Caspro EKE + More!

[al chernoff]

Cant answer question about timing, ut am curious why you are getting rid of 3.42
final drive. I just installed oned since I was having trouble with the 3.5
caspro, or at least I lost two transmissions when I had it in.... I seem to be
doing great with the 3.42 so i just thought I would ask.
al

> Okay, let me get this straight. I have paid close attention to the stories
> regarding setting timing and I have a general question: Does timing require
> retarding when travelling from high altitude to low? And thusly, does timing
> require advancing when travelling from low altitude to high? I realize that
> lots of factors come into play, but I am just wanting to get smarter. Will
> the Caspro EKE work with the Jacobs Ignition which I have, or does it even
> know?
>
> Now, in my effort to get another mile per gallon out of my rig, I have these
> thoughts. Does the vacuum that runs the cruise control exact some engine
> efficiency? How about this, magnetic clutch (ala a/c) for power steering
> pump? On the interstate, you don't need it, so you turn it off. In town, you
> do need it so you turn it on. I have been lurking on the bus conversion
> boards and have gleened some interesting "takes" and a lot of envy at getting
> 9 mpg with a 35,000# bus (usually std. tranny). Regarding mileage claims, I
> will tell you all about my (late) Uncle Bud someday. He was a great mechanic
> and driver, cause whatever he drove, he got 5 mpg more mileage than you (or
> anyone else within earshot) got. We used to whisper that one day we could
> just soak up the gas that his vehicles must surely be generating internally
> and must surely be overflowing out the fill tube.
>
> Now that I have told you all about Uncle Bud, I am conjuring up a plan for me
> to get a new CAspro 3.07 or possibly 3.21 (haven't made up my mind), and then
> offer someone my 2,000 mile 3.42 at a reduced price, using their old final
> drive as my core. More to come. Thanks for the help. Larry in MO, PB75

 

[richard guthart]

Larry-

At altitude, it takes a little longer for the flame to spread throughout the
air/fuel mixture because the air is less dense. Consequently you have to
trigger the spark a few degrees earlier in order to create peak pressure in
the combustion chamber at the optimal time. Spec. plus 2-3 degrees is what I
run on my vehicles at 5000-6000 ft above sea level. It makes a difference of
several % in fuel economy (and, presumably, horsepower.)

Richard ('77 Birchaven)
rguthart

Okay, let me get this straight. I have paid close attention to the stories
regarding setting timing and I have a general question: Does timing require
retarding when travelling from high altitude to low? And thusly, does timing
require advancing when travelling from low altitude to high?.....

Larry in MO, PB75

 

[richard waters]

In our airplane we control the mixture (fuel to air) as we climb to higher
altitudes. As far as I know, nothing changes with ignition timing. As we fly
higher we make the mixture leaner. Mixture makes a huge difference in
performance and fuel economy in reciprocating engine equipped airplanes. Even
though our airplane is turbocharged we still need to lean as we climb, but not
as much as you would in a normally aspirated engine. That's because we can
maintain manifold pressure with the turbo as we climb.

Consequently, it's hard for me to understand that timing alone is enough in the
GMC to compensate for high altitude driving. Do owners of GMC's that are based
up above 5,000' or so just adjust timing to compensate for altitude?
Richard Waters
'76 PB, Troy, MI

> Larry-
>
> At altitude, it takes a little longer for the flame to spread throughout the
> air/fuel mixture because the air is less dense. Consequently you have to
> trigger the spark a few degrees earlier in order to create peak pressure in
> the combustion chamber at the optimal time. Spec. plus 2-3 degrees is what I
> run on my vehicles at 5000-6000 ft above sea level. It makes a difference of
> several % in fuel economy (and, presumably, horsepower.)
>
> Richard ('77 Birchaven)
> rguthart
>
> Okay, let me get this straight. I have paid close attention to the stories
> regarding setting timing and I have a general question: Does timing require
> retarding when travelling from high altitude to low? And thusly, does timing
> require advancing when travelling from low altitude to high?.....
>
> Larry in MO, PB75

 

[bob mclaughlin]

Richard,
There is no vacuum advance on your aircraft either. Since you can't get as
much vacuum at altitude, the timing advance needed per Emery and others at
altitude makes up for the lack of full vacuum advance.
Bob McLaughlin

- -----Original Message-----
From: owner-gmcmotorhome
[mailtowner-gmcmotorhome]On Behalf Of Richard Waters
Sent: Tuesday, April 04, 2000 11:50 AM
To: gmcmotorhome
Subject: Re: GMC: Caspro EKE + More!

In our airplane we control the mixture (fuel to air) as we climb to higher
altitudes. As far as I know, nothing changes with ignition timing. As we
fly
higher we make the mixture leaner. Mixture makes a huge difference in
performance and fuel economy in reciprocating engine equipped airplanes.
Even
though our airplane is turbocharged we still need to lean as we climb, but
not
as much as you would in a normally aspirated engine. That's because we can
maintain manifold pressure with the turbo as we climb.

Consequently, it's hard for me to understand that timing alone is enough in
the
GMC to compensate for high altitude driving. Do owners of GMC's that are
based
up above 5,000' or so just adjust timing to compensate for altitude?
Richard Waters
'76 PB, Troy, MI

> Larry-
>
> At altitude, it takes a little longer for the flame to spread throughout
the
> air/fuel mixture because the air is less dense. Consequently you have to
> trigger the spark a few degrees earlier in order to create peak pressure
in
> the combustion chamber at the optimal time. Spec. plus 2-3 degrees is what
I
> run on my vehicles at 5000-6000 ft above sea level. It makes a difference
of
> several % in fuel economy (and, presumably, horsepower.)
>
> Richard ('77 Birchaven)
> rguthart
>
> Okay, let me get this straight. I have paid close attention to the stories
> regarding setting timing and I have a general question: Does timing
require
> retarding when travelling from high altitude to low? And thusly, does
timing
> require advancing when travelling from low altitude to high?.....
>
> Larry in MO, PB75

 

[richard guthart]

Richard,

> ... it's hard for me to understand that timing alone is
> enough in the
> GMC to compensate for high altitude driving. Do owners of GMC's
> that are based
> up above 5,000' or so just adjust timing to compensate for altitude?

Nope, we have to get the fuel mixture right, too.

If your coach is running the ideal air/fuel mixture at low elevation it will
run rich at altitude. The easiest way to "get by" for a brief trip at
altitude is to advance the timing a couple of degrees and (if you're fowling
spark plugs, etc) lean out the mixture a little with the adjustment screws.
Just remember to put both timing and mixture back upon returning to lower
elevation.

Emery's setup is really ideal for changing elevations.

Richard ('77 Birchaven)
rguthart

> Richard Waters
> '76 PB, Troy, MI
>

>
> > Larry-
> >
> > At altitude, it takes a little longer for the flame to spread
> throughout the
> > air/fuel mixture because the air is less dense. Consequently you have to
> > trigger the spark a few degrees earlier in order to create peak
> pressure in
> > the combustion chamber at the optimal time. Spec. plus 2-3
> degrees is what I
> > run on my vehicles at 5000-6000 ft above sea level. It makes a
> difference of
> > several % in fuel economy (and, presumably, horsepower.)
> >
> > Richard ('77 Birchaven)
> > rguthart

 

[al chernoff]

You asked about why I got rid of the 3.5: here tis the tale of woe....

I am not an expert, so here goes. when I bough my coath, I had a lemon -- 208
miles out of town the engine went (later to learn it was #7 which didn't get
enough oil)... got towed back to Abluquerque. osburn sent engine to Statkus to
rebuild ( statkus did a great job so far as i am doing great on the engine.)
When he had everything out he checked the trans and said it needed to be redone
as it was orig and looked like it would fail soon. When he sent out the trans,
he also had a 3.5 set of gears sent out. I left on a trip to Calif, happy as a
clam. Got connected with Gene and we were cruising up the tahachapi (sic)..
half way up the hill, I inquired to gene if he had shifted down. "no" came the
answer. funny I said to the cb, I did. Things chugged along with me in pain
and gene nursing me along. Gene was a real gentleman - as he only laughed at me
when he did not key the cb. got to his house, and tried it out... wouldn't
shift out of first. Called the guy who rebuilt it and he said "modulator"
don't worry, real simple... went to a transmission shop in dublin, and they said
no to modulator, yes to no good tranmsission. They rebuilt transmission and I
went on my way, happy, I thought. They did a great job putting in all sort of
heavy duty stuff, but went through 3 torque converters until they were
satisfied. When we left, it really felt like it had more power. Went to see my
son in Denver, only 440 miles from albuq. Nice trip - until - seems transmission
would wind up real high ( like torque converter ) not working. Time for another
tranmission. Darrell Winterfeld did that one and told me not to use the 3.5...
his argument. Anything you do should be done after the transmission as you put
undue pressure on components, ie, torque converter etc. Well, thought I would
ask Osburn for his opinion. he said "never had a problem with 3.5 gears," so I
called bob lamy. He said, stick to final drive, and forget the 3.5... so there
you have it. Changed the transmission to standard 425 with heavy duty torque
converter, per winterfeld, and other heavy duty stuff I don't understand.
ordered 3.42 final and winterfeld put that in. Took last two trips and - cross
my fingers, toes, and anything else that will cross - it is running great. So,
I have no plan, but I'm sticking to it. don't ask me any hard questions because
I will not know how to answer...tough ones get refered to gene, so there

al

> In a message dated 4/4/00 12:02:06 AM Central Daylight Time, mr.c

>
> of 3.42
> final drive. I just installed oned since I was having trouble with the 3.5
> caspro, or at least I lost two transmissions when I had it in.... I seem to
> be
> doing great with the 3.42 so i just thought I would ask.
> al >>
>
> Al, in an effort to get some power "out of the hole" , like being able to
> back up my driveway which isn't very steep, I bought and had installed a
> 3.42. This seemed (in my optimistic mind) to give me more power. It was not
> quite what it seemed. Shortly after having the 3.42 installed, we took the
> old girl on a trip through the Black Hills and, at the Crazy Horse monument,
> and having stopped for traffic up ahead, I was stuck on a steep road, unable
> to move except where gravity would let me move. So I unhooked the Sammy, had
> the wife move it to a side road, and I waited until I could see behind me
> clear of traffic so I could back down this hill and up the preceeding hill.
> Then I got a good run at it and made it to the top and into the C Horse
> parking lot. At that moment I knew that it was the torque converter all
> along. When we got home I ordered a Danny Dunn tranny which has the 3.50
> sprockets in it, but which he would have left off at my direction. I saw some
> discussion in GMCMM about combining the 3.42 and the 3.50 and also called a
> Flatlander who swore by his. It is just too low for me, although I swear I
> could pull a small house, on skids, up Pikes Peak from a standing start. I am
> travelling at 2950 at 58 mph, best mileage since it all was put in = 7.76.
> I am not sure what I am going to do (with the 3.42). I am going to fiddle
> with the timing and see if I can't squeeze 1 more mpg out of her. If I can, I
> will leave her alone. I am interested in your "trouble" with the 3.50 Caspro.
> Larry in MO, PB75