429 valves and petrol grade

[mustangandy]

Hi All.

I've been checking on this forum (and others) to see what opinions are as to the valve life of a 1971 cobra jet ram air 429 seeing as the original premium gas long since went out of production. The engine is original with 52,000 miles on it, runs sweet. I put 98 Octane in her (European petrol). As a Cobra Jet I know there were differences to the heads, cam and valve train but I can't find any information as to whether the valves seats themselves were already made hardened on the anticipation of having to run unleaded fuel in the coming years. If not then, without additives, will the valves already be wearing out? Would anyone have any idea's on this please? Thanks.

 

[NOT A T5]

I do not think any engine of that time has had hardened exhaust valve seats, that was the reason why leaded gas was around.

 

[Fabrice]

I wanted place hard seats for my 429 heads. Very pricy.

My machine shop was clear on this, they would do it for me for sure, but on all the hydraulic flat tapped V8's that they revised, they've rarely saw damaged seats.

It would need lots of miles, high rpms and poor cooling to damage them.

If you plan drive lots or push it hard, I'd do it, otherwise no fear. You can put some additive if you want. I add a bit every full tank, but thats probably pure wasted money

May they fail, you can always see when the time comes.

 

[secluff]

mustangandy,

No hardened valve seats in your 71. All the manufactures knew tougher emission standards were on the way. The 71's had a NOX option (Nitrogen  Oxide) emissions reduction that was a mandatory requirement for California. That system continued through 72 until the Government mandated EGR system came out in 73. The no lead fuel your thinking about was a result of the catalytic converters that came on the 1975 US built cars. You could still get leaded fuel in the US until our Government banned it for all on the road vehicles around 1995-96 You could still get leaded fuel but was restricted to Aviation ,off road equipment, racing and other such requirements.The market for "Test" pipes was a big business for a while. You could remove the converters, punch the flapper door out of the filler neck and run leaded fuel. Lots of them were swapped in the back yard, as most dealers didn't want to deal with a $10,000.00 fine if caught doing a swap!!

The  leaded fuel did have it's benefits although our Government claimed it was slowing killing us . As it burns, tetraethyl lead turned into a tan-coloured layer of lead oxide, which coated the valves and the combustion chamber. You figure how many thousand times a minute the valves hit hard against the valve seats and you can then see why the lead oxide was needed as a cushioning agent, and to protect the valve and the valve seats. The lead oxide was also a lubricating agent and  reduced wear in the valve guides, as the valves slide inside them.  

As Fabrice stated, if you have an occasional driver and don't try to kill your car every time you drove it (as I did) you could possibly get by adding an occasional lead additive to your fuel. Agree the machine work there to place hardened seats in your heads would probably be expensive. At least you do have the option to have the seats installed if you do suffer some valve/seat damage later on.

 

[Fabrice]

[The leaded fuel did have it's benefits although our Government claimed it was slowing killing us .]

I saw not long ago some nice documentaire about Clair Cameron Patterson. One of the guys who caused the end of leaded fuel. His main goal was to find a way to date the Earth. So far nobody had found an accurate enough way to know how old our rock was.

Its when he found/thought of a way to measure using lead, that he realised he needed to find a way to isolate his tests from contamination. No matter his efforts, lead was everywhere. That's when he found out by taking samples all over the world that there was this abnormal poisonous layer of lead on almost everything that was spread in recent decades. On the average US persons tested before and after the fuel change in the 80's showed a drop of more than 90% of lead in their bodies by the end of the 90's.

The funny part was that his early work was funded by the oil/fuel/lead industry...

 

[mustangandy]

Thanks guys. Been doing some more digging and, as has been said already, even though the 71 didn't have hardened valve seats there seems to be consensus that, with the 385 series big blocks, that unless you're towing (460 in a truck) or putting in a lot of high speed motorway miles then don't worry. Just doing a few thousand miles a year or the odd drag race is unlikely to hurt anything. Reassuring to know. Run on highest octane fuel you can get although some seem to run a bit of race fuel mixed in the tank at times. Additives use seems to produce mixed views.