Board index Flathead Power-Technical Questions, Answers, and Suggestions 45 Flatties No Lead Gas?

No Lead Gas?

Post Thu Dec 19, 2002 5:05 am

Posts: 3159
Location: Central Illinois, USA
Now consider this:

Perhaps the MMO is just slowing the oil from crusting up from the heat. Modern oils aren't made for aircooled flatties. The additives burn into hard soot.

There will never be enough flow of lube to cool a flattie's valve stems.
Nitrided stems and soft cast iron theory assumes next to no flow. Modern OHV's even have seals to prevent flow, lest carbonization fills the gap, resulting in sticking and wear.

MM Oil is the one lube that carbonizes the least. But you cannot run pure MMO!
Conventional oils with modern additives will carbonize and stick a properly fitted valve at flatty temperatures.

(Inspite of what Shell says, Aeroshell is probably the best motor oil for such an application, as it is ashless.)

And no doubt moderate use of MMO can only help.(You know when you have added too much when your plugs foul out!)

I have no qualms about using MMO as a safety net, but it is just that, and only that.

It is not a cure for the causes of elevated combustion temperatures. Only common sense does that.

Post Thu Dec 19, 2002 6:51 am

Posts: 382
Location: Hill City,Kansas
True fact and when I said loose valve guides I was not refering to "loose as a goose" just the loose side of the specs. Err to the side of richness and know what your engine is doing by sound and that takes and ear of experience I also failed to mention that I am running a thermostatic oil cooler. I definately recomend the cooler and thermostatic is the only way to go. And definately make sure of your intake seal as Cotton just might mention.(not to play it down as it is damned important!)


Post Thu Dec 19, 2002 8:39 am

Posts: 67
Location: Australia
try REDEX from Repco (maybe Aussie MMO)easy on the revs, compression & temps, (old stock wla's will run on kero!)our American friends gave(lend lease) us the gift of these fine machines 60 years ago, they have survived war, neglect and bush mechanics! A little bit of care & common sense & they'll survive "unleaded" crap gas too!



Post Fri Dec 20, 2002 2:18 am

Posts: 3159
Location: Central Illinois, USA
Conan asked about Aeroshell....

It's fantastic, but don't tell Shell that I said so.

The bad side is that it has no additives to inhibit corrosion, or wear beyond the mileage that most of us would have dumped it by anyway.

The great side is that it is ashless. Put a drop on a piece of glass and gently heat it with a propane torch and watch it vaporize sweetly to leave just a film.
Then put on a drop of Valvoline (another great oil that I heartily endorse as well, but has AUTO additives) and give it the same flame,.. But hold your nose, and prepare for a cinder that would require a knifeblade to scrape off.

That's the abrasive that will eat a valve guide and stem,.. or at east stick it when temperatures get out of hand.

With proper machine technique, proper timing and carburetion, and proper lubes for a flatty, you should INSIST on minimumspec for valve clearance. That's what you are paying good money for!

This is the way I have been putting them out for years and years. And I am somehow still in business. It's a miracle, huh.

Post Fri Dec 20, 2002 5:39 am

Posts: 118
Location: USA

I've really enjoyed this one. Lots of good input. I abuse my equipment under extreme conditions. I set my clearance loose, it's a race motor!!! I'm looking for a few fast miles, not longevity. What works for flatheads? Cast iron guides, nitrate valves, low octane fuel, well tuned carb, no air leaks and correct ignition timimg. When all this is in place, go for the snake oil and ride it like you stole it.

Post Fri Dec 20, 2002 11:50 am

Posts: 188
Location: Charlottesville, VA
A couple of points that come to mind. I seem to recall that lead was added to fuel as an anti-knock additive, and that was it's only use. It had nothing to do with valve seats, lubrication, or stems. When aviation fuel changed from 80 octane to 100 octane low lead (which still contains considerable lead) we were worried that we were going to have problems with valves, and started using an additive called TCP (tri-chresel-phosphate -sp?). Turns out we really didn't need it as the engines ran well for 2000 hours or so. We never modified any clearances in guides, or any other parts during overhaul, and stuck to the clearances mandidated by the manufacturer manuals.

Setting up our flattie motorcycle engines on the loose side goes against everything I ever learned as an aircraft mechanic, but when we did my 45, I went with the experience of a grizzled old motorcycle mechanic that had worked on flatheads longer than the Motor Company, and we set the guides up on the loose side.

The problem we had with the aircraft engines was when Shell and others changed to multi-viscosity oil from straight detergent. We had a lot of stuck valves, and until the right additives were formulated, we wouldn't use the multi oils from any manufacturer.

As far as aircraft oils go, the application is quite different from motorcycles. Our little aircraft engines normally run at a fixed rpm (say 2500) for hours on end. The heating and cooling cycles are different.

There were many articles on oil selection in American Iron, and several other motorcycle rags a year or so ago, and the bottom line was the additive package was critical to oil selection. As you might expect Aeroshell, and automotive oil has different additives than motorcycle oil. I use nothing but HD 50 (winter) and 60 (summer) because of its additive package, and temperature ratings. I change oil every 500 miles.

If I recall the magazine discussion, synthetic was recognized as the best, and that is really not surprising, but I just can't bring myself to use it.

Post Fri Dec 20, 2002 4:33 pm

I don't know if a/c VW beetle (Type 1, etc.) motors are a good analogue, but Gene Berg gets almost hysterical on the subject of oil viscosity - thick oil won'r go through the bearings when cold.

Post Fri Dec 20, 2002 5:11 pm

Posts: 382
Location: Hill City,Kansas
I wouldn't even consider it in an analogy.Horisontally opposed OHV 4 cylinder,aluminum heads ,bronze guides ,plain bearings fan cooled with oil cooler and if not disabled a thermostat.


Post Fri Dec 20, 2002 10:04 pm

Posts: 767
Location: CA USA
What type of oil do you run in your WR? Weight, detergents, brand, etc. What are you setting up your valve to guide clearances at? How about piston clearence? Are you using cast or forged pistons? What type rings are you using? What end gap? How many race miles do you get per top end rebuild? How many race miles on the ball bearings on the cams and flywheel shafts? How about life of rod bearings? I'd like to know how a modern day WR racer sets up his motor to compare it to what the OGs did. I'm sure lots of the guys out there would be interested in the knowledge you've gained from campaigning a WR today. Thanks much for any info you are willing to share. 'dog

Post Sat Dec 21, 2002 12:02 am

Posts: 732
Location: nekoosa,wisconsin,usa

It sounds like we could be compatible riding partners. If I want to drink beer, it seems to work out better at home. That way I don't have to worry about losing riding priveleges . Fat Dog speaks glowingly of you from his experiences at the AMCA meets. Maybe our paths will cross. I am hoping to make the Omaha Chapter Road Run. Maybe there?
I had heard that the Aero Shell oil had an additive package that had ingredients that were not good for M/C use. I don't remember the specifics. Anyone else?

Post Sat Dec 21, 2002 2:23 am

Posts: 3159
Location: Central Illinois, USA
That's why I posted to not tell Shell that I said it is fantastic. Even though it is.

As I posted, it does not have certain anti-wear or anti-corrosion additives. If you change your oil as often as most of us, that's irrelevant.

The ashless aspect has benefits that far outweigh the lack of these. They are probably what crust up at flatty temperatures anyway.

And do you really think that those engineers are considering 'motorcycles' to have flatty motors in them???? They are thinking Goldwings and electric-couch evos.

The best thing about Aeroshell is that when it pukes out of your rat and gets all over the pipes, it doesn't even burn to a crust!

It ain't a flatty, but my tired rat pan with a fully loaded hack was spewing oil (Valvoline60) to the tune of a quart every 60 miles when I tried to follow a pack of evos outastate in 90 degree weather at interstate speeds. I found Aeroshell at a gas station(!) and proceeded to get 80 miles per quart. When that ran out, and could only get more Valvoline,... it went back down to 60 mpq.


Post Sat Dec 21, 2002 7:21 am

Posts: 896
Location: Bixby,OK, USA
Conan I saw you on TV the other day......

Post Sun Dec 22, 2002 6:54 am

Posts: 896
Location: Bixby,OK, USA
Conan I'm gonna need that top tree also, I'll call or be by first of the week....jb


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