Dodge 318 to 360 Swap Questions

donald_r

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Is swaping a 318 to 360 as easy as unbolting the 318 and bolting in the 360?
Motor mounts, exhaust manifolds, transmission no problem?
The 318 is in a 1977 M887, the 360 is in a 1985 2 wheel drive 1 ton.
Both are automatics, and I have the comple running 1985 available.

The M887 just does not have the power to pull a trailer or another vehicle going up hill. I'm thinking the 360 with the 4 barrel carb will be a good improvment.

Any thoughts, advice, or pitfalls to avoid from those who have done this swap?

Don.
 

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DanMartin

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The upgrade should be simple. Externally they are nearly identical.

Make sure the 318 exhaust manifolds are properly sized and matched for the 360 heads (or better yet see if you can re-use the 360 manifolds if at all possible).

Of course the 360 will need a bigger carb (or at least some serious re-jetting of the old one assuming it's big enough). I would recommend at least 550CFM for that 360 to help it breathe. While the motor is out, consider a cam swap (something reasonable for the street) to help out a bit as well.

Should be a nice upgrade and give you a bit more poop where it counts. Nice looking truck....
 

M543A2

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It is a simple bolt for bolt swap. The flex plate has nothing to do with balance, but the converter might. Check both the 318 converter and the 360 converter. Look on the face of the converter that bolts to the flex plate. If you see a couple of small weights welded to the face of the converter out close to the ring gear on the converter on both engines, you can interchange converters. Vice versa, if there are no small weights on either converter, you can interchange them. The difference is because of internally balanced steel crank motors vs. externally balanced cast crank motors. Cast crank motors require the wieghts, steel crank motors do not. The 360 was made with both cast and steel cranks. If you have to add the weights to a converter off a steel crank motor to make it suitable for a cast crank motor, MOPAR offers a weight and template kit, P/N 4120241 from Mopar Performance to balance it correctly. Ignore the small weight detail and break a crank! I believe the front dampers will look different for the cast cranks and the steel cranks. I have done most of my years of work with "B" and "RB" series Mopars. The dampers are different on them, so I am assuming they are on the "A" series also. "Steel crank" means forged crank.
My problem with the 360 was the fuel mileage usually sucked.
Regards Marti
 

nattieleather

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Just bolts right in. Did that about 20 years ago because my friend got a M880 with no motor and we took the 360 out of an old truck and bolted it right in. They army should have put the 360 in from the get go...You'll like that motor in your turck!
 

Sephirothq

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the 318 and the 360 are balanced differently. YOu will find the flex plate is part of the converter for the transmission. So you will need to use the convertor for the 360. Otherwise the bolt pattern on the bck of the block is the same as is most of your other brackets. It will fit no problem.
 

Nonotagain

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the 318 and the 360 are balanced differently. YOu will find the flex plate is part of the converter for the transmission. So you will need to use the convertor for the 360. Otherwise the bolt pattern on the bck of the block is the same as is most of your other brackets. It will fit no problem.
The 318 is an internally balanced engine verses the 360 being an external balanced engine.

Both engines will have a 727 Torque Flight transmission. The flex plate/flywheel is a separate part. It attaches to the converter with four bolts.

When making the swap, use the exhaust manifolds from the 360 as well as the balancer and torque converter as the converter has a set of balance weights welded on it. While you have access to the converter you probably should have the converter flushed since Chrysler actually paid attention and installed a drain plug which seems to be a thing of the past.

The only supposed weak area of the 360 was that it used a cast iron crankshaft. Later year 318 engines also used a cast crank, but I don't remember what year the change was made.

I raced small block Mopars for years starting with a 68 Dart GTS with a 340 Raced in A-pure stock automatic when the class existed.
 

M543A2

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Thanks to Nonotagain for making me check my Mopar book again. ALL 360 engines have cast cranks. My statement in my previous post that they were made with both cast and forged was incorrect. Keep the torque converter and front damper that came with it on your 360 to prevent problems. The converter should have the welded weights I mentioned on its face. The front damper should have an offset cast portion on its front face also. Any flex plate that fits can be used because it is not part of the balance.
Regards Marti
 

The PIG Smith

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My thoughts on this why not use a more modern, updated Magnum 360 that is found in later model Dodge Trucks?
There are plenty of these Magnum 360s around.
Even a Mangum 318 (5.2L for you metric types) found in Dakotas, Durangos and Grand Cherokee would be a vast improvment over the LA model 318 that is stock in a M880.
I know the heads are totally different and along with many other things, but from I understanding, it should be a bolt it.

I wanted to swap in a Magnum 360 in a '88 Fifth Avenue at one point, but that's other story.
When I did the research, it physically would bolt in place of where the 5th's tired 318 once lived.

With an aftermarket intake for a nice 4BBL carb, it should make some nice power.
I suppose if you wanted to really get ambitious, you could work out some type of aftermarket brain (like MegaSquirt) and use the Mopar EFI.

BTW, I served in the Army in the early 80's, stationed in Germany and I was assigned a 1976 model M880 (turn signal light were horizontal and low on the face)
My Motor Sergeant was a hot rodder and rejetted the 2BBL carb.
I payed for the Jets and he did my 880 and his.
I tell you, that truck would cruise 90+ on the Autobahn without any issues at all.
 

Catfishn

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The 360 Magnum engine is nice but there are several differences between the Magnum engines and the LA small blocks.

Intakes will not interchange (unless redrilled by machine shop & I wouldn't advise this) there is no heat passage/EGR provision in the Magnum heads.
Valve train and oiling system is different. LA uses shaft mounted rockers and oiling through port in head, Magnum uses stud mounted rockers and oils through pushrod/lifters (like Ford/Chevy)
Imbalance on 360 Magnum is yet different than the imbalance on the LA 360
You can use an LA 360 oil pan on either the Magnum 318 or 360 and an LA timing chain cover to use LA style front dress/accessories buy you will have to shim the brackets as the provision bosses in the heads are spaced out differently.
Distributors will interchange, so you could use the earlier ignition system.
Just to name a few of the differences.....

I'm pretty sure the truck style exhaust manifolds for the LA small blocks are the same and interchangeable. To bypass the butterfly valve on the passenger side you can use (2) driver side manifolds (I have done this on my 360/300 magnum crate engine) as the manifolds are symetrical. Otherwise you can use your existing 318 exhuast system.

Balance issues/converters/etc.. have been properly addressed in earlier responses.
 

slinger1

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How about a 360 from a four speed 1985 pickup into a 1971 D-400 dump truck with an LA 318? Can you use the flywheel from the dump truck? Is the only "balancer" the front damper?
TIA
 

slinger1

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You would have to have the dump truck flywheel rebalanced for the 360.
Thank you.
Do I understand that the flywheel and the the front damper comprise what balances the 360s externally?
Would it be possible to use the 360 flywheel in the D400?
Art
 

msgjd

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The 360 Magnum engine is nice but there are several differences between the Magnum engines and the LA small blocks.... I'm pretty sure the truck style exhaust manifolds for the LA small blocks are the same and interchangeable.


I realize this is an older post but it came up in a recent search about manifolds and perhaps needs clarification.

The quote above is semi-correct if we include the late '60's-late 80's engines. Am unfamiliar with the newer 360 magnums. The exhaust manifolds on pre-magnum small-block LA engines (273/318/340/360) will interchange in the sense they will bolt up to each other. HOWEVER,,,, each size engine has its own specifically-engineered exhaust manifold set. The larger the displacement, the larger the ports. The only exception might be the 273/318 size since I do not know for sure between those two. But I DO KNOW FOR SURE the 340 manifolds and heads have larger ports than a 318. Likewise, the 360 also has larger-ported heads with matching larger-port exhaust manifolds. You can certainly put a 360 exhaust manifold on a 318 but you're gonna blow the manifold gaskets fairly soon if the truck works hard. I realize the gaskets may be the same part number but the mating surface is thinner when a 360 manifold is put on a 318. The machined surface area is different. Behind the cobwebs in my memory I think there once was an article about this in Mopar Magazine in the 70's or 80's.

Exh manifold gaskets seem to almost always fail on the passenger side first. I attribute this to the automatic manifold damper and the pressure it creates, especially in very cold weather. I have had dampers get stuck closed as well. Gasket blowing seems to almost vanish on mopars with the damper removed or with headers, or as someone here mentioned, replace the RH manifold with a spare LH manifold. Perfect!

Mods I did in the 1970's-80's were putting 360 heads/manifolds/intake on a "Low-budget HiPer" 318 to help it breath better, and 340/4bbl intakes on 318's and 360's. But with these mods there are carburation variables that need to be worked out. I also have run 318 heads on a rebuilt 360 (bored to 383ci) for a few months with no troubles and hardly any loss of power during normal driving, while rebuilding the 360 heads in my spare time.

True, there are a lot of components that interchange among SB-LA engines. Except the 360 has it's own oil pan (all 4x4 and 4x2 oil pans are also different) and 360's use a different model 727 than a 318. The 360 is truly an externally-balanced engine unlike the other SB's. I found that out the hard way in 1980 when a failed fuel pump seal ruined my 3yo 318. I put the 318's like-new flywheel/clutch/pp onto a replacement 360 that came bare. All was fine except whenever the rpm's went above 1800. Like the old song, a whole lotta shakin' going on! :sad:

As has been mentioned previously in this topic, 360's do have their own dedicated (balanced) torque converters, flywheels, and their own balanced crankshaft pulley. Sure these parts will bolt up to other SB engines, but it will be quick to let you know that it is not happy. aua

Slightly off-topic but deserves mentioning: Big Block engines also use a 727 automatic tranny. But that 727 is not interchangeable with small-block 727's, they absolutely will not bolt up. Just like the difference between SB/BB flywheel housings, the bolt-pattern diameter on a BB 727 is noticeably larger. I have had success putting small-block powerplants/trannys into 1970's vehicles originally big-blocked. As long as the recipient and donor were the same body type, don't have to relocate motor mounts nor tranny mounts nor do any body or frame mod. Have also converted automatics (including M880's) to standard, and vise-versa, without difficulty nor changing mounts.

On automatic tranny vehicles, SB driveshafts have a smaller-diameter input spline than a BB. It was smart to grab the donor's driveshaft too, even if the wheelbases were different. Usually rear-axle input yokes were the same size so you didn't have to change those out as long as the swap was to a similar class. (powerwagon to powerwagon, Ramcharger to Trail Duster, Sebring to Roadrunner to Charger, or Duster to Demon etc.)

Hope these experiments from 30+ years ago help someone out there :wink:
 
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oldman killins

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why not just swap the 360 head have them done and enlarge the exhaust valves to 2.02" then drop on a new intake and 4bbl carb... build I'm following says it dynos right at 300hp... that is double the stock 318
 

acudanut

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There are no flywheel's in any automatic. You are talking about the torque converter. They are Balanced differently, depending on internally balanced crank and a externally balanced crank. Head exhaust ports can differ in the 30 years they made both engines. Never heard of a 300 HP stock small block, Unless we are talking about a 1970 340 engine. Cheers
 
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