Magnum Questions

[kkritsilas]

Hello,

I am a new member here. I have a 1982 Dodge Mirada CMX (318 4 Barrel, fully loaded except leather, cruise control and automatic air conditioning, bucket seats and console shift) and a 1980 Cordoba Crown (318 4 Barrel, fully loaded with cruise, automatic air conditioning, but no rear amplifier, split bench, column shift, no leather). The Cordoba will probably be on the road by September, the Mirada has a ways to go. Both will need to be repainted. These are the replacements for the Magnum/Charger and first generation Cordoba, and are called the J bodies. They have the transverse torsion bar suspension set up.

I live in Calgary, Alberta, Canada.

That was more of an introduction. Closer to the subjects of this board, I would like to get an opinion, and some information regarding the 1979 Magnums. There are two that I can get to that are for sale, one is an XE, black with what is described with a full load of options except for the sunroof, including leather seats, no rust (but needs to have the vinyl roof replaced, and no engine for $600. The other is a green Magnum GT with T-Tops, no leather or sunroof, otherwise fully loaded, but has some rust and the ECU and power brake booster has been removed (replacement supplied) for $2600. Either car will need to be flat bed trailered out, which I can have a friend go out and do with me. The questions are:

1. I am leaning towards the XE due to lower amount of rust. It isn't the GT model, but I think it is overall a car that would be easier to get into good condition. Is the extra money and bodywork cost worth it on the GT? I am also not a big fan of the green color of the GT.

2. If I do get the XE, it will need an engine. I think that the Magnums in 1979 only had 360s as the biggest engines. I know a Big Block would probably fit with the correct engine mounts (like from Shumacker). What is the clearance around the suspension/steering components like? It can be an issue with the J body cars. How about header clearance on the big blocks. I know I will need to get a big block A727 transmission, and probably have to move the transmission mount around. I would appreciate knowing if this is worth it, or just stick to a 360. By big Block, I am talking about a 440.

3. What rear end was used in 1979? On the J Bodies that I have, it is an 8.25", both open differentials with 2.94 ratios. Did the 79s come with 8.25" or did they have 8.75" rear ends. Did the GT have a limited slip standard? Consensus on the forfmjbodiesonly.com web site is that the 8.25" is only good for about 300-325 horsepower (using street tires). If I get a big block into the XE, I guess I will probably be needing to find an 8.75"?

4. How bad is it trying to get the Magnum's headlight doors to work? Do they break often, and how hard is it to find parts for repairing them? Motors, linkages (if any) and covers.

I'd appreciate any guidance anybody could provide regarding buying either of these cars.

Kostas

 

[Car Nut]

aboard!

I agree with question #1, the other three questions I don't enough about them. Back in the late seventies, my dad had a brand new Cordoba with cloth interior. Loved that car.

Good luck.

 

[d9103365]

Buy both, and use one of them as a parts car.

 

[m79ded]

Hello,

I am a new member here. I have a 1982 Dodge Mirada CMX (318 4 Barrel, fully loaded except leather, cruise control and automatic air conditioning, bucket seats and console shift) and a 1980 Cordoba Crown (318 4 Barrel, fully loaded with cruise, automatic air conditioning, but no rear amplifier, split bench, column shift, no leather). The Cordoba will probably be on the road by September, the Mirada has a ways to go. Both will need to be repainted. These are the replacements for the Magnum/Charger and first generation Cordoba, and are called the J bodies. They have the transverse torsion bar suspension set up.

I live in Calgary, Alberta, Canada.

That was more of an introduction. Closer to the subjects of this board, I would like to get an opinion, and some information regarding the 1979 Magnums. There are two that I can get to that are for sale, one is an XE, black with what is described with a full load of options except for the sunroof, including leather seats, no rust (but needs to have the vinyl roof replaced, and no engine for $600. The other is a green Magnum GT with T-Tops, no leather or sunroof, otherwise fully loaded, but has some rust and the ECU and power brake booster has been removed (replacement supplied) for $2600. Either car will need to be flat bed trailered out, which I can have a friend go out and do with me. The questions are:

1. I am leaning towards the XE due to lower amount of rust. It isn't the GT model, but I think it is overall a car that would be easier to get into good condition. Is the extra money and bodywork cost worth it on the GT? I am also not a big fan of the green color of the GT.

2. If I do get the XE, it will need an engine. I think that the Magnums in 1979 only had 360s as the biggest engines. I know a Big Block would probably fit with the correct engine mounts (like from Shumacker). What is the clearance around the suspension/steering components like? It can be an issue with the J body cars. How about header clearance on the big blocks. I know I will need to get a big block A727 transmission, and probably have to move the transmission mount around. I would appreciate knowing if this is worth it, or just stick to a 360. By big Block, I am talking about a 440.

3. What rear end was used in 1979? On the J Bodies that I have, it is an 8.25", both open differentials with 2.94 ratios. Did the 79s come with 8.25" or did they have 8.75" rear ends. Did the GT have a limited slip standard? Consensus on the forfmjbodiesonly.com web site is that the 8.25" is only good for about 300-325 horsepower (using street tires). If I get a big block into the XE, I guess I will probably be needing to find an 8.75"?

4. How bad is it trying to get the Magnum's headlight doors to work? Do they break often, and how hard is it to find parts for repairing them? Motors, linkages (if any) and covers.

I'd appreciate any guidance anybody could provide regarding buying either of these cars.

Kostas

I also have a 79 magnum with a 440 that I put in it, at first I used mounts like what you specified (Schumacher) but it wasn't 100% correct things didn't line up like they should have and the headers needed to be banged up. I got fed up and found a cordoba with a factory big block and changed the K-member, yeah it was some extra work but well worth it. take it from someone that tried to cut corners, do it right the 1st time. The Tranny will line up 100% this way as well and the pinion angles will be correct. I was lucky and my car had a 9.25 from the factory and it holds up very well, I did have a dana 60 from a 71 road runner and put that in since it was a bolt on when you removed the iso rear suspension
Never dealt with headlight doors I am lucky so far no issues.

Good luck

 

[rumblefish360]

Christ! So many multiple questioned questions! I'd Perdue a phone call at this rate, my fibers are gonna bleed typing an answer back I this one!

(OK, you should be laughing now!)

I'm gonna address a couple of things and go to bed...

1. The 8-1/4 will hold over 400 HP, been there done that.
2. No 8-3/4 were stock, 9-1/4 are.
The GT is more sought after though fixing a rust bucket is expensive and time consuming.
360's were the big it in '79.
400's were the big ones in '78

360's can perform very well in the Magnum's.

The headlight doors are powered by a single centered electric motor. A simple title switch can replace bad wiring. The motor turns a single rod working both doors. Motors are easy to come by, sort of, but finding a guy that can fix them should be as close as a local electric motor repair shop.

Holy crap, I think I answer them all. I need to get a life and some sleep!

Have run! Thee great cars. I'd just look at the rear ISO suspension. The metal cups that hold the rubber biscuits can rip under heavy power. (Ask me how I know this! LOL! )
The rear mounting points of the ISO K frame tend to hold water and rot out. This is mostly only visible apon disassembley but easy to repair with sheet meal and a mug welder.
The T has are a odd ball length though there's a few companies that make bars for these cars.
The electric sucks in them.OH, in which, if you have a working lean burn, disconnect it and send it to a musem! It'll be one of the few last remaining in the world.

Hit me up for more info if ya need some.

 

[kkritsilas]

If a 360 (4 Barrel) is a good performer with Magnums, then I don't think I will need to chase after a big block. I will take into account the points that you have all brought up. I had a tendency to go with the black XE, due to the leather interior, better outside colour, and the reported rust free condition. I will need to find a 360, but these days, it is easier to find a 360 than a 400, at least up here. And with the 360, there is always the possibility of getting an overdrive transmission; a more difficult thing to do with a big block.

Kostas

 

[rumblefish360]

You cod always stroke the 360 to 408 easy enough.
Find a '89 plus 360 because they are a er cam engine. Open it up to be sure.
Magnum engines can not use LA heads but LA blocks can use Magnum heads.
A stroker is nice because the little small block will produce lots of torque early on.

 

[1toolguy]

I've got a 360 with a 904 trans and 8 1/4 rear end in the Cordoba and I've run consistent 14.02s (I'm sure high 13s are just a better tune up away) so while a big block might be cool, a small block can be fun (and a lot cheaper due to availability). As for the 8 1/4, slicks are probably not a good idea but mine has survived over a hundred drag strip launches with drag radials.

 

[rumblefish360]

The 8-1/4 will hold more than you give it credit for.

 

[sleepar]

A built 360 can have some serious power..... the A body forum will set you up with all you want to know about the 360/408 unless your trying to pull wheel stands a big block is a lot of work for nothing...MO

 

[kkritsilas]

Maybe a properly built 360 will be the best all around. I won't have to monkey around with the K member or conversion mounts, and can take the time and effort that it would take to get the big block in to just get the car overall into bettter shape. I never did intend to drag race, or even street race the car. I just want a good all around street car that I can live with day in and day out with some decent response when I hit the gas. I would like somewhere around the 325 HP mark, with may be a little bit more torque (350-375 ft. lbs) at a reasonably low torque rpm peak. The 8.25" is supposed to be somewhat marginal at those power levels on the 1980 up Cordobas/Miradas, and with the Magnums being 500-800 lbs. heavier, I would have thought that the 8.25" is truly undersized. I just want to build something reliable. After I build it, if I do, I don't want to have to continually go back and fix things. Mu intent is to build it, and then drive it/show it off.

Would getting a Sure-Grip allow the 8.25" to be stronger, or weaker? I would think stronger, but please explain why this is not so if it isn't the case.

Kostas

 

[1toolguy]

I don't think the sure grip will actually make the 8.25 stronger, but it won't make it weaker either. I can tell you that Chrysler used the 8.25 in a lot of "heavy" vehicle including full size vans, Dakotas, and SUVs, that were even set up for towing. In fact if you're on a budget you can probably find a limited slip in a junk yard cheap.

At the power level, and intended purpose, you're planning a properly set up 8.25 will be fine. Mine has been getting abused by 350 hp and close to 400lb-ft for over 8-years now. I've driven about 4000 miles a year and hundreds of drag strip launches.

FYI - You might find a rear end that's referred to as an 8 and 3/8ths. According to what I've been told it's actually an8.25.

 

[rumblefish360]

That's true. And I agree.
The 8-3/8 = 8-1/4. They interchange.
The newer rears have anti lock brakes and the insides are slightly different. But interchangeable as far as I know.

The power levels you stated, 325 HP & 375 lbs. of TQ is a stock 360 with headers and a very mild cam change. Something in the area of 212 - 216 intake duration would be enough to get there and possibly a little more.

A simple desmogging of the 360 with headers, an intake and a 750 will up the power to 300 HP.
FWIW, my '79 - 360 Magnum fully loaded minus moon roof and a 9-1/4 rear weighed in @ 3675 lbs. so a heavy weight car it really isn't. Considering all that it has. It is not so bad. Add aluminum parts and it'll drop some lbs..