High altitude fun

R

ronald b. kazi

New member
Aug 6, 1999
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I am planning our August three week trip to Colorado.
How will my 455 with HEI and Holley carb fair on the trip?
How will she do when we are at 11,000' or so in Rocky Mountain National
Park?
Any suggestions on campgrounds in Colorado would be much appreciated.

Ron and Julie
73 Painted Desert
 
Do I have to rejet or are there some external adjustments I can make on the fly?
I also noticed in a posting nearby, that someone advances their timing at
altitude. Will that help?

Of course, I have not had the beast running for four months, so maybe I should
take care of that first. Plan to start her up this weekend.

Ron and Julie
73 Painted Desert

>
> How will my 455 with HEI and Holley carb fair on the trip?
> How will she do when we are at 11,000' or so in Rocky Mountain National
> Park?
> Any suggestions on campgrounds in Colorado would be much appreciated.
>
> Ron and Julie >>
>
> You should be fine although you'll definitely notice the reduced power at
> that altitude and also that your carb will run rich due to the lower oxygen
> content. You might also notice some smoke coming from the tailpipe. When I
> moved from Tiburon, CA (San Francisco) in 1993 to Santa Fe (7000 ft.
> Elevation) I had very little power, especially when towing a car, so I put in
> the Holley TBI system.
>
> Years ago I had a 1969 27' Travco with a 318 Dodge truck engine. It ran fine
> in Michigan but once on a trip to the Rocky Mountain Nat. Park it would
> barely go up the mountains that lead to the park. It made it though albeit
> slowly. I later added dual exhaust and headers to that motorhome and really
> improved its performance.
>
> You are also going to find that you'll have to change the carb settings and
> probably the governor settings on the Onan when you get there or it won't
> function well at that altitude.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
 
> I am planning our August three week trip to Colorado.
> How will my 455 with HEI and Holley carb fair on the trip?
> How will she do when we are at 11,000' or so in Rocky Mountain
> National Park?

> Ron and Julie
> 73 Painted Desert

The coach will probably do better than two folks accustomed to what? 700
ft elevation?

Be careful ...3 weeks at 11000 feet can cause problems.>

David Lee Greenberg
GMC Motorhome Registry
Dedicated To The Preservation Of The GMC Classic!
www.gmcss.com/registry.htm
 
Moving slow with black smoke coming out of the tail....But what will happen
to the GMC?

> > I am planning our August three week trip to Colorado.
> > How will my 455 with HEI and Holley carb fair on the trip?
> > How will she do when we are at 11,000' or so in Rocky Mountain
> > National Park?
>
> > Ron and Julie
> > 73 Painted Desert
>
> The coach will probably do better than two folks accustomed to what? 700
> ft elevation?
>
> Be careful ...3 weeks at 11000 feet can cause problems.>
>
> David Lee Greenberg
> GMC Motorhome Registry
> Dedicated To The Preservation Of The GMC Classic!
> www.gmcss.com/registry.htm
 
>
> I am planning our August three week trip to Colorado.
> How will my 455 with HEI and Holley carb fair on the trip?
> How will she do when we are at 11,000' or so in Rocky Mountain National
> Park?
> Any suggestions on campgrounds in Colorado would be much appreciated.
>
Ron and Julie:

Glad to hear that you will be visiting our state in August.

It is my experience that both the engine and breaks are weak at ~11,000'
elevation.
Follow all the Truck speed limit and warning signs until you get a feel for
how your GMC is working. We at a higher altitude set our timing a couple of
degrees advanced. I plan to run air ducts to my front discs for mountain
driving (breaking).

Check out the following web sites:

http://estes.on-line.com/rmnp/

http://www:us-national-parks.net

http://www:explore-rocky.com

http://www:rmnp.com

Dave is talking about altitude sickness. It is caused by changing
(increasing) altitude to fast, ie from sea level to 10,000 feet. It is
brought on in some people by this altitude change, physical exertion. The
first symptoms are head ache, dizziness, weakness, upset stomach, etc.
If you are concerned about this, stay a day or so at increasing altitudes.
Grand Lake area would be nice place to stay a day or so, if you are planning
to camp at altitude in RMNP.

If you are looking for specific information, let us know.

Let us know what your itinerary is, maybe we could trade some lies.

Richard & Sharon at the Castle in Colorado\
76 Glenbrook - could be on the "test" road this weekend
 
That make sense. I like the idea of the automatic ping sensor gizmo. The only
thing that scares me about the manual method is the part where "my wife drives".
This, in my case, is not an option! She has hit more curbs than a New York city
dog!

Ron

>
> the fly?
> I also noticed in a posting nearby, that someone advances their timing at
> altitude. Will that help? >>
>
> I wouldn't go to all the trouble of rejetting just for an occasional trip
> because you'd just have to change back after getting back to a lower
> elevation.
>
> It is quite easy to advance the timing a few degrees and then back it down
> when at lower elevations. Prior to getting my Caspro Knock Eliminator, if I
> started to get pinging while on a trip, I would loosen the bolt holding the
> distributor just enough so that I could grab the vacuum advance can and use
> it to turn the distributor. I would have my wife drive and I'd turn the
> distributor counterclockwise (retard) until the pinging just stopped. Since
> I couldn't hear the pinging well we ended up with my wife doing the turning
> under the engine cover while I drove. You want to keep the advance as great
> as possible just so you don't have pinging, so when you get to a lower
> elevation, advance the distributor until it pings and back off slightly.
> This works best when going uphill to put a load on the engine.
>
> Both Al Chernoff and I experienced the fact that we had to retard our timing
> when at lower elevations. Must be due to the greater oxygen content of a
> given volume of air when at a lower elevation. When set up for 5000 and 7000
> feet, we found pinging when at a lower elevation. When you move from a lower
> elevation to mountain elevations you probably won't notice any pinging but
> will feel the reduced power. Advancing the timing will give you some of that
> power back.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
 
I am all too familiar with altitude sickness. I went from New York to 12,000 ft
in New Mexico (Philmont Scout Ranch) in 48 hours. Sick as a dog. I plan to
spend a couple of days at 6000 or so and work my way up from there.

We will be heading out about the 7th of August. Plan to camp Rocky Mountain
National Park with my college buddy that weekend and spend a couple of days
there after they leave. I have a buddy in Littleton and then we are headed to
Colorado Springs and Pikes Peak (we will take the cog railroad and spare the old
girl). I think a day at Mesa Verde and then up to Dinosaur area. All the above
is tentative after the Rocky Mountain Park. If we get bored with Colorado, we
might be headed to Zion. Not sure. Have never done any National Parks...sorry,
I have done Acadia and Wilton, Connecticut's very own National Park, the only
one in
Connecticut, Weir Farm. (only a couple of years old. No camping there, however.

Ron

> >
> > I am planning our August three week trip to Colorado.
> > How will my 455 with HEI and Holley carb fair on the trip?
> > How will she do when we are at 11,000' or so in Rocky Mountain National
> > Park?
> > Any suggestions on campgrounds in Colorado would be much appreciated.
> >
> Ron and Julie:
>
> Glad to hear that you will be visiting our state in August.
>
> It is my experience that both the engine and breaks are weak at ~11,000'
> elevation.
> Follow all the Truck speed limit and warning signs until you get a feel for
> how your GMC is working. We at a higher altitude set our timing a couple of
> degrees advanced. I plan to run air ducts to my front discs for mountain
> driving (breaking).
>
> Check out the following web sites:
>
> http://estes.on-line.com/rmnp/
>
> http://www:us-national-parks.net
>
> http://www:explore-rocky.com
>
> http://www:rmnp.com
>
> Dave is talking about altitude sickness. It is caused by changing
> (increasing) altitude to fast, ie from sea level to 10,000 feet. It is
> brought on in some people by this altitude change, physical exertion. The
> first symptoms are head ache, dizziness, weakness, upset stomach, etc.
> If you are concerned about this, stay a day or so at increasing altitudes.
> Grand Lake area would be nice place to stay a day or so, if you are planning
> to camp at altitude in RMNP.
>
> If you are looking for specific information, let us know.
>
> Let us know what your itinerary is, maybe we could trade some lies.
>
> Richard & Sharon at the Castle in Colorado\
> 76 Glenbrook - could be on the "test" road this weekend
 
Thanks Emery. Where do the air ducts come from? The wheel well or the A/C
unit...now that is an idea....
RON

>
>
> how your GMC is working. We at a higher altitude set our timing a couple of
>
> degrees advanced. I plan to run air ducts to my front discs for mountain
>
> driving (breaking). >>
>
> Ron -- Having my home base at 7000 feet, I've found that my engine will ping
> as I get closer to sea level and the timing must be retarded about 2 deg..
> Al Chernoff (about 5000 ft) found the same thing when he went to see Gene
> Fisher in Feb.
>
> Another suggestion, be sure to shift to S (GM called it Super rather than
> Second) when you are climbing a grade and your speed drops to below about 45.
> This will keep your rpm up and keep you closer to the peak power/torque
> curve. When you manually shift the transmission to S, it locks up one more
> clutch and one more band than the transmission does when it shifts itself to
> S. Also, when going downhill shift to S or L when at the top of the grade.
> It'll help keep your speed down so you don't have to use your brakes as much.
> It is not a problem to coast downhill in S. I have found that it will
> usually hold on most grades below 70 mph and it will not harm the
> transmission.
>
> Hope you have a great trip. Glad to hear its in August because they have
> early summer snow there at times.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
 
It can be done by yourself. When I was traveling to Calif (by myself), when I
heard the pinging, I would back off, then get to a rest stop. Increase the
settings on the EKsesnor. After a few tries, it did not need any more adjustment.
That's the way you do it if your wife does not drive or you are by yourself.
al

> That make sense. I like the idea of the automatic ping sensor gizmo. The only
> thing that scares me about the manual method is the part where "my wife drives".
> This, in my case, is not an option! She has hit more curbs than a New York city
> dog!
>
> Ron
>
 
I went to the top of Baldy Mountain (12,444) the second day we were there. I
was sick as a dog on the way up. Our itinerary got all messed up because our
scoutmaster's mother died. We combined crews and had to make it work. Thus the
first day we got bussed part of the way up Baldy, the second we summited. The
third day (at 10,000 or so) I was fine.

RON

>
> 12,000 ft
> in New Mexico (Philmont Scout Ranch) in 48 hours. Sick as a dog. I plan to
> spend a couple of days at 6000 or so and work my way up from there. >>
>
> Ron - it probably seemed like 12,000 feet to you but Philmont ranges from
> 6500 feet to 12441 feet. The highest elevation is only at the top of the
> tallest mountain with much of the Ranch below 7000 feet.
>
> If you were bothered by Philmont's elevation, you'll probably be bothered
> even more by Rocky Mountain Park. It has many peaks over 13,000 feet tall
> and I believe the average elevation is quite a bit in excess of Philmonts.
>
> My advice would be to drink plenty of liquids (water) and always carry water
> with you on hikes. It is very easily to get dehydrated at high elevations
> because the water in your body evaporates off more easily due to the lower
> air pressure. Some of what people experience and call altitude sickness is
> actually dehydration which can be very serious. You might also want to
> acclimate yourself somewhere like Denver for a couple of days where the
> elevation is about 5000 feet.
>
> Emery Stora
> Living at 7300 feet for the last 7 years
> Santa Fe, NM 87501
 
Previous message:

Date: Fri, 31 Mar 2000 16:57:20 -0500
From: Ronald Kazi
Subject: GMC: High altitude fun

I am planning our August three week trip to Colorado.
How will my 455 with HEI and Holley carb fair on the trip?
How will she do when we are at 11,000' or so in Rocky Mountain National
Park?
Any suggestions on campgrounds in Colorado would be much appreciated.

Ron and Julie
73 Painted Desert

Ron: IMNSHO, if you can work it into your plan, be sure to include the 70
mile drive north on 550 from Durango (where you can spend a day taking the
Durango - Silverton narrow gage railway) to Ouray. There are 3 passes above
10,500 ft., but if our stock 455 w/ 3.07 tuned at sea level makes it, you
should not have trouble. If you don't take the train ride, be sure to check
out Silverton. It's about 2/3 of the way to Ouray. There's a couple decent
RV parks in Ouray, and from there you can either continue north to I70, or
turn east @ Montrose and head for Colorado Springs / Pikes Peak.

Hard to go wrong in Colorado (West of I25, anyway). Remember, the GMC was
designed as a sight seeing couch, not a camper. Enjoy the travels, not just
the campgrounds.

HTH,

Dave (& Dege), '76 Royale, Santa Barbara, CA ("digesters")
 
- ----- Original Message -----
From:
To:
Sent: Sunday, April 02, 2000 8:24 PM
Subject: Re: GMC: High altitude fun

> Chocolate is one of the basic food groups together with beer, peanut
butter,
> ice cream and potato chips! Can we get a group buy?
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
>

I don't know about a group buy but one time in Montrose we came back with
25# of chocolate for about $35.00. (daughter used to live there)
Marlene Meineken
 
And If you go to Montrose which is a nice town there is a Russell Stovers
Chocolate Factory where you can get seconds for a really low price. It's on
the main Hwy coming into town from the South.
Marlene Meineken

- ----- Original Message -----
From: Dave Lowry
To:
Sent: Sunday, April 02, 2000 4:47 PM
Subject: GMC: High altitude fun

> Previous message:
>
> Date: Fri, 31 Mar 2000 16:57:20 -0500
> From: Ronald Kazi
> Subject: GMC: High altitude fun
>
> I am planning our August three week trip to Colorado.
> How will my 455 with HEI and Holley carb fair on the trip?
> How will she do when we are at 11,000' or so in Rocky Mountain National
> Park?
> Any suggestions on campgrounds in Colorado would be much appreciated.
>
> Ron and Julie
> 73 Painted Desert
>
> Ron: IMNSHO, if you can work it into your plan, be sure to include the 70
> mile drive north on 550 from Durango (where you can spend a day taking the
> Durango - Silverton narrow gage railway) to Ouray. There are 3 passes
above
> 10,500 ft., but if our stock 455 w/ 3.07 tuned at sea level makes it, you
> should not have trouble. If you don't take the train ride, be sure to
check
> out Silverton. It's about 2/3 of the way to Ouray. There's a couple decent
> RV parks in Ouray, and from there you can either continue north to I70, or
> turn east @ Montrose and head for Colorado Springs / Pikes Peak.
>
> Hard to go wrong in Colorado (West of I25, anyway). Remember, the GMC was
> designed as a sight seeing couch, not a camper. Enjoy the travels, not
just
> the campgrounds.
>
> HTH,
>
>
> Dave (& Dege), '76 Royale, Santa Barbara, CA ("digesters")
>
>
>
 
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