Replace the 318 with a Slant

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oneway71

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So I am thinking of replacing the 318 in my 3/4 Dodge truck with my 225 2brrl that I had built a few years ago.

Reasons are mostly mpg the 318 is runs great and has no problems.

How do these trucks do with the slants? Should I still get about 28 mpg or will it drop to 18?

Is it worth it to swap the motors?

I am not driving the car with the slant because it needs the whole suspension and brakes done.
 
I think you would get better MPGs with a 318.

You will need to have your foot so deep in the throttle with the /6 that you wouldn't gain anything from the swap..

(Thats my theory anyway)
 
is the slant motor stock or have an "RV" cam in it? probably easier to stick with the 318.
 
I had an 86 D100 w/6 it got about 15mpg when it was new,after about 60,000 miles the best it would get is 12mpg,I tuned that thing every way I could with no help.I put 180,000 miles on tha t truck before I traded it in on my 01 Quad Cab 1500 with 5.2 and it gets better mpg,16 consistantly.Keep the 318 just my .02
 
Looks like my experience is the same as the others here. I've had both as a daily driver and the 318 engine was the better option. My 225 2bbl combo never got better than 15MPG but the 318 would get 18 at times....16-17 most of the time. Plus the 318 has way more pulling power. Both are very reliable engines but to me the costs involved in the changeover wouldn't be worth while.
 
oneway71 said:
So I am thinking of replacing the 318 in my 3/4 Dodge truck with my 225 2brrl that I had built a few years ago.

Reasons are mostly mpg the 318 is runs great and has no problems.

How do these trucks do with the slants? Should I still get about 28 mpg or will it drop to 18?

Is it worth it to swap the motors?

I am not driving the car with the slant because it needs the whole suspension and brakes done.
Click to expand...

You're getting 28 mpg in a 3/4 ton truck with a 318?
 
ESP47 said:
You're getting 28 mpg in a 3/4 ton truck with a 318?
Click to expand...


No I am getting high 20's with the slant with 2 barrel. The motor was rebuilt and has few thousand miles on it in the orange '72.

I will probably keep the truck stock and save the / for my other Duster.

I am disappointed with my 2001 Jeep Grand Cherokee ltd 4.7 that only gets 12mpg. It has 6 thousand miles on the new motor. I am going to sell it and drive the truck.

I just need better mileage and thought the / would do well in the truck.

As for trans I was going to use the 3 spd in the car.

Thanks for the input.
 
If your getting high 20's outta the /6 in the Duster/Valaint and need the mileage, leave it in there. IDK about swaping it in to a V8 K frame though. Maybe one of the /6 nutz know how to do that.

The truck is higher up in the air and has more wind resistance. Bad for mileage. Leave the 318 in there for the ability to get the truck moving well and quicker since the 318 has more torque.

For a small price, the basic tips for mileage can be used on the 318 for slightly better mileage.
I'd start with a;

MSD ignition, or equal.

Headers for trucks are easy to get and can be had inexpensivly.

Dual exhaust you can do yourself easy. A simple system of striaght pipes from the header into the mufflers and a 90* bend to exit out the side by the rear wheels can be done very cheaply. Inexpensive mufflers like a set of Thrush's will be quite enuff for most everybodies neighbor.

Super tune the carb you have now.
 
I am a big slant fan, but if the 318 is in good condition, I would not pull it for the slant, to get better fuel mileage. Too much work involved, for the mileage gain, if any, and you would lose pulling power.
 
Thanks for all the reply's; I will leave the truck the way it is. I am still going to sell that Jeep with the horrible gas mileage, partly because of the EPA and part full time 4x4. Then back to driving the truck everyday.
 
Good choice.
Slant 6 in a truck is ok if you don't pull anything very often and you like shifting down and going uphill at 40 mph unloaded.
It probably wouldn't get better milage than the 318 unless you are on the flat.
And no passing power at all.
My 2 cents.
 
Dartnut said:
Good choice.
Slant 6 in a truck is ok if you don't pull anything very often and you like shifting down and going uphill at 40 mph unloaded.
It probably wouldn't get better milage than the 318 unless you are on the flat.
And no passing power at all.
My 2 cents.
Click to expand...



Sounds like time for a turbo.... probably cheaper than swapping in a V8...

________________________________________________________________
I'll forget sodomy by a frontal lobotomy on some other part of me....
 
My 2 door,king cab, 2 wd RAM with the 318 got well over 30 mph + on the highway..it was a very big shock to move to a 06 Ram Hemi 4wd. And my record weight carried (with rear air bladders and 10 ply tires) was about 2 ton. The local chrysler dealership couldn't tell me why it got this millage as well. Went to trade it in to a non chrysler dealership and the sales rep called my a liar. End of sale. ....the box was bigger by 6 inches..you would be surprised how much that made a difference. Unfortunately, it self distructed in a specutactular way @ 170Kms and I sold it for scrap.

It started out a s a long haul 5 wheel rig..the rear gears must have been changed but it felt really powerful and not a slug carrying 1000 pounds and pulling a 25 foot trailer.

I would think a /6 in a 3/4 ton would be underpowered and end up costing more..
 
Yeah I decided to leave the truck as is. I am going to pull the /6 from the orange Valiant and put it in the Duster that needs a motor and use it as a daily driver until I can get the suspension and brakes done on the Valiant.

Thanks for all the input.
 
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