2 cylinder Merc racing motors Rockets, Hurricanes & "converted" 20H's

**CALVIN** · 07-12-2013, 08:43 PM

We're the hot rods 15 or 20 cubic inches?

**53w** · 07-12-2013, 09:28 PM

The 20H tower housing story is a truth!!! I seen letters from merc at the time from these dyno tests at merc. The ONLY reason the toilet bowl was built was due to the Hot-Rod kicking the 20H butt. The champion tower also has a positive tuning effect also that pushed it a head of the 20H once on the stock racing towers. In a true open mod build the Hot-Rod is a far better racing engine then the 20H or kg4 can ever be do to the intake/reed system. A GOOD B Hot-rod on pipes with a good boat and prop is an easy 70mph+ ride!!!

**53w** · 07-12-2013, 09:33 PM

The kg4 was saved to let dominate stock by champion closing. The prototype 15 cubic A H-R would of dominated the A class over night if they went into production. It would of been interesting what carl's next step for an faster A engine if the A champ would of been built?

**champ20B** · 07-13-2013, 12:19 AM

Originally Posted by 53w

The 20H tower housing story is a truth!!! I seen letters from merc at the time from these dyno tests at merc. The ONLY reason the toilet bowl was built was due to the Hot-Rod kicking the 20H butt. The champion tower also has a positive tuning effect also that pushed it a head of the 20H once on the stock racing towers. In a true open mod build the Hot-Rod is a far better racing engine then the 20H or kg4 can ever be do to the intake/reed system. A GOOD B Hot-rod on pipes with a good boat and prop is an easy 70mph+ ride!!!

Your right on about the hotrod mod setup over the merc. One point though is that there wasnt anything wrong with the original stock 20H midsection. I am very familiar with these mercs and I like them. Mercs are great and well made racing engines. But I can assure all interested in this subject that the 20H tower was as good and worked exactly like the hotrod version. The midsection of my 6NHR hotrod actually looks sort of restrictive and a bit too compact for a good "B" racer. I had to take in consideration the conflict of interest on the facts though. I saw a pic of the letter also, and it was from those in good with mercury. Carl kiekhaefer was not a suttle player in sport or business. He would do anything he could get away with and was known to be rather ruthless. From stories Ive heard of him, I wouldnt trust him unless I was racing a Mercury if I lived back then and raced. About my motor, I have a 6NHR with all the accessories. That includes a special open racing stack (part# A-600) that was optional in the 1956 catalogue. The way I crank it is by using a squirt can with a heavy oil /gas mix. Would you beleive this hotrod calls for one pint of oil per gallon? That equates to 8:1 mix!!
I assume it is to keep those rotary valves good because that type of intake system can sure be trouble for easy starting. Crankcase pressure may tend to be a bit compromised at low speed, yet high speed operation is where such a design really pays off. One day, I would like to make a popper tower for the hotrod. That would be really cool. I am considering using my open racing stack as a base for the design as to add on to it. The stack is water cooled as well. I dont know why though, It doesnt look like it ever needed to be.

**olboatman** · 07-13-2013, 07:51 AM

Scribed! Thanks to all for sharing all the great history and info. Brings back the best memorys when I pitted for my best friends BSH and BSU ( his was 21 A) before anyone asks in the 70s and early 80s. I still play with modding some different 2cyls on some of my smaller boats--- Refuse to grow up! Gary

**Mark75H** · 07-13-2013, 04:09 PM

Originally Posted by champ20B

I dont believe anyone ever really tried this in a race on pump gasoline. The hotrods have carried on. Mercs are more of an antique hobby engine although they still let them run in A-Mod.

Huh? Ever hear of NOA Am-Pro? APBA B Mod in the 1980's?

Champion originally made A's & B's

On the current Champion based race motor, the reed valves have been replaced by reeds

**champ20B** · 07-13-2013, 05:34 PM

Originally Posted by Mark75H

Huh? Ever hear of NOA Am-Pro? APBA B Mod in the 1980's?

Champion originally made A's & B's

On the current Champion based race motor, the reed valves have been replaced by reeds

Yes , Im familiar on that. Currently, you can run a 20H converted type in A mod based on 1987 specs in accordance to the 2013 rules in apba. However in B-mod, although the 20 cid mercs are still allowed, there arent many people messing with them. They take too much modifying, allowed on old mercs,to get competitive. It is too difficult to compete with rotary valve hotrods and also the yamato 80 as well as moded 22 cid OMC and 25ss mercs. The new champion based motor is the Sidewinder. They utilize pyramid side cylinder reed valves with a press together crankshaft. They are much like a yamato or some of the current Arens pro stockers in that design. They are similar to hotrods but to keep production cost down and make it affordable to racers, they ditched the rotary valve. It is too much precision fitting and time consuming. Furthermore, reed valves make for a much more reliable start up and idle capability.

**Mark75H** · 07-13-2013, 05:40 PM

No, I'm not talking about 21st century, I'm refuting your claim that piped Hot Rods were never raced on gas in B mod against Mercs

Hot Rods were never competitive in alky, despite this assertion:

This engine was geared toward alchohol racing capability out of the box.

**olboatman** · 07-13-2013, 05:45 PM

Originally Posted by champ20B

Yes , Im familiar on that. Currently, you can run a 20H converted type in A mod based on 1987 specs in accordance to the 2013 rules in apba. However in B-mod, although the 20 cid mercs are still allowed, there arent many people messing with them. They take too much modifying, allowed on old mercs,to get competitive. It is too difficult to compete with rotary valve hotrods and also the yamato 80 as well as moded 22 cid OMC and 25ss mercs. The new champion based motor is the Sidewinder. They utilize pyramid side cylinder reed valves with a press together crankshaft. They are much like a yamato or some of the current Arens pro stockers in that design. They are similar to hotrods but to keep production cost down and make it affordable to racers, they ditched the rotary valve. It is too much precision fitting and time consuming. Furthermore, reed valves make for a much more reliable start up and idle capability.

Hey Champ20B Are you currently racing APBA. You have me reeled in with the info since I haven't been involved for over 30yrs. Thanks Gary

**Mark75H** · 07-13-2013, 05:51 PM

Races in Thompson CT this weekend if you can get over there: http://www.apba.org/races/coa-annual...n-regatta-5486

And the Stock, Mod & J Nationals in Whitney Pt NY Aug 6 thru 10 http://www.apba.org/races/coa-annual...n-regatta-5486

**champ20B** · 07-13-2013, 06:40 PM

Originally Posted by Mark75H

No, I'm not talking about 21st century, I'm refuting your claim that piped Hot Rods were never raced on gas in B mod against Mercs

Hot Rods were never competitive in alky, despite this assertion:

you are right about hotrods w/stacks raced on gas. However, they were raced in modified against modified mercs like this. I just never actually heard of anyone race a pure factory spec hotrod on pipes against a factory spec 20H conversion that they call the popper. That would be interesting.
I dont want anyone to get me all wrong though, I absolutely love the Mercury. The fishing motor I use all the time is a WM7 super 10 wizard. I put it together from a mark25 powerhead give to me by John C Renfroe. I disassembled old outboards for him while I was in High school about 15 years ago. He raced from 1927 till 1960 and was a Martin dealer in the 40s and 50s I think. He raced a shortened modified 60 and a 200-silverstreak. He told me many stories about the days of racing. What I know is just from pure interest and exposure to many antique outboards from 1930s models on to later ones. I have always been very interested in the A-D class racing engines most of all.

**champ20B** · 07-13-2013, 07:00 PM

Originally Posted by champ20B

you are right about hotrods w/stacks raced on gas. However, they were raced in modified against modified mercs like this. I just never actually heard of anyone race a pure factory spec hotrod on pipes against a factory spec 20H conversion that they call the popper. That would be interesting.
I dont want anyone to get me all wrong though, I absolutely love the Mercury. The fishing motor I use all the time is a WM7 super 10 wizard. I put it together from a mark25 powerhead give to me by John C Renfroe. I disassembled old outboards for him while I was in High school about 15 years ago. He raced from 1927 till 1960 and was a Martin dealer in the 40s and 50s I think. He raced a shortened modified 60 and a 200-silverstreak. He told me many stories about the days of racing. What I know is just from pure interest and exposure to many antique outboards from 1930s models on to later ones. I have always been very interested in the A-D class racing engines most of all.

One thing I forgot to mention in my previous reply, is that Champions were run on Alky. I dont know much about their success if any or if there was much, but my hotrod owners manual specifically states that either one pint oil/gallon or "C" grade alchohol can be used (upon a simple part replacement in the carberator). Furthermore it states that either can be done on a closed exhaust although the open racing stack (part # A-600) is recommended when permitted but not required.

**champ20B** · 07-13-2013, 08:49 PM

Originally Posted by 53w

The kg4 was saved to let dominate stock by champion closing. The prototype 15 cubic A H-R would of dominated the A class over night if they went into production. It would of been interesting what carl's next step for an faster A engine if the A champ would of been built?

Ive been thinking about the "A" motors alot lately. An experiment I want to try someday is to take a KG4 and use a 20H conversion kit on it with a 30MM Lectron carb. Another note I would like to mention is that upon my experience of working on old outboards years ago, I have seen motors I bet would have made good stockers for racing. Every time I hear of "A" class engines I think of the Eska 15 hp..... O.K dont laugh, but really, this was a 15 cubic inch motor. It was light-weight, it had flat-top pistons, it had dual intake ports (sort of like a looper), it had a carberator that would outflow the tillotsons on the old kg7 and mark 25 mercs, and it had " now let the drums roll " a rotary center crankshaft intake valve. I actually ran one of these on a 14' round chine aluminum fishing hull, and it would really go! its rpm capability was very high also. they were built from the early 1970s to the early 1980s. Just shorten the tower, put on a J/A gearcase, and see what can be done! These engines dont have much value in $$ unless it is a Ted Williams series.

**CALVIN** · 07-13-2013, 09:03 PM

Remember Brian Trolian running a 20 inch hot rod with a LeBlanc pipe on gas leading a field of C yamatos ....think it was deFiebos

**Mark75H** · 07-13-2013, 10:29 PM

Originally Posted by champ20B

Ive been thinking about the "A" motors alot lately. An experiment I want to try someday is to take a KG4 and use a 20H conversion kit on it with a 30MM Lectron carb.

That would be cool ... I probably would have run a 30MM Lectron on a Mk25 as a test rig for running 3 on a Mk75 if the Lectrons weren't so pricey ... decided to get Tillotson HR's instead.

Champion offered that A-600 open exhaust and the text is in the owner's manual, but it just wasn't competitive in alky ... Konigs and Anzanis blew them away ... not sure the Champion was even submitted for approval in APBA alky back then (motors had to be approved back then, it wasn't bore & stroke like modern times). There were lots of non-APBA races and if the Champion had a chance in alky, it would have been proven outside APBA and then they would have applied to run them in alky. I think the A-600 and the alky instructions were written just before the importation of Anzanis and Konigs when the Champions would have had a chance against the SR's and KG7's in alky. Its possible that the text was just never updated.