Just a quick question. I finally need an exhaust on my 75 Delta Convertible and was thinking of putting on a dual exhaust system. It didn't come with the dual hump crossmember and i'm pretty sure I can locate one if needed. So my question is do i have the exhaust custom done or locate the correct crossmember. Just curious on the plus and minus of either. Thank You and have a safe Memorial Day .

 

Did one of these 75 delta's ever come with dual exhaust ? I don't believe they did, so finding a cross-member with cut outs for duals may not be possible, unless a cross-member from another car with duals would work... so you probably will need to take this to a shop that can custom bend a system for you..Also finding a dual system if the car never came with it may be a real problem as well. Time for a custom exhaust shop. I am sure it is possible to do..Also this car has a big old converter under the pass side floor board if i remember correctly. Getting around that maybe a real problem as well. UNLESS YOU ARE THINKING OF,,,, NO YOU WOULD NOT DO THAT ????? LOL.....

 

I'm not sure what you mean by a "custom exhaust", as you will need the 71-74 double hump crossmember no matter what. All 1975 GM cars came with a single exhaust and catalytic converter, and in most cases the trans crossmember only accommodated the one pipe.

 

Get the double hump crossmember and find you a good muffler shop. Nobody is going to care about the catalytic converter so have it removed. You might want to make your muffler selection and take them with you. There is a vast selection of muffler depending on the sound you want. Many of use Dynomax Super Turbos wihich give a nice mellow sound. This will be one of the best improvements you can make to your car. Your butt dyno will make you think you have added 50HP.

 

no one is going to care about the converter ??? If you live in nys or many other states they will care., car will not pass insp. IF IT WERE A 1974 NO PROBLEM..CK WITH YOUR STATE INSP OFFICE BEFORE DOING IT. Just a fyi !!

 

Safety only after 25 years in NYC.

Depending on his location he may have aged out...

 

IN my state if the car left the factory with emission equipment on it, it must still be present, air pump,egr valve, pcv, cat ,heat tube etc..

 

I guess you can forget about putting dual exhaust on it. Maybe you could use twin high flow cats. I have them on my 75 Hurst. Of course in Texas, nobody cares if I have them at all.

 

He's in MA... so just the safety test
Hmmm maybe I should pull the cat off my car too

 

Absolutely.

5000 LBS and a big ole THM400 taxing that poor 350. The extra HP and Torque will be a win win.

Hear hear !

Harp if cats are optional, but you are leaning with them anyway i would recommend hi flow, also. Work well and do not hurt performance as best i can see with my 69.

These below are great and the price is a gift !

 

My 72 D88 Royale convertible has the dual hump cross member, but a single exhaust, planning on duals soon, guess there is some issues with manifolds, maybe someone can school me on them?

 

Is the 72 a 350 or 455 car?

350: use the existing manifolds and put a blank off plate on passenger side where the crossover connected to it. That's all the factory did for a 350 DE car.

455: the big-block DE big cars use the same exhaust manifolds as the A-body cars and I believe both sides are available reproduction.

 

455

 

Driver side has pipe to pass. side, I can fab a block off plate for pass side, do I need a different driver side mani.?

 

If you can find an exhaust shop with a good pipe bender, you can probably use the single exhaust LH factory manifold. You might run into some interference around the starter and wiring but a good bender can minimize that.