PDA

View Full Version : Question about exhaust equalizer pipe?


trvlr480
06-22-2008, 01:29 AM
I have a '73 Coupe DeVille. I have read recently that putting in an exhaust equalizer pipe is a very good idea. My question is. Where on this particular model of Cadillac is the best place to put one? Also, does it really make that much of a difference? I also want to be able to remove it for undercar repairs if need be.

When I had the engine rebuilt I was told they put in a cam that was a step up. Whatever that means. I do know that with a Quadrejet carb I just replaced my Perormer carb with I can't get it to idle smooth in drive under 600 rpm in drive which is 700 rpm in park.

The car has dual exhaust and I am putting one of the new Edelbrock spreadbore manifolds on it. Other than that and a complete MSD ignition system it is stock.

Schurkey
06-22-2008, 08:22 AM
Put the tube in behind the transmission mount so that it isn't in the way for dropping the trans. If you want to spend the money for some kind of flange system that makes it removable--fine. You have more money than I do. Mine are welded in--cheap, durable, leak-free.

trvlr480
06-22-2008, 03:22 PM
Thanks, Shurkey. If the cost of putting in a removeable tube is too high I won't do it. Moneybags, I'm not. Your location sounds like it won't be in the way of anything so a permanant tube sounds good.

I do have a friend of mine that was telling me about some kind of removable connector they make that don't leak. That's the reason he has them on his Scout and Audi. So he can take the exhaust apart in pieces. That is why I had the thought of the removeable one.

Tank
08-24-2008, 10:22 PM
Here is mine.
http://photos-674.ll.facebook.com/photos-ll-sf2p/v239/67/113/42103674/n42103674_32814554_320.jpg
http://photos-674.ll.facebook.com/photos-ll-sf2p/v239/67/113/42103674/n42103674_32814553_43.jpg

Schurkey
08-25-2008, 01:39 AM
Here is mine.

That's nice 'n' clean; out of the way of the transmission, and with a short 'n' direct crossover pipe.

Too bad the shop crush-bent the pipe, though.

I'm surprised you could get someone to build that exhaust system. They're risking a huge fine for not installing the catalytic converter since this is a '75 or newer chassis. (Is this car registered, or a race-only vehicle?)

Nashalac
08-25-2008, 10:26 AM
Not sure about the 75 / 76 Cadillacs but many Federal cars didn't have convertors those years. Virtually all Calif. cars did

~JM~
08-27-2008, 12:33 PM
I'm fairly certain that 1975 was the deadline year that all new cars were required to have cats.

On where to position a cross over pipe...

I have read a few articles suggesting that you should lightly fog your exhaust pipes with spray paint or use a temperature sensing crayon & draw a line along the pipes from just below the collector to about 6' back or so. Then you bring the vehicle up to normal operating temperature & drive it for a short time. Shut it down & let it cool. At the transition point of where the paint has burned off & where paint remains is where to place your cross over.

I am convinced that there is a substantial benefit to be had by a properly designed & placed X-pipe. I don't mean two elbows that the local muffler guy arbitrarily cut a section out of & then welded them together. There is more to the correct design than that.

Schurkey
08-27-2008, 03:28 PM
I'm fairly certain that 1975 was the deadline year that all new cars were required to have cats.
No, cats were not required. What was required was that the vehicle had to meet certain emissions regulations. And most vehicles (especially American iron) needed cats to do that. I had a 1980 Honda Civic 1300 that had no cat; the local Midas refused to work on it because I wouldn't let them install a cat--and--I haven't been back there since. The 1300 (Federal emissions) that year did not need-or receive--a cat from Honda; but the 1500 Civic did have a cat. I'm not sure if there was a 1300 California emissions model.

On where to position a cross over pipe...

I have read a few articles suggesting that you should lightly fog your exhaust pipes with spray paint or use a temperature sensing crayon & draw a line along the pipes from just below the collector to about 6' back or so. Then you bring the vehicle up to normal operating temperature & drive it for a short time. Shut it down & let it cool. At the transition point of where the paint has burned off & where paint remains is where to place your cross over.
Yup, I've heard that wive's tale too; and with different versions of what temperature-sensing material to use--including an ordinary tire crayon.

Problem is, the optimum crossover placement is based on tuned pipe length for a resonance effect, it is not based on BTU load.

Figuring out the "optimum" location for a tuned-resonance is an interesting mathematical problem; and of course it would all depend on the RPM you're tuning for.

For any kind of street use--and some competition use as well--slapping in an X- or H-pipe wherever it's convenient does the exhaust system good based on the reduced back pressure; going the "extra mile" to also achieve a precise resonance just isn't worth the hassle. Of course, you then need to jet the carb accordingly, to take advantage of that reduced back pressure.

I am convinced that there is a substantial benefit to be had by a properly designed & placed X-pipe. I don't mean two elbows that the local muffler guy arbitrarily cut a section out of & then welded them together. There is more to the correct design than that.
Agreed. But "close enough" is good enough most of the time.

trvlr480
08-28-2008, 01:23 AM
Well, the above picture is quite a bit different than my exhaust. I just have two pipes coming down either side of the car and out the back. No cat and no resonator with Flowmasters.

I've read about the spray paint trick and that is what I'll do as far as figuring out where to put the crossover.

I really appreciate ALL the input.

Tank
09-15-2008, 05:10 PM
That's nice 'n' clean; out of the way of the transmission, and with a short 'n' direct crossover pipe.

Too bad the shop crush-bent the pipe, though.

I'm surprised you could get someone to build that exhaust system. They're risking a huge fine for not installing the catalytic converter since this is a '75 or newer chassis. (Is this car registered, or a race-only vehicle?)

Yes the car is registered and driven on the road. You can get anything done in Chicago for cash. There is also no emisson testing for vehicles for pre 96 vehicles now in Illinois. I would of rather have gotten a different trans crossmember and ran a more euqal length setup but it needed to get finished asap. I was very aminent about having a equalizing tube installed.

I had a "true dual" exhaust also installed on my Tahoe and later added a singe dual in dual out cat and was pleased with the results. It had a stronger low end and sounded much better.