Rebuilding the 318... or going 360?

[Hilljack68]

I'm doing the initial planning for a Winter rebuild of my Coronet's 318. I'm looking to get about 300-325 hp. Nothing fancy - small cam upgrade, better heads, electronic ignition. I don't care about the bragging rights of bigger cid numbers, but would I be better of just coughing up money for a 360 block?

 

[rumblefish360]

In a sense, yes. This way, when the enginei done, you just swap them. You have a running driving car until then. Now what to do with the 318?

In a sense, no, as said, what to do with an extra 318 laying around?

325 HP from a 318 is easy enough with stock heads. I suggest headers, 2-1/2 X piped exhaust. An OE 4bbl. intake and TQ or large AVS, stock or Edelbrock and the upgraded 340 cam.

Same recipe for the 360 will net more HP and a lot more torque. Which is the better deal between the engines.

 

[Kern Dog]

Stock 318 heads are not that good. They are designed with small ports, small valves and weak springs. A 318/5.2 Magnum head is a different animal though. If you run 10.0 compression with the Magnum heads and a decent cam, 300 HP is an easy thing.

 

[LXguy]

www.magnumswap.com
Just food for thought..

 

[moper]

Like LX linked to... The MP 300hp crate engine was a production line Magnum 5.9L, with a 4bbl intake and carb and the conversion flex plate. So if you can find a running Magnum, stick an intake and carb on it, you're there. You could rebuild an 360. It will cost about the same as the 318. Regardless of the starting displacement - you don't need to replace heads. Stock port 318 heads will feed a 318 to 350hp with a camshaft. So the 300-325 hp deal is easy. The 360 will make more torque overall and at a lower rpm than any 318. That's about it.

 

[Hilljack68]

Thanks for the feedback. All good info. I like the Magnum idea if I can find one.

 

[BDL]

Like LX linked to... The MP 300hp crate engine was a production line Magnum 5.9L, with a 4bbl intake and carb and the conversion flex plate. So if you can find a running Magnum, stick an intake and carb on it, you're there. You could rebuild an 360. It will cost about the same as the 318. Regardless of the starting displacement - you don't need to replace heads. Stock port 318 heads will feed a 318 to 350hp with a camshaft. So the 300-325 hp deal is easy. The 360 will make more torque overall and at a lower rpm than any 318. That's about it.

I almost completely agree with this one... However... My experience has taught me to plan on replacing the heads. All three of the Magnum 5.9's I've pulled apart had cracked heads. It's an unfortunate "normal thing" for the magnum. The other "normal thing" to fail for the Magnum 5.9 was the gasket around the pan on the keg-style stock mpfi intake. When that gasket fails the engine draws too much air in and runs lean... Causing predetonation. Causing a big ol' frown on my face.

The 5.9 that really surprised me came out of a wrecked 2002 Ram and only had 52,000 miles on it. I expected a perfect motor. It was a sweet deal for $600 back in 2007 (I pulled the engine, trans, transfer case, all wiring, fuel pump and TCU). But alas... Both heads were cracked and needed to be replaced.

So yeah... If you're considering using a Magnum 5.9 (by the way, I really do like this motor and you can usually pick them up cheap), do it! You will not regret it. Replace the heads with a good set of factory replacements from a reputable place (I actually like a place on e-Bay, out of Clearwater, Florida - Odessa CylinderHead) for around $620 (seriously that inexpensive for both heads) or upgrade to something better, depending on budget. Then, definitely replace that keg-style intake with a carb style intake (Hughes, Mopar Performance, Edelbrock, Chinese knockoff - Each one touts itself to outperform the others). If you really want something, then do the cam while you're in there. Then, drive and enjoy! It will fit right in where your 318 was.

 

[rumblefish360]

LMAO! Well, the funny thing is the cracked head issue. If you didn't pull the heads you would never had known they were cracked.

Over rated crack worries.

 

[moper]

Yeah - All factory Magnum heads are prone to crack. Most do. Of those that do, a few crack into a jacket. So cracks are very common. Problems from those cracks are rather rare. If you want to solve the problem the EQ heads are great, cheap, abut have the same issues with valve lift. All Magnums with factory valve heights have issues with a very short valve spring and no room to address that cheaply.

 

[LXguy]

The cam in my EQ headed Magnum was .533/.544. That's not huge but way better than rumor would lead you to believe is possible.

 

[Hilljack68]

I keep hearing the 360 makes more torque and at a lower range than the 318. Looking at the specs for a 1968 318 and a post-1971 360, I ain't seeing it. http://www.mymopar.com/enginespecs.htm The 318 produces 340@2400, and the 360 makes 290@3200. Unless I'm missing something, I'm not feeling the 360 swap.

 

[WileERobby]

Different rating method 72 on

 

[Photon440]

I keep hearing the 360 makes more torque and at a lower range than the 318. Looking at the specs for a 1968 318 and a post-1971 360, I ain't seeing it. http://www.mymopar.com/enginespecs.htm The 318 produces 340@2400, and the 360 makes 290@3200. Unless I'm missing something, I'm not feeling the 360 swap.

You need to compare the same year of engine to see the torque and power differences. Such as this 1971 list which shows that the 2bbl 360 has even more torque than the 4bbl 340.

 

[BDL]

I heard once that (more than once, actually... but all from my Brother-in-law), in order to make the 318 a little less anemic, Dodge threw a nicer cam in the 318 than in the 360. I can't seem to find the numbers I want to find to back up his statement and I wonder if maybe it was just one year, or maybe just the Magnum motors. What I'm getting at is this... If my Brother-in-law is correct with his statement, then a 360 would beat that 318 hands down if you throw a better cam in it.

 

[rumblefish360]

That is true with the Magnum engines. I'm not so sure about the LA engines. I need to open up a book for that answer.

The 360 beats the 318 due to sheer cubic inches. More torque.

Would you think a 400 beat a 440 if otherwise built the same?

You must be new to this stuff.

 

[MoparLeo]

Follow the article in Mopar Muscle Magazine. Doing a junkyard 5.9 on the cheap. 400+ HP.

 

[rumblefish360]

Link?

Copy the MP create 360/380 which Dyno's over 400hp.

Add Edelbrock heads for more punch.

 

[MoparLeo]

http://www.hotrod.com/articles/make-big-power-magnum-5-9l-mopar-heads/
http://www.hotrod.com/articles/build-455hp-pump-gas-magnum-v8-around-4000/

 

[BDL]

The 360 beats the 318 due to sheer cubic inches. More torque.

Would you think a 400 beat a 440 if otherwise built the same?

You must be new to this stuff.

Lol... I was trying to make a point to the guy who started the thread. I am well aware that an engine with a larger displacement will have more potential for making power (both h.p. and tq.). But the thread starter was saying the difference between a 318 amd 360 wasn't worth the swap. I was pointing out the negligible difference could be because the 318 may have had a hotter can than the 360. Am I new at this? Yup... just saw my first car last week. It was real shiny!

 

[Hilljack68]

Did it have those round rubber thingys on it?...uhh... oh yeah, tires. )