<VV> gasoline - now no lead

jvhroberts at aol.com jvhroberts at aol.com
Sat Jul 6 18:04:50 EDT 2013

Corvairs don't have problems, since they have hardened seats. We're also running a 1942 Hercules JXD flathead six on our searchlight, and it'll run unleaded just fine. It was also designed to be a multifuel engine, so, lead was not guaranteed. 

John Roberts

-----Original Message-----
From: djtcz <djtcz at comcast.net>
To: virtualvairs <virtualvairs at corvair.org>
Sent: Sat, Jul 6, 2013 1:09 pm
Subject: <VV> gasoline - now no lead

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 
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 

" 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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