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  #11   Report Post  
Rick
 
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Default Leaded or Un-Leaded?

Jeepers wrote:

Could lead additive affect it's performance? So you are saying I don't
need to add additive, just use a bit higher octane?


Don't waste your time or money on additives. Plain old pump gas with an
octane of 89 or 90 will work fine. The old "leaded regular" was around
that octane so you will be fine.

Lead is nothing but a contaminant in 2-stroke engines anyway. Too much
lead as in the old high octane avgas would lead to "whiskering" of the
spark plugs and ignition problems.

Rick

  #14   Report Post  
Tony Thomas
 
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Default Leaded or Un-Leaded?

As stated before - use mid grade gas and you will be fine. On 2 stroke
engines you have no valves to worry about. However, you do have preignition
issues to worry about. The lead helped w/ this.
When leaded fuel went away - outboard manufacturers recommended you use at
least 90 octane fuel in the older engines or change the head gaskets to a
thicker gasket to reduce compression to prevent preignition.
Some will say use the cheap stuff but no more than you burn in a boat - the
10 cents a gallon is cheap insurance in my opinion.

--
Tony
my boats at http://t.thomas.home.mchsi.com

"Jeepers" wrote in message
...
In article ,
"Stanley Barthfarkle" wrote:

If these engines are in severe duty service, owners
should consider installing hard seat inserts or using lead substitute
additives to minimize valve recession.



Mine doesn't see sever duty unless going all out across a big lake is
severe duty. I used lead additive in the tank for my first fill up (I
just bought it) due to the label. Was Iwrong in doing so? Do I not need
to add lead? I have no idea what sort of valve inserts this engine has.

--
It's no good unless it makes your eyes water.



  #15   Report Post  
Jeepers
 
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Default Leaded or Un-Leaded?

In article 0O1Jc.50496$WX.15047@attbi_s51,
"Tony Thomas" wrote:

As stated before - use mid grade gas and you will be fine. On 2 stroke
engines you have no valves to worry about. However, you do have preignition
issues to worry about. The lead helped w/ this.
When leaded fuel went away - outboard manufacturers recommended you use at
least 90 octane fuel in the older engines or change the head gaskets to a
thicker gasket to reduce compression to prevent preignition.
Some will say use the cheap stuff but no more than you burn in a boat - the
10 cents a gallon is cheap insurance in my opinion.



Cool, will do.

--
It's no good unless it makes your eyes water.


  #16   Report Post  
FRANKWBELL
 
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Default Leaded or Un-Leaded?

In article , Jeepers
writes:

I thought Leaded fuel went out in the mid 70s. Why then do I need Leaded
fuel on a 1985 motor?


I don't know if this applies, but I have a 1985 Merc in-line 6. I don't know
if this is a mechanic's urban legend of what, but here goes:

Shortly after we got the boat in 1995, one of the pistons came up pitted.
$700.00 later, the mechanic told me that the pitting was from the use of
unleaded regular (87 octane) fuel and that the motor had been designed to use
regular leaded fuel (which was still available, he said, for marine use at that
time).

He recommended using premium fuel to avoid future problems. As of the last
tune up, last year, everything was still okay.

Frank Bell
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

A. Top Posting.

Q. What's the most annoying thing on Usenet?


  #18   Report Post  
HLAviation
 
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Default Leaded or Un-Leaded?

Old Wives Tale. The only difference in an engine designed for leaded vs.
unleaded fuel is the way the bottom of the valve guide is cut. For leaded,
they cut a square shoulder into the bottom so the lead that collects on the
stem gets scraped off and rolled up into a donut to lubricate the valve. For
unleaded its cut with a taper to prevent gauling the valve. The pitting is
caused by detonation which can be controlled either by retarding the timing
a bit or using a higher octane fuel.

"FRANKWBELL" wrote in message
...
In article , Jeepers
writes:

I thought Leaded fuel went out in the mid 70s. Why then do I need Leaded
fuel on a 1985 motor?


I don't know if this applies, but I have a 1985 Merc in-line 6. I don't

know
if this is a mechanic's urban legend of what, but here goes:

Shortly after we got the boat in 1995, one of the pistons came up pitted.
$700.00 later, the mechanic told me that the pitting was from the use of
unleaded regular (87 octane) fuel and that the motor had been designed to

use
regular leaded fuel (which was still available, he said, for marine use at

that
time).

He recommended using premium fuel to avoid future problems. As of the

last
tune up, last year, everything was still okay.

Frank Bell
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

A. Top Posting.

Q. What's the most annoying thing on Usenet?




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