First outing 77 Royal, 403, with 307 gears

[Matt Colie]

Lhochman,

Welcome to the group, family, cult, asylum.

I am very happy to hear that your first excursion was so successful. If you keep up with the regular maintenance, it can be this way a long time.

One of our early excursions was to Santa Fe and Albuquerque. I thought about starting east through Cloud Croft. I changed my mind when I saw the
elevations and the road that looked like it had been scribbled on the map. We have since encountered both higher and more twisty roads. I now might
drive though there without any trepidation.

Thank you for starting a good sigfile, but I will ask that you add your name to it. What ever you like to be addressed as will be good. This is
largely because we really like to know who we are helping. It is also more convenient when you meet other owners (and you will). (You can change the
alias easily.)

If you work the web just a little, you should be able to discover that there is a local chapter of GMC owners. Get hooked up with them as the support
will be of great value. There is a Western States Rally coming up but I fear that might be farther than you might like, but look for GMC rallies that
are closer and try to get to one.

You will soon discover that the coach is more than just a new big toy, but has much more value in the community that it connects you to. This is a
community of supportive and helping people that is very rare in the world. We all want to see that you get to enjoy what the coach can do for you as
well as the community that it connects you to. We have members here that total to millions of miles and centuries of hands on experience. The advice
given here should be valued. As the only other community like this that I know of is that of the watermen that are my world. For this very reason, I
like to welcome new owners here much as one would be welcomed there. So,

May the Good Lord bless this coach and all those that set forth within her.

Welcome Lhockman

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

 

[mark1]

Happily, the PO for my coach blessed it with a set of Thorley headers, a massive 3" exhaust system, and put in some 3.42 gears. I was impressed with
its ability to cruise up hills, often passing "lesser" motorhomes and semis with ease.

Then I did my first drive from the Phoenix valley to Flagstaff. This involves climbing 6-8% hills at 6,000 - 7,500 feet. My mighty 403 struggled
mightily over 5,000 feet, and a lot of the climbs were completed in first gear with my right foot planted in the carpet. Since then, I installed a
throttle body fuel injection system, and the difference is pretty amazing. What used to require winding out the engine in 1st gear now just causes a
kick-down to 2nd without drama. It also starts easier and looks like it's getting better gas mileage (had some other fuel issues that made it
impossible to know for sure). But the coach is just SO much easier to drive at altitude.

I'd echo what others have said about making sure the rest of your fuel system is intact. I did have some strange problems on the last drive "up the
hill" to Flagstaff, but when I got home I saw that the body spacer (rubber "hockey puck" between the frame and body) nearest the fuel tank vent lines
had slipped out, pinching the vent lines, causing a LOT of pressure in the fuel tanks. There's almost no clearance from the vent lines to the fuel
tanks and body with a good body spacer, and if it gets compressed (or goes missing) things are going to stop working right in pretty short order.
--
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen

 

[johnny]

Mease to Winslow running bobtailed, mine walked over the mountains and down the crooked roads without any histrionics - it has MSD Atomic injection.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell

 

[john r. lebetski]

1) see if accelerator pedal is fully opening the carb so the secondary throttle plates are vertical. Most do not and need adjustment
2) if your distributor has not been disassembled, cleaned and relubricated there is a good probability that the mechanical and/or vacuum advance is
not working properly. Continuing to operate the coach in severe conditions in this manner will kill the engine prematurely
3) not sure if your driving technique is the most optimal to put least stress on systems.
4) once all carb/ign is correct it's best to use WOT only as needed and for short intervals. Continuous WOT washes lube from walls and burns excess
fuel and creates more heat load. Better to find the right speed /throttle spot and let it work there

For comparison I did the Phoenix /Flagstaff run in my 77 455 when it still had 3.07s and was able to maintain speed vs temp but if road was steeper
would have been in 1st gear. Since then went to 3.42 and find it a good balance between speed and power with 455.

--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[Jim Hupy]

I found an interesting problem yesterday during a black list service call
to a stranded couple in a Walmart parking lot 25 miles from my home. They
complained of backfiring through the intake, and as I was diagnosing the
problem, I opened the HEI distributor to check the cap for carbon tracks,
and the centrifugal advance weights to see if they were stuck. (they were) .
So, I removed the rotor, which was blue in color, and identified as a
"STANDARD" brand name. The weights responded to a bit of tweaking and
penetrate, followed by lubrication. But I noticed that the upper side of
one of the weights had a shiny spot on it. Upon observation of the rotor, a
matching spot was noted. It seems the molded rotor had some poor quality
control during manufacture, and it really affected the operation of the
flyweights, when the rotor was in place. As in, it locked them up.
So, I replaced the blue rotor with an "Echlin" brand from NAPA. No
more interference with the Echlin rotor. The advance worked as it was
supposed to.
The coil was the correct one for the application, as was the 5 pin
module. All connections were checked and found to be tight, bright, and
shiny.
The backfiring, however, persisted, accompanied by a mechanical
clicking sound. So, I referred them to a local repair shop for a
compression test and further repairs.
Jim Hupy
Salem, Oregon

On Mon, Aug 26, 2019, 7:34 AM John R. Lebetski via Gmclist <

> 1) see if accelerator pedal is fully opening the carb so the secondary
> throttle plates are vertical. Most do not and need adjustment
> 2) if your distributor has not been disassembled, cleaned and relubricated
> there is a good probability that the mechanical and/or vacuum advance is
> not working properly. Continuing to operate the coach in severe conditions
> in this manner will kill the engine prematurely
> 3) not sure if your driving technique is the most optimal to put least
> stress on systems.
> 4) once all carb/ign is correct it's best to use WOT only as needed and
> for short intervals. Continuous WOT washes lube from walls and burns excess
> fuel and creates more heat load. Better to find the right speed /throttle
> spot and let it work there
>
> For comparison I did the Phoenix /Flagstaff run in my 77 455 when it still
> had 3.07s and was able to maintain speed vs temp but if road was steeper
> would have been in 1st gear. Since then went to 3.42 and find it a good
> balance between speed and power with 455.
>
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[john r. lebetski]

Perhaps running retarded burned a valve. Unfortunately.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[Randy Van Winkle]

> WE had our first outing with our 77 Royal 26ft unit with 403 CID. This was a shake down to find any problems. We live in southern NM and were
> going to a campground near Timberon NM. We had a huge climb from Alamogordo NM to Cloudcroft NM, at least a 4000 ft. climb in about 15 miles.
> Ok now for our problems along the way. We had not gone too many miles when our fuel pump went out. Since these RVs need fuel we replaced it on the
> side of the road. My wife was following me with her car for a backup AND A GOOD THING. I found that Auto Zone in Alamogordo had one in stock. This
> took some time, to get the part and travel up and down the mountian for the part and fix a fuel leak on fuel filter on carburetor. Well got it fixed
> and we were off again.
> Next big thing was we did not have much power to make the climb up the mountian. This is time to let you know I was towing a heavy car trailer
> with a Polaris RZR. The camping was great, we stayed at the Circle Cross Ranch Campground.
> Now that you have a quick synopsis of our first time out camping with our GMC. I could use some advice on getting more power for us out west and
> in the mountains. I think a popular option is to change gearing from 3.07 to 3.70. , this is an expensive option, but could be the best. I could
> also change the front tires to a smaller diameter, has anyone done this, I am running 16" wheels.

I have a 403 as well. The two best upgrades I made to make the 403 come alive was changing the final drive to a 3.70 and installing fuel injection
with good spark control capability (most aftermarket efi systems do not provide much help with spark control). I can out pull most stock 455 coaches
on about any grade. When I approach a long 6% + grade, I will manually pull down to 2nd and can maintain 60 mph until the top. I usually pull a car
weighting in at around 3000 I know of another with the same configuration that I have who pulls gross weight of 17000# to 22000# without issue. Not
sure you would gain enough with smaller diameter tires to make that a worth while approach - clearance of calipers might be problematic.

I love the 403 and will not change to anything else as I consider a rebuild. Currently have 165,000 almost trouble free miles and still runs strong.

--
Randy & Margie
'77 Eleganza II '403'
Battlefield, MO

 

[Jim Hupy]

Probably a good bet, but they might get lucky and it will prove to be a
cracked intake manifold or a bent pushrod or failed rocker arm. In any
event, it is internal.
Jim Hupy
Salem,Oregon

On Mon, Aug 26, 2019, 9:33 AM John R. Lebetski via Gmclist <

> Perhaps running retarded burned a valve. Unfortunately.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[Larry Davick]

You are getting good advise here. If my beloved PO hadn't installed the Marvin Peck gears, lower gears would have been high on my list. I honestly
think the best thing I've done is the Howell EFI and the spark controlled EBL. I have no experience with other EFI's but I'd take her up the grade at
Baker going to Vegas any day. Heck, we came from Ohio to Fremont on Rt 80 that had some climbs, and we've been over the Grapevine many times without
a thought.

So, Gears. EFI.

So long as everything else is safe - brakes (including brake lines), suspension, tires, fuel lines, wheel bearings. Safety is first. The rest is
improving on the original design.

Man we're lucky to have these worries!
--
Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy

 

[john r. lebetski]

If you were to change tire diameter, understand that that changes steering axis., as the point where the imaginary line through the ball joints
intersects the pavement moves.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[Len]

The tire size was just a thought, I will probably leave that alone, thanks
--
1977 26 foot, royale
Alamogordo NM