Introduction oversight

Seeburg220

Seeburg220

Active member
Oct 25, 2021
318
152
43
Berryville, VA
Hi all. I realize that I made my first post over a year ago, but neglected to post here with my introduction.

I am on my 2nd GMC. My first GMC, a '78 Kingsley, I bought shortly before I retired from the FAA in 2015. After spending about $15k to get it decent, my late wife and I took off on a 6-month, 12k mile trip across the U.S. We ended up in Florida and bought a house. She got cancer shortly after moving in, and I figured we should sell it. I really wish I hadn't. She passed away in 2021 and in a fog of grief, I went and bought another one, - a '77 Palm Beach with the 403. Looking back, it was not a good purchase, as I overpaid for it. It has a laundry list of needs that I intend to remedy in the coming year(s). The first order of business is to get a 3.70 final drive for it. Currently, it won't get out of its own way, with the 3.07. Horrible is an understatement. After that, re-do the roof seams and fix all of the leaks. Then, on to gutting the interior and bringing it into the 21 century. The cabinets have lots of water damage, so I'll be making new ones.

I plan on traveling in it in the coming years and look forward to showing up at the various rallies. Glad to be here !

- Mark


20210829_091034.webp
 
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Thanks for the intro. Nice looking coach you have there! When we picked up our coach 20yrs ago, we experienced the same " it won't get out of its own way" syndrome. Many others have experienced the same issue and there is a simple solution should the following exist. Open the engine hatch, and take the air cleaner off. Look down the throat of the primary and secondary throttle bores. Have a second person press the gas pedal to the floor and observe the throttle plates. They should open fully. If they don't, grab the throttle petal and bend the throttle arm up. Observe the throttle plates and bend the arm some more until the throttle plates open fully. Somehow over the 40 some odd years of use, that arm gets bent a little at a time until it no longer has enough swing to fully open the throttle plates, making it seem like it " it won't get out of its own way". This may not be the problem, but considering the cost of making this repair, it is worth checking out. JWID
 
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LarryW said:
Thanks for the intro. Nice looking coach you have there! When we picked up our coach 20yrs ago, we experienced the same " it won't get out of its own way" syndrome. Many others have experienced the same issue and there is a simple solution should the following exist. Open the engine hatch, and take the air cleaner off. Look down the throat of the primary and secondary throttle bores. Have a second person press the gas pedal to the floor and observe the throttle plates. They should open fully. If they don't, grab the throttle petal and bend the throttle arm up. Observe the throttle plates and bend the arm some more until the throttle plates open fully. Somehow over the 40 some odd years of use, that arm gets bent a little at a time until it no longer has enough swing to fully open the throttle plates, making it seem like it " it won't get out of its own way". This may not be the problem, but considering the cost of making this repair, it is worth checking out. JWID
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Just to add to Larry"s suggestion, I had the same problem and have fixed mine and several others by bending back that rod.

Second, could be spark advance weights rusted and stuck in place. Pull the distributor cap and rotate the rotor slightly by hand. See if the weights move freely. They are easier to observe if you take the two mounting screws out of rotor and remove it.

I have driven both 403s and 455s cross country and in the mountains. Both perform similarly. So don't blame the 403.
 
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LarryW said:
Thanks for the intro. Nice looking coach you have there! When we picked up our coach 20yrs ago, we experienced the same " it won't get out of its own way" syndrome. Many others have experienced the same issue and there is a simple solution should the following exist. Open the engine hatch, and take the air cleaner off. Look down the throat of the primary and secondary throttle bores. Have a second person press the gas pedal to the floor and observe the throttle plates. They should open fully. If they don't, grab the throttle petal and bend the throttle arm up. Observe the throttle plates and bend the arm some more until the throttle plates open fully. Somehow over the 40 some odd years of use, that arm gets bent a little at a time until it no longer has enough swing to fully open the throttle plates, making it seem like it " it won't get out of its own way". This may not be the problem, but considering the cost of making this repair, it is worth checking out. JWID
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Note, on a Quadrajet only the primaries will open if the engine isn't running. The Quad's secondaries do not open via mechanical linkage. It is worth testing them, too, by accelerating heavily while driving at about 45 mph and observing the secondaries' air doors. Be sure not to fully floor it during this step, though, because doing so may activate the transmission kickdown if it's still connected. You want the transmission to stay in 3rd gear.
 
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Seeburg220 said:
Hi all. I realize that I made my first post over a year ago, but neglected to post here with my introduction.
Click to expand...
Hi Mark.
And welcome back to the GMC family.

For the purpose of locating and keeping track of all Classic GMC Motorhomes.
Please fill out and submit the online form at www.gmcmhregistry.com/contact/form.html
(There are currently over 8,900 GMCs accounted for)

Find the VIN tag is on the firewall behind the passenger side hood.
Or on the inner glove box door tag.
Or on the title.

* Note about the Build Date of your GMC: From the decal on the inside of the glove box door - look for a number on the top line just left of center, similar to "032174". The example indicates the build date as March 21st, 1974. *

Thank you
Billy Massey
The GMC Motorhome Registry
 
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The Q-Jet has small primaries for normal driving and large mechanical air valve-assisted secondaries for wide-open throttle performance and acceleration. The vacuum operated air valves above the secondaries, when properly adjusted, open at a slower clip to compensate for the large mechanical secondary throttle plates. It is a simple matter with the engine not running using your finger to open the air valve and observe the secondary throttle plates which do open via a direct mechanical linkage to the primary's. JFWIW
 
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Mark,

Welcome to the group, family, cult, asylum.....
I missed the first post when you arrived here and I am really glad that you did find us. For some undiscovered reason, the picture I see is just a gable end and half of a rooftop A/C. That does not matter today.
What does matter is that you get what you need to make her a pleasant travel coach.

Two things of import:
1-You are in the area of "Tidewater Crabs" chapter. I suggest that you look them up and make contact. I might have said friends, but for the most part, all GMC owners (or even no longer an owners) are all friends. That brings me to the second.
2-Please fill in a sigfile with your name, a short about the coach including major mods and a geographic reference. This will assist your several hundred new old friends that choose to, to be of real help. And they can be. We all want to see you enjoy both the coach and your life.
I don't know how long you were not a part of this community, but I have only been aboard for sixteen years and it has gotten better every year. If you are contacted and whomsoever does comes on a bit like a used car salesman, that is just the nature of the amazingly supportive community.
The signature file can be entered by clicking up at the top right where your avatar is showing.

Now, because this community is so like that of the watermen of my world, I like to welcome new owners here much as you might be welcomed there. So,

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

Welcome Mark

Matt
 
Matt Colie said:
Mark,

Welcome to the group, family, cult, asylum.....
I missed the first post when you arrived here and I am really glad that you did find us. For some undiscovered reason, the picture I see is just a gable end and half of a rooftop A/C. That does not matter today.
What does matter is that you get what you need to make her a pleasant travel coach.

Two things of import:
1-You are in the area of "Tidewater Crabs" chapter. I suggest that you look them up and make contact. I might have said friends, but for the most part, all GMC owners (or even no longer an owners) are all friends. That brings me to the second.
2-Please fill in a sigfile with your name, a short about the coach including major mods and a geographic reference. This will assist your several hundred new old friends that choose to, to be of real help. And they can be. We all want to see you enjoy both the coach and your life.
I don't know how long you were not a part of this community, but I have only been aboard for sixteen years and it has gotten better every year. If you are contacted and whomsoever does comes on a bit like a used car salesman, that is just the nature of the amazingly supportive community.
The signature file can be entered by clicking up at the top right where your avatar is showing.

Now, because this community is so like that of the watermen of my world, I like to welcome new owners here much as you might be welcomed there. So,

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

Welcome Mark

Matt
Click to expand...
Thanks Matt. I have actually been in with the Tidewater Crabs since I bought it, but I haven't been able to participate much, due to the condition of it so far. Also, I did fill out the sig file. Perhaps your computer isn't displaying it correctly? It's been on there for a while. Thank you for the welcoming and I look forward to many interactions here.
 
Mark,
Glad to hear you have hooked up with the Tidewater folks.
I think your sig got trimmed by what ever took out the bottom half of you picture.
And yes, by all accounts, a 3.70 is about right for a 403 coach.
Matt
 
Matt Colie said:
Mark,
Glad to hear you have hooked up with the Tidewater folks.
I think your sig got trimmed by what ever took out the bottom half of you picture.
And yes, by all accounts, a 3.70 is about right for a 403 coach.
Matt
Click to expand...
I switched the pic to a thumbnail version. Does it display correctly now? Thanks!
 
kbeefy said:
Welcome Mark!

Just curious, did your '78 still have the original gears?
Did it perform better than your current GMC?
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Hi Ken. The '78 had a 3.55 Caspro drive chain set in it, which made it run really well. That made up for the 3.07 final drive, I believe. The only time I remember it struggling some, was somewhere on my way back East in the Rockies. It performed a lot better than this '77.
 
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Seeburg220 said:
Hi Ken. The '78 had a 3.55 Caspro drive chain set in it, which made it run really well. That made up for the 3.07 final drive, I believe. The only time I remember it struggling some, was somewhere on my way back East in the Rockies. It performed a lot better than this '77.
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Thanks Mark, good feedback.

I just bought a '78 and am unimpressed by it's performance while towing my VW Golf. I don't have any experience with any other GMC's. I will most likely be getting a 3.7:1 gearset in the future...
 
kbeefy said:
Thanks Mark, good feedback.

I just bought a '78 and am unimpressed by it's performance while towing my VW Golf. I don't have any experience with any other GMC's. I will most likely be getting a 3.7:1 gearset in the future...
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I've never towed with either one, but would like to have that option in the future. The 3.70 is supposed to be a good fit for the 403 engine, and that's where I'm headed. I'm on the waiting list from Applied GMC for the 3.70 final drive part.
 
GMCMI Spring 2026 Rally
Applied GMC

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