[AJD] Antique-johndeere Digest, Vol 82, Issue 4

[Mike Scholl]

One has to remember why lead was added to fuel... When exhaust gases are very hot, like when the system is under high load, the molecules on the contacting surfaces of the exhaust valve and seat tend to stick together and transfer from seat to valve and valve to seat.  Each successive time creating a rougher and rougher valve contact surface.  The lead molecules act as buffers that 'lubricate' the contacting surface.  Lubricate in this sense means that it causes the molecules from the adjacent parts to resist sticking together.

If your tractor will be used for work, and you have the original (not hardened) valve seats, lead or lead substitute is a must.  If all you are doing is driving the tractor around for fun, unleaded fuel should work fine.  Aside from owning an antique tractor, I also have a collector car with a 1964 engine (without hardened valves).
  

-----Original Message-----
From: antique-johndeere-bounces at lists.antique-tractor.com [mailto:antique-johndeere-bounces at lists.antique-tractor.com] On Behalf Of John
Sent: Wednesday, January 11, 2012 8:13 AM
To: Antique John Deere mailing list
Subject: Re: [AJD] Antique-johndeere Digest, Vol 82, Issue 4


    Lead additives??  Its my "opinion" for use on our relatively low 
compression, relatively low RPM and low hour use old tractors LEAD ADDITIVES 
ARE NOT NECESSARY.  I would say there may be possibly a tiny tiny tiny bit 
more (Probably not even measureable) valve seat and face wear which the lead 
might help cushion and lubricate but that’s a reason for hardened valve 
seats.  Again, since the old tractors are such relative low compression I 
see no reason for an additive to prevent pre ignition "spark knock" or the 
use of purposely harder to ignite high octane fuel or additives (i.e. 87 
octane is fine).  For extended storage and to lessen gas varnish and gum 
problems and oxidation on cast carb parts, I use Sta Bil plus a bit of low 
ash two cycle (mixes well with gas) motor oil in my fuel prior to shutdown 
then drain the carb before I put them to bed for the winter and in the 
spring I turn on the gas and open the carb drain and let gas run a good time 
to wash n flush off the needle valve and seat and then they start right up.

  Ol John T in Indiana,  Long retired Electrical Enginneer and NOT a 
mechanical so NO WARRANTY lol

-----Original Message----- 
From: Troy
Sent: Wednesday, January 11, 2012 5:20 AM
To: Antique John Deere mailing list
Subject: Re: [AJD] Antique-johndeere Digest, Vol 82, Issue 4


Continuing this discussion, I don't have access to any fancy fuel, so I just 
use regular unleaded.

I do add lead substitute occasionally, but not religiously.  To me, it seems 
to make the exhaust smell bad, and I don't like breathing it in.  I always 
wonder if I am breathing lead?

Does anyone have an opinion if lead substitute is worth the cost and effort 
to use it?

I have to say that my tractors have lasted, and I do work them hard, so it 
might've helped some over the years.  As for plug fouling . . . plugs aren't 
as good as they used to be, so yes, I find they do foul easier than they 
once did.  I go through plugs about annually now on  my main tractor the 
#70.

Someone mentioned Stabil . . . that is a requirement for winter.  Any gas 
sitting in gas cans or in the gas tank (chainsaws, lawnmowers too), gets 
stabil.  Gas just won't last without it anymore.

One year I forgot to put Stabil in my lawnmower, and it just wouldn't start 
up next Spring . . . drained the gas, added new fresh stuff, and it fired 
right up.

Troy


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