Dayton, 1975 D Runabout

[Ron Hill]

Mark 15 Vs Tight Cases??

Anyone want to express an opinion here. My dad always believed in "TIGHT" cases, but we had two very good Mark 15's...One block came from Andy Hansen...

DeDeo's mark 15 went to Earl Desioto...how ever you sell it..for $300 bucks!

[rumleyfips]

There's an explanation of big case volume ( Sam Cullis) I think on BRF. In an engine with lots of restrictions
John McManus

[rumleyfips]

Well; that didn't work very well.

The explanation seemed to be that in an engine with lots of restriction, ports,card.reedcage, the extra mixture in a big case helps cylinder filling.

I tried allan rod cases, KG sandcast cases, KG diecast, Mk15 and barndoor on one block ( 595220H). The difference were small but they ran in that order with the barndoor fastest.

505 and 506 blocks were a mystery to me : I never got my hands on one.

Years ago I saw a web enrty about how to build a hot KG4. It said use a barndoor case.

John McManus

[Mark 72@E]

Steve DeFeo' Mark 15

Robert E. Lee

You are correct. I am amazed. Is there some sort of "Book of Secrets" you inherited when you were born? This was before your time!

Ron Hill -- you might remember DeFeo selling >>a<< Mark 15 to Desiato, but his 1974 national champion engine with the silver top and hand-painted details I saw being carried off in the arms of that guy at the Bedford, VA race in October.

The reason why this made such an impact on me at the time (and I remembered it) was because:

A) nobody knew who he was (this was before he started racing)
2) he paid what I considered at the time to be an outrageous sum for the engine

At least two people here on Hydroracer know the answer to the Super Bonus Trivia Question...

[TPLACE31]

for the record..........

Before the entry list breaks 2,000......per the 1974 and 1975 October issues of Propeller magazine:

1974 Dayton - 834 entries topped off with ASH running eight elimination heats.

1975 Dayton - 872 entries with ASH leading the way with 107 entries. The only time a class has ever exceeded 100 entries at a Stock Nationals.

1978 Saranac Lake, NY is third on the list with around 815, although by then the 35SSH, 35SSR were added to the schedule and 20SSH and 20SSR were also run as probationary classes adding to the boat count.

STOCK ONLY!

[j hydro racer]

$1500

[1977 ASH]

TPLACE31

Thanks for the correction on entry numbers at Dayton - I meant to correct my earlier post as I counted the number of entries from the result sheets and looked at Rusty Rae's very cool book "Speed and Spray" on the 1974 Dayton race and your numbers above are correct. It was a long week and a huge job for the scorers with that many entries. I seem to recall the drivers meeting being held in a large theatre - the good old days.

Mark

[rumleyfips]

Ron:
I searched BRF and found posts by Dean Hobart and Mark Demaray about KG4's. They both used barndoor cases with 506 blocks. Maybe one of them has a theory on crancase compression ratios.

Bob;
I probably got the year wrong.

John McManus

[bill van steenwyk]

As i posted elsewhere sometime ago..........

..........and do not remember now whether it was on HR or BRF, Harry ZAK postulated that because in the RB class that was run in the PRO Category with a single 25.4mm carb max size ONLY legal, and NO OTHER restrictions except displacement, and no open exhaust (must use expansion chambers), we found after discussion and my agreement to experiment on one of my engines, that enlarging the crankcase volume by material removal did have a beneficial effect that led to increased RPM and hence, speed.

The first example he tried was a simple spacer between the intake manifold and crankcase machined from an aluminum plate that was thick enough to add approximately 1 cubic inch of volume to each cylinders crankcase volume.

When through testing that (the increase in volume) was found beneficial, he then removed material from the actual interior of the crankcase with a die grinder and got about another 2 cubic inches out of each area. According to him, the reason this worked, (against all other two stroke theory at the time, and even to the present) was because of the restriction posed by the very small reed valves on the Model 80. Plans were under way to go to a different reed type by opening up the crankcase openings, but his untimely death put an end to those plans.

The reason this provides an increase (according to Harry) is because with the restriction of carb size, if you increase the crankcase volume, the crankcase then becomes somewhat of a "storage vessel" allowing as much fuel as the cylinders can use, with help from a good pipe design, and not limited strictly by the amount coming in thru the restricted carb opening. In other words, somewhat like a balloon, although one that does not expand and contract, but is just larger.

Would be interesting to see if it would work and then pass inspection at a stock race, especially one with an enhanced exhaust system (tuner) in the down housing, but I can't imagine anyone would try to fool an inspector, would they?

You can "poo-poo" the idea if you want, but this engine still holds the RB Kilo record of 90.803MPH set in April of 1985, from an engine of 327CC displacement.


ADD: I still have a "short block" 80 powerhead, albeit with an enlarged crankcase with balanced rods. Not legal for stock the way it is. All the rest is stock as far as I know. Would like to sell to somebody as it is taking up space in the basement Eileen want's cleaned out. Let me know if interested.

[David Weaver]

How abut Hinton 1976?

I recall 106 A stock hydro's alone. Tough to qualify!!

Before the entry list breaks 2,000......per the 1974 and 1975 October issues of Propeller magazine:

1974 Dayton - 834 entries topped off with ASH running eight elimination heats.

1975 Dayton - 872 entries with ASH leading the way with 107 entries. The only time a class has ever exceeded 100 entries at a Stock Nationals.

1978 Saranac Lake, NY is third on the list with around 815, although by then the 35SSH, 35SSR were added to the schedule and 20SSH and 20SSR were also run as probationary classes adding to the boat count.

STOCK ONLY!

[TPLACE31]

I recall 106 A stock hydro's alone. Tough to qualify!!

October 1976 Propeller Magazine, Region 2 news referenced 784 entries at Hinton. No other information relating to the Nationals that year. That would put Hinton 1976 in the Top Five all time Stock Nationals from an entry perspective.

[Ron Hill]

How Much Did The &quot;A&quot; Motor Sell For?

Was $1,500 correct??? Do leave me hanging...

In the fall of 1979, I sold Jimmy Dawe, two "D" Motors, 2 "D" props and 2 "D" boats and a trailer for $2,200. That is what I needed to finish up my first MOD VP...

[pearson95m]

Great Thread!

[Matt Dagostino]

Mark 15

Was $1,500 correct??? Do leave me hanging...

In the fall of 1979, I sold Jimmy Dawe, two "D" Motors, 2 "D" props and 2 "D" boats and a trailer for $2,200. That is what I needed to finish up my first MOD VP...

Ron
Gary US Pond owns that engine and it is on his motor rack in Richmond............his uncle, Robert e. Lee bought it from Defeo and Gary wound up with it.

The engine has a interesting history part of which involved a fistfight at Dayton which Harold Barnes had to break up..............

For more interesting details call Gary. He knows the actual sales price and the history.

Matt

[rumleyfips]

Bill:

Sorry about misatributing your info.

Page 25 of the thread " name that outboard " discusses puting a shim between the carb and case on a modified OMC 22 or 31. 1/4" shim = 1 hp or 2%. For a KG4, 2% = 1 mph; enough to get from 3rd to first.

I think Paul Chrisner ( although my memory has proven faulty twice on this thread) spoke to the stuffed case, sayying there was little difference with a stock engine but a tiny case made a big difference on a looper.

I proved to my satisfaction that more crankcae volume was better with a KG4 but never really knew why. I thought that maybe the mixture found a better path to the transfer ports with a bigger case.

John McManus