Fuel with ethanol?

[K31]

When I bought my Pinz, the owner told me not to use anything but unleaded fuel without ethanol, and to add a lead substitute to that. It looks like fuel without ethanol is going to be going away in the near future as more states pass legislation to require ethanol to be added. Has anybody been using fuel with ethanol?

[Jim LaGuardia]

Run whatever gas you want, I have over 50,000 miles using unleaded with no cylinder head problems.

[mjnims]

yeah what Jim said. I also have a bunch of miles on my 712 and 710 with just what ever gas is available and neither turck has had any fuel related issues.

[Erik712m]

Jim, Doesn't ethanol run cooler?

[Hawkeye Pinz]

I live in Iowa, ya know the state where corn is EVERYWHERE! Well, gas with 10% ethenol is the cheapest fuel you can buy around here so thats what I use. Haven't had any problems at all .

[indigoth]

Does anyone have any issues at all, with the unleaded gas?

I know the unleaded stuff doesn't provide the valve seat lubrication that the leaded gas used to provide and all the cars now have hardened valve seats to deal with that.

and

from what I understand, that's the reasoning for suggesting adding a lead substitute at each gas fill up. the real "cure" would be to pull the head and have hardened valve seats installed, but, that's not as fun as just "climbing in the truck and going".

with the stock seats, I'd expect to see accelerated wear, but just how accelerated is kind of what I'm wondering about.

anyone have any stories to tell along those lines?

[ScottishPinz]

I remember a while back reading an article that stated the lead in fuel was a cheap antiknock additive and did nothing to lubricate valve seats... I wish I had kept it as the research seemed good science. I have often asked those in the motor trade whether they have ever encountered damage that WAS as a result of unleaded fuel use. All have agreed when considering this that engines suffered just as much (if not more) valve damage problems when all fuel had lead in it!

I have always run everything with unleaded and not ever had problems.

[Jimm391730]

I remember a while back reading an article that stated the lead in fuel was a cheap antiknock additive and did nothing to lubricate valve seats...

What is really happening is that the extremely hot exhaust valve (which is hard) and the exhaust valve seat (not as hard, at least on older vehicles) tends to "stick" or microweld when they come together. On the next valve opening some of the softer seat is pulled away, stuck to the valve. The amount is microscopic, but after millions of operations the seat is gradually eroded and ends up getting blown off of the valve and out the exhaust.

The tetra-ethyl lead was added as a antiknock additive, but a side effect was that a thin coating of lead was spread everywhere including the valve surfaces. Since lead is obviously softer than the valve or seat, it gets ripped apart and protects the steel. It's not so much a lubricant, but a sacrificial surface to protect the valve seat.

As the seat erodes, the valve closes a little further, reducing the valve lash clearance. If the clearance goes to zero the valve won't seal well, compression drops, and sometimes the valve gets overheated since the heat of the valve is drawn away by its contact with the seat in the relatively cold cylinder head.

So, the "just get in and go" mentality works just fine as long as you check the valve clearance regularly. If you notice that the clearance is too tight you probably have some valve recession. Eventually you will have to install hardended valve seats, but you might as well wait until it is needed.

So far (and I've driven my 712 across the country at 60mph) I've not noticed any recession, but I occasionally add lead substitute. In other words, I wouldn't worry about it much!

Jim Mettler
712W and 710M

[75pinz]

I had a conversation with Scott @EI the other day about speeds in a 712. I have always run 55-60 mph without issue in the 712s I have had. He indicated 50 should probably be about as fast as a 712 should be driven for any length of time. On my tach, at 55 I am about 4K RPM. Thoughts on this?

[Erik712m]

I never go faster than 50mph 3,500 rpm.

[krick3tt]

I installed a new electronic speedo and checked with the GPS that Jim L. loaned me for the calibration. With the larger tires the original speedo was a bit off. The new one is spot on. So at 50 mph I am at 3200 rpm. Very comfortable speed for me, others on the road may be a bit perturbed at the slow green thing in front of them, especially these big logging trucks here. I just pull over and let them pass.

Cheers,
Morris