Calling all 318 guys....318 vs 5.2 magnum, info needed please

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ValerianMagnum

ValerianMagnum

the little car that could
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montreal , canada
Thinking about buying a 5.2 magnum complete for cheap..or i have a friend who sells me a 1971 318 base with 30 over pistons...., i want to go with a 318 to replace the 340 that i never had , always played with 5.9s....but im sure than a roller cammed 5.2 carburated can kick *** for my 71 cuda ......5.9 needs a 700$ flywheel and a 5.2 is internaly balanced like a old 318.....whiplash cams sound incredible with the old 318s....im shooting for 300hp but the cheapest way possible to hook up with my 1971 a833 4 speed and 3.23 gears.... old 318 ? Seen a 1990 roller 318 for sale , 5.2 magnum ??? Or plain Jane 5.9 ???? Im going carburated and 4 speed..let me know please
 
I run a 5.2 Magnum out of a 94 pickup in my 72 Valiant. Magnum intake and carb, regular small block distributor, flywheel and 3 speed manual out of an Aspen, earlier small block timing cover and water pump and alternator brackets, 50 dollar set of used headers, it was easy. I believe some of the later Magnums have a different vibration damper.
 
And...are you satisfied, stock cam, enough power ? ?? Connect an engine to my 4 speed A833 and cheap solution is my priority right now
 
It goes pretty well but it’s not geared right, it has an 8.25 with 2.71s which is a little tough on the clutch from a standstill. Incredible fuel mileage, I took it on a 13 hour road trip and it averaged 25 MPG. I have a set of 3.55s out of a 90s Dakota to put into it when I find a sure-grip. I am leaning towards a 5.9 but that balanced flywheel is out of the budget right now.
 
If you want that 340 you never had out of the 5.2, then sonic check it for the max bore and go there. While I doubt you’ll get to the 4.04 bore size, it’s the bigger bore size that that top end charge the 340 is known for.

I did a 5.9 in a ‘79 B body Magnum w/a 727 & 3.55’s on 245/60/15’s. RPM intake, 600 Edelbrock carb, super comp 1-3/4 into a 2-1/2 exhaust JY distributor. I used a B&M flexplate to couple it all up. It was good on power until approximately 4500 rpm where it started to odd over. A cam to replace any stock one is a good place to seek additional power and rpm.
 
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I was thinking to bump it up a little....with this cam , or a whiplash cam...but i always heard that a big cam and low compressions 318 are a no no....
 
212 @050 is a good replacement street cam that should deliver that 350 hp for you. I like that cam. Are you running the stock FI?

Those are not big cams in anyway shape or form. Add 30*’s @050 and now your in that range.
 
$700 flywheel?

$350 gets you a Mcleod SFI flywheel that utilizes bolt on weights for different engine balances, I run one on my cast crank 340 Duster and one in my 5.9 mag powered W-150.
 
ValerianMagnum said:
Thinking about buying a 5.2 magnum complete for cheap..or i have a friend who sells me a 1971 318 base with 30 over pistons...., i want to go with a 318 to replace the 340 that i never had , always played with 5.9s....but im sure than a roller cammed 5.2 carburated can kick *** for my 71 cuda ......5.9 needs a 700$ flywheel and a 5.2 is internaly balanced like a old 318.....whiplash cams sound incredible with the old 318s....im shooting for 300hp but the cheapest way possible to hook up with my 1971 a833 4 speed and 3.23 gears.... old 318 ? Seen a 1990 roller 318 for sale , 5.2 magnum ??? Or plain Jane 5.9 ???? Im going carburated and 4 speed..let me know please
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In what you have listed, my pecking order would be 5.9 mag, 5.2 mag, then the LA. And yes, I personally like the LA rocker shaft better. Truth is, all 3 will work.
 
No....not for now unfortunately $$$ wise i might go with a fitech or holley efi later one...i would love to keep it factory efi but running a 4 speed and having an auto pcm..f*cks everything up and im not a efi wizard either....just want a dead dead reliable combo and goodin gas etc....i want something as powerfull as the 340 but more reliable and cheap.
 
Its still more expensive to buil the 5.9 than the 5.2...i have a bunch of parts of old 318s ad 340s cranks etc...i love love the 5.9 but something tells me that a light rotating 5.2 can really be the key....*** do the 89-90 318 roller cams share the same cams than the magnums ?
 
ValerianMagnum said:
Its still more expensive to buil the 5.9 than the 5.2...i have a bunch of parts of old 318s ad 340s cranks etc...i love love the 5.9 but something tells me that a light rotating 5.2 can really be the key....*** do the 89-90 318 roller cams share the same cams than the magnums ?
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no and yes. Yes you can interchange them, no because one is ground for a 1.5 rocker ratio and the other 1.6 rocker ratio. I right now have a '89 roller 360 cam in a 360 magnum.
 
KB107s are advertised at 502 grams, lighter than most 318 pistons. My 367LA revs like lightning, to anywhere I want it to or dare to.

but with 3.23s it hardly matters because 60mph is less than 4700rpm with 26.7 inch tires, at the top of 1.92 second gear. Try not to get caught up in the horsepower crap, even 250 hp can spin 245 street tires all the way thru first and most of second.
The whiplash sounds great and all but but it ain't easy on gas, IMO, better to go for efficiency and sacrifice the funny-car idle. Ok Super-Stock idle.
If the 3.23s gotta stay, with the 2.66 low gear of the regular 4-speed, then IMO get one of the bigger engines so you can run less cam, for more bottom end, cuz like I said; 60= less than 4700 with 26.7" tires, at the top of second.
And 32 mph in second is 2500, so the 318 will be sucked out unless you downshift, then the Rs will jump to 3560, which will be right at the very bottom of the power curve. Right at the very bottom. While you are busy downshifting, and learning how to slip the clutch, the guy in the next lane with an automatic will be LONG gone. So get the biggest small-block you can, with a modest cam, to pump up the take-off and low-rpm power.
my opinion
Now, if it was me, with a 318, those 3.23s would be long gone.

From the decks down, a 340 is just a big-bore 318 ; don't lose sleep over never having had one. A 5.2 is as strong on the bottom, and not far behind on top.
That's why I'd go for the 5.9 or 360LA.
But If I fell into a cheap zero-decked 318LA, well that's sortof a no-brainer.
 
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ValerianMagnum said:
Thinking about buying a 5.2 magnum complete for cheap..or i have a friend who sells me a 1971 318 base with 30 over pistons...., i want to go with a 318 to replace the 340 that i never had , always played with 5.9s....but im sure than a roller cammed 5.2 carburated can kick *** for my 71 cuda ......5.9 needs a 700$ flywheel and a 5.2 is internaly balanced like a old 318.....whiplash cams sound incredible with the old 318s....im shooting for 300hp but the cheapest way possible to hook up with my 1971 a833 4 speed and 3.23 gears.... old 318 ? Seen a 1990 roller 318 for sale , 5.2 magnum ??? Or plain Jane 5.9 ???? Im going carburated and 4 speed..let me know please
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$700 flywheel? $285.55 and in stock.
SCIENCE FRICTION Billet Steel Flywheel, SFI Quality, 130t/10.5", 360 Magnum, 6-bolt - American Powertrain
 
I dont need necesseraly to stay with 3.23....i know i ask a lo but my last 2x 340s and las 360la were miserable in traffic and overheated like crazy all the time no matter what....im thinking since in my area ( montreal , canada ) the 5.9s are getting rare and expensive and forget the 340 blocks...i saw on internet some 1989-90 318s and 5.2s for like 150$...5.9s they go for 600-900$ more..i did everything i could for the body of the cuda , its all done , bought the 4 speed....but can afford a high dollar engine....and like i said i just want a small block that can equals or beat the 340 in power and mpg and be reliable and that the parts can be bought everywere , i can afford a 3-4-5k engine right now , just want to make the car move by its own power. So 5.9 is the only to go ? I had an offer today for a 1971 318la with 30 over pistons.....but im looking for 300+ hp .....trow out your ideas guys , if the only small block bang for the buck is the 5.9 then ill go with it , but i was thinking about the cheap and smaller 5.2.....underdog !
 
Everything about the Magnum is a plus over the old 318. Better heads, valve cover sealing, cam, rollers, block. Everything that is the same as the 5.9 just smaller displacement.
360's have always been external balance and still get used a lot...
The 340 relied on high rpm's to do the job. You need lower rpm grunt to drive on the street.
Remember that the Magnum series engines were only used on trucks that needed low end torque. Torque is what moves your car not H.P.
A 5.9/360 is nothing more than a bored and stroked 318.
 
ValerianMagnum said:
Mopar Performance Flywheel .....this one i not sfi approved , i bought a mopar performance one 5 years ago for 699$....i dont know wich one is okay for a carbed engine
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Either one works for a carb application.
The MP one is listed as "carb only" because it does not have the pickups (?) for the factory crank sensor to run the MPI. The American Powertrain unit does, so it is compatible with the factory injection setup- but it's perfectly capable of running without it; the balance is the same.
ValerianMagnum said:
$$$ wise i might go with a fitech or holley efi later one...i would love to keep it factory efi but running a 4 speed and having an auto pcm..f*cks everything up and im not a efi wizard either....just want a dead dead reliable combo and goodin gas etc...
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To run factory injection, just get a factory manual transmission crank sensor and a manual trans pcm. Done. Some
pcms from non-electronic OD/lockup transmissions also work. You just need to decide if your going with OBDI or OBDII. Most people like OBDII (more tuning options), but it's easier to find pcms for manual applications (for me, anyways) with OBDI.
 
sireland67 said:
$700 flywheel?

$350 gets you a Mcleod SFI flywheel that utilizes bolt on weights for different engine balances, I run one on my cast crank 340 Duster and one in my 5.9 mag powered W-150.
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199 gets one from Brewers.
 
ValerianMagnum said:
All stock ? Cam and springs ? I think that it can do well with a 4 speed and 3.23s...mpg and power
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All stock, and the engine only cost me 200 Canuck bucks. I really should put some gears in and leave it alone but I’ve seen what a good 5.9 can do and I’ve got the itch.
 
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