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#1 |
F’B’D guy
![]() Join Date: Feb 2004
Location: Texas/Maine
Posts: 2,220
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1970 to 72 truck motors, do they require a lead additive?
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!
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#2 |
Registered User
![]() Join Date: Dec 2008
Location: K.C. Missouri
Posts: 1,024
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Re: 1970 to 72 truck motors, do they require a lead additive?
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.
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1969 Short Stepside 1969 4 WD Suburban 1970 1 Ton Dually....Misfit oh, and a 2001 HD 2500, 8.1 Allison Shortbed 4 Door |
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#3 |
Senior Member
![]() Join Date: Jul 2004
Location: Estherville, Iowa
Posts: 3,371
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Re: 1970 to 72 truck motors, do they require a lead additive?
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.
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1968 C10 307 3spd Long Fleet ------ http://67-72chevytrucks.com/vboard/s...d.php?t=201103 1970 C10 305 Super T10 Long Fleet --- http://67-72chevytrucks.com/vboard/s...d.php?t=202285 1971 C20 383 TH350 Dana Posi ----- http://67-72chevytrucks.com/vboard/s...d.php?t=206894 2001 GMC Sierra 1500 C3 6.0 Last edited by Green Machine; 08-01-2009 at 10:16 AM. |
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#4 |
Registered User
Join Date: Jan 2006
Location: Take Off
Posts: 1,908
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Re: 1970 to 72 truck motors, do they require a lead additive?
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.
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#5 |
Registered User
Join Date: May 2009
Location: Eliot, Maine
Posts: 1,314
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Re: 1970 to 72 truck motors, do they require a lead additive?
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!
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#6 |
Registered User
Join Date: Mar 2007
Location: San Pedro River, SE Arizona
Posts: 734
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Re: 1970 to 72 truck motors, do they require a lead additive?
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
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CCCC 67 Sting Ray Coupe 327 4sp; 68 K10 Suburban 327 4sp; 69 K20 Lifted 383 4sp; 69 C80 Fire Truck 478 V6 5sp/2sp; 69 C20 Longhorn 327 4sp; 70 C30 Wrecker 350 4sp; 70 C30 Flat Bed 350 4sp; 71 C20 LWB 350 4sp; 72 K5 Blazer 350 4sp; 72 C30 Flat Bed Gooseneck Hauler with sleeper 350/TH400; 72 C20 Longhorn 402 4sp; 52 Mack LTL Supercharged Cummins 5sp x 3sp; 01 Dodge 5.9 HO Cummins 6spd; 02 Safari Trek 2430 8.1 Vortec on Workhorse Chassis; 03 Silverado 2500 HD 4wd Duramax/Allison Moved but still in the family 70 C20 Custom Camper 350/TH350; 72 K5 Blazer CST Highlander 350/TH350 Recently sent to new homes 72 C30 MoHome 402 4sp; 72 K5 Blazer Conv 350 4sp; 75 GMC 6000 Aerial 350 w Allison; 72 GMC 3500 Utility 350 4sp; 70 GMC 3500, 350 4sp |
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#7 | |
Registered User
![]() Join Date: Dec 2008
Location: K.C. Missouri
Posts: 1,024
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Re: 1970 to 72 truck motors, do they require a lead additive?
Quote:
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)
__________________
1969 Short Stepside 1969 4 WD Suburban 1970 1 Ton Dually....Misfit oh, and a 2001 HD 2500, 8.1 Allison Shortbed 4 Door |
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