Cutting valve seats.

[Peter Cooke]

Hi Cotten,
ULP is Unleaded Petrol. That's what lead free petrol is called in Australia. Some people in OZ also run there cars on Liquid Petroleum Gas (LPG) and because it burns hotter there have been problems with older vehicles with cast iron heads where the valve hammers it way into the cast iron resulting in the need for hardened inserts.
I was wondering if perhaps the result might be the same using unleaded fuel and the original valve seats in a VL due to the higher operating temp.

Based on what you and Steve have said if the valve seats are ok I think I'll take the 'if it aint broke don't fix it' approach and leave the seats alone.

[T. Cotten]

Peter!

American flattys were not designed to require lead in the first place, as they do not require high octane fuel.
Tetraethyl lead was added to fuel only to raise octane, not for other benefits, real or imagined.

....Cotten

[knuckleheadtim]

Lead also cushioned the valve when it closed, preventing pitting of the seat and valve. An excellent machinist pointed out to me in the 70s that I must be running unleaded gas in my car (Amoco) because everythig was pitted so badly.

I've had no problem running hardened Sportster seats in a flattie. Along with nitrided valves, they work well, but must be put in with a lot of interference. I use liquid nitrogen, which shrinks them about .005" and chill the driver as well.

[harleytoprock]

As valve wear preventive

Tetraethyl lead works as a buffer against microwelds forming between the hot exhaust valves and their seats.[3] Once these valves reopen, the microwelds pull apart and leave the valves with a rough surface that would abrade the seats, leading to valve recession. When lead began to be phased out of motor fuel, the automotive industry began specifying hardened valve seats and upgraded exhaust valve materials to prevent valve recession without lead.[4]

[harleytoprock]

I pasted the info on lead as a buffer just to stir the pot a bit. It seems for years now, that there is one group that says lead is not needed for valve seat lube and yet another group that add all sorts of lead substitutes like 2cycle oil, diesel fuel and Marevel mystery oil. I wonder if any scientific tests have ever been studied on no lead fuel with stock cast iron valve seats.

[Daking]

Need some help here guys....I have my 38 ULH cylinders over at Midwest Cylinder Head in Nevada Iowa for fin repair and was thinking about the valve seats as they are gone.....do I try and repair what is there while they have it in the oven or do I do inserts? It is going to need sleeved also......

[Peter Cooke]

If by repair you mean build up with weld and remachine and they have the ability to do that then that would seem to be the way to go.
I've now inspected mine and as they're in good condition I wont be doing anything other than new guides and recutting/lapping the seats to suit new valves.

[sswaney]

Cutting valve seats

"do I try and repair what is there while they have it in the oven or do I do inserts? It is going to need sleeved also......"

The question is if there is even the clearances needed to sleeve it and install valve seat inserts without getting the insert O.D. right up next to or interfering with the Sleeve O.D. Sounds like the welding repair to the original seats would be preferable. I didn't think there was even room to sleeve it to the stock 3 7/16" bore (80"), you'll have to reduce the bore diameter to 3 5/16" bore (74") to make it work out won't you?

[Daking]

Ok we are going to try and weld up the intake and do inserts to the exhaust......keeping with the 80 3-7/16 standard boar 1/16 sleeves.