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CaseDawg 04-12-2004 07:23 PM

i want a 318 with good gas mileage...possible?
 
hi all, this is my fist post on this site. i have a 1970 dart swinger that has a /6 in it and i want to put a 318 in it. what can i do to get good performace out of it and still have good gas mileage? i've heard that i could get anywhere from 13-25 so i don't know what to think. i got a 318 for free from my friend and i'm debating still whether or not it's worth it to swap the 318 in for the slant 6. the slant just doesn't seem to cut it and the performance parts are pretty expensive. what kind of gas mileage could i expect from a 2 or 4bbl slant with headers and new exhaust? thanks for your help.


casey

rumblefish360 04-13-2004 12:07 AM

This is a slice of cake. However, there are give and takes to the performance end. How fast you want to go and what kind of mileage you can live with. It's a catch 22. You can do preety well without bad gas mileage.
My question(s) to you is;
How much mileage are you looking to get?
How fast do you want to go?
If it's just basic pep, your in good shape.
I yanked 20 mpg's out of my '79 Dodge Magnum with a 360 4bbl.
My mech nail 25 out of his 318 in a car like yours. So yes, it's possible.
IMO, take that slant six and ride yourself of it.

CaseDawg 04-13-2004 12:07 PM

i would like to get in the low 20's. overall top speed is not what i'm looking for. i just want to be able to get some good acceleration, maybe burn some tires, but i doubt it. what could i do to it to make it perform but with good mileage? i was thinking of an eldebrock intake and cam package for idle to 5500rpm power, a set of headers(i don't know what tube size and all that yet), a 4bbl carb(probably a remanufactured eldebrock to save some cash), dual exhaust(what would you recommend?), and probably just a 2.76 rear end cause that is all thats available to me. what do you think? any suggestions? i really don't know what i'm doing so any help would be great. thanks.


casey

MoparMarcIdaho 04-13-2004 01:33 PM

fuel economy
 
With the price going up up and away,I get this question more and more.Go ahead and put a 4 barrel intake on but consider for street use a 2 barrel on an adapter plate.Once its all set up you can change it over in about 15 minutes.Its been my experience that something off a GM (sorry guys) will do better on gas.Small baseplate off a 283-307.Lots of tricks to make the other stuff do better but this works too.;)

rumblefish360 04-13-2004 05:35 PM

My all stock 360 2bbl got a whooppping 10 mpg's on the Hwy. So I fussed around. The 4bbl 625 Carter did a better job in the power and mileage dept. hands down. Never do a 2 bbl. Never never never. There flow ratings are different to start with. So you can be fooled easy.

CaseDawg;

That rear ratio is ideal for mileage on the hwy. Hold on to that.
For the moment, skip the cam.
Open aircleaner is best.
600 cfm carb max. Holley, Carter, whatever. (I like the AVS or T-Q)
A dual plane. The Edel. Performer for a 318. (Thumbs up!)
Headers. Hooker makes them preety well. Search threads for opions and fitting problems. The with "A" bodys is room. TTI makes the best headers, but, at a whooping price.
2-1/4 inch exhaust with a nice turbo muffler. A "H" pipe would be good to use in the system.
Upgrade the ignition box. Go MoPars Chrome at a min. An MSD would be better/best.
Mopars Viscous fan or an electric fan.

rumblefish360 04-13-2004 06:12 PM

Why O why must I have only 2 min.s to make an edit?????????????????????????????????????????????? ?????????????????????????????????????????????????? ?????????????????????????????????????????????????? ?????????????????????????????????????????????????? ?????????????????????????????????????????????????? ?????????????????????????????????????????????????? ????????????????????????????:mad:

1 freakin mistake on the mouse and your screwed!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!:mad:

MoparMarcIdaho;

The adapter plate for a 2bbl. use is more of a headache to do then just useing the foot wisely. The primarys on a Carter/Holley 4bbl of 600 cfm are slighty under 300 cfm at a greater pressure drop than a 2bbl carb with a lesser presure drop.
Use of another 2bbl. carb on a 4bbl intake now requires ethier some fab work or a purchase of an adapter plate. Then you have to make the linkage work on off angles.
Why bother??????
Then to reuse the stock aircleaner???? Or an adapter ring for a 5-1/4 neck aircleaner?

I scored a cheap J-yard intake, boiled, blasted and painted for $55. Gaskets, intake, carb and valve covers, $35.
New, out of the box Carter 625 for something like $235. (???) (I forget, it's been awhile)
You could go the route of a Cheap open aircleaner for about $25.
Total, $350.00 done right. 20 mpg's from a '79 Dodge Magnum. Full tank, reggie weight of 3750. Never mind the stero, full tank of gas and me.

(Never got to headers thogh, damn :crying: I did wanna try that.

CaseDawg 04-13-2004 06:35 PM

ok, so i need to hold off on the cam. do i really even need the cam? am i going to get some good acceleration and power from the intake and exhaust upgrades? also, i found an engine rebuild package that includes a 4bbl cam for $40 more onto the overall price. do you think that is just a stock carb? would that be any good? thanks.


casey

hotrod7043 04-13-2004 07:11 PM

Ihad a 76 aspen rt bone stoxk with a 318 2bbl ir got15 mpg and ran 17.70 atsears point. we put a 3.21 81/4 and dual exhaust Tq 340 intake with a 73 400 Tq it ran 15.20s and got 21 mpg.

MoparMarcIdaho 04-13-2004 09:01 PM

OK then
 
2 barrel with adapter plate bad ju ju.On an 84 gmc short step 4x4 I had,I replaced the edelbarf performer on an adapter plate for a rochester 2 barrel off a 262 olds v8.Looked like a Qjet and took the same kit,but back of the thing was closed off, no throttle plates of anything, and brought it from 5 mpg to 17 with a 4sp.Just lucky I guess.:D

aDjUSTER 04-13-2004 09:38 PM

Case Dawg

Just going to the 318 from the 6 is going to be a power boost which should run 19's easily. Don't know what your looking for as the other posts have given you some good advice for a beefier set up than a stock 318. You mention that your looking for 20's and good gas mileage. A stock 318 will fit the bill. It will give you more performance than the 6 and will give you good mileage.

If your looking for something that will give you a seat of the pants feel with a 2:76 gear then you will have to step up the ladder a bit. Then a dual plane stock 340 manifold and carb with 1-5/8" headers and dual exhaust will take you to the next level of perfomance without sacrificing too much in the way of mileage. Again this is dependent on the way your foot reacts with the gas pedal because of the extra power. If you abuse it you will lose it.

If you want to impress the crowd with burn outs and want to run 14's then your next step is a cam with a better gear and convertor, if automatic. Possibly time to pocket port the heads and think of more compression and suspension upgrades. This route will probalbly still give decent mileage if not abused. But what is decent to you? If your looking at impressing everyone with your burn outs and are looking at your time slips in awe con't expect to get 25 to 30 gpm.

Speed is relative to the amount of fuel utilized to get there. The more you step on it the less the fuel mileage. You can get some decent mileage out of a high horsepower car if you limit the pressure on the old gas pedal. It all up to you with what you want. If your looking for some one to tell you that with this and that you can go around town full throttle, all day long, beating every other car you see and get 30 mpg then you better do a re think. All of the suggestions given before this have been good suggestions to take you to several different levels from bare stock to a good performer, but, there is no one going to tell you that you can get 30 mpg because it depends on your foot and only your foot.

Rumblefish gave you a good performer package and stated that he got some decent mileage with his package. This doesn't mean that you will get the same because you may not drive the same way as he did to achieve his results.

Every package given will give you a better performance than the 6 and will give you some decent mileage if the gas pedal is treated with respect. Now you will have to make a decision on how much power you want. Your pocket book will tell you how much you can get at this point. You can always go up from there. Hope that your decision will bring a smile to your face and you will always have the option of slowly sneaking up on better and better performance. You have a lot of options going for you with starting with the stock 318.

GaryS 04-13-2004 10:18 PM

Gas mileage in the 20's is a snap with any 318. My stock '68 Fury III got 22 on trips. My '85 Fifth Ave got as high as 25, but didn't have near the performance of the Fury.

One thing to remember, if you dump the slant, you will also have to swap the transmission and driveshaft. If you have a 7-1/4" rear end, it won't take many burn-outs before you are looking for an 8-1/4 or 8-3/4. Those rear ends for A bodies are getting rare and expensive. Also don't forget a new radiator, exhaust system and a bunch of miscellaneous junk. If you have 13" tires and wheels, you will need to get 14" rims and bigger tires.

Oops!...almost forgot. If you have 9" brakes, they won't begin to stop that car.

I would suggest that if you want a V8 powered car, that you trade yours off. Unless the body is super cherry, you will spend far more swapping engines than swapping cars.

Also don't sell the slant short when it comes to performance. A Super Six setup with duals and electronic iginition will put you in about the same performance and mileage range as a stock 318 and for a lot less money than a swap. I've seen several street driven slants that easily run 15's and that's not shabby.

rumblefish360 04-13-2004 10:54 PM

aDjUSTER
Quote:

Rumblefish gave you a good performer package and stated that he got some decent mileage with his package. This doesn't mean that you will get the same because you may not drive the same way as he did to achieve his results.
Thank you, the secret to the mileage is a light foot on the thottle and a lean jetting on the carb. Steady, constant speed on the Hwy. was how I deterimed max mileage. Drove the car till near empty and filled up. Did the math. best I ever got was 22 mpg. But that was not constant every week. Overall, it was 20 mpg for the norm. It would dip to 17 if I was a little heavy on the pedal, out who-harring.

CaseDawg;
Quote:

am i going to get some good acceleration and power from the intake and exhaust upgrades?
Yes! This is the basic bolt on horse power mods. They do not really tax the engine. There just letting the power free instead of being corked up.
Lay of the cam for now. If you want to try it out later, do it. Just save the old cam. Oil it down and wrap it up in plastic wrap. Like your Mom used for storeing food in the fridge.
This way, if the new cam is not the "IT" you were looking for, it's just a afternoon to swing it back in.
Otherwise, doing a cam swap, the right way, will included the extra price of timing chane, springs and possible liffters in addition. This can add up fast. Lets do the K.I.S.S method first. (Keep It Simple Silly) It'll also save you money.
Quote:

do you think that is just a stock carb?
In the rebuild kit?
The stock 4bbl carb that came on a 318 is the small T-Q. The only other carb I would use is an AVS. But thats me. You'll only need 600 cfm for this engine. MAX. Holley, Demon, Edel, OE Carter AFB, AVS, or T-Q or a Rochester. Whats your flavor?
Will it be good you ask? Ans. Yes. It'll be fine. Not to worry.
Read GaryS post on possible parts needed. The slant6 tranny will not bolt up. New driveshaft needed. Rear end is fragile if you start upping the power anti. Don't beat on the car with that rear. (Boooom!) An 8-1/4 will do. Plenty of them around.

MoparMarcIdaho; Now I see where you got some of that mileage. 262 carb ='s a lean runner and smaller carb probably. That 262 made in the 80's? (Mom had one in a Cutlass.)

CaseDawg 04-14-2004 12:40 AM

thank you all for your input. this is what i know about the swap that i should have told you all that i knew when i started this thread. i have to put in a bigger radiator, V8 904 tranny, 8.25 rear end, new driveshaft, kickdown linkage, bigger tortion bars, i'm getting some 15in cragar ss wheels, i have disk brakes on the front, i might eventually get a sway bar, some of those nifty engine mounts that make it so i don't have to swap the k-member, the 318 of course(which i have already, got for free:D), i think thats all that i need. its getting late and i can't think. any suggestions? one of you said that i should put the stock 360 intake on, is this a cheap and easy way to gain HP and mileage? all this just is probably going to happen next year. i'm saving for wheels and paint right now. i'd rather have a sweet looking car than one that has power but just looks ok. don't you think? thank you all.


casey

rumblefish360 04-14-2004 01:48 AM

Quote:

i'd rather have a sweet looking car than one that has power but just looks ok. don't you think?
Yes and no. I'm saving bucks for a good looking Dodge Magnum. (My second Magnum) And my Cuda is a hooorrrroorr show on the body. Likely to stay that way. (Owner of the Cuda for the last 16 years)
Do the performer from a swap meet. (Cheaper) over the 360 intake. Ports line up.

68fury 04-14-2004 09:01 AM

hey GaryS - good choice of cars there! I have a '68 Sport Fury and a '86 Fifth Avenue...

No idea what that Fury does to the gallon but its better on gas than the fifth which gets about 15-18 MPG. I've never got 20 out of it. but its still all fitted up with the emissions junk and lean burn. I'm happy reading about the guy with the Aspen as its similar size car and gets about the same gas miles and 1/4 time as my fifth does now, and I've got the parts in for the same kind of upgrades, so I'm looking to get the same kind of improvements I hope...

hotrod7043 04-14-2004 09:36 AM

my aspen was done back in 79&80 good have got 24 to 25 with todays stuff my boss had a 79 lebaron 318 4barrel lean burn got 24 all day long goin to tahoe from the bay area. was a demo so he never kept the car.

GaryS 04-14-2004 09:47 AM

Quote:

Originally posted by 68fury
hey GaryS - good choice of cars there! I have a '68 Sport Fury and a '86 Fifth Avenue...

No idea what that Fury does to the gallon but its better on gas than the fifth which gets about 15-18 MPG. I've never got 20 out of it. but its still all fitted up with the emissions junk and lean burn. I'm happy reading about the guy with the Aspen as its similar size car and gets about the same gas miles and 1/4 time as my fifth does now, and I've got the parts in for the same kind of upgrades, so I'm looking to get the same kind of improvements I hope...

I had two Fury III hardtops. The first was baby blue and it was the first new car I owned. It was absolutely trouble free and I traded it at 98,000 miles. It's the only car I truly regret losing.

The second was equipped exactly the same, but was metallic brown. I drove it as a second car for a few years and gave it to my daughter when she got her license. It too, was a wonderful car and trouble free, though I did give it a valve job at around 100,000.

There is something wrong with your Fifth Ave, if you are getting only 15-18. Mine never averaged less than 18 with all in-town driving. Typical on the freeway was 22-23, while running at 70-80 mph. Mine was completely stock, with lean burn and all emissions controls in place. I think the gearing was something like 2.72:1, so it wasn't quick off the line.

skydome 04-14-2004 10:16 PM

My secret recipe
318 short block, put in a windage tray and 360 2 bbl cam. Add 360 heads and TQ setup. MP distributor and good plugs/wires. 340 manifolds and a good set of duals.Low first gear 904 with lockup convertor. 8-1/4 axle with 2.94 gear.
I had this setup in a 3800 pound loaded Valiant Brougham. It turned low 15's all day, and gave 21 MPG at 75 MPH
Your mileage may vary

CaseDawg 04-15-2004 12:45 AM

thanks, skydome. i was wondering, whats the windage tray? i'll have to look into those parts. can i get most of them pretty cheap? and that's a stock 2bbl cam? if you don't mind me asking, what is the TQ setup? thank you for your input. is there anyone else out there who can give me their 318 setup and what mileage they get? thanks all.


casey

rumblefish360 04-15-2004 02:52 AM

Allow me skydome;

A 360 cam is slightly larger. Specs are not on hand, but I can dig'em up later. A windage tray is a simple device. A flat metal plate, bent like a "U" that attachs to the engine mains (Under the crankshaft) with holes or cut outs to allow oil to travel down, not up and hit the crank. This mod is worth 15 HP upstairs.
A "T-Q" set up is a Thermo-Quad (T-Q) carb and intake manifold. (Thats ethier a stock 360 4bbl/318 4bbl intake or an Edel. Performer/Weiands Action+ intake manifolds.)
Windage trays are cheap from MoPar or Milodon etc...
You need to get a few books. How to rebuild and hot to hot rod my small block moPar andthe "Engines" book for the small block MoPar from MoPar.
These books will answer alot of your question and intro you to alot of parts. Of course, it will generate alot of new questions, but we'll be here.

CaseDawg 04-15-2004 11:56 AM

i'm been meaning to buy some of those books, but at the moment i have to conserve money for prom this weekend. after that, i'll gladly pick them up! is a stock 360 intake fairly cheap and easy to find? thanks.


casey

rumblefish360 04-16-2004 02:10 AM

Quote:

is a stock 360 intake fairly cheap and easy to find? thanks.
Heres the kicker in my side to this.
Yes, there preety easy to find. They should not be to hard.
When I got my first one, I paid the pocket emptying sum of $25! 1 year later, I go back for another, and the guy says to me, "There rare right?" I'm like not really. He comes back with,"But the gas crunch was on and nobody wanted a 4bbl."
The end all was he wanted $175.00 for it, and it's being shipped from Mich. (Price did not included shipping this 2 ton heavy thing.) My response...
:dis: Your kidding right. He got a little attitude.
So I just , :crazy: and said I can get an aftermarket one cheaper. He said go get it.
OK, Hello Summit, yea, I'll take one of those new Edel. RPM manifolds please. Thank you. (Cell phones are great for a quick dial in front of someone loosing a sale.)

Enjoy your prom, I did, I think, wait, no, that was the senior trip, no, wait, er-ya, no, I was wrong, that was the prom. (I think):D
Get home safe, use your head, the big one on top of your neck. ;)

CxCx 04-16-2004 02:55 AM

Wondering
 
If you keep your foot out of it :D couldn't you get better MPG w/a 4bbl than a 2bbl, considering the size of the primaries on the 4bbl? CxCx

rumblefish360 04-16-2004 09:35 AM

Now your catching on.
Yes, to a degree. What are the primary sizes?
A 2bbl is rated differently than a 4bbl.
This is also why a T-Q is recomended so much here on hot street / street strip cars. The primarys flow around 200 cfm.

avhoppet 04-16-2004 04:58 PM

Re: i want a 318 with good gas mileage...possible?
 
Quote:

[i] what can i do to get good performace out of it and still have good gas mileage? i've heard that i could get anywhere from 13-25 so i don't know what to think. i got a 318 for free
casey [/B]
I got 20,57 mpg with a 528 Hemi with tunnel ram and a 264 @50 cam. 3000 pound car and steady no trottle movement 65 mph constant speed over 100-mile distance. The solution is port fuel injection. Then we can program a perfect ignition timing and fuel delivery at cruising speed without sacrifice at power.

Ok, itÂ’s a bit of trouble if used to carburettors, but still possible.

Goran Malmber

CxCx 04-17-2004 10:20 PM

T/Q
 
Quote:

Originally posted by rumblefish360

This is also why a T-Q is recomended so much here on hot street / street strip cars. The primarys flow around 200 cfm.

So the primaries on the T/Q flow about 1/2 as much as a 2bbl, hmmm......Now, if only I could lighten my foot. lol :D CxCx

rumblefish360 04-18-2004 11:04 AM

T-Q primarys flow only about 200 cfm.

pipelineaudio73 04-18-2004 01:21 PM

I had a 73 318 automatic 904 duster. I put regular cheapie headers, dual 1 3/4" exhaust, no balance pipe, an ld4b ( I think) intake, mopar orange box, and an edelbrock 600 on it.

It got gas mileage in the 20's, and ran consistent mid 14's while spinning the tires down the track on a peg leg rearend.

If you follow the better advice from others on this thread, itll only go even faster than mine did. Even mine had NO trouble burning out all day long (of course it was only one tire but hey)

CaseDawg 04-19-2004 01:25 PM

so will a 7.25 rear end be enough for a souped up slant that i'm not really going to be burning out with, just some decent acceleration out of turns and that sort of thing? because that could make my life a whole lot easier if i just got a 7.25 with a 4.5in bolt pattern instead of putting in the 8.25. i also read that the 7.25 with the 4.5in bolt pattern was made with disk brakes. is this true? are they any good? cause that would be sweet since i already have disks on the front. thanks



casey

goose 04-19-2004 01:49 PM

Case, one important thing to look into is exactly what engine you have; there were a few different varieties of 318 made which can have a noticeable effect on your power and mileage. They came with a few different kinds of heads and intake manfolds etc. Do you know what vehicle and year the 318 came from?

The 7.25 rear end ought to last ok with your 318 as long as you don't drive it too hard very often. If you wanna get into the throttle more then the 8.25 will be needed.


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