Announcement

Collapse
No announcement yet.

Exhaust Magnum vs 79 300

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Exhaust Magnum vs 79 300

    I have been preparing my low milage Magnum for a duel exhaust, and I thought I would share some of the things I have discovered. The 1979 Cordoba 300 was the first american car with a true duel exhaust with the catalitic converters, (duel pipes and duel converters). The corvette's of 1979 did not even have them. So I decided to get some peices from a 79 300 being parted out, to help with my conversion. The 79 300's have a different floor pan from the Magnum's, in that it was formed to alow the driver side to have the converter in place under the drivers seat. This was one of the reasons that no 1979 300's come with an electric drivers seat from the factory. The 1979 300's came with complete set of aluminum and steel exhaust sheilds, that were attached about where the converters started, and ending on the forward side of the diferential hump. My Magnum only had a short sheild uner the passenger side seat, for the passenger side converter, there was no evidence that there was ever any sheilds under the muffler or into the diferential hump. The tail pipe hanger from the Magnum's passenger side can be used on the driver side, and there is a hole present on the frame rail to do that. The bracket that the 79 300 used to hang the muffler is the same as other duel b body cars, and you can purchase those from Year One, or other places. When drilling the 4 holes for this bracket, the interior hump area of the Magnum has the 4 places you need to drill dimpled in the sheet metal. The heat sheilds from the 79 300 can be attached to the Magnum, except for the driver side under where the converter would have been, because the floor pans are different. The 300's exhaust did not have a crossover tube. The pipes were also attached to a bracket bolted to the rear transmission mount, simular to the Magnum's bracket bolted there, but longer to attach the driver side pipes to the bracket as well. My Magnum also had a factory resonator before the exhaust tip, the 300's just have their two converters, and two mufflers, no resonators.


    Paul

  • #2
    I'm looking into doing the same to my low mileage Magnum.

    Is the fuel tank different between the two?
    TNT

    '78 30K Magnum XE Survivor

    Comment


    • #3
      All the L-code & P-code B-bodies from 75-79 had the dual exhausts with cat's. Drivers floor pan and gas tank is different and the associated hardware.
      1971 Challenger - Autocross & Track Day Project
      2015 Dart GT 6spd - Daily Driver

      Comment


      • #4
        Gas tank is no problem, plenty of room on the drivers side for an exhaust tube.

        Paul

        Comment


        • #5
          Let me update the gas tank issue. My Magnum is a 79, and I believe the 79 had a smaller gas tank than the 78 Magnum. So the 79 Magnum will have the gas tank centered, with the same distance on both sides of the frame rail....thus no problems. But a 78 may have issues.

          Paul

          Comment


          • #6
            1979 used the Dual exhaust gas tank. 75-78 had 2 different tanks. 79 also has a 1 year only trunk floor because of the gas tank. The "single exhaust" gas tank necessitated a "bump" in the trunk floor. Been 5 years since I messed with Late-Bs.
            1971 Challenger - Autocross & Track Day Project
            2015 Dart GT 6spd - Daily Driver

            Comment


            • #7
              My 1978 Magnum XE 360 lean burn has the big tank(25 gal I think) that fits tight to the drivers frame rail. It also has a single converter floor pan.

              Lucky me...
              TNT

              '78 30K Magnum XE Survivor

              Comment


              • #8
                Pretty much what Cudazappa said. But you can put duals on a bigger-tanked car, but the exhaust guy must bend it appropriately. I had it done on my 78.

                There was a dual exhaust for sale on here at one time, fellow in Alabama? had it. Might go digging in the classifieds.
                .


                bringin' em back ~ to the Dodge Mahal !!....

                Where old Magnums can find a home.. :angel:

                Comment


                • #9
                  Well, my plan is to get everything ready for spring and the duels..........the Magnum feels like it is being held back when you drive it. Once that is done, I will also consider a new intake and carb (4bbl). I had a 79 300 new back in 79, and it was a good ride back then, but I searched a while for the right Magnum to pick up, because you see less of them around. In fact I only remember seeing 2 GT's ever on the road when they were new.

                  Paul

                  Comment


                  • #10
                    Originally posted by Magnumguy View Post
                    Pretty much what Cudazappa said. But you can put duals on a bigger-tanked car, but the exhaust guy must bend it appropriately. I had it done on my 78.

                    There was a dual exhaust for sale on here at one time, fellow in Alabama? had it. Might go digging in the classifieds.
                    Bill, here is the listing for the dual exhaust (NOS) Mopar....but I have no idea if this is still available. This would be the way to go for a conversion, but be aware that the pipes may not be stainless steel; I purchase two similar systems from a Canadian dealer, without cats, for my R-body cars, and they fit great....just don't hold up to daily driving in the "salt belt"!! For an ocassional driver in good weather, they should last for years! But if you are concerned, these would be GREAT patterns for a custom muffler shop to duplicate in aluminized or stainless steel!!!! Highly recommended.....and patterns could be sold to other Magnum/Cordoba/300, even R-body owners.:

                    http://www.moparstyle.com/classified...-magnum&cat=16



                    Originally posted by 300jeep View Post
                    Well, my plan is to get everything ready for spring and the duels..........the Magnum feels like it is being held back when you drive it. Once that is done, I will also consider a new intake and carb (4bbl). I had a 79 300 new back in 79, and it was a good ride back then, but I searched a while for the right Magnum to pick up, because you see less of them around. In fact I only remember seeing 2 GT's ever on the road when they were new.

                    Paul
                    Paul.....welcome to Style!! The '79 300 was the first Mopar to actually handle (outside of the police package R-body!), and had mostly "police package" equipment, including the E58 360, and HD suspension; I think some Magnum GT's were ordered this way....and it was essential to the car...!

                    If you are considering updating you GT Magnum, it is really essential to convert the "leanburn" ignition to a better electronic ignition (you will not believe the difference from the leanburn!).....but stay with the stock 4 bbl manifold and Thermoquad! Not a bad package!

                    Comment


                    • #11
                      If anyone is interested, I have a complete set of shields ( non California package) in good condition ( along with most of the exhaust hangers ) and a gas tank in excellent condition off of a 79 300. Also exhaust manifolds off the same car ( 360 motor). Lets make a deal! johncailey@yahoo.com.

                      Comment


                      • #12
                        I have one of the GTs, and it is a single exhaust.

                        Comment

                        Working...
                        X