Question: Timing and idle?!?

[jpburks]

I am looking to get better gas milage out of my car and I am at the point now where I know my vacuum is good, I have good intake and new full exhaust, and have done a tuneup with nnew plugs, wires, distributer and ignition coil. Still, my car is running at 9/10 MPG and I am not running it hard at all. I am about to rebuild the carb and am not sure if this is going to solve my problems. I know timing is huge but I don't know how it is set (electronically or vacuum). I also know that the 3 speed auto tranny that I have in it is not the most efficient and am wondering how much that will affect my milage. I am not sure where to look next but I am wanting to fix this issue as soon as possible. Any ideas where I should start or any other ideas that might help me out? I really appreciate it guys!!

 

[bill81vette]

I average between 15-17 mpg in mine
around town and on the highway!!!!!
bone stock!!!!
there is a procedure for setting the timing in the service manual.
you might want to try rebuilding the carb if that's your last option...

 

[Peer81]

Check the timing and carb settings. I think this will also improve the mpg.

Greetings Peter

 

[Sensei]

Your mileage is obscene! With everything set stock you should get around 15-16 in town if all is working correctly. I get 17 in town and 23 on the highway with near 400 hp using the original computer and carb (highly modified)

The carb could be the problem, but you need to know what you are doing if you rebuild an E4ME (I have a waiting list of people wanting E4ME rebuilds). The computer controlled MC solenoid is something you will want to look at closely (function and adjustment).

The first thing I would do is to be absolutely sure your new exhaust is sealed good at the heads. A header leak will kill mileage. Also, what headers are you using? If you did not replace the originals, they are notorious for developing a hole right where the primary tubes merge. Again, a mileage killer.

Finally, let's talk about your timing. Timing is not what is causing 9/10 MPG, but you do need to have it set right. Do NOT set the timing to stock settings unless you enjoy poor performance. Unplug the 4 pin connector at the distributor and set timing at 14 BTDC (don't forget to plug the 4-pin back in). If you notice any detonation, immediately lower it to 12 BTDC (or just start there if you don't feel the need to push the performance envelope).

God bless, Sensei