'68 318 to carbed Magnum 5.2: Check my checklist

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cudak888

cudak888

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I've been learning and planning about this swap, and I believe I've got most of the compatibility issues worked out for my setup.

The end result is to replace a worn-to-a-nub '68 318 with a '94-97 Magnum 5.2 - possibly from a Ram Van, possibly not. The Magnum will be converted to a carburetor and mated to an A904 transmission. Mechanical fuel pump, V-belt drive, and provisions for a Sanden A/C compressor are part of the plan.

This said, following is my checklist for the necessary parts and modifications to achieve this goal. If anything sticks out as missing or wrong, let me know, as I'm going to use this thread as my shopping list:

Magnum 5.2, modify as follows:

  • Magnum cam snout extender, or - preferably - roller cam from 89-91 LA 318 w/long snout.
  • LA fuel pump eccentric (from 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/Magnum 5.2 harmonic balancer (separated pulley style)
  • 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)
  • 1980's-era LA accessory brackets from an M-body (junkyard) or similar, thus adapting directly to the later water pump with provisions for the Sanden compressor and the earlier alternator (don't quote me on this, but I believe one hole in this bracket may need to be revised to adapt to the Magnum head - am I correct?).
  • V-belt pulleys from the same M-body (junkyard)
  • 1970+ lower radiator hose, upper determined by new radiator (RockAuto)
  • Speedcrap China Magnum intake, which will allow for a carburetor swap on the Magnum AND retain the LA-style thermostat outlet, which provides the necessary room to mount the Sanden A/C unit with the M-body bracket. (eBay)
  • Factory 340/360 SBM throttle cable bracket for 4V carburetor (FABO wanted ad)
  • Weld extension to factory 2V A904 kickdown rod or source used aftermarket kickdown cable that isn't prohibitively expensive

Ideally, this requires the Magnum 5.2 donor, plus a good junkyard 89-91 for cam and timing chain cover, and possibly a mid-80s donor for the brackets.

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. Also not sure whether the '68 power steering pump will fit the later M-body bracket, or whether I should adapt the later Saginaw to the existing PS gear (in which case, do the pressures differ, or is it plug-and-play?)

Exhaust on the existing car is trash, so I'll be using the Magnum manifolds with no problems.

Have I forgotten anything?

-Kurt
 
What are you using for a flexplate for the 904 trans? I too am considering doing the same thing.
 
737jetdr said:
What are you using for a flexplate for the 904 trans? I too am considering doing the same thing.
Click to expand...

I'd imagine the stock Magnum flexplate would work; at least, I thought such from my research - unless I'm dead wrong here.

That said, I did find a 1989 TBI LA 360 in the junkyard which is a real consideration too (with a carb conversion). We'll see.

-Kurt
 
If you want to use the magnum fan, you have to use the magnum front dress (water pump, timing cover, etc)...it's threaded on to the water pump stubshaft, so unless you modify the fan/clutch assembly to fit an LA style pump, it won't directly bolt on. A factory A body LA fan shroud fits since you'll be bolting on LA style accessories.

I don't have the ps pumps in front of me, but if you don't have a saginaw style pump, I'm pretty sure it won't be a bolt on affair--do you have a shop that can make you some lines? Or if you have a legit parts store near you, they have books that you could probably sift through and find one with the correct ends.

737jetdr--if you're swapping from a 318 to a 5.2, any 318 LA flexplate will work with the 5.2/904--it's the same internal balance, no need to use a different one unless you need the magnum flexplate for the EFI swap...that's a whole different story. I have the stock '72 318 flexplate on my 5.2/904, and it bolted on no issue.

If you get a 360LA that's a little different, but B&M makes a the counterweighted flexplate so you can use a neutral converter. If you have a 360 available to you, and it's a good price, I'd almost say go that direction.

here's the flexplate for the 360LA/904 swap: http://www.summitracing.com/parts/bmm-10239/applications/make/dodge?prefilter=1
 
txstang84 said:
If you want to use the magnum fan, you have to use the magnum front dress (water pump, timing cover, etc)...it's threaded on to the water pump stubshaft, so unless you modify the fan/clutch assembly to fit an LA style pump, it won't directly bolt on. A factory A body LA fan shroud fits since you'll be bolting on LA style accessories.
Click to expand...

Point taken - though I forgot that the older fans are clutch style to begin with, and not flex fans. Either way, all I need to do is stick with whatever fan came from factory to the water pump that I ultimately use.

I also considered whether it would be ultimately cheaper to stick with the stock MPFI and Magnum serpentine by adding in the cost of a Tanks Inc. EFI tank and pump. It was a serious consideration for a while - until the LA 360 showed up.

txstang84 said:
I don't have the ps pumps in front of me, but if you don't have a saginaw style pump, I'm pretty sure it won't be a bolt on affair--do you have a shop that can make you some lines? Or if you have a legit parts store near you, they have books that you could probably sift through and find one with the correct ends.
Click to expand...

The car has an early Saginaw pump in it, not a Federal. I wouldn't be against using the late, spam-can shell Saginaw from the LA either (especially if I can kick the original pump on eBay for a few bucks). I also have a spare from a junkyard slant six 1976 Aspen; don't recall the type. At any rate, I hear the van-style brackets allow it to fit, so if I go with the LA 360 from the yard, I may not have to do much experimenting at all.

Lines won't be a problem. I'll have to get them done for the Sanden AC unit anyway.

txstang84 said:
If you get a 360LA that's a little different, but B&M makes a the counterweighted flexplate so you can use a neutral converter. If you have a 360 available to you, and it's a good price, I'd almost say go that direction.

here's the flexplate for the 360LA/904 swap: http://www.summitracing.com/parts/bmm-10239/applications/make/dodge?prefilter=1
Click to expand...

Of course, I could have counterweights added to the 904 converter instead of the flexplate (IIRC, the only option if running the Mag 5.9 due to the crank position sensor), but this is undoubtedly the most convenient solution.

-Kurt
 
Yes, you could have the weights added to the converter, but I think it's better to have the flexplate balanced [to the reciprocating assembly]. I don't know that your place would charge any extra to have the weights added to the converter during any balancing operation, but should you choose to swap converters later down the road with a weighted converter, you'll be paying for the balancing on the next converter too. But, if you run the balanced flexplate, that need disappears...just my opinion though.
 
txstang84 said:
Yes, you could have the weights added to the converter, but I think it's better to have the flexplate balanced [to the reciprocating assembly]. I don't know that your place would charge any extra to have the weights added to the converter during any balancing operation, but should you choose to swap converters later down the road with a weighted converter, you'll be paying for the balancing on the next converter too. But, if you run the balanced flexplate, that need disappears...just my opinion though.
Click to expand...

TX , it's a good opinion, especially for a build that is planned ahead of time.
 
txstang84 said:
Yes, you could have the weights added to the converter, but I think it's better to have the flexplate balanced [to the reciprocating assembly]. I don't know that your place would charge any extra to have the weights added to the converter during any balancing operation, but should you choose to swap converters later down the road with a weighted converter, you'll be paying for the balancing on the next converter too. But, if you run the balanced flexplate, that need disappears...just my opinion though.
Click to expand...

Good point.

With any luck, maybe I can chuck the TBI stuff on eBay to cover a part of the converter too.

-Kurt
 
tx, so you're saying a flexplate from an LA318/904 will also work on a magnum 5.2/904 setup? I realize they are both internally balanced.
 
737jetdr said:
tx, so you're saying a flexplate from an LA318/904 will also work on a magnum 5.2/904 setup? I realize they are both internally balanced.
Click to expand...

While I can't say for sure if the LA flexplate would work on a carb-coverted Magnum 5.2, I do know for sure that the Magnum 5.2 requires the factory flexplate to run its stock MPFI, as the crankshaft position sensor takes its reading from it (see: http://www.dakotaforumz.com/showthread.php?t=2753).

-Kurt
 
cudak888 said:
While I can't say for sure if the LA flexplate would work on a carb-coverted Magnum 5.2, I do know for sure that the Magnum 5.2 requires the factory flexplate to run its stock MPFI, as the crankshaft position sensor takes its reading from it (see: http://www.dakotaforumz.com/showthread.php?t=2753).

-Kurt
Click to expand...
I'm fairly sure the bolt circle's the same on the crank. The TC pattern's not the same- for a Mag flexplate it will need a bit of oblonging to use the stock TC. You can use the stock MPI flexplate even if you don't run MPI.
 
737jetdr said:
tx, so you're saying a flexplate from an LA318/904 will also work on a magnum 5.2/904 setup? I realize they are both internally balanced.
Click to expand...


If it's not, I have a freak...I pulled the flexplate off the 318 in my '72 Scamp (which the shortblock was actually swapped with one from an '80 Roadrunner, but the flexplate was original), and bolted it directly to my 5.2...for that matter, the crankshafts out of both engines had the same casting number...and yes, mine is carbed
 
TX - a friend of mine who has used the B&M 10239 pointed out that the B&M unit does everything well EXCEPT flex; it's too stiff for its own good. Any comments on that? Curious what your opinion would be. Haven't seen any such criticism mentioned about B&M plates until now.

One thing did come to mind - some Googling seems to suggest the factory 1996+ Magnum 5.9 flexplate is weighted. Would it be possible to use one of those on the LA 360 / 904 combo instead of the B&M unit? Or is the factory bolt pattern on the Mag 5.9 flexplate incompatible with the 904?

EDIT: Answered my own question, won't work. 122t / 904 vs 130t / 727, thus different bolt patterns.

Hell with it, B&M 10239 flexplate it is.

-Kurt
 
Do you really want it to flex? I don't... My brother and I used a B&M flexplate on his cast crank ('73, therefore external balance) 340, and it worked perfectly fine. Lots of people use them on their engines...and although I'll cop to not knowing that many people in the world, those with an aftermarket flex plate are happy with them.

EDIT: just saw your want ad...good idea
 
txstang84 said:
Do you really want it to flex? I don't... My brother and I used a B&M flexplate on his cast crank ('73, therefore external balance) 340, and it worked perfectly fine. Lots of people use them on their engines...and although I'll cop to not knowing that many people in the world, those with an aftermarket flex plate are happy with them.

EDIT: just saw your want ad...good idea
Click to expand...

Good enough for me. B&M plate it is then.

Yep, might as well put out the feelers. No point in paying top dollar when someone may be begging to get rid of one used.

-Kurt
 
I know for a fact that a Federal PS pump and brackets will bolt on a 94 360 mag.

Also if you end up with a 360 mag they are balanced different than a 360 LA.
 
sireland67 said:
I know for a fact that a Federal PS pump and brackets will bolt on a 94 360 mag.

Also if you end up with a 360 mag they are balanced different than a 360 LA.
Click to expand...

I don't mind the later brackets, but I'd like to stick the old-casing Saganaw on there for looks over the later spam can.

Wound up with a 1989 roller-cam LA 360. Perfect for the build; should have the longer cam snout and eccentric already on it.

15grxxf.jpg


I ditched the Magnum idea when I found this one. Cheaper in the long run, and could never find a 5.9 at any of the junkyards. Only found two 5.2s anywhere: One in the junkyard - it looked like crap (van huge rust holes in the roof - right over the doghouse), and one that looked about as bad at a used engine shop.

Paid $400 for it, which is a bit steep, but they don't grow on trees in this town. Local Craigslist is full of idiots who think rusted-up smogger 318's are worth $1,500 each. I think I did OK.

-Kurt
 
Wow-people are asking that much for a used 318? I don't suppose $400 is that bad, if it ran recently. It looks good externally...are you planning on disassemble/inspect/reassemble or just toss it straight in with the new intake and swapped oil pan/pickup/accessories? I'd almost say you might want to consider keeping the front parts on that 360...free compressor and newer style high amp alternator...
 
txstang84 said:
Wow-people are asking that much for a used 318? I don't suppose $400 is that bad, if it ran recently. It looks good externally...are you planning on disassemble/inspect/reassemble or just toss it straight in with the new intake and swapped oil pan/pickup/accessories? I'd almost say you might want to consider keeping the front parts on that 360...free compressor and newer style high amp alternator...
Click to expand...

http://miami.craigslist.org/brw/pts/5104522290.html

That's just our Craigslist's most recent engine numbskull. Get a load of this:

http://miami.craigslist.org/brw/cto/5141075317.html

I did a compression test on it in the yard; all cylinders at 145psi on cranking. Looks super clean at the rockers too, so I probably did good. I'm planning a tear down for inspection and new seals; no bearings if it doesn't need them.

The Sanden is chipped on the mounting tab, and the plastic back of the alternator is cracked. While I can use both, am NOT using the factory brackets. The compressor mounting is the biggest pain in the arse you could imagine, and removal of the intake requires pulling the compressor AND everything in front short of the PS bracket and water pump (though multiple bolts must be removed from the latter). I plan on using Bouchillon's Sanden bracket instead, and worry about the alternator second.

-Kurt
 
cudak888 said:
That's just our Craigslist's most recent engine numbskull. Get a load of this:
-Kurt
Click to expand...
He must love 318s to want to keep it that bad. Sometimes those pop up like that here, not usually THAT bad, but most 318s are <$400 (carbs and intakes are expensive- and those add up into them too), and the 5.2s are right in that range- usually $550 can buy a 5.2 with all the spaghetti and the lumps of plastic to run it- and not too much more'll buy a running vehicle that doesn't smoke albeit with higher miles.
 
cudak888 said:
http://miami.craigslist.org/brw/pts/5104522290.html

That's just our Craigslist's most recent engine numbskull. Get a load of this:

http://miami.craigslist.org/brw/cto/5141075317.html

I did a compression test on it in the yard; all cylinders at 145psi on cranking. Looks super clean at the rockers too, so I probably did good. I'm planning a tear down for inspection and new seals; no bearings if it doesn't need them.

The Sanden is chipped on the mounting tab, and the plastic back of the alternator is cracked. While I can use both, am NOT using the factory brackets. The compressor mounting is the biggest pain in the arse you could imagine, and removal of the intake requires pulling the compressor AND everything in front short of the PS bracket and water pump (though multiple bolts must be removed from the latter). I plan on using Bouchillon's Sanden bracket instead, and worry about the alternator second.

-Kurt
Click to expand...

That's more than a little ridiculous. Understood on the accessories though, I couldn't really tell from the pic, but I guess considering it came out of an 80s vehicle, I shouldn't be too surprised how convoluted the bracketry was then.

Happy about your find though-at least it's all looking good so far and you plan to go through it. I recall you mentioned something about kick down cables...if you need one, I'd recommend the lokar setup...worked well in my car; easy to configure and installs cleanly.
 
Infecteddog said:
He must love 318s to want to keep it that bad. Sometimes those pop up like that here, not usually THAT bad, but most 318s are <$400 (carbs and intakes are expensive- and those add up into them too), and the 5.2s are right in that range- usually $550 can buy a 5.2 with all the spaghetti and the lumps of plastic to run it- and not too much more'll buy a running vehicle that doesn't smoke albeit with higher miles.
Click to expand...

txstang84 said:
That's more than a little ridiculous. Understood on the accessories though, I couldn't really tell from the pic, but I guess considering it came out of an 80s vehicle, I shouldn't be too surprised how convoluted the bracketry was then.

Happy about your find though-at least it's all looking good so far and you plan to go through it. I recall you mentioned something about kick down cables...if you need one, I'd recommend the lokar setup...worked well in my car; easy to configure and installs cleanly.
Click to expand...

Wouldn't be the first local jackass on Craigslist to think that car collectors are all a bunch of easy-to-scam chumps. LA engines are usually attached to these jerks due to the engines' age; junkyards and engine yards don't bother with LA's anymore. Magnums are the only option, and those start at $500 around here without accessories or harnessees.

I'll send a picture of the brackets once my internet connection is back up.

-Kurt
 
Took the valve covers and intake manifold off today. Clean enough to eat off of.

I opened the block off plate for the fuel pump to have a look at the timing chain. Since this is a heavy duty 360, it has a double roller installed from the factory (and special locks on the exhaust spring retainers). I was quite surprised to find that it has almost a quarter inch of play in it - much more stretch than I figured.

I have a stock replacement done rain on the way so it's not an issue. Also going to install the Magnum 3.9 timing chain tensioner (which I believe has to be drilled for one oiling port).

I'll post some photos soon as I have an internet connection again.

-Kurt
 
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