With the attitude of "don't fix it if it ain't broke" (re: your 235),
considering many on the road today have already been in service for 40+
years, it could be quite a while before you install that 350!
Regards,
Doug Pewterbaugh
dpewter@msn.com
Denton, TX
49 3104 216 5-Window
-----Original Message-----
From: Passnb4U@aol.com <Passnb4U@aol.com>
To: sheldon@ssmachine.com <sheldon@ssmachine.com>; oletrucks@autox.team.net
<oletrucks@autox.team.net>
Date: Thursday, June 03, 1999 9:39 AM
Subject: Re: [oletrucks] Octane inquiry/ Lead additive
>In a message dated 6/2/99 7:56:46 PM Pacific Daylight Time,
>sheldon@ssmachine.com writes:
>
><<
> Mike,
>
> I gotta go with Gene on this one. With cyl temps above 1800 Deg F there
is
>no oil to lube the valves! The lead
> coats the valve faces and seats and keeps them from sticking to each
other.
>Newer engines have hardened valves
> and seats (or stellite faced valves). Even if you grind the new style
>valves, they will not last. (the stellite coating
> is very thin). You may not have noticable compression loss on your engine
>yet, but if you are running old "soft"
> valves/seats, and unleaded fuel (any octane), you will! You may want to
>stock up on valves/seats for your head
> rebuild if you should come across some in the near future! (or just use
an
>approved additive)
>
>
> You may be right, I was just going by what I was told, no matter
though,
>when and if the valve and/or seats recede, in goes the 350/400 combo
sittting
>in my Dads shop.
> Before I got the truck together and running, I built the combo
>anticipating installing it before I put the truck on the road, but that
>damned 235 ran so well, I couldn't see fixing something that wasn't broke!
>
> Mike
>
> Passnb4U@aol.com wrote:
> >
> > In a message dated 99-06-02 10:37:44 EDT, genedavis@tritel.net writes:
> >
> > << To: oletrucks@autox.team.net
> >
> > Terry White wrote:
> > >
> > > Mike,
> > >
> > > I am not by any means trying to lead anyone to believe that I am a
> > > mechanic, but this is my experience.
> > >
> > > I bought my 56 in late 95, drove it almost everyday for 3+ years
using
> > > 92 and 93 octane fuel. I was told that sooner or later if the head
> > > did not have hardened exhaust seats I would lose compression. Guess
> > > what, I did. I have decided to put a newer model 292 because of
> > > the lack of parts availability here in Alabama. My advice would be
to
> > > use the highest octane you can buy, drive it till you get a
noticeable
> > > loss of power, then look at the possibility of a rebuild, chances are
> > > if you have the head worked now it will only put higher compression
on
> > > the worn cylinders.
> > >
> > > Just my thoughts..
> > >
> > > Terry White
> > > 56 3100
> > > Harpersville AL.
> > >
> > > >>> <Mushgilday@aol.com> 06/01 6:37 PM >>>
> > >
> > > How critical is it for these old engines
> > > to be
> > > fueled with lead additives? Is the overall performance diminished if
> > > only
> > > using an 87 octane with nothing added? I've been running my 235 for a
> > > year
> > > now and have yet to mix anything in with a fillup. Lately I have
> > > noticed a
> > > slight hint of exhaust smoke which was not the case last year. Oil is
> > > changed
> > > frequently and it's been tuned up lately. Any recommendations on the
> > > use of
> > > lead mixtures in the gas? Thanks
> > >
> > > Mike Gilday
> > > 59 Apache Fleetside 3200
> > > oletrucks is devoted to Chevy and GM trucks built between 1941 and
> > > 1959
> > >
> > > oletrucks is devoted to Chevy and GM trucks built between 1941 and
1959
> >
> >
> > My $.02 on octane/lead;
> >
> > Higher octane is needed to combat detonation. Lead is needed for
valve,
> > especially exaust valve, lubrication. Confusing because lead is also a
> > cheap octane booster. You need higher octane fuel if you have a higher
> > compression engine, (hence 100LL for aircraft,- higher compression,
high
> > prformance, low end torque, opposed piston engines.) You need leaded,
> > or comparable, fuel for top (valve) lubrication in older auto or
> > aircraft engines.
> >
> > I am no expert, but have some experience with both truck and aircraft
> > engines. It tells me that older engines, not designed to run without
> > lead, need a lead replacement. If you have a engine that is not a high
> > compression engine, and are getting some pinging,(detonation) check
your
> > timing before running higher octane fuels. Its alot cheaper to time
the
> > thing than to spend extra money on octane you don't really need.
> >
> > I did have a Fo#d w/ a stock 460 that no amount of timing work would
> > stop from pinging. Had to run at least 89 octane in it.
> >
> > Help, or just confuse everything more?
> >
> > Gene Davis
> > '58 GMC 1/2 T NAPCO
> > '63 Cessna 182 >>
> >
> > My understanding in the lead is used to cool the combustion chambers,
> > decreasing detonation. Lubrication comes from the oil, not the fuel.
> >
> > The use of hardened seats is to keep little hot spots forming from the
> > possibility when the valves close, the valves kinda nick on the seat,
>making
> > a little high knurl that creates a glowing hot spot, whick leads to
pinging
> > and seat recession in some cases.
> >
> > FWIW, my '235 run's at 3Krpm whenever it's driven (damn, I gotta get
that
> > rearend done), usually on 85-90 miles runs, each way. I have about
> > 15-16Kmiles on it (don't know how many before I ran it), no apparent
losses
> > of any kind that I can tell.
> >
> > Mike
>
> Mike is very probably right about lead and lubrication, but I can't see
> how oil can lube a exhaust valve in the upper guide with cylinder temps
> as high as they get. An aircraft IA Mechanic told me that lead does
> most of the lube work on exhaust valves in airplane engines as the oil
> in the guide turns to carbon in the upper part of the valve guide due to
> temperature. Lead also forms a barrier between the valve and the seat
> as I understand it, preventing metal to metal contact. I'm not even
> close to being an expert on this, but do know from experience, that if
> you don't run a lead subsitute in engines designed for leaded gas, you
> will be very lucky if you don't eventually have valve trouble.
>
> Gene Davis
> '58 GMC 1/2T
> NAPCO
> '63 Cessna 182
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
> >>
>oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
|