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.

[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