Formula 3 & Evinrude fr 31-m

[Tokate]

Hey,

I just bought an old formula 3 boat and evinrude fr 31-m. I'm quite lost with the engine and I have many questions.

The package i bought includes two powerheads, two lower units, propellers and lots of different parts. I have two almost similar rigs. There is couple differences and one is that the exhaust pipe is on the other side. Is that from the older fr-19s? (Look second photo down right corner)

I have understood that I need to use avgas and oil ratio is something between 4-6%?
I'm not going to race with the boat so I don't need to take everything out of the engine so what rpm would be good if I dont want to change pistons after every run. I read 8500-9000rpm is okey?

I know the engine need to warm up when the boat is on a trailer. But why some people use some kind of plate instead propeller while warming up the engine? Why can't I warm up the engine without a propeller or with the propeller?

Does anyone have a parts catalogue for the fr 31-m?

I would like to get any tips and information related to fr 31-m!
And sorry for my bad english.

58937
58938

[upyours]

I wish I had one good find can't help with set up looks good

[LittleCharger]

Same here wish I had just one of those. Good luck, I'm sure guys with more knowledge on this particular 3 cylinder will chime in.

[Fast Fred]

7800 rpms, 50 to 1 oil mix, fuel av 100- 120 oct, 120hp.

[NERSTROM]

Congrats on finding two FR-31M's. Yes exhaust was put on right side for improved performance over earlier versions. A fuel-oil ratio of 24:1 using a premium blend of oil with Avgas will work. RPM range of 8500-9000 is where we raced these engines. The plate used when running on the trailer was a test wheel, you can simply run with a propeller to warm up. I would not run without the prop. A parts catalog was produced perhaps Sea-Way Marine can help. Good Luck.

[Tokate]

Thanks for the answers those helped a lot!

What oil you use in a lower unit? ATF?

Starter motor looks like "normal" OMC's starter motor so it propably is 12V, am I right?
But what about engines own trim motor and "lift"? Are they 12V or 24V?

I haven't checked cylinder compressions yet, but when I check them what would be good? And I haven't checked the timing deg yet either so what would be good? There was marked 18 deg on a flywheel.

[Steve Pinson]

Congrats on finding two FR-31M's. Yes exhaust was put on right side for improved performance over earlier versions. A fuel-oil ratio of 24:1 using a premium blend of oil with Avgas will work. RPM range of 8500-9000 is where we raced these engines. The plate used when running on the trailer was a test wheel, you can simply run with a propeller to warm up. I would not run without the prop. A parts catalog was produced perhaps Sea-Way Marine can help. Good Luck. Hi Jim I have been told you new my old friend Rodger Jenkins many moons ago` have you changed your mind yet about writing a book about OMC and your time there with the race engines it would be a very interesting read and a big part of racing engine history if you did. Maybe you can remember when they altered the 3cyl production block must have been around 1975 I was a regular test driver over at the OMC Factory at Brugge in Belgium they used to take about a week to cut and calve a 3 cyl block to modify for race use they used to fit oversize forged pistons from Cosworth made in the UK this was to the early 3cyl engine when they ordered some new blocks from the USA Paul Kalb was told someone had as I remember this scrapped the old production moulds and he could only get engine blocks for the new models` well I can tell you he was really angry about this and worried that the new blocks may not be as tunable as the old engine.Were you around at OMC around this time?

[MGR]

Hey Fred you message is full

[NERSTROM]

Lower unit ATF, we used Dexron II. Starter is standard OMC 12V with mounting tabs relocated for FR-31M. Most used 24V system for starting. Trim and lift are 12V. 18 deg good.

Yes, Roger Jenkins and I go way back to his 3-cylinder days. Great friend. My first 3-cylinders to race in Europe were raced in Paris and won Index of Performance award, Jim Wagner was in Brugge at the time. Paul Kalb replaced Jim and I supplied him with engines with included all versions of the OE / Mod50. Paul loved to modify the engines I sent. John Hill won the OE World Championships with one of my engines. Paul promised to race it as received which turned out to be a good idea.

[Fast Fred]

ya it fills up all the time , best to just Email, gots the counter guys workin on that number, takin notes hear

[MGR]

ya it fills up all the time , best to just Email, gots the counter guys workin on that number, takin notes hear

whats your email i did not see it on your page?

[Fast Fred]

Tboats@ comcast. net

[Tokate]

And couple follow-up questions more..

Why wouldn't you NERSTROM warm up the engine without a propeller? Because the motor won't warm properly?

And what two stroke oil you recommend? I have used Castrol A747 on yamaha 70ces and OMC stinger and it has worked fine so would it work on FR31-M too?

[LittleCharger]

And couple follow-up questions more..

Why wouldn't you NERSTROM warm up the engine without a propeller? Because the motor won't warm properly?

And what two stroke oil you recommend? I have used Castrol A747 on yamaha 70ces and OMC stinger and it has worked fine so would it work on FR31-M too?


I think what Nerstrom is saying is that you need a load on the motor (whether a test wheel or propeller) when warming it up.

[Fastjeff57]

I'm surprised OMC would go to all the trouble of casting a special block with the exhaust on the other side! Does anyone have photos of its interior?

Jeff (old Merc guy, but still interested)

[Fast Fred]

looks like the straight in, bridge port with finger ports is what i'm thinkin. load on , makes heat, or more heat. did see a merc 850 cc special moda once, it had a head gasket.... not lookin like thats got a thermo in it, so work is the only way to get to temp.............

[Powerabout]

31m and f1 v8 are 2 omc custom blocks
And the rare 2.0 ltr v6 looper that were never sold afaik
All 3 were winners right Jim?

[Seagull 170]

Without a suitable load very little throttle is required to reach maximum revs, little throttle = little fuel = insufficient lubricant!

[Fastjeff57]

Right! I my old dirt bike days, we used to blip the throttle constantly when descending a long hill, to keep some oil flowing in with the gas (20:1 premix).

Jeff

[Tokate]

Hello guys long time no see !

The summer with F3 didnt go very well.. I managed to drive it couple of times but every time something was wrong.
On the first test a trim system didnt work properly so I needed to test drive without it. Here's a video from the first test: https://www.youtube.com/watch?v=I2IlN9TiPts

On the second test our fuel pump broke and it might have damaged our other engine. I need to find out what's wrong with the powerhead. And on top of everything the tunnel of the boat cracked while pulling the boat on trailer.

But now the boat itself is fixed and the trim system should work now. So next step is to open up the engine and test out the other powerhead.

I also find out an interesting information according to my boat. It holds the finnish speed record at 157km/h (97.5mph). The record was set in 1991.

[Fast Fred]

make sure the power head gets to a runnin temp, or she will bog down.

[upyours]

Very good to hear from you sorry for your trouble's maybe you have all the bugs out let us know how it goes

[Steve Pinson]

Hello guys long time no see !

The summer with F3 didnt go very well.. I managed to drive it couple of times but every time something was wrong.
On the first test a trim system didnt work properly so I needed to test drive without it. Here's a video from the first test: https://www.youtube.com/watch?v=I2IlN9TiPts

On the second test our fuel pump broke and it might have damaged our other engine. I need to find out what's wrong with the powerhead. And on top of everything the tunnel of the boat cracked while pulling the boat on trailer.

But now the boat itself is fixed and the trim system should work now. So next step is to open up the engine and test out the other powerhead.

I also find out an interesting information according to my boat. It holds the finnish speed record at 157km/h (97.5mph). The record was set in 1991. When I was over at the OMC factory in Brugge testing boats before going to race events my old teamate John Hill would go out and test his OMC 3 cyl outfit and in race trim he would be doing 96mph this was in 1977.