A long time ago, my Dad had a 454 in a 1981 Winnebago gross weight approximately 15,000 pounds. We used to use it to tow my Carburetor Shop van (loaded, approximately 9000 pounds) to Hershey.
454 came from the factory with a 800 CFM Q-Jet.
Power through the mountains in Pennsylvania using cruise control was terrible. Often the cruise would kick out, and we would be down to as low as 20~25 MPH when we crested the mountain. Heat gauge would be maximum. Of course, it would cool off going down the other side.
My theory was the primary side of the Q-Jet (spread-bore, little primary) was insufficient for the load.
I custom built a genuine Carter 750 CFM AFB (note smaller overall) and installed it on an Offenhauser intake.
I did not have a dynamometer, but power on the "power hill" seemed to be improved.
Next year, same roads, same load to Hershey. 20 hour trip reduced to 18 hour because we never got below 50 MPH in the mountains. Temperature gauge never rose above center of "normal".
Fuel economy INCREASED from 6.1 to 6.4 MPG loaded, and from 9.0 to 10.4 not towing my van.
For a vehicle with this much weight, the square bore is the way to go.
Jon.
Last edited by carbking; 01/22/2011 2:22 PM.
