Magnum 5.2 retrofit w/V-belts and mech. pump: Check my checklist

[cudak888]

I posted this to the Magnum forum, but it seems dead over there.

I plan on converting a Magnum 5.2 to a carburetor and a mechanical fuel pump to replace a worn-out LA 318. Donor engine may or may not come from a '94-97 Ram Van.

Requirements of the swap (to suit my purposes) 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 bolted to factory 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). I'm almost sure I have the important stuff correct, but I'd appreciate it if you fellows could double-check my list below. 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 (no Hughes extender failure worries in the back of my mind)
• LA fuel pump eccentric (from existing 318 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 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

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

 

[Infecteddog]

You're going to have to modify the brackets for the alternator, my memory was the Saginaw P/S pump didn't have much trouble at all going on. The late '70s alternator- as much was clearanced on the block as possible and then a small amount was clearanced on the back of the alt. On the A/C- I think it actually worked really well- been a while since I ran an LA intake, I switched to a Magnum intake a while back and that took a lot of modifying for the RV2 and very little of the stock bracketry was retained- I think this is an improvement over the stock.

 

[cudak888]

You're going to have to modify the brackets for the alternator, my memory was the Saginaw P/S pump didn't have much trouble at all going on. The late '70s alternator- as much was clearanced on the block as possible and then a small amount was clearanced on the back of the alt. On the A/C- I think it actually worked really well- been a while since I ran an LA intake, I switched to a Magnum intake a while back and that took a lot of modifying for the RV2 and very little of the stock bracketry was retained- I think this is an improvement over the stock.

The alternator clearance is something I hadn't considered, though both the Ram/Ramcharger bracket and M-body brackets look as if they would accommodate the earlier alternator without issue:

'89 Ramcharger:

M-body (Chrysler Fifth Avenue):

In fact, it looks as if the alternator in the M-body isn't much different in overall size to the squareback '70+ unit, maybe even based on the same shell dimensions. I would be surprised if the earlier alternator wasn't a drop in fit.

Were either of these the bracket you used for your conversion?

-Kurt

 

[Infecteddog]

The alternator clearance is something I hadn't considered, though both the Ram/Ramcharger bracket and M-body brackets look as if they would accommodate the earlier alternator without issue:

'89 Ramcharger:

M-body (Chrysler Fifth Avenue):

In fact, it looks as if the alternator in the M-body isn't much different in overall size to the squareback '70+ unit, maybe even based on the same shell dimensions. I would be surprised if the earlier alternator wasn't a drop in fit.

Were either of these the bracket you used for your conversion?

-Kurt

I'm running the brackets from my '77 car or a '73 C body. Yeah, until the Densos and excepting the Leece-Neville or whatever the 100 amp externals are the square-back was basically the alternator. So the square-back is what I'm referring to as the stock alternator for these cases. As far as the '89 style alternator goes I'm not sure how bad you'd have to clearance that- the Magnum heads have a lot more meat at on the F/R near the block than the LA heads do. IIRC when the starter changed in '88 the alternator did too.

If you're going to use the correct rad than you can retain the correct shroud- shouldn't be a problem unless you use a fan much larger than stock.

 

[cudak888]

I'm running the brackets from my '77 car or a '73 C body. Yeah, until the Densos and excepting the Leece-Neville or whatever the 100 amp externals are the square-back was basically the alternator. So the square-back is what I'm referring to as the stock alternator for these cases. As far as the '89 style alternator goes I'm not sure how bad you'd have to clearance that- the Magnum heads have a lot more meat at on the F/R near the block than the LA heads do. IIRC when the starter changed in '88 the alternator did too.

If you're going to use the correct rad than you can retain the correct shroud- shouldn't be a problem unless you use a fan much larger than stock.

If the '70+ alternator can't clear the Magnum heads, it's probably easier to replace the serpentine pulley on the Denso to the dual V-belt, and retrofit the electrical system accordingly.

I'm considering swapping the driver's-side inlet '68 radiator for a '70+ passenger-side inlet. Far as I know, a 26" shroud should be the same for either, though mine came cracked with a cheap aluminum bar stock repair job on it. Stock fan.

-Kurt

 

[subcom]

Don't forget the harmonic balancer.

 

[cudak888]

Don't forget the harmonic balancer.

I have it listed:

• 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 Magnum 5.2 harmonic balancer (separated pulley style)

-Kurt

 

[subcom]

Oops I missed that.
Check out http://www.magnumswap.com for extra tips/hints.

 

[cudak888]

Oops I missed that.
Check out http://www.magnumswap.com for extra tips/hints.

No problem; at least I know I've done my homework right

-Kurt

 

[acpat]

Magnum gasket with the ends chopped off. No need to modify magnum one piece gasket. Just take a hammer and work out the stamped recess in the pan. I did it this way and it worked great.

 

[cudak888]

Magnum gasket with the ends chopped off. No need to modify magnum one piece gasket. Just take a hammer and work out the stamped recess in the pan. I did it this way and it worked great.

I understand about the pan, but I'm not sure I follow about the gasket - should I cut the ends of the Magnum gasket or don't modify it at all? Your post suggests both.

-Kurt

 

[cudak888]

I'm running the brackets from my '77 car or a '73 C body. Yeah, until the Densos and excepting the Leece-Neville or whatever the 100 amp externals are the square-back was basically the alternator. So the square-back is what I'm referring to as the stock alternator for these cases. As far as the '89 style alternator goes I'm not sure how bad you'd have to clearance that- the Magnum heads have a lot more meat at on the F/R near the block than the LA heads do. IIRC when the starter changed in '88 the alternator did too.

FYI, I just popped under the hood this evening, and the alternator-to-head clearance issue became painfully obvious, now that I look at it:

This is the pre-'70 style alternator, but figuring in the extra "meat" of the Magnum cylinder heads explains itself - either of the older Mopar alternators probably wouldn't have any chance of fitting at all.

-Kurt

 

[txstang84]

I'm using a squareback on my 5.2 in my '72...I was able to use the existing brackets, but I have factory a/c brackets, and I believe they put the alternator further outboard of the non-a/c models...and I couldn't run a powermaster 75A alternator due to increased size to accommodate the different internals. If you need to have a Sanden compressor on V belts, you may want to look at Bouchillon Performance...they have kits that will enable the use of V belts with a magnum and sanden mini compressor...

 

[magnumdust]

On the alternator note, does it have to be a mopar alternator?? I found that a specific gm alternator fits extremely well.(mid 90s v6 firebird, 100amp)

All it took to fit was some grinding on the inner part of the alternator mount arm so that I could get enough movement to tighten the belt.

 

[cudak888]

I'm using a squareback on my 5.2 in my '72...I was able to use the existing brackets, but I have factory a/c brackets, and I believe they put the alternator further outboard of the non-a/c models...and I couldn't run a powermaster 75A alternator due to increased size to accommodate the different internals. If you need to have a Sanden compressor on V belts, you may want to look at Bouchillon Performance...they have kits that will enable the use of V belts with a magnum and sanden mini compressor...

Have a photo of your brackets? Or are they like the Ram/Ramcharger brackets above? Those seem to stick the alternator out quite a bit, but I can't tell from that photo if it accommodates the larger alternator.

I can use the Sanden off the vehicle that donates the brackets, which should be V-belt to start with. No sense in spending more money on boutique stuff if good junkyard parts are available.

On the alternator note, does it have to be a mopar alternator?? I found that a specific gm alternator fits extremely well.(mid 90s v6 firebird, 100amp)

All it took to fit was some grinding on the inner part of the alternator mount arm so that I could get enough movement to tighten the belt.

Good to know. I don't mind the occasional "wrong" brand accessory, so long as it doesn't look out of place (though I draw the line at motors!). Externally regulated, I assume?

Any chance you have a part number for it?

-Kurt

 

[magnumdust]

Good to know. I don't mind the occasional "wrong" brand accessory, so long as it doesn't look out of place (though I draw the line at motors!). Externally regulated, I assume?

Any chance you have a part number for it?

-Kurt

You can decide for yourself on if its out of place(see picture). Its an internally regulated alternator that's incredibly simple to wire seperate from the oem harness(which was limited in amperage capacity)

I tried a bunch of different higher amperage nippon densos(found on new mopars) and fitment was a crapshoot filled sawing down pieces.

Sorry, no part number. I figured this out when i did a day at pick and pull and eyeballed the fitment. I *think* its a CS130 alternator, but i might be wrong.

 

[cudak888]

You can decide for yourself on if its out of place(see picture). Its an internally regulated alternator that's incredibly simple to wire seperate from the oem harness(which was limited in amperage capacity)

I tried a bunch of different higher amperage nippon densos(found on new mopars) and fitment was a crapshoot filled sawing down pieces.

Sorry, no part number. I figured this out when i did a day at pick and pull and eyeballed the fitment. I *think* its a CS130 alternator, but i might be wrong.

Interesting. Doesn't look too out of place. What amperage?

Are you circumventing the dash AMP gauge with your wiring?

-Kurt

 

[txstang84]

Sorry, I can't really access any pictures at the moment-my Scamp's in Texas, and I'm in Hawaii. That being said, the brackets currently installed on the car are stock for a 1972 LA with factory AC. The factory brackets for the '89 Ram you show should physically bolt up, but I can't speak to whether or not they would mate with your carbed magnum intake...clearance for the t-stat housing is kinda close on mine with the V-twin compressor, so you might want to look into possibly having the magnum heads drilled for an LA intake bolt pattern...that is an option.

I'm thinking RustyRatRod and/or Abodybomber may have some experience with this one...or you could check out the magnum swap tech pages. Sometimes the search function leaves a little to be desired, but if you use different keywords, you might have some luck.

 

[txstang84]

OK, I was wrong, I do have a couple of pictures--I think I might've posted them somewhere else on this site, but not in the SB page. They aren't the greatest, but the one with my finger points to where the interference was with a Powermaster 75A alternator. You may or may not be able to discern, but like I said, the magnum intake moves the t-stat mounting boss where it may interfere with your sanden compressor, hence the reason I suggested Bouchillon...and while I fully understand you'd rather use parts bin engineering than "boutique" parts, at least it's an option.

Honestly, I think if you're dead set on using a magnum and want to retain as much LA dress as possible, you're best bet would be to drill the heads for an LA bolt pattern, then the only interference you'd have to worry about would be the alternator/right cyl head...even at that, a stock one with a/c type bracketry did fit on my car, rather cozy, but it does fit.

 

[magnumdust]

Interesting. Doesn't look too out of place. What amperage?

Are you circumventing the dash AMP gauge with your wiring?

-Kurt

Its a 100amp alternator, and I don't have the amp gauge anymore. My car doesn't have the oem gauge set. If you were dead set on keep that, your best bet would be to convert the amp gauge to a volt gauge and wire it appropriately.

The wiring(if i remember right) was as simple as a main charge wire to the battery or starter solenoid and a wire to switched ignition. Like most GM alternators from this era, it uses an "idiot light" wire as the third wire, but there are readily available pigtail harnesses with a built in resistor to bypass the need for a light.

The only downside right now is that the setup does have a slight belt wobble. So far I haven't thrown a belt, but I intend to add a bar from the engine a bolt hole on the back of the alternator for extra support.

 

[cudak888]

he factory brackets for the '89 Ram you show should physically bolt up, but I can't speak to whether or not they would mate with your carbed magnum intake...clearance for the t-stat housing is kinda close on mine with the V-twin compressor,

That happens to be the only reason I'm willing to use the cheap Crosswind intake over the Edelbrock. Among its oddities is that it uses an LA-style thermostat outlet and angled water pump connections. For all its drawbacks, this is a big enough plus to consider butting my head up against it:

I'll admit that I'd prefer drilling the Magnum heads for the LA bolt pattern, but I don't think I'll find any machine shop locally with the jig to do it. Even though I do know one fantastic machine shop that has done a pair of 351C heads for me before, I wouldn't trust them to get the holes in the right place. Bridgeport mill or otherwise (which reminds me, a friend has one I could use...)

Its a 100amp alternator, and I don't have the amp gauge anymore. My car doesn't have the oem gauge set. If you were dead set on keep that, your best bet would be to convert the amp gauge to a volt gauge and wire it appropriately.

The wiring(if i remember right) was as simple as a main charge wire to the battery or starter solenoid and a wire to switched ignition. Like most GM alternators from this era, it uses an "idiot light" wire as the third wire, but there are readily available pigtail harnesses with a built in resistor to bypass the need for a light.

The only downside right now is that the setup does have a slight belt wobble. So far I haven't thrown a belt, but I intend to add a bar from the engine a bolt hole on the back of the alternator for extra support.

Well, seeing that the car it's going into is such a mess already, tearing into the gauge cluster shouldn't be more drastic than anything else I have to do already.

I'll keep it in mind - looks like cylinder head interference and/or factory bracket clearance is going to determine what alternator winds up on this thing (either that, or my own cheapness!).

-Kurt

 

[txstang84]

...you could also do this...

http://www.hughesengines.com/Index/...bnVt&level1=Q3lsaW5kZXIgSGVhZHM=&partid=23827

But I guess if you already have the intake, I'm just pissing in the tall weeds...I had a crosswind intake when I first put my 5.2 together...I took it off because it leaked, or at least I think it may've played a role in drinking coolant. I wish you better luck.

Tearing into the gage cluster is not scary...the worst part is the concern of breaking pins off a 40 year old circuit board. Beyond that, it's easy, and I believe there's a thread in the electrical section to make the voltmeter swap with the factory gage panel so it looks stock...and the beauty of it is you get to delete the 10ga charging wire from your dash and all but eliminate the possibility of a dash fire. I remember the first time I smelled electrical burning in the cab of my Plymouth...at night...nowhere near home...I think my *** ate my shorts.