[DMCForum] Re: Working on DeLoreans

["content22207" <brobertson@xxxxxxxxxxxx>]

I'm in DC for the Holidays. Wanna come up to Mike Cohee's house?

DeLoreans come late in blissful age when you could actually work on
own car. Only three onboard electronic modules (Lambda, CIS, and
Ignition), and they are not integrated. Can jetison all but ignition
(if PRV distributor was set up for breaker points even that would be
optional. But trust me -- you don't want points). Rest of engine
responds solely to ITSELF. Even fuel injection is vacuum driven.

New rocket science cars are totally dependent on onboard computers.
Fuel is metered with electic signals. Ignition coil packs fire
according to computer instructions, not camshaft rotation. I've even
heard that some cars now have no direct connection between pedal and
throttle plates (or whatever now regulates air into engine). Give me a
break.

BTW: What year and model is your truck? Which engine?

Bill Robertson
#5939

>--- In DMCForum@xxxxxxxxxxxxxxx, "Farrar Hudkins" <fhudkins@xxxx> wrote:
> Bill,
> 
> When I'm in Charlotte for the holidays I need to see if some of your
> knowledge can rub off on me. Wanna work on some cars? :P
> 
> Farrar
> 
> > -----Original Message-----
> > From: content22207 [mailto:brobertson@xxxx]
> > Sent: Thursday, December 18, 2003 11:43 PM
> > To: DMCForum@xxxxxxxxxxxxxxx
> > Subject: [DMCForum] Re: Andrew's "Knocking"
> >
> >
> > Most performance engines are timed closer to TDC, not advanced. Moving
> > spark earlier in stroke lowers power. That's one reason HP killed in
> > domestic blocks throughout 1970's: 1969 Ford 460 timed 10 degrees
> > BTDC. By 1977 moved to 17 degrees. 1978 (last year 460 in automobiles)
> > timed 20 degrees BTDC.
> >
> > If you're "knocking" are two different potential problems:
> > pre-ignition and pre-detonation.
> >
> > Pre-ignition:
> > Spark ignites fuel mixture too soon
> > Sounds like constant drumming of diesel engine
> > Worst at higher RPM's, accelerating, under load, etc
> > May be unaffected by octane
> >
> > Pre-detonation:
> > Fuel mixture spontaneously combusts before spark
> > Is random, like popcorn
> > Worst when cruising
> > Usually improves with octane
> >
> > Pre-ignition can be a timing issue. Lots of higher mileage engines
> > have never been re-timed.
> >
> > Pre-detonation usually indicates something wrong inside combustion
> > chamber. Can be as simple as carbon buildup (glows red hot, and also
> > reduces chamber volume -- increases compression). I suppose a weak
> > coil could cause as well (little or no spark).
> >
> > If you're knocking on 93 octane, suspect ignition time. Even the 11:1
> > engine in one of my Lincolns can be timed to run on 93 alone (no
> > octane boost). Interestingly do so by ADVANCING time just a little
> > from factory spec.
> >
> > Is your car difficult to start cold? One thing I've noticed about over
> > advanced cars is engine has to spin much longer than normal before it
> > will catch.
> >
> > Bill Robertson
> > #5939
> >
> > >--- In DMCForum@xxxxxxxxxxxxxxx, Andrew <aos+yahoo@xxxx> wrote:
> > > > Better gas. We have no knock sensor to control this. The new
ignition
> > > > system may also help.  What are you going to do for a coil. His
> > package
> > > > didn't include one. Is it extra and how much.
> > >
> > > I've got no reason to believe I have bad gas.  I'm using 93
octane, and
> > > only buy major brand names, and not always at the same station.
> > I've got
> > > a couple of jugs of Sunoco 104 in the garage (for fun weekends
with the
> > > other car).  Maybe I should toss a few gallons in the DMC and
see if it
> > > manages to knock with that.  That is, if it can even ignite it at
> > all.  :)
> > >
> > > I'm not expecting much, if anything, from the ignition upgrade
stuff.  I
> > > know a lot of people claim it's snake oil, but since I enjoy
tinkering
> > > with things, and it's fairly easy for me to get over to DMCH to
pick up
> > > the parts, I figured I'd give it an unbiased opinion.  Hopefully
I'll
> > > finish the install tomorrow.  I ran out of light today.
> > >
> > > Right now I'm still on the stock coil, which I assume is 20 years
> > old.  I
> > > don't believe it was replaced when the performance engine was put
> > in.  I
> > > plan to leave it as it is for the time being, at least until I've
> > had the
> > > opportunity to determine what, if any, is gained by adding the
> > performance
> > > ignition package.  After that point, I may well upgrade it.
> > >
> > > Since I have the performance engine, this may well just be a case of
> > > slightly too aggressive timing, so backing it off a little may also
> > be of
> > > some help.
> > >
> > > -andrew
> >
> >
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> >
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> >



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