Smog everything has come off the 73 3.o CSA. What is the correct setup for all the various nipples? And how to handle the distributor? Thanks.
Vacuum Setup -73 desmogged??
- Thread starter andyleonard
- Start date
Mike Goble
Well-Known Member
I run my VA on full manifold vacuum along with my vacuum gauge, everything else is plugged.
not an straight forward issue andy, a lot of "nipples" to touch !
probably the first thing to do is identify the carbs, pictures help too
then you can explain what sympthoms are you experiencing
on carbs and distributors there are several threads already
regards
Honolulu
Well-Known Member
I'm in Mike's camp, though I wonder why he is using a (presumably full-time) vacuum gage. As I understand it, when they became widely available many years ago, it was found that they are not good indicators of your likely mpg...?
I also run manifold vac for distrib advance instead of ported vacuum. This gives cooler idle temps. Or you can run ported vacuum for the advance like stock. Don't use the retard function on the dist. Everything else should be plugged.
Mike Goble
Well-Known Member
It's there because I had it and a hole to fill. It's not a full-time vacuum gauge, there is no light in it so I only use it during daylight hours. It reads from a common line between the two plenums to give me basic average engine vacuum.
My next step is to put one on each plenum so I can monitor each bank under load. Guys spend a lot of time getting the vacuum equalized at idle but don't really know what each carb delivers under load.
I also am working on an MSD 8680 timing control unit to vary the timing from inside the car. We used one of these while running the Lacarrera to keep the power up while running on the available gasoline.
My next step is to put one on each plenum so I can monitor each bank under load. Guys spend a lot of time getting the vacuum equalized at idle but don't really know what each carb delivers under load.
I also am working on an MSD 8680 timing control unit to vary the timing from inside the car. We used one of these while running the Lacarrera to keep the power up while running on the available gasoline.
This is kind of where I was headed...but what about the 2 nipples on the bottom of the stock air cleaner? Ignore them and plug their sources?
Thanks for the replies by the way. I'm usually on the E23 forum and it can take a week to get this much input.
Someone posted a picture of a green 2800CS convertible, asking about it. I built it. A long time ago.
Keep the oil breather tube connected to the valve cover. When I had the stock cleaner I plugged the small nipple that goes to the charcoal canister which I removed. I plugged the line from the cannister that goes to the trunk. Then I removed the hose into the expansion tank in the trunk and capped it and the tank. I then routed the neck breather tube out the bootom of the trunk aft of the gas tank. No smells ever.
Is there more than one small nipple on the air cleaner-I forgot.
Is there more than one small nipple on the air cleaner-I forgot.
Bottom of my air cleaner has a little nipple on the tube to the valve cover and a larger one out the bottom between the carbs.
Search indicates it might be smart to connect 2 engine-side ported nipples together (one each carb) and then use that T'd on to the vacuum advance, leaving the retard open.
And then running a balance line between the 2 smaller nipples on the battery side.
Which leaves the question of the larger manifold to air cleaner can line and then the smaller air cleaner to valve cover nipple.
Comments?
And then running a balance line between the 2 smaller nipples on the battery side.
Which leaves the question of the larger manifold to air cleaner can line and then the smaller air cleaner to valve cover nipple.
Comments?
Mike Goble
Well-Known Member
It makes no sense to me to run ported vacuum to the vacuum advance while removing the other smog equipment.
Here's a little treatise on timing and vacuum advance from a GM engineer:
"For peak engine performance, driveability, idle cooling and efficiency in a street-driven car, you need vacuum advance,connected to full manifold vacuum. Absolutely. Positively."
http://rockridgefarm.com/vettdoc/Timing_101.pdf
Here's a little treatise on timing and vacuum advance from a GM engineer:
"For peak engine performance, driveability, idle cooling and efficiency in a street-driven car, you need vacuum advance,connected to full manifold vacuum. Absolutely. Positively."
http://rockridgefarm.com/vettdoc/Timing_101.pdf
Carl recommends retard off the carb, adv off the manifold. Ireland says that retard doesnt do much and to leave it off, but to run adv off the manifold.
I think the balance line that folks have found helpful is off the old EGR ports on the bottom of manifold.