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Re: Back to the Future/ "Cold air" and "Timing" - Judson applications! 2

To: bugeye15@hotmail.com (brian S)
Subject: Re: Back to the Future/ "Cold air" and "Timing" - Judson applications! 2001 18:04:26 -0400
Date: Fri, 26 Oct 2001 09:03:48 -0400 (EDT)
Cc: spridgets@autox.team.net
Right on "both" counts, Brian S.

Too much advance causes "overheating"
due to pre-ignition/detonation.

Too much retard causes "overheating" due
to combustion "heat" going out the exhaust system (raisiing under-bonnet
temps. rather unbelievably).

"Correct" timing has peak cylinder pressures occurring at about 12-13
degrees ATDC for maximum torque
to crank, with minimum combustion temp.

It can be seen why "dialing in" any
specific application on a dyno is such
a good investment!

F'rinstance, on Mike's Judson blown
8.3-1 948 motor, the Sprite owner's
manual lists 5 degrees BTDC as the
"correct" static setting for 96RON gas.

Yet, the official maintenance manual
lists 1 degree BTDC as the correct setting
for this motor and 4 degrees BTDC for
the high compression (9.0-1?) unit (I
am still trying to figure this one out as
usually it would be the other way 'round;
this might be a "backward" misprint and
I would welcome an explanation on this
from other lister's more knowedgeable
than I in these respects for usually, the
high compression motor would take "less"
timing than a lower compression version
of the same motor).

To confuse even further, the original Judson literature mentions the
"stock"
manufacturer's ignition setting of 5
degrees BTDC (though a colder plug
is recommended, I believe) for their
application, utilizing the highest octane
fuel of that era, which would be 100+
RON back in those days. (I know, I was
"there"!). By the way, "blown" head gaskets and/or overheating were not
unknown in these applications, even
with cars "tested" by pro's for the various
magazines of that era. In other words,
even when not mistreated, these applications had their problems.

Now, 4 degrees is a "bunch", most especially when "boost" comes
into play and I did mention the foregoing
to Mike but, by that time, he had more or
less removed the blower. 

As it is in life, "timing is everything" and
so it is with engines, as well. Too much
timing can "dry out" the "wettest" mixture
and this is especially true at the higher
combustion temps. generated by raising
the "dynamic" compression ratio throughout the entire "boosted" curve
of any cam grind, wherein unlike normally
aspirated "tuned" applications, you are getting 100% cylinder filling
(peak torque),

It is interesting to note that original Judson users who were "engine-
knowledgeable" types to begin with,
either backed off 3 degrees or so from
Judson's recommended "stock" static
ignition setting or limited their mechanical 
advance to no more than the "race" recommended (normally aspirated)26-28
degrees, were they proximate to
a distributor machine along with going to the colder N3 plugs, using
102+RON
Sunoco '260" Super-Premium.

I did not make the investment in a new
Aldon distributor "programmed" for my
specific Judson application utilizing 93PON for the heck of it, I assure
you!
I've done my homework after a little
Judson experimenting on my old '67
stock 1275! Having a basically correct
advance curve to begin with is definitely
the way to go, especially on today's readily available octanes. Yes,
I've got
racing fuels available, but at today's gasoline prices! I can always add
it if
I want it but, I should not "need" it.

Your point on a cold air intake is absolutely spot on. The addition of
an oil cooler for highway cruise is
bascially essential, also. The Bugeye
cooling system was marginal to begin
with when driven in hot weather conditions, most especailly in any
traffic
at low forward speed. "Compression", let
alone "boost" heating, quickly overtaxes
the system under the aforementioned circumstances.

We have a fellow who is developing a water injection system for his
Judson blown Frogeye application. Fellow is
a bit of a brain and is a computer software
engineer; he should have his little "black
box" perfected by next Spring, I would imagine. This lowers blower case
temps.
(160F, running in hot weather conditions)
by about 30F and cools intake and compression temps. accordingly. THIS,
I am really looking forward to as it will
definitely increase the margin to overheating/pre-ignition/detonation
and
allow a choice of more timing or less octane.

Kennedy will be my new domicile as of
November 1st, so should be "boring" you
with transmission no less than 3-4 days
a week or so in coming year; you'll most
likely ask for a transfer!! :)

I believe I have seen the Corvette "green"
color you are referring to in another recent
post but do not know the name of the color. It does change shades in
different
light, for sure.

Recent posts indicate Chuck is going racing this weekend; hard to keep a
good
man down!

Otherwse, how is Chuck making out on your Frog's restoration?

Regards!
Bob S.



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