what was done to this crank?

[Bill Van Steenwyk]

I certainly am not going to say that Mike O'brien never ran C Service with a 4 cyl Merc, but I don't remember him ever doing it. I had a good deal of interaction with Harry along in this time frame, as I had loaned him a boat that Kay Harrison was running with his (Harrys) A & B Mod motors on. I remember him strictly as a Mod person at that time and also Mike was running a couple the smaller displacement Alky classes along later on also, and I don't believe I ever saw him drive a Merc C Service or any other for that matter. Also were not most of the motors Harry O'brien worked on being used for Mod, Super Stock, and whatever else the sanctioning bodies such as AOF, NOA, APBA were calling what is the MOD category today?

He was certainly capable I am sure, I just have a hard time visualizing Harry involved in C Service. Also there weren't really that many of the motors (Mercs) around being run, at least at National events, that I remember anyway, as it was almost as devisive a subject as radios in the PRO category 35 years later.

P.S. Thought Bakersfield was in '82?

[Danny Thayer]

We didn't fool with C's that much but from the pics this look like a C mod that has been converted to a service motor. The plate over the exhaust has been added later. I have ran against Harry's motors for 27 years and this looks like one.

[Aeroliner]

Here is a photo of a typical Harry Brinkman crank. In the parts that I bought there was a simular crank that hand been contoured to accelerate the air flow away from the reeds. Note the bevel on the upper crank counter weight. I assume that this contour could created a vacuum over the reed blocks allowing the engine to increase airflow. Note the simularity of the crank in the photo I have posted.

Alan

[John Schubert T*A*R*T]

It looks like the intention of the machining is to scoop mixture away from the reeds and force it to the center of the rod area to align and force it to the transfer passage

Sam,
I had the same thought. Pete Hellsten did have 4 cylinders as well as 2 cylinder Merc C Service engines. However, I don't recall that he ever did that kind of work on the crank. His son Chris, current racer & new 350 c.c. National hydro champ visits hydroracer.net. Frank, put a post there with a subject line "Hellsten C Service". He'll pick it up & post.

[Mark75H]

Mercury switched to beveled cranks in their 66 and 99ci production motors in 1970, but I do not know if any of this is especially effective without the concurrent switch to reeds anchored at the center toward the crankshaft that open into the space created by the bevel.

[Powerabout]

whats the brown stuff
looks like the engine was running on Permatex

[Mark75H]

whats the brown stuff
looks like the engine was running on Permatex

That is typical castor bean oil residue. Unless an alky is flushed with a gas/mineral oil flush run for a few minutes after a race, that brown stuff will be on everything. In a very short time it polymerizes into stuff that might as well be glue or Permatex.

Lots of old motors are "castor stuck"

[Powerabout]

I didn't know that.

thanks Sam

[fbref5269]

hi all,

here are some pictures of the filler black, wow nice job on that one, and the exhaust ports. i will try to get a better picture of the ports tomorrow, the camera died. i'l also posy on hydroracer later tonight anout the hellman c service. thanks for all the input.

that orange stuff is permatex gasket seal. it's all over the place.

frank

[fbref5269]

sam,

you are sooo right about the castor stuck. this one had it big time. a good parts cleaner did free it up in about 2 days of soaking.

frank