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Re: Timing Vs Over Heating--Longish!

To: Larry Macy <macy@bblmail.psycha.upenn.edu>
Subject: Re: Timing Vs Over Heating--Longish!
Date: Tue, 25 Jul 2000 20:10:03 -0400
Cc: spridgets <spridgets@autox.team.net> charset=ISO-8859-1
OK All,

I couldn't find my 40 plus year old notes taken from my Allen Tune Up
course I took, (thought I saved everything!) so I went snooping on the
internet.

Found a pretty good explanation at several sites, so recapped it to below.

Retarded timing will result in more heat transfer to the block as a result
of the piston being closer to the bottom of the stroke instead of at a more
advantageous angle where the can transmit maximum power to the crankshaft
at the moment of maximum piston power.  It will also allow more burning
fuel out the exhaust chambers and into the manifold.  The manifold can act
as a heat sink, but when it turns cherry red it will be radiating heat to
the underhood area.

There are additional reasons, but these are the crux of them to explain
higher heat transfer to the cooling system while running retarded.

FWIW, Paul A


FROM:   Larry Macy, INTERNET:macy at bblmail.psycha.upenn.edu

Re:     Re: Timing Vs Over Heating--Longish!

 
Very good discussion about timing curves and dizzys (It made me dizzy to 
read it) But unless 
I missed something, you didn't explain the heating issue.

Your turn is over - NEXT!!

Thanks for participating

Larry

At this exact moment in time 7/25/00 15:01, PAsgeirsson@compuserve.com 
made the profound statement:

>Hi All,
>
>Not wnting to get in a real pissing match here, but I would like to drop
in
>a few items.
>
>The majority of the performance Spridgets are running 1275's. The dizzys
on
>these engines that were sold in the states had less centrifugal advance
>than did the 1098 dizzy or the 948 dizzy.  This was done to be able to
>reduce the emissions on the 1275.  Most of these dizzys had a vacuum
>advance unit on them, the exception was the 23D4 which didn't have one.
>
>Now the centrifugal advance unit varied from 12 to 16 degrees and also
>varied by what RPM they kicked in and advanced.  The vacuum advance units
>that were supplied or were initially available varied from as low as 4 to
a
>high of 8 degrees advance.  I think the only one still available in the
>parts store is a 4 degree one.
>
>With a generally recognized maximum advance on the timing to prevent
>destruction of the engine being about 30 degrees, it's pretty easy to
>figure out where you should have an initial dynamic timing set.
>
>An example would be something like this.  
>        Total vacuum advance=   6       
>        Maximum centrifugal adv=        16
>        Dynamic timing set              8 BTDC
>                                ________
>        Total advance degrees   30
>
>This would likely keep you out of trouble for early destruction of your
>engine.  The reality of this example is it is based on a 948 dizzy.  If
you
>had a 1275 dizzy it would be more like this.
>
>        Total v adv             2               
>        Max cent adv            12
>        Dynamic timing set              8 BTDC
>                                ________
>        Total advance degrees   22
>
>This would hardly get you into a decent performance bracket so advancing
>the dynamic timing another 8 degrees would still keep you in the total
>degree range of 30.  However, it would alter the performance
>characteristics of the engine, flatter at lower RPM or vice versa, or
>flatter at higher RPM or vice versa, depending on your carburation, cam
>design and CR.
>
>Remember that you might not ever get to the advance feature of the vacuum
>unit if you are driving with your foot stuck to the floorboards and the
>vacuum will never be high enough to advance the timing.
>
>Putting a dizzy on a dizzy machine and getting the right response curve
>built into it is usually money well spent.  Another cheaper option is to
>use an earlier dizzy, one from a 948 or 1098 to get greter advance over a
>longer range of RPMs.  Another way is to keep playing with your dynamic
>spark setting and leave it where it works the best.  If you have
electronic
>ignition, then you would never have to fuss with that again
>
>The 23D4 dizzy usually calls for a dynamic spark setting of 22 BTDC.  I
>don't know the advance on this dizzy, but it is likely about 14 degrees.
>
>With all the variables that we put into our engines in head improvement,
>exhaust extraction or nor, carburation and ram pipes, compression ratio
and
>cam design, it's entirely possible that all the responses to this initial
>thread are in the correct category, or close enough to be right.  A huge
>variable could possibly be whether or not Zappa is on the stereo or you
>have a cat stuck in the undercarriage!
>
>There may be a few minor technical errors here, but I think you can get
the
>picture fairly well with the above illustrations, and I also don't have a
>spell checker on this e mail program, so don't send over the spell cops!
>
>FWIW, Paul A
>
>
>FROM:   Bryan Vandiver, INTERNET:Bryan.Vandiver@Eng.Sun.COM
>TO:     Larry Macy, INTERNET:macy@bblmail.psycha.upenn.edu
>        spridgets, INTERNET:spridgets@autox.team.net
>        Larry Miller, INTERNET:millerls@ado13.com
>DATE:   7/25/00 1:32 PM
>
>Re:     Re: Timing Vs Over Heating
>
> 
>FWIW - I just changed the timing om my 1275, from 8 degrees BTDC, to 16
>degrees 
>BTDC, about a week ago. The car is now running hotter.
>
>I also noticed that the more retarded the timing is, the power band shifts
>to 
>higher RPM, and the more advanced it is, the power band moves to lower
RPM,
>and 
>becomes flatter. Any thoughts on this??
>
> - Bryan
> 
>>Subject: Re: Timing Vs Over Heating
>>To: "Larry Miller" <millerls@ado13.com>, "Spridgets@Autox. Team. Net
>(E-mail)" 
><spridgets@autox.team.net>
>>Mime-Version: 1.0
>>
>>Well for what its worth, I always heard it was too retarded makes it run 
>>cool, something like not burning all the gas and leaving liquid fuel in 
>>the cylinder. (That is likely as far off the wall as it is off the top of

>>my head) 
>>
>>Too advanced makes it run hot, the engine is working too hard and 
>>compression is not finished before the spark front hits the A-F mix. the 
>>engie then has to compress the exploding gases. 
>>
>>At least that is the way I answered it when I applied for the "Who Wants 
>>To Be a Millionaire" show. 
>>
>>Larry
>>
>>At this exact moment in time 7/25/00 12:46, millerls@ado13.com made the 
>>profound statement:
>>
>>>>From: "Toby Atwater" <Toby@intri-plex.com>
>>>> I always heard kind of the opposite. Spark too advanced (early) will
of
>>>> course ping. Spark too retarded (late) will result in a loss of power
>and
>>>> overheating. It kind of makes sense. There is the same amount of
>gasoline
>>>in
>>>> the charge but less power is developed, the wasted energy goes into
>heat
>>>> instead of usable pushing power. That is how it was explained to me...
>>>>
>>>> Good luck
>>>
>>>Toby
>>>I don't have an over heating problem I just wanted to hear some thoughts
>on
>>>timing Vs over heating.
>>>
>>>Thanks,
>>>Larry
>>
>>
>>Larry B. Macy, Ph.D.
>>macy@bblmail.psycha.upenn.edu
>>System Administrator/Manager
>>Neuropsychiatry Section
>>Department of Psychiatry
>>University of Pennsylvania
>>3400 Spruce St. - 1015 Gates
>>Philadelphia, PA 19104
>>
>> Ask a question and you're a fool for three minutes; do not ask a 
>>question and you're a fool for the rest of your life. 
>>
>>
>
>
>
>
>
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>From: Bryan Vandiver <Bryan.Vandiver@Eng.Sun.COM>
>Subject: Re: Timing Vs Over Heating
>To: millerls@ado13.com, spridgets@autox.team.net,
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Larry B. Macy, Ph.D.
macy@bblmail.psycha.upenn.edu
System Administrator/Manager
Neuropsychiatry Section
Department of Psychiatry
University of Pennsylvania
3400 Spruce St. - 1015 Gates
Philadelphia, PA 19104

 Ask a question and you're a fool for three minutes; do not ask a 
question and you're a fool for the rest of your life. 






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Subject: Re: Timing Vs Over Heating--Longish!
Date: Tue, 25 Jul 2000 15:36:44 -0400
x-mailer: Claris Emailer 2.0v3, January 22, 1998
From Larry Macy <macy at bblmail.psycha.upenn.edu>
To: "Paul A. Asgeirsson" <PAsgeirsson@compuserve.com>,
        "Spridgets" <spridgets@autox.team.net>

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