360 options for mileage and performance

[71dusterdan]

Hey guys, thanks for the comments...all of them! I did not mention that I do in fact have a set of Magnum heads. I am also willing to do what is nessecary for good quench. I have been reading Steve Dulcich articles for years where he was a big proponent of quench. I know 20mpg, and 13's is a tall order, but I do believe it can be done. However the rest of my car might be the killer....245's on the front and 275's on the rear wont help much. I am glad to see the thumbs up on the od trans, seems everywhere else I turn it gets beat down pretty badly. Call me a dummy, but I just have a love for the idea behind the Thermoquad. I have never run one, but I own a couple, and have had them tweaked by a guy goes by Demonsizzler on Moparts. Oops I lied, I did install one on my last f250 and it was fun. I would be interested in hearing about more engine combos like the one brought up earlier, I was also thinking smallish cam. thanks again everyone!

 

[yellowdartdave]

The great thing about a Thermobog is you run around on those small primaries, which are great for fuel mileage and response, and you have those huge secondaries that are standing by, waiting to suck in the hood at full throttle.

Don't ask how I know of this....just watch any Dukes Of Hazzard chase scene.

 

[dodgetkboy78]

The secret to good MPG and power..........


Compression about 9-1.
Smallish cam, think 260 ISKY/COMP, degreed in dead nuts, higher ratio rockers. (stock 360 cam was 252 if I recall, with a real low lift)
Lower ratio accessory pulleys.
Cool air for the carb.
Well tuned metering rod carb.
Distributer timing.... with the vac advance ran funky (in minute)
Headers, smaller exhaust, X or H.
Chambered mufflers like aerochambers.
mild gears, like 3.23. Key is to run the engine about 2300-2600 at cruise, 2.76 gears take more power to get the car moving, and you stay longer in first/second which robs power compared to first.
Skinny (ish) front tires.
Drum brakes. (yup, and don't argue with me)

Here's the MPG distributer thing.

I like a distributer with about 18* of advance, all by 2400RPM, then, I run the total timing right at 36*, limit the vacuum advance to about 6*, and hook it up to manifold vacuum. It will be tricky with carb tuning, and sometimes you have to re-work the carb butterflies to get the idle to close small enough to idle where it should, and drill out the idle circuit a bit to get the mixture rich enough to feed at such a low throttle setting. The carb has to be in real good shape, any leaking shafts and it won't idle low enough.

The theory, is that timing is running pretty far advanced at idle, AND cruise, but when the throttle is opened, the vac drops the timing off and you basically run on mech advance.

It's a tricky lil ***** to tune, but I have done it to a couple of my trucks, and got over 20 with a dual port manifold, 3.55 gears 71 D200. I also have done it to a few Fords, like M blocks and 460's, and even got 17MPG out of a 429 power, C6 transmission F250 4 door, with 35" tires. (Todd palins Green 78, FYI)

But if you aren't a tuner type of guy, don't try it!

 

[rumblefish360]

While the Magnum heads will help compresion, you'll have zero quench due to the OE piston being deep in the hole.

 

[Supershafts]

My truck at 418" will do 17mpg between 60 and 68 mph, and nearly twice the weight of your duster...on 35's and 4.10's w/GV.
You can buy it.....

418" w/demon AN VS carb.... Though the heads are modified and the piston is a custom quench for that head, if she shed the additional 3250 lbs probably could get 20 mpg or better in a light duster...


Why you're shooting to do that with a 360 is beyond me...

Stay away from the mag junk....

The mag head is a fix for 2 motors that have 2 unique differences between them, and was a money issue so mopar didn't have to have a 360 head and a 318 head anymore, but have 2 motors that performed better...

Why everyone is so in love with that **** is beyond me.

Yes i built a mag motor to duplicate another stroker i had, to the t, except it was mag junk, guess what it didn't do.... it didn't perform.

Mag heads are great for a 7.8 to 1 stock 1973 318... after that, scrap.

 

[Supershafts]

Me personally I think todays cars get good mileage from a combo of things;
A) ligghtweight building materials
B) tecnology like direct injection,fuel inj,multispark ign,modern combustion chambers etc etc
C) Multiple gear tranmissions like 5,6 and 7 speed transmisions are a huge advantage
D)Aerodynamics.Flush mount glass,door handles and slippery shapes really help mpg. I think this is where many restomods fail to take advantage. Not many guys mod the body for better air flow! Heck even a simple splitter on front and diffuser out back will help.

A).....lightweight, what new fat bastard car have you weighed that is light....
New cars are weigh what suv's did in the late 80's and 90's

D)....A air dam will help, splitters will add down force, and not done properly will add drag

Also aero doesn't work or have any effect until after 75 mph...

 

[dodgetkboy78]

The mag head is a fix for 2 motors that have 2 unique differences between them, and was a money issue so mopar didn't have to have a 360 head and a 318 head anymore, but have 2 motors that performed better...

Ever driven a stock 318 magnum? What a turd.

 

[Supershafts]

Yes actually i own a few, want to buy some junk?

 

[needsaresto]

Hey if thier junk why not give em away?lol...

 

[dodgetkboy78]

Yes actually i own a few, want to buy some junk?

Hell no.......... Weak over 300RPM, and even weaker under 3000RPM...

They too all that a 318 was good at, and ruined it.

However, my 95 has 218K miles of plow truck duty, is weaker than a stale jar of Kool Aid, burns some oil........ BUt has lasted.....

 

[Supershafts]

I got 400+k on my dak...