMercs website:

•This model was painted "Mercury Green" and "Gold."
•Model & serial numbers were on the instruction plate riveted to the swivel bracket above and between the clamp screws.
•Serial numbers range from 786613 thru 790612.
•This model was sold in 1954-55-56. Low numbers in this serial group can be assumed to be 1954, high numbers 1956, and mid-range numbers 1955 area.
•Many of these models were "converted" in about 1959 to make them faster and more powerful. The Conversion Kits changed the exhaust system, fuel system, and lower unit gear ratio. Conversion engines have a remarkably different appearance. (See photo.)
•Original, unconverted engines used a special pressurized 2-line fuel system.

Although there might be some 20-H engines produced with the deep skeg I have never seen one that is unmolested with the unit installed. I just bought a never run 20-H S/N 789158 which is in the 1956 range and it has a short skeg. The short skeg was still being produced when Mercury introduced the 22 cubic inch SS engines, of which I have 2. These units have the same water pickup as the deep skeg units.

Alan

[A/B Speedliner]

Early gear conversions that used the original gear case required some minor scraping of the inside for clearance. When I put Alan's conversion together for him in 1959 the instructions that came with the kit showed how to do the relief.

The only parts that are different when you use the later gear case with either 1:1 or 16:21 gears is the driveshaft pilot, driveshaft seal and the upper ball bearing. The thin S7K bearing used a thick pilot which was changed to the thin pilot when the thick bearing 16MM ID bearing is used. The OD of the ball bearing may be a little different also. The thicker bearing also required the use of the heavy duty driveshaft which required a different seal.

David

[Mark75H]

Can you give me the part numbers of the 2 different driveshafts?


Although there might be some 20-H engines produced with the deep skeg I have never seen one that is unmolested with the unit installed. I just bought a never run 20-H S/N 789158 which is in the 1956 range and it has a short skeg.

Unmolested 20H's of all variations are rare; easily accounts for any particular person not seeing any particular variation. Your serial number is 1,454 from the end, not sure that is truly in the '56 range; again a serial number well within the range where I expect to find a small skeg.

With the help of several friends I surveyed hundreds of 20H's ... The survey started giving a consistent result at about 100 motors and continued no matter how many we checked, so we stopped after several hundred. About 25% have large skegs, well over 95% of these have serial numbers in the last 1,000. I attribute the remaining 5% to parts swapping over the years. The <5% number also held well for early numbers with large skegs. I welcome you to do the same research for comparison.

[Aeroliner]

Hi Sam,
Thanks for the info on the 20-H. I have all of the old Mercury racing parts manuals and looked up this data so far. Starting with the KG-4/7 the drive shaft is listed as M50-1360 which became the 45-20909 in the short skeg lower unit. These shafts had the thin lower section and also used a thin ball bearing and thick pilot. The original lower unit part number was 1604-135A1 and I believe the empty housing was 1604-135. The deep skeg housing assembly was 1604-1162A1 and the open housing was 1604-1162 I believe. From the 30-H info and my 1968 Mercury parts status report the open deep housing became the 1604-1116A4 for the 20-H as well as being used on the 30-H. Some time after May 1968 Mercury introduced the metric shaft as a replacement for the normal 20-H drive shafts as the P/N is not listed in the report. I believe they made these shafts with the run of 22 cubic inch black 25SS engines, which had the short skeg lower unit. The early deep skeg lower units came with the standard 45-20909 drive shaft from my parts manual which would indicate that they came installed on an engine. I am still looking for the SB that introduced the metric drive shaft to the 20-H.
If anyone would like to have a copy of the 20-H, 30-H and 55-H status report I will take the time to scan it and make it available by Email.

Alan

Note: The 25SS engine was a 1973 offering.

[Mark75H]

Great info! Thanks!

[MTECHMARINE]

This 20h has a very small "1956" steel stamped between the model and serial number on the id plate.

Serial number 790039

pretty sure it has the original gearcase. :D

[Aeroliner]

Great info on the 20-H. At least we now have one S/N for the 1956 run. Maybe other folks will share their S/N info.

Alan

[A/B Speedliner]

Here are a few more numbers to digest. The H length driveshaft for the KG4 & 7 H and the original 20H is 45-20909, the 30H part number is 45-25726 the 25SS part number is 45-65844 which uses a narrow bearing and is the same length as the H 2 cylinder engines and the same spines for the crank shaft. It is thickened above the pinion gear but not like done on the 20H metric shaft or the 30H. There were two shafts for the 25XS engines a short one 45-14544 and a longer one 45-12639. The 2 cylinder H engines used the gear case 1604-135A1 which is the small skeg. The empty gear case for the large skeg 30H, 25XS is 1604-1116A2. The empty case for the 20H is 1604-1162A2 large skeg. The 7.5J full case is 1604-1116A8 I do not know the driveshaft used but they did have an adapter to fit the smaller splines in the crank shaft. The 25XS short shaft full case was 1604-1116A17 and the long shaft 25XS full case is 1604-1116A14.

[Mark75H]

I have never seen the year stamped between the model and serial on any others. If someone else has one like this, please share a picture.

The last 20H number is supposed to be 790612 ... so this long skeg 20H, approximately 600 from the end of production, is again what I would expect.

[Aeroliner]

Well I decided to do a little more looking into the lower units on my engines. The early 25SS engine I have has the classic deep skeg lower unit. This engine has the square exhaust opening in the tower housing. The later 25SS has the short skeg with the single water inlet hole and an exhaust snout that is round. My early 25XS has the exact same tower housing and foot while the late mode 25XS has the very short tower and the lost foam foot. I guess the lost foam unit is a result of the tooling to make the classic die cast items to be either worn out or scrapped in a cleanup. I can take some photos if anyone would like.

Alan

[Mark75H]

Well I decided to do a little more looking into the lower units on my engines. The early 25SS engine I have has the classic deep skeg lower unit. This engine has the square exhaust opening in the tower housing. The later 25SS has the short skeg with the single water inlet hole and an exhaust snout that is round. My early 25XS has the exact same tower housing and foot while the late mode 25XS has the very short tower and the lost foam foot. I guess the lost foam unit is a result of the tooling to make the classic die cast items to be either worn out or scrapped in a cleanup. I can take some photos if anyone would like.

Alan

The dies were lost in a clean up. Fred Hauenstein says many engineering man-hours were spent looking for the dies in hopes of not having to re-engineer.

[Ron Hill]

This 20h has a very small "1956" steel stamped between the model and serial number on the id plate.

Serial number 790039

pretty sure it has the original gearcase. :D

The only long skeg 20-H foot I ever saw was just like the one posted in MTECHMARINE picture. That was just like I remembered it. We sanded the gold paint off and painted is 30-H.

That 1956 stamp gives me thoughts....the first 20-H I ever saw was Stu Down's 20-H and we took it to Pep Hubbell and ran it on the dyno. That was in the spring of 1954 I was 10.


By 1956 wasn't the Hot Rod beating the 20-H all to hell??

Thanks for all the great posts!

[Mark75H]

The only long skeg 20-H foot I ever swa was just like the one posted in MTECHMARINE picture. That was just like I remembered it. We sanded the gold paint off and painted is 30-H.

That 1956 stamp gives me thoughts....the first 20-H I ever saw was Stu Down's 20-H and we took it to Pep Hubbell and ran it on the dyno. That was in the spring of 1954 I was 10.


By 1956 wasn't the Hot Rod beating the 20-H all to hell??

Thanks for all the great posts!

There were so many more 20H's than new Hot Rods set up with championship proficiency that at most you could say they were competitive. By 1957 the top Hot Rod drivers were getting things dialed in, but still, the sales numbers were low. At many races there just weren't any new Hot Rods showing up and the 20H generally ruled over KG7H's, Martin racers & older Hot Rod B's. At the big races in '57 & '58, well set up Hot Rods started handing Mercs their butts ... and Charlie and Edgar went to work.

By the time the conversion kits were delivered to market, the overall Champion Hot Rod Outboard company had folded ... no new motors were being sold; the inventory was boxed up on railcars to clear the buildings and property for bankruptcy sale. It sat on those railcars on an unused rail siding until it was rescued by Swanson and he assembled motors from previously manufactured parts from those railcars in the early '60's.

[champ20B]

There were so many more 20H's than new Hot Rods set up with championship proficiency that at most you could say they were competitive. By 1957 the top Hot Rod drivers were getting things dialed in, but still, the sales numbers were low. At many races there just weren't any new Hot Rods showing up and the 20H generally ruled over KG7H's, Martin racers & older Hot Rod B's. At the big races in '57 & '58, well set up Hot Rods started handing Mercs their butts ... and Charlie and Edgar went to work.

By the time the conversion kits were delivered to market, the overall Champion Hot Rod Outboard company had folded ... no new motors were being sold; the inventory was boxed up on railcars to clear the buildings and property for bankruptcy sale. It sat on those railcars on an unused rail siding until it was rescued by Swanson and he assembled motors from previously manufactured parts from those railcars in the early '60's.

The 20H was a better choice in the marathons. The hotrods suffered in its early stage due to limited choices on props. Prop pin was in different place than mercs.

The 20H showed its worth as a marathon engine but suffered with a high gear ratio in short coarse against the hotrod and was shy by a horsepower or so.

[Ron Hill]

My dad had "JUMPED" on being a Mercury dealer in 1949-50. When the Hot Rod appeared being a dealer seems to make sense. Problem was times they were a changing. People in California were having great fun racing their little Mercury motors (Damn Mercuries to the "Alky" racer.)

Let's say SoCal had 25 BU's with KG-7's. When the 20-H came out we dropped to 12 BU's. When the Hot Rod came out we dropped to 6 BU's.

A Champion Hot Rod weighed 43 pounds. They sold for $430 or ten buck a pound. Buck Parrish who was a Bakersfield cotton farmer/oil man, called the Hot Rod a "TIN CAN MONSTER" as you need four engines to run a weekend race in BU and BSH.

The expense and the cost of rebuilding the Hot Rod basically killed B Racing in SoCal.

Johnny Alden in Oakland, California modified the Hot Rod and made it go faster than anyone would believe, then Harry Bartolomei moded them and made them faster. But the John Q. Public had given up on them...

By the time the 20-H Kit came alone the Hot Rod waws in complete pieces....but opened the exhaust on a Rod 1960 at Beloit proved the Hot Rod could beat the 20-H if someone allowed them "OPEN EXHAUST"...Seems either John Van Epps or Roger Stearman "SMOKED" the 20-H's for a few laps...then pulled off.

Stock Outboard racing was in a "TAIL SPIN" but 1960 of which they have never recovered.

[champ20B]

Absolutely!!! Those little blue devils were something!! But the truth is, hard to say, that the 20H was way better as far as a good block, strong heavy-duty crank, and good rods. Those Merc rods were thicker than Hotrod type connecting rods. The flywheels were the same model, but the Hotrod taper was smaller equal to a regular Mark20 fishing engine. One thing one could be sure of, is that a merc would last and was pretty reliable under power.

The Hotrod cranks were a bit slim for the kind of power it had. The block and midsection of the hotrod should have never been more than 15 cubes to start with. The bad part was that the aluminum used on the hotrod was a bit thin. The block was way way overstressed for its weight and size. Its like they were trying to squeeze 20 cubes and 25+ HP out of a 7.5 hp engine format!! And they did!!! That was a super fast and temperamental engine to say the least. It was like the "Stage Three Max Wedge Mopar" of outboards.

One thing that gets me about the 20H is that I know more power could have been made simply by factory square ports on a new cylinder block and a exhaust cover furthure extended from those dang exhaust ports!! They might well have not needed that ridiculous looking commode mid to at least gain parity with all previous tech rules unchanged.

[Mark75H]

One thing that gets me about the 20H is that I know more power could have been made simply by factory square ports on a new cylinder block and a exhaust cover furthure extended from those dang exhaust ports!! They might well have not needed that ridiculous looking commode mid to at least gain parity with all previous tech rules unchanged.

The way APBA rules and rule making worked then and now, this would have been unlikely. Bolt on parts with the same internal specs are a lot easier to get approved. There are too many variances in changing and allowing porting changes.

[zul8tr]

The way APBA rules and rule making worked then and now, this would have been unlikely. Bolt on parts with the same internal specs are a lot easier to get approved. There are too many variances in changing and allowing porting changes.

I think what Champ20B was referring to was the factory doing the ports and the exhaust plate mods for more power to beat the Hot Rod rather than all the R&D for the toilet bowl? Then inspection would not be a problem over DIY'ers doing it to some spec. The drivers who didn't have this upgrade would of course want it and they would have to replace the block for these mods. The cost difference between toilet bowl mod vs above would have been an issue for drivers and to Mr. K and his development team. But Mr. was a beat them at all costs guy just to be ahead?

[Mark75H]

I think what Champ20B was referring to was the factory doing the ports and the exhaust plate mods for more power to beat the Hot Rod rather than all the R&D for the toilet bowl? Then inspection would not be a problem over DIY'ers doing it to some spec. The drivers who didn't have this upgrade would of course want it and they would have to replace the block for these mods. The cost difference between toilet bowl mod vs above would have been an issue for drivers and to Mr. K and his development team. But Mr. was a beat them at all costs guy just to be ahead?

As evidenced by the debates about chamfering, where to measure etc, inspection would be a problem. All is sidestepped with bolt-on parts. Back in 1960, there were a lot more racers that never saw the inside of a motor; having to disassemble and do the work or send it out to be done would have reeked to high hell of alky racing.

[zul8tr]

As evidenced by the debates about chamfering, where to measure etc, inspection would be a problem. All is sidestepped with bolt-on parts. Back in 1960, there were a lot more racers that never saw the inside of a motor; having to disassemble and do the work or send it out to be done would have reeked to high hell of alky racing.

Good point, agreed!

What about those 20H drivers when the conversion came out and the detailed work of R&R and grind inside the gear case for the 16:21 etc? Bet that caused some bitching?

[Aeroliner]

Having done a number of 16:21 changes that David and I have done the amount of material removal was minor. I will dig up my old documents and get them posted. Not all the cases needed this step in that some already had enough clearance.

Alan

[Allen J. Lang]

Hi Alan, my old 20-H I ran in EORC back in the 60s was converted to 16:21 and did not need to be clearanced. I did not have the toilet bowl conversion. Did have the Carter carb. It did run pretty well until I snapped rolled it at the starting line and blew it wide open from flywheel to gear case.
Al

[MTECHMARINE]

In reference to John Alden - - My friend Stu Lowe from Mercer Island WA gave him a run for the $$ in BOH. It was a crap shoot as to who would win. We blew up a bunch of Hot rods doing this. We had to put steel rods around the crankcase with flat bar on the head to keep the block from blowing off! Rods were the downfall, followed by broken cranks.

I have one Alden prop in my old props box - -

Good times!

[champ20B]

In reference to John Alden - - My friend Stu Lowe from Mercer Island WA gave him a run for the $$ in BOH. It was a crap shoot as to who would win. We blew up a bunch of Hot rods doing this. We had to put steel rods around the crankcase with flat bar on the head to keep the block from blowing off! Rods were the downfall, followed by broken cranks.

I have one Alden prop in my old props box - -

Good times!

I can certainly believe it...I was messing around with my 6NHR and as I looked over it, I could see tiny squiggly cracks all over the cylinder block around a 1/4" long and shaped like wool strands every inch or so apart. The cylinder block actually looks like some possible later casting because it is bare aluminum and super clean (not a grease stain anywhere). The engine was built by Cooper Jess several years ago, and I sold an old 20H (not running) to buy it from another collector. It will start up in one pull every time and has 160lbs compression. The only thing is that there are little wrinkles in the casting and water actually seeps through one on the upper side of the block. Its not a stress crack at all, and poses no concern as such, as it turned out to be a common casting imperfection found on some hotrods. What I wonder is if this is found on the original versions or if this flaw results from later reproduction blocks.

[Ron Hill]

In reference to John Alden - - My friend Stu Lowe from Mercer Island WA gave him a run for the $$ in BOH. It was a crap shoot as to who would win. We blew up a bunch of Hot rods doing this. We had to put steel rods around the crankcase with flat bar on the head to keep the block from blowing off! Rods were the downfall, followed by broken cranks.

I have one Alden prop in my old props box - -

Good times!

Was Jeff Lowe, Stu Lowe's kid? Seems Jeff was fast as hell in B Stock Hydro in the 1960's

[MTECHMARINE]

Was Jeff Lowe, Stu Lowe's kid? Seems Jeff was fast as hell in B Stock Hydro in the 1960's

Jeff is Stu's younger brother.

[champ20B]

When the 20H popper kit was fixed into B-stock, were there guys running real 20H motors that abandoned racing because of this? I have heard that it was that they didn't want to go spending more money modifying their motors just to stay in the game, but I wonder if it was the principle of fair play that played a role as well. After all, the idea of the hotrod having a tuned exhaust was a dubious claim to say the least....fact is, when the cover was removed running as just "open" the engine was faster and that's a fact. With an actual tuned exhaust, it would be slower after removing the exhaust cover! That's a physical fact....

Caution: you are entering a "NO SPIN ZONE"!!!

[Aeroliner]

Having played with 20-H's since 1955 I don't believe that a lot of folks left racing because of it. My 20-H cost $411.00 with bar and prop which was a lot of money. The guys with the KG-7's were mad in that the had to buy a whole new engine to race B. In order to make them happy Mercury introduced a kit to convert the engine to a 15 inch A unit. If I remember correctly it also came with a S/N tag with the new block and pistons. The HR engine were beating the Merc's hands down with there higher HP and lower weight so the conversion was what was needed to keep you in the game. Now here is where the turn comes in. Shortly after the conversions were out Mercury started testing the lower unit for the new B engine which was going to be the 25-H. Although the a few towers and lower units were produced and tested no real power heads ever were assembled with the 12 reed valve setup. The new lower unit and tower proved to be very fast running under a Mark 20-H power head. I have posted photos of the 25-H foot I own but can do it again if folks want to see it.

Racer were really upset with having to look at the new B engine so Mercury dropped the idea.

Alan

[Fastjeff57]

..."no real power heads ever were assembled with the 12 reed valve setup."

Any idea what that set up looked like?

Jeff

[hydroplay]

Mercury experimented with numerous lower unit designs in the Quicksilver era, including some extended prop shaft designs for straightaway records. Del Snyder has a poster of maybe 10-12 different ones. I don't know if this was just an in-house poster or for general release. I should try to get a picture of it someday. Cooper Jess has probably seen it as well.

[ampsjunkie]

Mercury experimented with numerous lower unit designs in the Quicksilver era, including some extended prop shaft designs for straightaway records. Del Snyder has a poster of maybe 10-12 different ones. I don't know if this was just an in-house poster or for general release. I should try to get a picture of it someday. Cooper Jess has probably seen it as well.

Yes pics! Please

[Mark75H]

Mercury experimented with numerous lower unit designs in the Quicksilver era, including some extended prop shaft designs for straightaway records. Del Snyder has a poster of maybe 10-12 different ones. I don't know if this was just an in-house poster or for general release. I should try to get a picture of it someday. Cooper Jess has probably seen it as well.

Leek and Strang said there were at least 9 in the Mark25H program alone. I would really like to see that poster too! :)

[A/B Speedliner]

Alan is on his way to pick up a brand new never run 20H complete with new tank. This engine has been stored in a glass case since new. Show have some pictures available in a few days after he arrives back home.

David

[zul8tr]

Alan is on his way to pick up a brand new never run 20H complete with new tank. This engine has been stored in a glass case since new. Show have some pictures available in a few days after he arrives back home.

David

David
Stored in a glass case, why:confused: Was it in a museum;)?

[A/B Speedliner]

The engine was owned by a Mercury dealer in MN. He kept it in a case in his home. It will be in the museum Alan is building.