Home » Public Forums » GMCnet » Survived: ONE lane road, Steep Grades & Thin Mountain air (24% Grade...YES 24%!)
| Survived: ONE lane road, Steep Grades & Thin Mountain air [message #93520] |
Tue, 27 July 2010 16:03  |
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1977Production#0001
Messages: 197
Registered: January 2010
Location: Vallejo, California
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The trip to Pacific Valley was a success. The Drive to Pacific Grade Summit was mostly uneventful(had a tiny bit of vapor lock when outside temps were at 103) until the road became one lane and just after the pass at 8,050 ft we came into a sharp left turn with a precipitous cliff with no guardrails greeting us eastbound California 4 motorists upon leaving the summit. Ahead is a series of downhill, 24% grade switchbacks. Of course I had my right tires on the edge of the pavement when an oncoming van went into panic mode and she stopped in the road (Not fully to the side. I slowly squeaked by and sent a few pebbles off the cliff before tackling the steep switchbacks. Second gear all the way down (I could/should? have done 1st and saved some brakes). The brakes had a bit of a smell and squeak at the bottom, but we turned into Pacific Valley campsite (SO beautiful, another story).
Fast forward to the end of the trip...
Yesterday, a warm afternon, we started her up, warmed her up and attempted to drive down the campground to say bye to friends... LOW RPM...No brakes...then stall... no start...opening the carb we got her restarted... barely. Could not move her and putting air filter on caused her to stall. Without air filter she limped. Finally figured out that being in the mountains she was starving for air with the choke on. After warming up fully she was back to normal. Said our goodbyes(not final haha) and bothered a friend to follow us UP the 24% grade since we were worried about the lack of air and the steepness of the mountain. checked fluids/braked/nerves and then we got a running start that helped up the first of 15 switchbacks, dropped it to first gear and we sailed up that mountain at a constant 15 MPH not even slowing for the full crank switchbacks. Got to the top and pulled over...All systems normal! Success! I'd have to say this trip gave us confidence in the GMC for mountainous roads.
YES it WAS that STEEP
http://www.gmcmhphotos.com/photos/data/5552/STEEP_SIGN.jpg
A precipitous cliff with no guardrails?Ummm...ok..Bring it on!
http://www.gmcmhphotos.com/photos/data/5552/medium/ca-004_eb_ebbetts_pass_069.jpg
Giovanni(Carlo) 1977 GMC Kingsley 26ft
"Carbon Footprint"
Rear Twin, Dry Bath, Original Headliner
[Updated on: Tue, 27 July 2010 16:38] Report message to a moderator |
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| choke problem [message #93575 is a reply to message #93520] |
Tue, 27 July 2010 20:48  |
bukzin
Messages: 840
Registered: April 2004
Location: North California
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Could you help me understand?
The choke was closing when it should not have?
How did you adjust it?
Also, is yours an electric choke?
Thanks!
PS Is this the coach you bought in Corning CA?
Bukzin
1977 Palm Beach
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| Re: choke problem [message #93584 is a reply to message #93575] |
Tue, 27 July 2010 22:42 |
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1977Production#0001
Messages: 197
Registered: January 2010
Location: Vallejo, California
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| bukzin wrote on Tue, 27 July 2010 18:48 |
Could you help me understand?
The choke was closing when it should not have?
How did you adjust it?
Also, is yours an electric choke?
Thanks!
PS Is this the coach you bought in Corning CA?
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Yes, this is the Burgundy Corning, CA coach.
I think it was just a lack of air/altitude problem when cold that was relieved when the choke closed as the temp rose. Not completely sure. Choke is not electric, it is a newly rebuilt Carb installed by applied GMC. When the choke was adjusted it had many great cold starts. the first problem occured when at 8,000 feet.
Maybe someone can chime in as to what my problem was?
Giovanni(Carlo) 1977 GMC Kingsley 26ft
"Carbon Footprint"
Rear Twin, Dry Bath, Original Headliner
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| Re: Survived: ONE lane road, Steep Grades & Thin Mountain air [message #93600 is a reply to message #93593] |
Wed, 28 July 2010 07:43 |
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1977Production#0001
Messages: 197
Registered: January 2010
Location: Vallejo, California
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| mcolie wrote on Wed, 28 July 2010 04:37 |
Carlo,
[Cannot quote with pictures present]
Your set of symptoms does not completely jive here.
If the choke was closed and the engine ran at all, you should have brakes.
Yes, things can get strange at high altitude, but with lots of time at 6~8K, I have never had to force the choke open.
You say you opened up the carburetor - by this I am guessing you mean you pushed the choke open. Lots of us are still running the OE carburetor and I would love to know what happened.
Matt
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the symptoms may not jive but I tried to describe them as accurately as possible. We were instructed to not let this rebuilt engine idle, so after the first cold start(it was 75 outside) we rolled thru campground. The brakes were weak/ going in out because the engine was in the process of sputtering out while rolling slowly and then it fully stalled. It was a challenge to stop the coach. The brakes did not have full feel again until the engine was back to normal. It would not restart until I opened the smaller of the two flaps in the carb which seemed to let more air in. I did read up on high altitude problems on the edelbrock website, and I'm sure hat was the problemhere... Running extremely rich and choking for air, until it was at operating temp.
Giovanni(Carlo) 1977 GMC Kingsley 26ft
"Carbon Footprint"
Rear Twin, Dry Bath, Original Headliner
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| Re: Survived: ONE lane road, Steep Grades & Thin Mountain air [message #93605 is a reply to message #93600] |
Wed, 28 July 2010 08:13 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| 1977Production#0001 wrote on Wed, 28 July 2010 08:43 |
The symptoms may not jive but I tried to describe them as accurately as possible. We were instructed to not let this rebuilt engine idle, so after the first cold start(it was 75 outside) we rolled thru campground. The brakes were weak/ going in out because the engine was in the process of sputtering out while rolling slowly and then it fully stalled. It was a challenge to stop the coach. The brakes did not have full feel again until the engine was back to normal. It would not restart until I opened the smaller of the two flaps in the carb which seemed to let more air in. I did read up on high altitude problems on the edelbrock website, and I'm sure hat was the problem here... Running extremely rich and choking for air, until it was at operating temp.
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Carlo,
The advise to not idle a new rebuild of a flat tappet engine is a very good thing to follow. Idling is really tough on a flat tappet valve train.
As you now describe the situation, the brake issue now makes some sense.
There is a feature in the carburetor called a "choke pull-off" and if you put enough load on the engine, it will open the choke. If your choke has been set on the rich end of the adjustment, then this could be bad at altitude.
In short, what you needed to do was drive the coach. This will get the engine warmed up faster and the choke will open.
Good Luck Guy
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Survived: ONE lane road, Steep Grades & Thin Mountain air [message #93616 is a reply to message #93613] |
Wed, 28 July 2010 09:22 |
Ron
Messages: 250
Registered: February 2004
Location: Conifer, Colorado
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Hi All..
Now what you have seen are the conditions that have plagued my brakes for the time I have owned the coach..
I live at 9300 feet and have had this issue always.. The installation of an auxiliary Vacuum pump and an electric choke are the only real things that have helped..
I now have "acceptable" brakes.. They work great when warmed and work well when at lower altitudes..
Ron
now a P.O.
Conifer, CO
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| Re: [GMCnet] Survived: ONE lane road, Steep Grades & Thin Mountain air [message #93627 is a reply to message #93625] |
Wed, 28 July 2010 10:21 |
Ron
Messages: 250
Registered: February 2004
Location: Conifer, Colorado
Karma: 0
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Larry..
At initial start cold I run about 9 inches.. That improves to about 12 or 13 at idle.. That doesn't cut it for our (my) brake systems.. Some on this list may recall all of the work I have gone through to improve the brakes.
I now have the "best" brakes I have ever had.. Still not great but adequate..
I have a complete Power Master that I was considering installing.. I looked into Hydro-boost systems but they are even sketchier that their power Master stuff as far as installation goes..
Well.. I am delivering my coach to a new owner on Saturday.. Any changes will now be at his discretion.. He is in Salt Lake so he may decide to leave well enough alone.
Ron
Still up high but normal (I Think)
now a P.O.
Conifer, CO
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| Re: Survived: ONE lane road, Steep Grades & Thin Mountain air [message #93635 is a reply to message #93629] |
Wed, 28 July 2010 10:54 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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What you are describing about the choke is pretty normal at that kind of altitude. When adjusted correctly for lower altitude, they can be overly rich at high altitude. When they do pull fully open, all is well, but in between it will be way too rich. Not too much you can do about it other than readjusting it which is about a 10 minute job--but then it will need readjustment again later.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] Survived: ONE lane road, Steep Grades & Thin Mountain air [message #93647 is a reply to message #93638] |
Wed, 28 July 2010 11:26 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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[quote title=k2gkk wrote on Wed, 28 July 2010 12:01]
The choke on Money Pit's carb doesn't work at all!
Lots of pumping will get the motor running and a
minute or maybe two of intermittent stabs will get
it warmed up sufficiently to continue running,
at least until it vapor locks again!
~ ~ ~ ~ ~ ~ ~ ~ ~
~ Mac Macdonald ~
~ Hamcall-K2GKK ~
~ Oklahoma City ~
~~ "Money Pit" ~~
~ '76 ex - P.B. ~
~ ~ ~ ~ ~ ~ ~ ~ ~
Sir: riching the initial starting mixture with pumpimg the pedal adds gas, the choke subtracts air. Totally different. Pumpimg has a tendency of flooding the cylinders and wiping the rings causing scratching of the cyl wall and loosing compression over time. Not to mention what could happen if it backfired. Its new name could be "fire pit". By using a choke it also activates the fast idle cam during warm up. I use an elec choke from a 76 Elderado. One wire to switched ignition. Available at Auto Zone #E6008 $27.99.
Hope this helps....
C. Boyd
76 Crestmont
East Tennessee
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