To De-Smog or not to De-Smog...

[ESP47]

Keep the smog stuff after you tear it off. I don't know if it will totally be compatible, but it's definitely still worth something for those of us who want to run 1975+ cars here in CA where we still have to smog them.

 

[fjr]

At the same time, I know what I did. To defeat EGR, I hogged out the hole under the carburetor in the intake and pounded an oil gallery plug into it. I then replaced the exhaust manifold with one that can not provide an exhaust gas source for EGR, nor for carb heat. I also made sure the vacuum source to the EGR valve I had disabled was plugged. Due to the removal of the exhaust manifold, I had to fabricate stand-offs in order to retain the factory throttle & kickdown linkage.

What was your intention with the fabrication of the exhaust manifold? With the stubbed-in pipes, you've made the exhaust less free-flowing. With the elimination of the hot-spot under the carb, you've made your car more suited to the drag strip than the street. See Intake Manifold Heat for more information and check the references provided.

 

[slantsixdan]

I then replaced the exhaust manifold with one (...) that cannot provide carb heat.

Why? The hot spot doesn't provide carb heat (that's provided by the thermostatic air cleaner), it provides intake manifold heat, which is a good thing, not a bad thing -- see here (see the video!).

 

[slantsixdan]

What was your intention with the fabrication of the exhaust manifold? With the stubbed-in pipes, you've made the exhaust less free-flowing.

You're right, but he didn't fab it, he bought it off "Mister Twister", who until very recently has been trying to substitute marketeering, ignorance, and occasionally his shrill wife/girlfriend for his very apparent lack of knowledge and skill -- see threads here and here and (especially) here.

 

[2 Darts]

Why? The hot spot doesn't provide carb heat (that's provided by the thermostatic air cleaner), it provides intake manifold heat, which is a good thing, not a bad thing -- see here (see the video!).

Not quite. The hot spot is for carb and fuel mixture heat. If this was not true, it would not have been designed into the engine from the beginning. The thermostatic air filter eventually provides warmer air that helps the fuel stay suspended in the air better.

For those of us who don't live in the rust belt and points north, there is such a thing as excess heat. Here at the Edge of the World, we have lots of it. Because of the proximity of the intake to the exhaust ports, the intake on the /6 will heat up without a supplementary source.

 

[2 Darts]

You're right, but he didn't fab it, he bought it off "Mister Twister", who until very recently has been trying to substitute ... -- see threads here and here and (especially) here.

Dan and Twister have been at it for a while. The basis of Dan's objections, as I understand it, has been a lack of empirical data to back up Twister's claims. FWIW, I do not support Twister's claims for this pipe, either.

I purchased it wanting something that would work with a larger pipe than the stock manifold would support. The Super 6 exhaust manifold that is supposedly able to mate up with a 2¼" pipe seems to be made of unobtanium in these parts, hence the purchase of Twister's piece.

In it's defense, I will say that it is well made and has proven durable for the 15,000 miles I have used it. In my own tests, removing all the variables I possibly could, I got 3 mpg better gas mileage on the highway and another 7 mph top speed. These were areas I wanted to improve. The changes were the installation of this pipe and a 2¼" exhaust system.

The car runs like crap when cold, but it did that with the stock manifold. I don't see any gain or loss in that regard. As for changes in exhaust flow, I couldn't tell you.

The entire point of the whole EGR thing is that to eliminate it, you have to isolate the intake from the exhaust system and make sure a vacuum loss is not created in so doing. The choice to do this is the reader's.

IMO, EGR shot drivability of the internal combustion engine in the head. It has not been until fuel injection and closed-loop computer controlled emissions systems were implemented, that EGR has been able to do the job it was intended to do with minimal adverse impact on drivability.

 

[slantsixdan]

The hot spot is for carb and fuel mixture heat.

Incorrect. The hot spot is for intake manifold heat. Period. It does not provide significant carb heat. If it did, the throttle plate anti-ice system made available in Canada starting in '61 and put on all North American-market slant-6s in '69, and the '70-up thermostatic air cleaner, would not have been necessary or desirable.

If this was not true, it would not have been designed into the engine from the beginning.

The one doesn't follow from the other.

It runs like crap when cold

Well, that's a damnuisance. You can probably find and fix the problem if you will learn how the various components and systems actually work. My '73 Dart with 225 started immediately and ran damn near flawlessly all winter in Toronto. The '71 I had before the '73 behaved likewise...breaker points and all.