318 drinking gas like hell

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mopar_persson

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hey have a 318 in my Dodge van that drink much gasoline,
it's a carter 600 cfm on the engine, with 395 nozzles in the primary ports, and 385 at secondary ports. I have tried to put in 385 nozzles in the primary ports but then it spits and spark slams only and runs really bad. it's a new distributor on it hei style, set on 12 degrees. it consume around 0,76 gallons on 6,3 mils

help me to make it drink less gas.
sorry for my bad english
 
You need to jack the base timing up to around 17 btdc. Other than that... I don't know. Factors like rear gear ratio, weight, aerodynamics of a van, make a difference too.
 
To many variable here to even guess..................and as Red said

gearing of the van...........

what sort of driving...........if this is not highway driving, then the figures mean nothing

what is the timing, the advance, that is the total advance, is it working correctly, and is the vacuum advance working?

What is the manifold? Torker, example, would be a poor choice for "torq" engine and mileage?

What are you running for camshaft?

Could it be that the timing drive is worn?

How many miles on the engine, what shape is the engine in? Bad valves? Worn otherwise?

And if you folks are using alcoholized gas, that does nothing for mileage, either

And..........................on........................and .......................on................................
 
auto trans? = bad mileage if it's the old style converters
360 heads on 318? = bad mileage because of loss in compression, you have to give more gas to compensate and boy do they flow better
headers are better for mileage than stock manifolds.
dual exhaust is better for mileage than single
thermoquad carb is better for mileage than most of the others.

------ summary -----
4-speed, thermoquad, headers, dual exhaust and the right compression ratio (9:1 or higher) will get you good mileage.
 
Is this something that has just started or has it always sucked?
 
Any information beyond "318 in my dodge van" would be helpful

please state the year of manufacturer and vehicle tare weight.

Please state any and all known modifications including but not limited to
Camshaft, Intake manifold, Cylinder heads, Fuel pump, Pistons, torque converter etc.

The more information you can provide to us, no matter how seemingly unimportant. The more accurately we can help you diagnose a fault.

If it is a standard unmodified motor and I had to take a guess I would be looking for a vacuum leak.
 
also, does the engine's exhaust blow black smoke or smell of gas at all?
 
the engine and the van is from 1988 so it has been a tbi from the start, but I put on the carburetor because the tbi dident work.

the intake is a edebrock performanc plus, and the carb is a carter 600cfm,
the heads has been rebuilt with machined valves and new seals so they are totally sealed, no blue smoke the heads are 302 with close chambers . the cam is a original roller cam, the pistons is flat top, the fuel pump is a carter mechanical,

the gear in the axel is 2,76 and the gearbox is a 904 lock up that works great.

it has always drink alot of gas when highway driving.

it has stock manifolds and dual exhaust with H-pipe.

the engine is in very good condition

the van weighs is about 2900 kg or 6393 pounds
 
Put a new cam and timing chain in it and degree the cam. The chains in the newer mopar motors were junk and caused problems from the beginning. One reason they went to a tension-er on the later motors.

The tension-er keeps the chain tight on the slack side for guarantee.It also moves the cam timing as wear progresses. Also none of the cams were degreed. They were ground and installed straight up with where ever the keyway put them.

You will all find that this is a great improvement on performance and fuel mileage on any motor. Something the factory did not take the time to do on all builds. And the reason why some ran better than others. We degree all cams on motors we build. Or if just replacing the chains. Most of them are way out on timing if installed , especially with cheap chains.
 
And then dig into the distributor curve and find out "what it is doing."

Do you even HAVE a distributor which advances, or is it locked?
 
If you still running the factory electric fuel pump it needs to be regulated down, it is way to high for a carb.
 
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