Facts about Evinrude/Johnson racing outboards made my OMC

**Rotary John** · 02-06-2023, 03:07 PM

Originally Posted by Lake X Kid

It looks like the Rotor engine has a longer mid-section, than the V6 Evinrude.

The rotaries didn't have a mid section. That's all engine basically bolted to the gearcase.

**Rotary John** · 02-06-2023, 06:38 PM

Click image for larger version.

Name: 001 (2).jpeg
Views: 31
Size: 234.4 KB
ID: 515221

This is a picture of the rotary ready for the dyno. The side of the bucket was cut out so I could adjust the carbs. Notice the bottom of the engine is at the very bottom of the bucket which the gearcase attached to.

**oldschoolltv** · 02-06-2023, 06:40 PM

I don’t know anything about rotary engines but I’m curious does exhaust length or Tuning have any effect on a rotary?

**lars strom** · 02-06-2023, 07:17 PM

Originally Posted by Rotary John

This is a picture of the rotary ready for the dyno. The side of the bucket was cut out so I could adjust the carbs. Notice the bottom of the engine is at the very bottom of the bucket which the gearcase attached to.

Thanks Rotary John,

This was a very smart/unique design and done over 50 years ago.
A bigger picture of Rotary Johns and you see how the gear case is attached to the power-head with the lower bucket in between..

I guess you can say it was around one inch + mid section..!!..

**WaterZebra** · 02-06-2023, 08:24 PM

Was there ever a discussion about putting a water tight access panel near the 4th carb? I remember something about one of the rotaries dropping out of a race due to "sabotage" with a loose carb? Sure it wasn't the number 4 carb coming loose because nobody could get to it? Was the clamp bracket unique for a rotary or adapted from a V6?

**lars strom** · 02-06-2023, 08:27 PM

The start Paris 6 Hours 1986.
Yes..Lennart and me was part of the race.

**lars strom** · 02-06-2023, 09:11 PM

Originally Posted by WaterZebra

Was the clamp bracket unique for a rotary or adapted from a V6?

The Super Strangler V4 and Stinger GP V4 used the same clamp bracket and some early V6.
My 1973 Evinrude 65 SS also used the same clamp bracket.

**Rotary John** · 02-07-2023, 04:49 AM

Originally Posted by oldschoolltv

I don’t know anything about rotary engines but I’m curious does exhaust length or Tuning have any effect on a rotary?

Yes. The black manifold in the picture housed 4 equal length pipes. The blue part in the picture is a collector where all 4 pipes dumped. The length was determined by dyno runs starting at 24" and cutting off 1" at a time. Remember people including me were in the dyno room during the runs. Anyone who heard the Mazda IMSA cars run knows the sound energy of these engines. Now imagine being in a 12 x 12 room while it was running.

**Rotary John** · 02-07-2023, 05:02 AM

Originally Posted by WaterZebra

Was there ever a discussion about putting a water tight access panel near the 4th carb? I remember something about one of the rotaries dropping out of a race due to "sabotage" with a loose carb? Sure it wasn't the number 4 carb coming loose because nobody could get to it? Was the clamp bracket unique for a rotary or adapted from a V6?

As a matter of fact, screw in plugs were added to the bucket to access the jet on the 4th carb and the 4th spark plug. Some where I have a picture where you can see the white plugs. There was no way to access the mounting bolts for either # 3 or 4 carbs while the engine was in the bucket. As far as the loose carbs in the '74 Paris race, all 4 carbs were completely loose. that's 8 nuts with star washers. I personally adjusted the carbs on the dyno and could have easily determined if any one of the carbs were loose. It had never happened before or after. Not even 1 nut, let alone all 8.
The V-6 didn't exist when the rotary was developed and is actually why the rotary was discontinued after it was. The clamp brackets were from the V-4.

**keith scotton** · 02-07-2023, 08:26 AM

Looking for good pictures all sides or a decal set OF Johnson F1 V8 6 inch motor cover. part number for decal set was 567890.
Thanks Keith

**RogerH** · 02-07-2023, 08:55 AM

Good Morning Keith, Here's the only pictures I have of the 6" Johnson V8. Hope that helps.

Click image for larger version.

Name: John-RudeV8s.jpg
Views: 62
Size: 43.4 KB
ID: 515234

Click image for larger version.

Name: v8f1-6inch.jpeg
Views: 62
Size: 215.2 KB
ID: 515235

Click image for larger version.

Name: JohnsonV8.jpg
Views: 62
Size: 99.6 KB
ID: 515236

**lars strom** · 02-07-2023, 11:17 AM

...

**Lake X Kid** · 02-07-2023, 01:28 PM

Originally Posted by Rotary John

Yes. The black manifold in the picture housed 4 equal length pipes. The blue part in the picture is a collector where all 4 pipes dumped. The length was determined by dyno runs starting at 24" and cutting off 1" at a time.
Remember people including me were in the dyno room during the runs. Anyone who heard the Mazda IMSA cars run knows the sound energy of these engines. Now imagine being in a 12 x 12 room while it was running.

**Lake X Kid** · 02-07-2023, 01:35 PM

In the early 70's the refueling & start barges were secured next to the river bank.

In this photo to haul all the refueling equipment and fuel to those last barges would be a killer.
I remember my arms were tired hauling fuel from the truck to the refueling tank on the barge (manual labor it was in the 70s).

**BarryStrawn** · 02-07-2023, 03:34 PM

Originally Posted by lars strom

No..not correct..BRP gave Greg Jacobsen some stuff and he got lots of parts from Cees Van Der Velden. BRP is still the owner of the Johnson name.

You probably know better, but my recollection of the rumors around the time just before the bankruptcy is OMC sold all their racing inventory and design rights to Sea-Way so it would survive. Then there was some uncertainty or confusion of who owned some of the inventory stored at the Velden shops. Some stayed in Holland and some came back to the US. I heard it was all offered to at least one other dealer as well but Sea-Way stepped up and saved it.