Worn out LA 318 to Magnum 5.2 or 5.9: Check my Checklist

[cudak888]

I plan on pulling the worn-out (22psi wet/dry compression when cranking in worst cylinder) 318LA out of my '68 Satellite in favor of a junkyard-sourced Magnum 5.2 or Magnum 5.9. This said, I want to run my shopping list by the experts to make sure I haven't missed anything.

Requirements of the swap (to suit my tastes) are as follows:

• Must be carbureted
• Fuel pump must be mechanical
• V-belt accessory drive
• End result must allow for a Sanden A/C compressor to be used with factory or factory-like brackets
• Mates to an A904 transmission

I wish to stick with factory parts as much as I can, thus giving me an edge at the junkyard (and in the pocketbook). If anything sticks out as missing or wrong, let me know.

Modify Magnum 5.2 as follows (since I'm using this as my shopping list, I've also noted to myself where I should find the parts):

• Roller cam from 89-91 LA 318 w/long snout (junkyard donor - avoids Hughes cam extender to drive fuel pump)
• LA fuel pump eccentric (junkyard donor)
• 1979-90 LA timing chain cover (seal from front, timing marks on driver's side - my cover is a '67-earlier with a bolt-on tab) w/stock harmonic balancer (separated pulley style for V-belt conversion
• Factory weighted flexplate (if Magnum 5.9 - does not apply to 5.2 swap)
• LA 360 center-sump oil pan (or Summit SUM-G3536) and pickup tube.
• LA oil pan gasket (Milodon crush proof) or Magnum gasket with the ends chopped off and the LA timing chain cover gasket installed in its place
• LA '70+ water pump with passenger-side intake - easier to find (RockAuto) than '69 A/C style and cheaper.
• 1970+ style 26" radiator to match up with '70+ water pump (eBay)
• Bouchillon Performance Sanden left-offset A/C compressor brackets to clear Magnum intake water outlet
• V-belt pulleys (junkyard donor)
• 1970+ lower radiator hose, upper determined by new radiator (RockAuto)
• Edelbrock 7577 intake (eBay - considered the Chinese Speedcrap intake, but realized the LA water outlet wouldn't work with Ram/Ramcharger-style A/C brackets, as those intakes had the T-stat outlet angled to the left, thus allowing the compressor to sit on the right)
• Factory 340/360 SBM throttle cable bracket for 4V carburetor
• Weld extension to factory 2V A904 kickdown rod or source used aftermarket kickdown cable that isn't prohibitively expensive

One of the things not on this list and not clarified yet is whether the Magnum clutch fan will fit - and which radiator shroud will work for this updated combo.

Exhaust on the existing car is trash, so I'll be using the Magnum manifolds without worry of exhaust fit.

Have I forgotten anything?

-Kurt

 

[Mr Gorsky]

I'm doing the same swap in the new year, but with a 360 Magnum. You gotta go the 360.

My brother has been running a 360 Magnum in his Dodge for five years, with the Magnum sump gasket....it's the way to go.

 

[cudak888]

I'm doing the same swap in the new year, but with a 360 Magnum. You gotta go the 360.

Provided my stock 904 and 741 diff (8-3/4) are up to the extra HP.

I'm not changing either of those if I can help it - the engine will cost enough on its own.

-Kurt

 

[Northern Runner]

As long as you don't go throwing too much power through the 904 and you don't abuse it, you should be ok. A common misconception is that the 741 diff can't handle any power, but many people run them behind big blocks and are ok.
Mainly it is all about what you want to use the car for. A fun cruiser? A hot street car? If you are just cruising with it and running low compression and a little cam, your current setup is golden. Personally I would still go through that 904 if you've never had it apart and get a nice rebuild kit from Summit or Jegs. You can get a decent kit for around $200 with all the gaskets, seals, bands, and clutches you need to freshen it up.

 

[dieseldazzle]

If you go magnu 360 isn't there a driver side motor mount issue?

 

[jenkins71]

Definitely go with the 5.9 (360) !!!!! Make the swap WORTH IT!

For what it's worth, I have a mildly souped-up 440, and a 741 rear with no problems so far.

I've known plenty of guys who use a 904 backed to a 360. In fact, drag racers like em because they suck up less HP than a heavier 727. You'll be fine!

The only thing I can think to change on your list would be the camshaft. I'd rather get one a little hotter than the stock 318 cam.

 

[Mr Gorsky]

^^^Good call re: the cam.

Also, have a gander at http://magnumswap.com

Lots of good info there.

 

[cudak888]

As long as you don't go throwing too much power through the 904 and you don't abuse it, you should be ok. A common misconception is that the 741 diff can't handle any power, but many people run them behind big blocks and are ok.
Mainly it is all about what you want to use the car for. A fun cruiser? A hot street car? If you are just cruising with it and running low compression and a little cam, your current setup is golden. Personally I would still go through that 904 if you've never had it apart and get a nice rebuild kit from Summit or Jegs. You can get a decent kit for around $200 with all the gaskets, seals, bands, and clutches you need to freshen it up.

Fun cruiser, but I have standards about my engines being able to breath. I'm no friend of smogger cams and restrictive ports, but I'm fine with the stock non-adjustable valvetrain. Not against a better cam, but I'm not keen on lumpy idles (but I'm not necessarily aiming for Slant Six smoothness).

The 904 is a bit of a question mark, as though the PO claimed that it was rebuilt, this is the same schmuck who didn't breath a word about the engine being worn to a nub.

If you go magnu 360 isn't there a driver side motor mount issue?

Supposed to be identical to the LA 360, according to Magnum Swap.

Definitely go with the 5.9 (360) !!!!! Make the swap WORTH IT!

For what it's worth, I have a mildly souped-up 440, and a 741 rear with no problems so far.

I've known plenty of guys who use a 904 backed to a 360. In fact, drag racers like em because they suck up less HP than a heavier 727. You'll be fine!

The only thing I can think to change on your list would be the camshaft. I'd rather get one a little hotter than the stock 318 cam.

I'm glad to hear the collective agreement that the 741 will not pose an issue, though I bet those 904 drag transmissions have been improved on a bit over stock.

-Kurt