I give up. I got an 85 El Camino blown engine, swaped in the firebird-truck engine 305, this engine has seen 3 cars in less then a year, ***** engine! LOL.

Anyways the setup is basicly the same as it was when it was in the firebird except I had the heads done, stock bore 305, MTC-1 cam, Stealth intake, 600CFM Holley. The plugs/wires cap & rotor are new ignition timing is set 12* "high altitude standard."
The best MPG city I can get from this pig is 10 I was getting around 21MPG in the firebird and 21/22 in the TBI truck. Nothing has really changed except the heads were worked on.

Suggestions????

Thanks!

Oh and this isnt exactly non thirdgen, Ive got a 89 RS front clip/hood I am in the process of installing on the Elcamino.

 

What is a MTC cam? What ever it is it is probabily too big
for mileage. Get rid of any carb adapters. Mount the carb right on the manifold. Lean down the primary jetting on your holley. Especially at high altitude. Go leaner till drivability goes away
then up 2 jet sizes. Se if you can get it down to 58 to 61 jets. (#66 is stock) Check for a leaking power valve. Swap in a #39 or #21 sec metering plate (stock in 750vs 3310) to compensate at WOT.
Some one you know will have one laying around.
Check if the ignition advance weights are working. Check the vacuum advance canister is working and plugged into ported
vaccuum. Turn the idle speed down. Most of your time is spent at or close to idle.

 

Thats just it I know it's running a little rich@ idle that being the only problem, jets are 62's. I cant lean it down anymore by the screws it just runs too rough. The mtc-1 Melling performance cam is a very mild 208- 214@.50 cam perfect for a 305. The distributor is a new accel.
This just makes no sence to me why its not getting at least 18 MPG city.

 

O2 Sensor??? I hate computers on cars......

 

May be it's not the motor but the car. Check to see if the front brakes
are dragging. Mine had bad flex lines and was not letting the
brake fluid back when you release the brakes.
That extra drag made a big difference in ET and mileage.

 

What kind of transmission do you have in the car? What about the gear ratio? How aggressive do you drive the car????
Rudy

 

I havent checked the brakes since it doesent give any indication of dragging or pulling. It was a TBI 5.0 or CCqjet before but someone had already guted the CC goodies before I got the car so there was no choice in going non CC. It does have a 700R4 and I'm thinking it has 3.23 or 3.42 gears I havent checked anything in that area except gear oil.
This just sucks! I really need a truck for work. "TruckMaro"