Daily driver small block build
Whatever you do, the quickest way to lose cylinder pressure is with a wide LSA cam, and with the loss of pressure, goes the fuel economy.
Bingo!
Oh sure, you can get away with using the stock Magnum cam but look where the factory installed it!
Magnum heads on a Magnum engine deliver a 9.0-1 or slightly less ratio. Mine runs well on 89. On 87, regarding the timing is needed and mileage gets lost. It’s a catch 22 between the mileage I get with more expensive fuel that can at times be closer to 93 octane in cost or the cheap to fill the gas tank 87 and less mileage. I still have to play around with it to find a better balance. Hummm, I think I’ll change the cam out for more power instead.
If yur serious about fuel-economy, you need cylinder pressure. And if yur going that route, yur doing pistons. And then it don't matter anymore as to LA or Magnum.
The easiest engine to get pressure with, when doing flat-tops, has the most swept volume, and the tiniest closed chambers, so you might as well marry the Magnum heads to whatever flavor 360 cubes; then pump the Dcr up to around 9.0. Good luck running that with iron heads. even on best gas. and forget the stock Magnum cam.
AJ, as I stated above with my Magnum
So
at this level you are looking at Pistons, boring, decking, a crank rebalance; plus alloy heads, a cam kit, an induction set-up, and an ignition system, and yes headers and a free-flowing exhaust system.
Not on a good Magnum core.
So basically, from the 360/5.9, all you will be reusing is the engine block, the rebalanced crank, maybe the rods, and the various covers..
You might as well call up one of the vendors, and just order up what you want, and have it done right in the first place,
And that's
AJs Opinion.
Hands off = EZ button. Sometimes that pays. No issue here.
Or
you can do just slam some tall crown pistons, like KB107s into a 360/5.9, which sometimes come in at .012 below deck on a LA
.020 on my LA
that with an .028 gasket and closed-chamber ALLOY heads will get you a nice decent quench, a nice Dcr potential, and
To much! Lighten the quench up for regular fuel and a small cam.
Then you can reuse the oddball Magnum cam and time it just about anywhere you need to, to get the pressure DOWN to 87 gas,
Get a better cam rather than alter the OEM unit. I wouldn’t really move it more than 4*’s, which is a lot.
which will then get you a buncha power duration,
How does moving the cam around net you “A bunch of duration?”
to really suck the energy out of the hot gasses. With this combo headers are optional, cuz there is not gonna be much effective overlap to speak of.
Find the video by Richard Holdner where he puts on a set of huge 1-7/8 headers on a 360/300hp crate engine with a M1 dual plane, 1/2 spacer and a 750 Holley.
Power goes up everywhere and the fuel curve levels out making it more efficient.
I put Hooker 1-3/4 Super Comps on my 2000, OEM 5.9 Magnum with a RPM, Edelbrock 600. Excellent response, good mileage. 3.55 gears on 26-1/2-ish tires and a 727 in a B body that gets 18 mpg @3800+ lbs.
Looking forward to an OD trans.
But, you still need a free-flowing dual exhaust.
100%! Use headers!
Even without EFI, this might go into the mid to high 20s mpg, if not, an overdrive will get you close to 30. IDK how much power it will make, and don't care, cuz the low-rpm torque will be ridiculously much fun. Run it with any gears/any stall/ and wipe that sillygrin off your face. lol.
The only thing that could make it better would be the 1-2-3 combination of deeper gears, overdrive, and a LU convertor .... like
3.73s/A518LU/65=2130rpm; with a starter-gear of 9.14 or
3.23s/A500LU/65=1840rpm; with a starter-gear of 8.85
both with 26.5" tires.
Rear gear ratio multiplied by what first gear?
Or if you like to row gears, how about the Commando 4-speed with a GVod behind it, and 3.23s, for 65= 2040 and a starter of 9.98
Course if you have this hi-torque 360, you could probably get away with the A833od (3+1) and 3.23s, for 65=1950 and a starter of 9.98. Second gear is a lil shy at 5.39 but for a DD should work out Ok, cuz with it, 35mph is a nice 2400 rpm.
I like rowing gears. I found a A833-OD for my ride.
Thanks everyone for all the advice. Sounds like either 5.9 or 5.2 magnum makes the most sense. Probably leaning towards the former but I'll keep my eyes peeled for both. Not having to bring the block to the machine shop would be great, which it sounds like is totally possible with a magnum. I'm not that concerned with gas mileage, 12 in the city would be tolerable.
Sounds like a 5.9 magnum with a small cam, thin headgasket and 650 holley would be about right. Already have a good exhaust system, and a ford 8.8 is the current project.
I like the 360 over the 318 unless the car is light and the gear ratio is right for high mileage. In an A body, if it is light because there not all as light as we would hope, the 318 can do very well once at highway speeds.
What is your gear ratio and cars weight.
I think AJ offered some good tips if not a little confusing.