Question for C stock drivers

[David_L6]

Are any of you running motors just exactly as they arrived here in the U.S. from Yamato? i.e. No lower unit shaping, prop shaft turning, or any other modifications?
Is anyone racing a bone stock C stock or is everyone racing a modified C stock?

[Jack Stotts]

I've seen some running with the lower unit in it's original configuration but all have had the prop shaft changed as required by rule. On the prop shaft, as received from Japan, the shear pin hole is at the front of the prop instead of at the rear in the US configuration.

[mercguy]

I've seen some running with the lower unit in it's original configuration but all have had the prop shaft changed as required by rule. On the prop shaft, as received from Japan, the shear pin hole is at the front of the prop instead of at the rear in the US configuration.

Jack, the prop shaft does NOT have to be changed, but only is done so to run the more readily available 9/16 props............the rule only states one sheer pin hole allowed........

[B Walker]

stock as it gets

Not sure where this is going but.....

One the prop shaft is turned, (for greater propeller flexibility) once the foot is thinned and shaped (more for handling than speed) and once the head is taken down to near minimum CC's theres not much else to be done in a 302 and it will be highly competitive.

No, its not stock in the purest sense, but its not even close to modified.

But ya still gotta drive it.

So why you asking, David?

BW

Note on heads: We got one right out of the box once that had a "Mt Fuji" head on it and did not meet the APBA H and I dimensions for stock, worked on the Mod though.

[Bill Huson]

Yes . . .

Many moons go I ran a Yamato C without touching the lower unit save for prop shaft change to 9/16". It was a wild ride! Lesson learned, NEVER, EVER run a Yamato before the lower unit has been cleaned up.

[Andrew 4CE]

So why does the rest of the world not have a problem with the foot? Do they run the motor deeper or something?

[B Walker]

Stock Foot

In Japan, the motors are run deeper, the boats have a little vee to them and the courses are much shorter. I been told they dont even break 50MPH in Japan racing.

The handling issues of the stock Yamato foot dont become noticeable untill you get into the high 50's. Just as Bill said, at 65+ its a wild ride on a stock foot.

BW

[Dave M]

I heard

That the only thing most do to make them a Mod is bolt on a chamber ? I do not know the engine rules for 500CCMH, but I listen to talk at the races about it. I hear guys talk about they are stock engines with chambers bolted on because the rules prevent them from really modifying it. They also say a highly modified 102 or 302 would run 750CCM speeds easily. Is there truth to this ?

[B Walker]

You got it, David

In a word, yes.

Our Mod is exactly the same as our Stock with a short tower (ty Lee Tietze @ Machined Components) a chamber, a noseconed and hatchet style modified 302 foot (better handling jacked to the moon and better water pickup) and a head cut to the Mod spec.

Thats it.

I hear through the grapevine that 80+ on a 500H has been seen in competition by several people. But I think a really really good 750 will still beat it. The problem is theres only a few of the really really good 750's around, and less every year. Its relatively easy, cheap, and reliable to get a Mod 302 up and running at a very high level of competition.

BW

[sam]

One the prop shaft is turned, (for greater propeller flexibility) once the foot is thinned and shaped (more for handling than speed) and once the head is taken down to near minimum CC's theres not much else to be done in a 302 and it will be highly competitive.

No, its not stock in the purest sense, but its not even close to modified.

I thought there was an issue with tight con rods slowing out of the box 302's and they were honed to get more rpm's. Is this not true?

[David_L6]

So why you asking, David?

Seems like anytime I see a C Stock motor for sale some part of it has been "reworked or reshaped" or something by someone..... i.e. Lower unit shaped by XYZ. Just seems funny (as in strange) to me that motors for a so called stock class are modified before they are raced. I think that I understand why that is allowed though.

[Joe J]

If you want to talk about "So called stock" engines, I suggerst you pay attention to the OMC A engines.

Joe Johnson

Seems like anytime I see a C Stock motor for sale some part of it has been "reworked or reshaped" or something by someone..... i.e. Lower unit shaped by XYZ. Just seems funny (as in strange) to me that motors for a so called stock class are modified before they are raced. I think that I understand why that is allowed though.

[Tim Weber]

Sam,

The connecting rod thing is sort of tricky. If you hone too much the bearings don't work properly and that's a real bad thing. It's sort of like honing the rods on a merc. A little goes a long way but....

I have run motors both ways and I can't tell a difference but maybe for some it works.

Cutting the head to H & I is the biggest one thing in my opinion.

Tim

[B Walker]

Newsflash......

David, There is no such thing as a "Stock" Stock Outboard.....

not even close.

Until we have a sealed motor concept like the World Karting Association (WKA) Box Stock classes, we never will.

BW

[B Walker]

tight motors

Best way to loosen up a Yamato is run the crap out of it. We did not know anything about tight rods (or anything else) in our first motor. It took 2-3 years for that motor to start "coming on" and back then we were going to 20+ weekends of racing a year.

BW