1970 to 72 truck motors, do they require a lead additive?

[57NAPCO]

I am looking at a stock 1971 (350 motor) truck and I was wondering if the valve seats will hold up to today's fuel or do you have add lead? I am guessing if they have a rebuilt motor that is no longer an issue? Thanks for you help!

[Skirkpat]

Originally Posted by 57NAPCO

I am looking at a stock 1971 (350 motor) truck and I was wondering if the valve seats will hold up to today's fuel or do you have add lead? I am guessing if they have a rebuilt motor that is no longer an issue? Thanks for you help!

You should also be looking at an oil additive, I believe it is Zinc? Thet started taking it out a few years ago, or use diesel oil like Rottela, but I heard they are taking it out of that also now...I am sure another member here will elaborate.

[Green Machine]

The exhust valve seats if they have never been touched, have enough lead pounded into them they should be OK until rebuild time. When you do a valve job, that built up hardeness gets removed and hard seats should or some nice aftermarket or newer heads could be installed then. Lead substitute additive sure would not hurt anything, except your wallet, guess it depends how many miles your are planning on driving it.

Some claim that if the truck will be just a toy, hard seats might not be needed even at rebuild time. But if you plan on using it a lot hard seats is best. Opinions vary, but the 487 castings commonly used in 71-72, the exhaust may have been slightly hardened as the switch to unleaded was in the works then, if they were that would help some.

Take off a valve cover and see if there are rotators on the exhaust valves, if so that helps seat life too.

[mclairmo]

I agree with Green Machine. I also use ZDDPlus from Eastwood that adds plenty of zinc to my oil to prevent wearing my cam lobes off. New oils do not contain zinc b/c new engines have roller cams and don't need it. Diesel oils still have some, but I think it is getting less, too. You can also add EOS to the oil but not sure if GM still makes it.

[capev86]

all vehicles should be unleaded friendly by 1972. and if you run good oil (synthetic) then you shouldn't have to worry about excessive wear on the cam or anything, although roller cams are still rule in the quest to lower parasitic drag and friction!

[CCCC]

The comments here have been enlightening especially in that, during college days in the 50s, my summer job was working in the R&D lab for Sun Oil - and every day we did octane tests for their "blend" pump (Oh, that 260) with Ethyl Corp ICC - tetraethyl lead compund (very toxic stuff). Wish I had thought to get and save a gallon back then.

This leads to an inquiry of those who know the metallurgy of the friction components of engines built 67-72.

With a bunch of these trucks and engines here, I actually drive VERY long miles on two of them - 1972 BB402 (motorhome) and a 1972 SB350 (Blazer hunting rig) and soon hope to do some long miles on a 1970 GMC 3500 with SB350.

capev86 noted that, by 1972, the engines should have been "unleaded friendly". I like that. But, what about the 1970, or some of the earlier ones here? What is current best knowledge on most effective products to use and how much and how often to treat an oldie that is going to go out over the road?

Thanks for any info.
CCCC

[Skirkpat]

Originally Posted by capev86

all vehicles should be unleaded friendly by 1972. and if you run good oil (synthetic) then you shouldn't have to worry about excessive wear on the cam or anything, although roller cams are still rule in the quest to lower parasitic drag and friction!

You might want to check on this, Alot of people have had problems with excessive cam lobe wear with flat tappet lifters and using the newer formulations of oil. The GOV. mandated that alot of the additives found in previous formulations be removed...on a side note the real casualties are going to be small 4 cycle engines, and having seen the carnage first hand I will have to side with the engine rebuilders that I associate with and recommend that a zinc additive should be mandatory on non-roller engines.

http://www.enginebuildermag.com/Arti..._got_zinc.aspx

http://www.hotrod.com/techarticles/e...ech/index.html

And as far as synthetic oils are concerned... while they are more stable, they have a smaller molecular makeup which in hi-mileage/high wear engines will produce those annoying and sometimes harmful leaks. At least that is my experience, if you have an engine that has been ran on Dinosaur sauce for 30+ years, I would not change the equation, If it's been reliable for that long stick with it.....now at rebuild time it may make sense to go synthetic (unless you have a flat tappet cam, and then break it in with convetional motor oil NO EXCEPTIONS)