Calif certification
- Thread starter chuck botts
- Start date
> But I
> guess you're looking at a '77 or '78 since it has a 403. If you're
> pulling the engine anyway, put in a 455(no substitute for
> displacement). Actually, I think the blocks might be identical, with
> the crank throw determining displacement. If so, you could rebuild your
> motor as a 455 and there would be no way to tell externally that
> anything had been changed.
Given the size and weight of these vehicles, is there any significant
difference in fuel economy between the 403 and 455? Also, what are
typical MPG figures for the 23' vs 26'. Thanks.
Gary
> guess you're looking at a '77 or '78 since it has a 403. If you're
> pulling the engine anyway, put in a 455(no substitute for
> displacement). Actually, I think the blocks might be identical, with
> the crank throw determining displacement. If so, you could rebuild your
> motor as a 455 and there would be no way to tell externally that
> anything had been changed.
Given the size and weight of these vehicles, is there any significant
difference in fuel economy between the 403 and 455? Also, what are
typical MPG figures for the 23' vs 26'. Thanks.
Gary
>
> Given the size and weight of these vehicles, is there any significant
> difference in fuel economy between the 403 and 455? Also, what are
> typical MPG figures for the 23' vs 26'. Thanks.
I think "significant" is the key. I only have experience with the
455's, but I doubt there is any noticeable difference in fuel economy
with the 403. My experience has averaged 7 to 8 mpg. I've heard that
the 23ft models can get as high as 10, but I certainly wouldn't count on
any more than that. I think Zak Zehnacker is on the list. He has a
23ft that he uses to pull a race car trailer. How about it Zak, what
kind of mileage does a 23ft GMC get?
BTW, if an RV salesperson tells you that a 30ft+ Class A with a big
block GM or Dodge engine will get anything more than 5mpg, place your
hand over your wallet and back away quickly
)
Patrick
- --
Patrick Flowers
Mailto
atri63
The GMC Motorhome Page
http://www.gmcmotorhome.com
> Given the size and weight of these vehicles, is there any significant
> difference in fuel economy between the 403 and 455? Also, what are
> typical MPG figures for the 23' vs 26'. Thanks.
I think "significant" is the key. I only have experience with the
455's, but I doubt there is any noticeable difference in fuel economy
with the 403. My experience has averaged 7 to 8 mpg. I've heard that
the 23ft models can get as high as 10, but I certainly wouldn't count on
any more than that. I think Zak Zehnacker is on the list. He has a
23ft that he uses to pull a race car trailer. How about it Zak, what
kind of mileage does a 23ft GMC get?
BTW, if an RV salesperson tells you that a 30ft+ Class A with a big
block GM or Dodge engine will get anything more than 5mpg, place your
hand over your wallet and back away quickly
)Patrick
- --
Patrick Flowers
Mailto
atri63The GMC Motorhome Page
http://www.gmcmotorhome.com
>
> >
> > Given the size and weight of these vehicles, is there any significant
> > difference in fuel economy between the 403 and 455? Also, what are
> > typical MPG figures for the 23' vs 26'. Thanks.
>
> I think "significant" is the key. I only have experience with the
> 455's, but I doubt there is any noticeable difference in fuel economy
> with the 403. My experience has averaged 7 to 8 mpg. I've heard that
> the 23ft models can get as high as 10, but I certainly wouldn't count on
> any more than that. I think Zak Zehnacker is on the list. He has a
> 23ft that he uses to pull a race car trailer. How about it Zak, what
> kind of mileage does a 23ft GMC get?
>
> BTW, if an RV salesperson tells you that a 30ft+ Class A with a big
> block GM or Dodge engine will get anything more than 5mpg, place your
> hand over your wallet and back away quickly)
Hi, I am Bill Wallace, I have a '78 GMC Royale 26' My mileage pulling a
'93 Saturn SL2 on a towbar over 2796 miles using 288.66 gal. of 89
octane gas figures out to 9.686 mpg. I have 403 engine standard 3.07
gear ratio and 8.75x16.5 radial tires. My speedometer is accurate. I run
cruise control at 58 to 60 steady. This was from Florida to Virginia
Beach to New Bedford PA to St. Paul MN and return to New Bedford, PA. I
can fax my vcalc printout to any one who is skeptical. My coach has
65000 mi. and the carburater was rebuilt by Bob Wallace of Wallace
Bearing and hub of Tucson, AZ. See pictures of coach at
gmcmotorhome.com.
Thank, Bill
> >
> > Given the size and weight of these vehicles, is there any significant
> > difference in fuel economy between the 403 and 455? Also, what are
> > typical MPG figures for the 23' vs 26'. Thanks.
>
> I think "significant" is the key. I only have experience with the
> 455's, but I doubt there is any noticeable difference in fuel economy
> with the 403. My experience has averaged 7 to 8 mpg. I've heard that
> the 23ft models can get as high as 10, but I certainly wouldn't count on
> any more than that. I think Zak Zehnacker is on the list. He has a
> 23ft that he uses to pull a race car trailer. How about it Zak, what
> kind of mileage does a 23ft GMC get?
>
> BTW, if an RV salesperson tells you that a 30ft+ Class A with a big
> block GM or Dodge engine will get anything more than 5mpg, place your
> hand over your wallet and back away quickly
)Hi, I am Bill Wallace, I have a '78 GMC Royale 26' My mileage pulling a
'93 Saturn SL2 on a towbar over 2796 miles using 288.66 gal. of 89
octane gas figures out to 9.686 mpg. I have 403 engine standard 3.07
gear ratio and 8.75x16.5 radial tires. My speedometer is accurate. I run
cruise control at 58 to 60 steady. This was from Florida to Virginia
Beach to New Bedford PA to St. Paul MN and return to New Bedford, PA. I
can fax my vcalc printout to any one who is skeptical. My coach has
65000 mi. and the carburater was rebuilt by Bob Wallace of Wallace
Bearing and hub of Tucson, AZ. See pictures of coach at
gmcmotorhome.com.
Thank, Bill
>
> Hi, I am Bill Wallace, I have a '78 GMC Royale 26' My mileage pulling a
> '93 Saturn SL2 on a towbar over 2796 miles using 288.66 gal. of 89
> octane gas figures out to 9.686 mpg. I have 403 engine standard 3.07
> gear ratio and 8.75x16.5 radial tires. My speedometer is accurate. I run
> cruise control at 58 to 60 steady. This was from Florida to Virginia
> Beach to New Bedford PA to St. Paul MN and return to New Bedford, PA. I
> can fax my vcalc printout to any one who is skeptical. My coach has
> 65000 mi. and the carburater was rebuilt by Bob Wallace of Wallace
> Bearing and hub of Tucson, AZ. See pictures of coach at
> gmcmotorhome.com.
> Thank, Bill
Well, there ain't nothin' like hard numbers. That's probably 1mpg
better than the best I've ever seen on mine or my father's 455(although
I'm pretty sure they both could use a carb rebuild). It sounds like a
pretty good overall average, not just flatland driving, so it's probably
at least 2mpg better than my coach would average. So, maybe a well
tuned 403 is good for 1 to 1.5 more mpg? Could be...
Patrick "Egg looks good on me" Flowers
Mailtoatri63
The GMC Motorhome Page
http://www.gmcmotorhome.com
> Hi, I am Bill Wallace, I have a '78 GMC Royale 26' My mileage pulling a
> '93 Saturn SL2 on a towbar over 2796 miles using 288.66 gal. of 89
> octane gas figures out to 9.686 mpg. I have 403 engine standard 3.07
> gear ratio and 8.75x16.5 radial tires. My speedometer is accurate. I run
> cruise control at 58 to 60 steady. This was from Florida to Virginia
> Beach to New Bedford PA to St. Paul MN and return to New Bedford, PA. I
> can fax my vcalc printout to any one who is skeptical. My coach has
> 65000 mi. and the carburater was rebuilt by Bob Wallace of Wallace
> Bearing and hub of Tucson, AZ. See pictures of coach at
> gmcmotorhome.com.
> Thank, Bill
Well, there ain't nothin' like hard numbers. That's probably 1mpg
better than the best I've ever seen on mine or my father's 455(although
I'm pretty sure they both could use a carb rebuild). It sounds like a
pretty good overall average, not just flatland driving, so it's probably
at least 2mpg better than my coach would average. So, maybe a well
tuned 403 is good for 1 to 1.5 more mpg? Could be...
Patrick "Egg looks good on me" Flowers
Mailto
atri63The GMC Motorhome Page
http://www.gmcmotorhome.com
The 1973 23' GMC we have got about 12 MPG when we first got it. It also,
however, only got 3.5 MPG towing our trailer. After modifications
including Holley Pro-Jection, Headers, Edelbrock cam and intake, MSD timing
control and ignition box, we had gotten the towing mileage up to about 9
with that trailer. The mileage, however, does not go up much without the
trailer on it anymore. It might get the 12 MPG that it originally got (not
really sure because we rarely use it without the trailer). We currently
tow a trailer with two cars in it (bigger and not as aerodynamic) and are
getting about 6 MPG. Some of the loss in mileage could be from a tired
engine, however, as we have about 100,000 miles towing on it.
The headers actually seemed to have decreased the non-towing mileage. The
Edelbrock cam and intake really picked up the power and mileage, but the
intake requires modification to the engine cover. The Pro-Jection seemed
to help quite a bit as well but has not been as reliable as we would like
it to be.
Zachary Zehnacker
however, only got 3.5 MPG towing our trailer. After modifications
including Holley Pro-Jection, Headers, Edelbrock cam and intake, MSD timing
control and ignition box, we had gotten the towing mileage up to about 9
with that trailer. The mileage, however, does not go up much without the
trailer on it anymore. It might get the 12 MPG that it originally got (not
really sure because we rarely use it without the trailer). We currently
tow a trailer with two cars in it (bigger and not as aerodynamic) and are
getting about 6 MPG. Some of the loss in mileage could be from a tired
engine, however, as we have about 100,000 miles towing on it.
The headers actually seemed to have decreased the non-towing mileage. The
Edelbrock cam and intake really picked up the power and mileage, but the
intake requires modification to the engine cover. The Pro-Jection seemed
to help quite a bit as well but has not been as reliable as we would like
it to be.
Zachary Zehnacker
Recent news on an older thread. Copied from another list I am on.
>From: Office SC08
>Subject: SB 42 signed
>Posting-date: Thu, 09 Oct 1997 11:39:00 -0700 (PDT)
> Dear Friends of SB 42:
>
> The Governor today signed SB 42 exempting 1973 and older
> vehicles from the biennial smog check requirement.
>
> Chapert #801, the legislation will take effect January 1, 1998.
>
> Thanks for your unwavering support!
>
> Sincerely yours,
>
> QUENTIN L. KOPP
>
> QLK:SS
At least that helps one production year.
Gary
>From: Office SC08
>Subject: SB 42 signed
>Posting-date: Thu, 09 Oct 1997 11:39:00 -0700 (PDT)
> Dear Friends of SB 42:
>
> The Governor today signed SB 42 exempting 1973 and older
> vehicles from the biennial smog check requirement.
>
> Chapert #801, the legislation will take effect January 1, 1998.
>
> Thanks for your unwavering support!
>
> Sincerely yours,
>
> QUENTIN L. KOPP
>
> QLK:SS
At least that helps one production year.
Gary
