[Farmall] gasoline/spark plugs

[Mike Sloane]

The problem, as I understand it, is that the older tractors are designed 
to operate at full rated load and at "high idle" (maximum RPM) over long 
periods of time, and the cooling systems are designed for that kind of 
operation. When you do that, the plugs will not foul. But when you 
operate at lower speeds and for short periods, the combustion chambers 
and head will not get hot enough to properly heat up the plug tips. 
Going to a "hotter" plug in the charts may help with low speed fouling, 
but you run the risk of burning the plugs in normal operation. I have 
been using D15Y plugs in all of my Farmalls (from 1948 Cub through 1964 
706) with no (spark plug related) problems whatsoever. If you ignition 
system is up to specification, there will be sufficient spark to light 
off the fuel mixture, in spite of a little fouling. Additionally, this 
is one reason why it is important to always keep your cooling system 
operating properly - correct thermostat, tight fan belt, clean radiator 
fins, etc. The reality is that the "cooling system" should really be 
called the "temperature control system" - the engine needs to be quite 
hot to run efficiently.

Second, it should also be understood that the octane rating of various 
grades of gasoline is ONLY related to their ability to resist 
pre-ignition (pinging) at higher compression. ALL other factors of the 
fuel are identical - higher octane won't give you any more "power", burn 
cleaner, smell nicer, or anything else. Any increased power obtained 
from higher octane gasoline is only the result of raising the 
compression ratio or possibly changing the ignition advance. At current 
gas prices, you are just throwing good money into the manure pit by 
going to a higher octane ("premium") fuel.

Mike

E. John Puckett wrote:
> I know this is probably opening a can of worms, but I've been having to 
> replace the spark plugs in my working cubs fairly often lately.  I run 
> Champion D21 plugs, midgrade fuel, and neither tractor burns oil.  Plugs 
> won't appear fouled, and tractor doesn't smoke, but old plugs will be 
> solid black when removed.  I told the parts man I wanted something 
> besides Champions this time.  He gave me AC 87s, but said they probably 
> won't help.  According to him most of the local guys still using the 
> older IH, John Deeres, etc. for work have all changed over to using 
> premium grade fuel.  Only way they could find to keep from having to 
> replace plugs every few hours of work time.  Anyone else running into this?
> 

-- 
Mike Sloane
Allamuchy NJ
mikesloane at verizon.net
Website: <www.geocities.com/mikesloane>
Images: <www.fotki.com/mikesloane>

  "A people that values its privileges above its principles soon loses 
both."    Dwight D. Eisenhower (1890-1969), US general & politician


-- 
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.344 / Virus Database: 267.11.13/124 - Release Date: 10/7/2005