Topic: 1950 Speeditwin 6039 Rods – Antique Outboard Motor Club,Inc

This topic has 27 replies, 6 voices, and was last updated 4 years, 3 months ago by Buccaneer.

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December 23, 2019 at 4:32 pm #189829
Buccaneer
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I asked prior, but never received an answer, so will try again.
Sage advisers told me that the oil holes in the connecting rods
should go “UP”.

On my Speeditwin, both rods are the same part number.
The wrist pin end of the rod boss are “off-set”, and therefore
on this opposed engine, the oil holes on one rod, end up
going “Down”.

I can’t tell by my fuzzy parts diagram for sure, but I think I only see one
rod part number listed.

Can anyone settle my delimma?
Do I have one incorrect rod, or did Evinrude save some money and
decided that the oil hole “down” would be okay on one rod?

Thank, and Merry Christmas!

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December 23, 2019 at 8:40 pm #189850
Buccaneer
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My Notifications say I have two replies from Garry.
I see none. Can some one please fix this problem?

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December 24, 2019 at 8:58 am #189857
squierka39
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Can you post a picture of the rods. Somehow I’m picturing it and if you swivel it from one side to the other the hole should still be up.
December 24, 2019 at 9:57 am #189868
Buccaneer
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squierka39 wrote:

Can you post a picture of the rods. Somehow I’m picturing it and if you swivel it from one side to the other the hole should still be up.

This photo shows the oil holes are on the short side of the wrist pin boss off-set.
When disassymbled, one rod had oil holes UP, the other DOWN, so I assume
with the offset that I can’t simply flip the one rod so the oil holes are then UP.

“If” I get a chance today, I’ll look it over, but Tiny Tim is coming for an early diner,
so I may be wondering aimlessly around the kitchen today.

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December 24, 2019 at 11:52 am #189880
Buccaneer
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I snuck out to the garage and took a photo with the parts oriented the way they must go.
Note that the Port side rod oil holes end up “Down”,
and the Starboard side oil holes “UP”.
The rods can’t be re-arranged and have the correct
alignment to bolt everything back together.

Guessing that’s per Evinrude design, unless they
had a port & starboard rod drilled different, but
I’ve heard or seen no evidence of that yet.

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December 24, 2019 at 3:04 pm #189894
garry-in-michigan
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Lifetime Member
I will try a fourth time to post here –

As I said in my private message there is only ONE part number in the parts book. The Speeditwin book specifies two, the Speedifour parts book specifies four. they are all the same period. The port side connecting rods WILL have the oil holes pointing DOWN. (My dad took exception to this and ground off enough of the port connecting rod to instal it with the oil hole in the up position.)
- This reply was modified 4 years, 4 months ago by garry-in-michigan.
December 24, 2019 at 9:29 pm #189926
squierka39
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That’s interesting. Sounds like they were trying to save a few pennies. How well does the down side hold up in the long run I wonder?
December 24, 2019 at 10:37 pm #189927
Buccaneer
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garry-in-michigan wrote:

I will try a fourth time to post here –

As I said in my private message there is only ONE part number in the parts book. The Speeditwin book specifies two, the Speedifour parts book specifies four. they are all the same period. The port side connecting rods WILL have the oil holes pointing DOWN. (My dad took exception to this and ground off enough of the port connecting rod to instal it with the oil hole in the up position.)
- This reply was modified 4 years, 4 months ago by garry-in-michigan.
Sorry I couldn’t decipher your message 100 %. It came thru as below, but
I understand you loud and clear now. THANKS!
Merry Christmas to All, and to All, Goodnight!
=========================================
My post disappeared – I said some things to the computer that made my cat hide. second try . . .The last superseding number is 276776, two specified. The Speedifour uses the same connecting rod. On the Speeddifour you can see the oil hole is on the short side of the offset, which is the port cylinder.

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December 24, 2019 at 11:59 pm #189933
fmanracer
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US Member - 2 Years
Here is the real answer, On a Speeditwin that just gets run as a fishing motor and has the clearances it was set up at the factory to run on gasoline/oil it was determined that the hole was no problem. If you wanted to race the Speeditwin at 6500 RPM you would need to set it up with the modern V4 rods and do the modifications to those rods tp be able to run them. In the early days of “C” Service builders got away with working with these stock rods but as RPM’s went up the stock rods would break. When OMC came out with the 75 HP V4 Starflight most all racers got rid of the stock rods and went to the 75 HP rod as it could be modified to run and could stand the RPM. Racers of today run any of the rods up to the 100HP V4 rod. When your building one you do the machining so that the oil holes are up on both rods and the clearances are right for running lots of RPM’s.
Jay
December 25, 2019 at 9:45 am #189941
Buccaneer
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US Member
Jay, Thanks for the information! This motor won’t get run much, let alone raced.
I just wanted to make sure I put it together the correct way.

Regarding V4 rod conversions, I have no idea what that entails.
I am curious though if anyone has had their Speeditwin crankshaft
rod journals turned down, and succsessfully found an over size
roller bearing set-up?
My crank journals are worn some with some etching. I read that this is
less of a problem when the rollers are in cages like the Speeditwins,
as compared to loose roller setups.
Merry Christmas.

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