<VV> gasoline - now no lead

djtcz at comcast.net djtcz at comcast.net
Sat Jul 6 13:53:52 EDT 2013

Hi John, 

I had purposely laced my comments with dilutants like "rumor" and "possibility". 

I have no details of which engines may have been behind the 1960s Amoco rumor, or how widespread the problem may have been. 
But, when Amoco was selling their unique lead-free hi-test there weren;t many aluminum headed engines cruising around the US except maybe mostly air cooled V-dubs. 
I believe some thoughtful manufacturers elected to outfit their iron headed passenger car engines with inserts even back then. 
- The description of Chevy and Pontiac's new 1955 V8s in the 1955 SAE transactions gloss right over details of valve seats, but based on cross sectional views I believe they both were using integral seats with no hardening. 
- The 1953 SAE paper announcing and describing the Buick V8 engine also does not mention the seat design, but shows integral seats, even in their OHV combustion chambers back in the 30s. 

"Wooden boat" magazine did some kind of "effects of no-lead" test a few decades back. I have no feel for typical engine spec of the Chris Craft marine era. I'd like to think Chrysler industrial engines came with installed exhaust seats as standard, as PowerWagon flat head sixes and the hotter hemis allegedly did. 
I think "Wooden boat" onclusion was also "wait and see" unless the boat would be worked hard, consistently. 

Here is a 2011 report from someone who claims to have lived thru the transition to no-lead, and was in a position to see the worst of it. No details are provided if the affected vehicles were hard working trucks, or if 8s just loafing around got hit too. There is the additional question about the impact of ignition timing and jetting used to sqeak carbureted engines by emissions then also. 

" I am a machinist & was in the thick of things when Leaded gas was phased out altogether in the late 80's around here. Saw more pre-unleded cylinder heads pull exhaust valves up through the heads that I care to remember. Did I say that I saw a lot of them? Yes, I think I did. 

Curiously when Kettering and his team were working on raising octane in the 20s, some of them felt TELead's affect on valve life was such a significant negative (I'm guessing probably from deposits preventing valve seating, resulting in burning, not directly from seat recession), along with toxicity, that some felt adding "alcohol" was a better solution. page 17 here - 

Dan T 
----- Original Message -----

Original message 
Date: Fri, 5 Jul 2013 16:56:51 -0400 (EDT) 
From: jvhroberts at aol.com 

Valve recession is a non issue for Corvairs, or most aluminum head engines, as they have hardened seats. Also, valve recession even in iron head engines seems to be a bit overblown. 

John Roberts 

-----Original Message----- 
From: djtcz <djtcz at comcast.net> 
To: virtualvairs <virtualvairs at corvair.org> 
Sent: Fri, Jul 5, 2013 4:31 pm 
Subject: <VV> gasoline - now no lead 

From: jvhroberts at aol.com 
Subject: Re: <VV> Gasoline gasolene? 

That was back in the days of tetraethyllead, long gone, thankfully! 

The problem with using a TEL concentrate is a little does a lot for octane, but 
a lot more doesn't get you much further up the octane curve. 

But hey, at least there's the lead fouling! 

John Roberts 


Amoco sold lead free (super) premium practically from the beginning. 

At the time there were some rumors that it caused valve burning. 
With the known possibility of valve recession in old engines these days it seems 
like there might have been some truth to it. 

Dan T 

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