Gear Ratio/mileage

[gmcmail]

Vic
There seems to be a growing BC fleet of GMCs ! It sounds like
you've given this some thought.
However, since you're at the planning stages, let me suggest that
you consider the humble 403.

If you're considerably lighter and have changed gears, you don't
need the slight additional torque of the 455 or the mere 12 extra
horses.

>
In PEI two years ago, I got 12mpg (Imperial), traveling at golf cart
speeds so as not to run over Anne at Green Gables
On the highway, I generally get the following:
55-60.........10 mpg
60-65......... 9 mpg
65-75...........8.mpg
I have the 403 stock 3:07s and a radar detector mounted behind
the mirror. That tells you where the 100+ mile Travelin' Bear is
most comfortable.
Information for what it's worth.....

MikeBeaton

gmcmail is a 'temporary' address for
Homebase
1977 Kingsley Antigonish, Nova Scotia

 

[brent covey]

Hi Mike!

While we're having fun playing around with ideas, heres one idea for
everyone as a 'superefficient' GMC powertrain-

Cadillac 368 OR Olds 350 (both fit) with MPFI (Cadillac systems)
,turbocharged for adequate acceleration, and geared to cruise at high vacuum
levels, say a 3.90. You could have your cake and eat it;-)

I think the Cadillac Seville 350 FI system fits the 403 also, as I recall-
403 is the narrow manifold block isn't it (compared to the 455) if I recall
correctly.

>However, since you're at the planning stages, let me suggest that
>you consider the humble 403.
>
>If you're considerably lighter and have changed gears, you don't
>need the slight additional torque of the 455 or the mere 12 extra
>horses.
>
>>>>
>In PEI two years ago, I got 12mpg (Imperial), traveling at golf cart
>speeds so as not to run over Anne at Green Gables
>On the highway, I generally get the following:
>55-60.........10 mpg
>60-65......... 9 mpg
>65-75...........8.mpg

>Information for what it's worth.....

 

[travis martin]

> I think the Cadillac Seville 350 FI system fits the 403 also, as I recall-
> 403 is the narrow manifold block isn't it (compared to the 455) if I
recall
> correctly.

You may be onto something there, Brent. When Cadillac brought out the
Seville in '75 through '79, it had an Oldsmobile 350 in it. So did the new
little Eldorado in '79, except it was front wheel drive.

I hadn't thought of it earlier, but perhaps that would be an easy retrofit
to the 403. These were pretty good EFI systems too. They were actually made
by Bosch and were port injectors. GM brought out the TBI in '80 for the 368
CID cadillacs.

Maybe Tom knows if the 350 and 403 intakes are interchangeable? I know that
the 455 is a tall block, but not sure on the 403.

Travis