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Author Topic: Magnum engine rebuild - 318 or 360  (Read 2597 times)

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Offline rjtx667

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Magnum engine rebuild - 318 or 360
« on: April 13, 2012, 02:16:18 PM »
I am about to start a complete rebuild on my 92 magnum for my RC project.

I currently have a 5.2l/ 318 magnum with a crane cam and a M1 intake. It also has headers and dual's on it.

My question is would it be worth finding a 360 to rebuild instead of my 318?

The factory specs are +15hp and +30 ft lbs of torque for the 360. By my 318 is not stock and probably is close to that or more already.

Would it be worth my time and money to find a 360 to fix up with a master rebuild kit or just stick to my 318?

All of my parts work on either. I have newly rebuild heads (same for 318/360) the fuel injectors are the same, the cam is the same, the intake is the same. All my bolt ons go either way. The only concern would be the 360 externally balanced as far as the torque convert goes.

This is not a daily driver, and I am not worried about gas millage, but at the same time I prefer for it to not get 8 or 9. The 318 currently gets about 14 in town and that's with 31's on 3.55 gears.
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Offline Captain Obvious

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Re: Magnum engine rebuild - 318 or 360
« Reply #1 on: April 13, 2012, 10:27:40 PM »
The factory numbers don't really mean a whole lot when you are talking about an aftermarket crane 262º and m1 single plane.

The 360 with stock heads/pistons/truck cam with a production-type dual plane forms the basis of the 300hp crate motor.

It would be tempting that is for sure. One draw might be the fact that most of the rest of the rebuild kit minor parts are the same. The exception is main bearings/rings/oil pan gasket and obviously the pistons. The 360 has a 4" bore which means there are a LOT more options in pistons available from mild to wild. Essentially you would be dealing with mostly the same costs, but a higher likely hood of being able to achieve good "quench".

Most all of the 318 pistons are straight up flat tops no dishes or reliefs or domes for most. They simply vary compression by how far they set down in the hole and may not come up to the surface for a good quench. Quench allows you to get away with more compression on a given fuel grade, or conversely not having good compression may cause extra pinging.

Offline mopar_daddy

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Re: Magnum engine rebuild - 318 or 360
« Reply #2 on: April 13, 2012, 11:27:13 PM »
I would go with the 360. The magnum 5.9 flex plate has the weights on it for the external balance.
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Online SuperBurban

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Re: Magnum engine rebuild - 318 or 360
« Reply #3 on: April 13, 2012, 11:32:47 PM »
I would go with the 360. The magnum 5.9 flex plate has the weights on it for the external balance.
only for 96,or 97, and later.
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Offline Captain Obvious

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Re: Magnum engine rebuild - 318 or 360
« Reply #4 on: April 13, 2012, 11:59:02 PM »
I wonder if the balance is the same and if he can just swap flexplates?

Code: [Select]
DODGE B1500 1998
DODGE B2500 (1996 - 1998)
DODGE B3500 (1996 - 1998)
DODGE DAKOTA (1998 - 2003)
DODGE DURANGO (1998 - 2003)
DODGE RAM 1500 PICKUP (1996 - 2003)
DODGE RAM 1500 VAN (1999 - 2003)
DODGE RAM 2500 PICKUP (1996 - 2002)
DODGE RAM 2500 VAN (1999 - 2003)
DODGE RAM 3500 PICKUP (1996 - 2002)
DODGE RAM 3500 VAN (1999 - 2003)
JEEP GRAND CHEROKEE 1998

Then again, he never mentioned what year this craigslist engine came out of? It might be an OBD2 engine and already have that flexplate.

Online SuperBurban

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Re: Magnum engine rebuild - 318 or 360
« Reply #5 on: April 14, 2012, 12:08:54 AM »
Early ones use an unbalanced flexplate, and need the torque converter with a balance weight (is it the same balance as the pre magnum 360's  {noclue} )

The later ones use the flexplate with the weights, and a neutral balance torque converter.

Can you use the weighted flexplate, and the neutral bal TQ, with the early magnums?  {noclue}
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Offline Captain Obvious

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Re: Magnum engine rebuild - 318 or 360
« Reply #6 on: April 14, 2012, 12:24:07 AM »
That is what i am wondering.

Trying to figure out if balance weight changed during the magnum run. Or bolt holes (neither is likely as I believe cranks interchanged completely) or even the position of the crank sensor window slot offset.

Offline rjtx667

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Re: Magnum engine rebuild - 318 or 360
« Reply #7 on: April 14, 2012, 04:25:24 PM »
The 360 I found is from a 98 (according to the owner).

I know that EGR was removed in 96 with ODB II, but that is intake + exhaust manifolds.... no real change to the engine.

I have a 2000 318 and a 92 318, so I am going to try and compare the sensors and inputs to see if there are any major differences but I have yet to see any.

It also means I should be able to look at the flex plate on the 98 and see the weights on it or not. that would be good if I could keep using my torque converter as it seems to be in working order.

My issues now are more $$ and wife related  :o

Wife does not want me spending all the time right now rebuilding an engine, or spending the $$ for that mater.  So that leaves me with a few choices I am trying to consider.

I think I am going to be sneaky and get the 360 bought (the prices seems too good to pass up), then I can just wait for our tax return and maybe snag some out of it to get the rebuild started.

I will get the 318 magnum pulled and ready to sell (I have to get the cam and a few other things off it).

In the mean time I will have to keep running the TBI I have in the truck, I am not completely convinced it would be worth it / wise to drop the magnum in it for 6-12 mo just to pull it to put the 360 in it. Not to mention the 318 has parts I need for the 360 rebuild.

It just means I need to move up my plans for a shed so that I have more room in my garage  ;D

Thanks for all the help.
1991 Ramcharger Canyon Sport 4x4 5.2l
1993 Ramcharger 4x4 5.2l - Trail Rig
2000  Mexico Ramcharger 5.2l
  408 Stroker
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Re: Magnum engine rebuild - 318 or 360
« Reply #8 on: April 14, 2012, 07:47:55 PM »
Here is a pic of a 97 360 flexplate, and a 92 360 torque converter.

You do not say what year your trans is, you might run into the offset bolts on the earlier ones, I think that stopped with the weighted flexplate (they are symmetrical on the 97).

When you compare the sensors, look close at the connecters, some look the same, but have different connecters. Some of it is because they switched from 5 volts, to 9 volts (or the other way), others I see no reason why they changed the connecters, except to piss me off.
« Last Edit: April 14, 2012, 07:50:16 PM by SuperBurban »
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