MPG on an 82 El Camino

Just 2 days ago, I bought the car I've wanted since I was 5, an El Camino. It needs a good deal of work, but it has a great deal of new parts.

Orriginally it was a V6, but 3 years ago it had a Chevy 305 V8 installed, and a new transmission to match.

After having driven it for awhile, I find I get about 12-15 MPG's average... so my question is, is there anything I can do to help bring this up to arround 20? of course, more would be better... I am referring more to parts rather than tuning and driving methods..

I've heard a rumor about a special carburetor that can significantly increase mileage aswell as horse power.. does such a unit exist?

Thank you for your responses.

Your mileage does seem to be pretty low.

There are many reasons why your mileage is poor. Generally, they fall into 2 categories: the state of tune of your car; and the equipment it has.

If you are not experienced with auto mechanics, this is an excellent learning opportunity to pick up some service manuals, or do-it-yourself manuals (Haynes, Chiltons, etc) and begin to do some research and do some work yourself. This car is actually quite simple and straightforward to work on.

Go over your car throughly. It's possible the previous owner neglected to do some maitenance, it may need a tune up, including a new air filter, spark plugs, plug wires, distributor cap and rotor, and resetting the ignition timing.

Have a look at the carb and make sure the choke is working properly, that is, the choke blade is notpartly closed when warm, and that the idle mixture (if adjustible) is not set up too rich.

Also, this may sound silly, but make sure your brakes are not dragging. If you can push the car yourself on a level serface, it's probably ok.

Depending on your year of engine, it may have a thermal operated vacuum switch that changes the vacuum source for the distributor from manifold vacuum to ported vacuum as the engine warms up. These are notorious for getting stuck on manifold vacuum, which affects mileage and power. For that matter, make sure the vacuum line is hooked up to the distributor.

As for the equipment that is on the car......because the engine is not original for that vehicle, it becomes difficult to advise you on this. Sometimes high performance parts, particularly camshafts can kill mileage. Some aftermarket carbs, particuarly the Holley carbs can be adjusted incorrectly and use excess fuel.

Finally, it's possible the engine swap was poorly done and something was missed, such as missing or poorly installd vacuum lines, etc.
Sometimes, people can mix-and -match small block Chevy engine parts (blocks and heads) and end up with something that runs and looks ok, but is actually very ineffiecient due to low compression ratios. Do you know anything about the 305 that is in there now, such as the year or what vehicle it came from?

Finally, those old-style GM catalytic converters were inefficient and liked to get plugged up, which kills power and mileage.

I don't know very much about mechanics... But when I bought this I was looking forward to learning... It was impossible to learn on my Toronado, which is pretty much a giant computer with an engine....

The orriginal owner of the vehicle was a mechanic, and it was he who installed the engine... Unfortunately, I know absolutely nothing about him, or the engine... I read that there is a plate on the engine that has a code which could tell me the year and such, I'll look for that later today...

Other than that, the carburetor has been very well cared for, it seems to function properly, and is very, very clean. My mechaninc adjusted the idle when I took it in for a once-over... I checked the air-filter, oil, and various other standard things, they are all OK...

It seams that there may be some equipment and connections missing under the hood... as I said, I'm no mechanic, I don't know... but i see ports and such that seem like they should be connected... I do know that the AC Compressor and resevour are gone.

Oh, also, there is an unusual black sphere about 5" in diameter with a green tube running into, and out of it, which says oxford on it.... I've never seen anything like it, and was wondering what it is...

The black sphere is probably a vacuum resevoir. This device allows the vacuum accessories (such as the ventilation duct doors, and the manifold vacuum advance at the distributor) to work for a little bit when the engine is off or operating at full throttle, where the manifold vacuum goes to zero.

Well, it turns out my feul pump was on it's way out, with a new one in its stead, perhaps my feul economy will improve :)

maybe you could look for an old holley economizer carb. i hear they are very easy to get decent mileage out of and they are 4 barrel carbs. i think the 550cfm flow should be plenty for that lil 305 to be happy at any rpm... is the engine pretty low miles?

I don't know much about the engine... All I know was that it was put in three years ago, though it appears it was taken from another car and is not new...

I don't know weather it was rebuilt, or if it was just shoved in... I don't even know what year it is... I know there is a plate on it somewhere with a code for where and when it was made... but I can't seem to locate it.

the number you probably want is behind the driver's side cylinder head on the back of the block right by where the transmission bellhousing is bolted to the back of the engine... mine say heche en mexico lmao!!! its one of them 4 bolt 350's from mexico where gm makes them now...

Wow... talk about reviving a dead thread... Heh, but I've got /alot/ more information then I did back then, and would like to continue this topic.

I finally got the engine code: V0511SFD

Translated: 190HP LB9 305cu/in from a Pontiac Firebird, cast in Flint on May 11th, of 1987.

Now, something that strikes me as very odd, is according to Wikipedia, LB9 types are Tuned-Port Fuel Injection (TPI) engines... yet, I have a carbeurator? O.o

Speaking of which, the Carb is a 4bbl Rochester model, so, standard stock model. It's designed to be computer controlled, however none of the wires go to it anymore... except the one I installed for the AC i'm working on repairing.

As I understand, the engine was rebuilt before it was installed... but I'm affraid I'm not 100% sure...

I've since changed the feul filter, transmission fluid/filter, oil, as well as a few other basic maintanence measures.


My feul economy is down to 11.8 MPG on average... though, admitedly, I'm driving with a bit more fun... so the drop is probably my own doing *cough*


Also, I've been considering installing a super/turbo-charger. I've heard that one can help with feul economy a great deal, As well as of course a significant boost in power... Is it true it would help with my mileage? And how much of a change could I expect from one?