Fuel tubing sizes

Rdenney

Well-known member
Dec 29, 2005
6,270
95
48
NoVA
While we had the coach over the pit at Bean Station, we noticed that the
rubber bits on the fuel inlet plumbing was in rather poor condition. Given
that I replaced all of these in 2004, it's a little disappointing--I would
have thought that if the stuff installed in the 70's is still not leaking
for many folks, the stuff installed in the 2000's should still be good.

I don't want to use the special elbow, because it's too...special. And the
tee even moreso. I want to find metal couplers, elbows, tees, and adapters
so that I can use straight sections of hose to fit things together. I have
found a website that sells metal fuel filler tubing and fittings in these
shapes for those who are starting from scratch (Filler Neck Supply Co.) and
I think they will have what I need. But they only change sizes in straight
couplers. That leads to some questions.

First question: The books don't identify sizes, but I know they changed
between early coaches (like mine) and later coaches. I also know that the
filler hose bits I got from Cinnabar when I did this before didn't fit and
had to be adapted to different sizes. Does anybody recall the size of the
inlet on the tanks, and whether that size remained the same over the whole
production? I have Cinnabar tanks, which I am sure were sized to match
later coaches, if there is a difference between early and late.

Second question: Does anybody recall the sizes of the metal tubing bits on
early coaches? Sure, I can get under my coach with calipers, and will if I
have to, but I'm no longer over the pit at Bean Station and have to jack up
the coach over a gravel driveway to do that. I'd rather have parts in hand
when I do that.

Third question: Does anybody know of a material that is better than the
nitrile rubber used for the usual replacements? I wondered about pure
silicone, which is magic stuff on vacuum hoses (nitrile rubber seems to
crack in about 15 minutes when I use it for vacuum on the engine), but I
have read that silicone is not recommended for fuel applications. I might
have more choices if I am using straight sections instead of tees and
elbows.

Rick "who could see metal filler tube through the cracks, but surprisingly
they weren't leaking--yet" Denney

--
'73 230 "Jaws"
Northern Virginia
 
> ...I want to find metal couplers, elbows, tees, and adapters so that I can use straight sections of hose to fit things together. ...

Would Electrical Metallic Tubing work?
--
73 23' Sequoia 4 Sale
73 23' CanyonLands Parts Unit 4 Sale
Upper Alabama
"Every day I become more convinced that I am the only person left on the planet that recognizes nonsense for what it is."
 
I think I can find the metal tubing I need, already configured for use with
fuel hose (with the bubble barbs, etc.). And metal adapters for changing
sizes are readily available, rather than having to use a custom elbow to
mate two different sizes..

I'm just trying to remember the factory sizes used without having to jack
up the coach to crawl under just to measure them. GM could have made it
easier by specifying sizes in the Parts Book.

Rick "some is 1-1/4" and some is 1-3/8", or something like that, from fuzzy
memory" Denney

> > ...I want to find metal couplers, elbows, tees, and adapters so that I
> can use straight sections of hose to fit things together. ...
>
> Would Electrical Metallic Tubing work?
> --
> 73 23' Sequoia 4 Sale
> 73 23' CanyonLands Parts Unit 4 Sale
> Upper Alabama
> "Every day I become more convinced that I am the only person left on the
> planet that recognizes nonsense for what it is."
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
'73 230 "Jaws"
Northern Virginia
rick at rickdenney dot com
 
Hose sizes are:

Filler rail to front tank is 1-1/8" hose.
Filler rail to rear tank is 1-3/8" X 1-1/8" 90 elbow.

However
On the early (1973-74) coaches the elbow to the rear tank 1 1/8 X 1 1/8”

Emery Stora
77 Kingsley
Frederick, CO
--

>
> I think I can find the metal tubing I need, already configured for use with
> fuel hose (with the bubble barbs, etc.). And metal adapters for changing
> sizes are readily available, rather than having to use a custom elbow to
> mate two different sizes..
>
> I'm just trying to remember the factory sizes used without having to jack
> up the coach to crawl under just to measure them. GM could have made it
> easier by specifying sizes in the Parts Book.
>
> Rick "some is 1-1/4" and some is 1-3/8", or something like that, from fuzzy
> memory" Denney
>
>

>

>>> ...I want to find metal couplers, elbows, tees, and adapters so that I
>> can use straight sections of hose to fit things together. ...
>>
>> Would Electrical Metallic Tubing work?
>> --
>> 73 23' Sequoia 4 Sale
>> 73 23' CanyonLands Parts Unit 4 Sale
>> Upper Alabama
>> "Every day I become more convinced that I am the only person left on the
>> planet that recognizes nonsense for what it is."
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
>
> --
> '73 230 "Jaws"
> Northern Virginia
> rick at rickdenney dot com
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Emery, thanks for the memory boost, it's starting to come back to me. In
the Parts Book, item 26 is the fuel tubing (metal) that provides the tee at
the front tank and a square barb at the rear tank. If this is 1-1/8"
tubing, and the if the tanks have 1-1/8" barbs, then the front hose would
be 1-1/8" straight and the rear elbow would be 1-1/8 x 1/18" elbow. That's
the way the picture looks and I think that's what they provided in the
early coaches. consistent with what you wrote.

With the dimensions you provided, do the later coaches use a tube that is
1-3/8" over its whole length, but with a 1-1/8" barb poking out the side
for the front tank? My memory is coming back: When I installed the Cinnabar
tanks, the elbow they provided was too big for the filler tube, but was
tapered in way that I could cut down the large part and get a tight fit on
the taper. But I recall having other tubing issues. too--it's just been too
long.

Rick "CRS" Denney

> Hose sizes are:
>
> Filler rail to front tank is 1-1/8" hose.
> Filler rail to rear tank is 1-3/8" X 1-1/8" 90 elbow.
>
> However
> On the early (1973-74) coaches the elbow to the rear tank 1 1/8 X 1 1/8”
>
> Emery Stora
> 77 Kingsley
> Frederick, CO
> --
>
>

> >
> > I think I can find the metal tubing I need, already configured for use
> with
> > fuel hose (with the bubble barbs, etc.). And metal adapters for changing
> > sizes are readily available, rather than having to use a custom elbow to
> > mate two different sizes..
> >
> > I'm just trying to remember the factory sizes used without having to jack
> > up the coach to crawl under just to measure them. GM could have made it
> > easier by specifying sizes in the Parts Book.
> >
> > Rick "some is 1-1/4" and some is 1-3/8", or something like that, from
> fuzzy
> > memory" Denney
> >
> >

> >

> >>> ...I want to find metal couplers, elbows, tees, and adapters so that I
> >> can use straight sections of hose to fit things together. ...
> >>
> >> Would Electrical Metallic Tubing work?
> >> --
> >> 73 23' Sequoia 4 Sale
> >> 73 23' CanyonLands Parts Unit 4 Sale
> >> Upper Alabama
> >> "Every day I become more convinced that I am the only person left on the
> >> planet that recognizes nonsense for what it is."
> >>
> >> _______________________________________________
> >> GMCnet mailing list
> >> Unsubscribe or Change List Options:
> >> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >>
> >
> >
> >
> > --
> > '73 230 "Jaws"
> > Northern Virginia
> > rick at rickdenney dot com
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
'73 230 "Jaws"
Northern Virginia
rick at rickdenney dot com
 
Moving tanks around between a 74 that is 1 1/8 both the elbow and straight rubber and a 75 seems to be bigger 1 3/8? on the pipe end for the elbow.
The (expensive) replacement I ordered looked like it had the size step. Thought of using a copper elbow with straight rubber connectors but there is
not much room to get the rubber parts on. The 75 has the 1 piece steel pipe. 74 at least the rear pipe after the T comes off and i believe the T is
separate also. The straight rubber on both I believe is 1 1/8
--
Eric & Ree '74 ex-Sequoia + '75 Eleganza Alexandria, Ontario, Canada
 
I put new ones on our GMC in 2003 that came from Applied GMC. They were still fine when I pulled the tanks. When I put the tanks back in. I put some oil on the hose ID, and the OD of the tank inlets. I believe all years are the same. No mater the size. Applied will send what you need. Bob Dunahugh
 
No, as I said in an earlier message the early 73 & 74 used a smaller elbow on the rear tank.

Emery Stora

>
> I put new ones on our GMC in 2003 that came from Applied GMC. They were still fine when I pulled the tanks. When I put the tanks back in. I put some oil on the hose ID, and the OD of the tank inlets. I believe all years are the same. No mater the size. Applied will send what you need. Bob Dunahugh
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
I would be upset too. But those hoses are like 13 years old and i am not sure parts houses were too smart about ethonal at that point. Time will
tell, but the cinnibar set i just installed for someone were to be rated to handle ethonal.

Metal fillers can rust, aluminum can corrode. Rubber can rot. I know trying to flex the tanks in and out with rubber hose is a little tricky, but
cant imagine trying to deal with the tanks if the fillers were metal and had no give.
--
Jon Roche
75 palm beach
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
And there is no telling how old the hose sections were when Cinnabar pulled
them off the shelf. They have stuff made in batches.

I'm going to have to get under there--I was an idiot for not measuring and
photographing the stuff at Bean Station. I'm sure I have hoses that are
different from what is pictured in the Parts Book. But part of what I was
trying to ascertain was whether something like this could be used--I found
it after my first post:

http://racebikebitzusa.com/Samco-Silicone-Elbows/90-Degree-Samco-Silicone-Profuel-petrol-hose

These are lined with fluoro-something to provide a barrier to the high fuel
permeability of silicone, and are intended for continuous fuel contact.
These are really expensive, but my experience with silicone is that it does
not rot, and it may keep me from having to do this again.

They come in 1-1/8", but not with different sizes on each end.

But it sounds as though I won't have to adapt anything. The metal bits are
indeed too big to fit, but I could have adapted hose sizes if necessary
using a metal adapter, without making installation any more difficult.

I was deeply frightened by the condition of the existing hoses, and I
bought them recently enough that ethanol should have been accommodated. I
had already been planning to drop the tanks, to do what I should have done
from the start, which is replace the senders, so now is the time to solve
this completely.

Rick "thanks for the info" Denney

> I would be upset too. But those hoses are like 13 years old and i am
> not sure parts houses were too smart about ethonal at that point. Time
> will
> tell, but the cinnibar set i just installed for someone were to be rated
> to handle ethonal.
>
> Metal fillers can rust, aluminum can corrode. Rubber can rot. I know
> trying to flex the tanks in and out with rubber hose is a little tricky, but
> cant imagine trying to deal with the tanks if the fillers were metal and
> had no give.
>
--
'73 230 "Jaws"
Northern Virginia
rick at rickdenney dot com