I can't get the idea out of my head of putting a big block in my 73. I have read the topics and have an unusual idea to bounce off you. I drive 250 miles a week so gas milage is a concern. I am getting 15 MPG with my 350/TH400, which is on the low side of acceptable. I was going to add a 700R4 with expectations of getting 17-18 MPG. I then thought of a Vortec 5.7 TBI from a 96-98 full size pickup with the 4L60E tranny and maybe 20-22 MPG and fairly stock appearance under the hood. The next step in my mind was a 454 TBI from a full size truck with the 4L80E? tranny. What do you think of that idea? Will I be in the 17-18MPG range? Will it still feel like a big block vette? Any ideas? I don't want to lose the factory appearance, as the car is 100% stock right now, and I like it that way. (Obviously a new motor isn't stock, but other than valve covers it will look stock.) Thanks, Joe

I've read some posts from another forum, that a fellow changed the trans to the 700r4 and with the lower first gear, and the O.D., he could smoke the tires from a dead stop, and get 20-22 mpg on the highway. Supposedly, that is all he changed, was the trans...

Sometimes you have to take gas mileage figures with a grain of salt, so to speak...



|QUOTE|joe73vette said: I can't get the idea out of my head of putting a big block in my 73. I have read the topics and have an unusual idea to bounce off you. I drive 250 miles a week so gas milage is a concern. I am getting 15 MPG with my 350/TH400, which is on the low side of acceptable. I was going to add a 700R4 with expectations of getting 17-18 MPG. I then thought of a Vortec 5.7 TBI from a 96-98 full size pickup with the 4L60E tranny and maybe 20-22 MPG and fairly stock appearance under the hood. The next step in my mind was a 454 TBI from a full size truck with the 4L80E? tranny. What do you think of that idea? Will I be in the 17-18MPG range? Will it still feel like a big block vette? Any ideas? I don't want to lose the factory appearance, as the car is 100% stock right now, and I like it that way. (Obviously a new motor isn't stock, but other than valve covers it will look stock.) Thanks, Joe|/QUOTE|

|UPDATED|6/22/2002 4:16:19 PM|/UPDATED|

Give Adam a chance to get some miles on his crate engine and see what kind of mileage he gets. Is your 350 a stock number matching motor? Maybe you could do something to it to use a lower octane gas and the difference in the gas price would balance out the low mileage. Somehow, I don't think you are going to see over 15 mpg with a 454. I had a stock 454 in my '74 and was very lucky to get 12 mpg around town and that was a low compression one year old engine.

Since I have an L48, I am not having any trouble with 93 octane right now. The motor is original, but the heads need rework. Perhaps some vortec heads and a manifold will get me where I want to be with the 700R4 and Q-jet.

Adam, after you get your new motor broken in, keep us posted on the gas milage.

Thanks, Joe