Tucson trip. 8.35 MPG with a 17, 300 GVW. Good for that weight I think.

[Bob Dunahugh]

78 Royale 403 with Howell/GM EFI with computer distributor spark control, stock exhaust system, and 3:70 FD. 3,497 miles round trip that makes up a good average. The Royale's are the heaviest GMC's at about 12,000lbs, Chevy Uplander handicap lift van on dolly. 5,324 lbs. Be interesting to see what we'd get not pulling anything. That never happens. As the rest of the time I'm pulling my enclosed 24ft race car trailer. That comes in at 24,000 GVW. Bob Dunahugh 78 Royale

 

[jim kanomata1]

Bob,
I receive many comments from people that are running the 3.70 Final drive
ratio that have improve there performance and milage on both the 455 and
403.
It is all about the torque curve.

> 78 Royale 403 with Howell/GM EFI with computer distributor spark
> control, stock exhaust system, and 3:70 FD. 3,497 miles round trip that
> makes up a good average. The Royale's are the heaviest GMC's at about
> 12,000lbs, Chevy Uplander handicap lift van on dolly. 5,324 lbs. Be
> interesting to see what we'd get not pulling anything. That never happens.
> As the rest of the time I'm pulling my enclosed 24ft race car trailer.
> That comes in at 24,000 GVW. Bob Dunahugh 78 Royale
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--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502