rebuilding 72 carb: is this the egr? (and advice)

[dochawk]

I have the rebuild kit for the carb on my 72 Eldorado convertible, but I'm new at this.

There is a small metal "box" on the driver's side of the air filter housing--is this the egr connection?

When I had it checked out before buying it, it was blowing 2.0% CO; my limit is 1.2%. I'll rebuild the carb and give it a full tune up; is this likely to be enough?

I absolutely have to meet the standard for initial registration (the car came from out of state). I can either smog it yearly, or smog it once and get an exemption for the future (with a 2,500 mile/year limit). Either way, though, I need to get it down at least once.

I have my rebuild kit, chilton, hanes, a bottle of spray cleaner, and the can of carb cleaner. Any other advice?

Thanks

hawk

[submariner409]

EGR valves are usually bolted to the exhaust passage crossover in the intake manifold and dump into the intake area directly under the carb. The metal box sounds like some sort of air door for controlling heated inlet air. Not sure, but FYI, EGR controls NO (oxides of nitrogen) while CO (carbon monoxide) is from incomplete combustion or a slightly rich mixture. Not sure if your car had a cat yet, but a cat also lowers CO.

[devillemannen]

When we want low CO in Sweden, we just fill the tank with E85, about 50%, before technical control. Then we are all set (-:

[jk1000]

Sounds more like the crankcase breather. One end of the "small metal box" connects to the air cleaner and the other end fits into a hole in the valve cover on the driver's side.

As mentioned by submariner409, the EGR is attached to the intake manifold and controls NOX. It's located at the passenger side, rear of the intake manifold. It has a vacuum hose attached to it.

As far as CO, that is purely a mixture problem (too rich). Adjusting the needle valves (inward) on the carburetor should help. How much? I don't know. A carb rebuild will probably help too. The solid floats tend to absorb fuel over time. This makes it somewhat heavier, and will raise the fuel level in the float bowl. This too, equals a richer mixture.

Also, make sure the engine is fully warmed up and the choke fully open before your emissions test.

No CATS on a 72. Hmmmm, maybe you could put one on (temporarily). That would probably clean things up enough to pass.

Emissions testing sucks and really should not be required on a vehicle that age. Never mind the diesels spewing huge clouds of black smoke. Let's pick on the antique vehicle owner that only drives a few miles each year.

Good luck and get that exemption. Let us know what happens.

[dochawk]

This car probably sat in a garage for a few years before the prior owner started having things done to it, then changed her mind, and just signed it over to the mechanic. Then sat until he sold it to a body shop (actually, it only has one dent!), and sat there taking space for five years until he gave up on getting around to it and sold it to me. So it probably sat for several years . . .

I paid $80 to have it evaluated, and was told that it was generally solid, although the carb was way out of adjustment. Aside from blowing 2.0% CO, it produces 4MPG at the moment

I've circled the box in question; is this the crankcase breather? I noticed that it wasn't connected (even before I pulled off the filter assembly). Would that have made any difference?

I did notice that when I open up the throttle when already moving, the car sags instead of accelerating. I assume this is a carb issue (the second pair kicking in wrong?)

[submariner409]

Judging by the picture, and the amount of time the car sat, you need to replace the points, cap, rotor, wires, plugs, pull the carb and totally overhaul it because all the gaskets, seals, leather pump cups, etc. are toast. Coolant change. Oil, filter, air filter, fuel filter.

Might as well replace all belts, too. Pull everything apart, seal it up, and use Gunk engine cleaner, then start from scratch.

I'll bet that every rubber vacuum line needs replacement, too.

If that box in question is also attached to the side of the air filter housing, some sort of early rocker cover/crankcase ventilation system, and would make no difference in emissions UNLESS the flow was controlled by a rattle-type PCV valve, which would connect through a 5/8" ID rubber hose to a tit on the carb front base.

[cadillac_al]

I think that "box" is a crankcase breather. I don't think that car had EGR in 72. I'm sure a carb rebuild and a lean mixture setting and a complete ignition tune up should clean it up quite a bit. Good luck.

[dochawk]

Originally Posted by submariner409

Judging by the picture, and the amount of time the car sat, you need to replace the points, cap, rotor, wires, plugs, pull the carb and totally overhaul it because all the gaskets, seals, leather pump cups, etc. are toast. Coolant change. Oil, filter, air filter, fuel filter.

I have all of these, ready to go. I'll get a float, too, and I have the coolant flush stuff, woo.

Might as well replace all belts, too.

Yep, have those all sitting in the trunk.

Pull everything apart, seal it up, and use Gunk engine cleaner, then start from scratch.

I'll bet that every rubber vacuum line needs replacement, too.

The rubber doesn't look very good, no. After driving a few miles today, one of them was making hissing-spurting sounds.

How do I use gunk? Put it in the tank, or is it a spray.

If that box in question is also attached to the side of the air filter housing, some sort of early rocker cover/crankcase ventilation system, and would make no difference in emissions UNLESS the flow was controlled by a rattle-type PCV valve, which would connect through a 5/8" ID rubber hose to a tit on the carb front base.

I don't think there are any hoses that big to the carb, but I'll check.

I've run into another problem. In the spec sheets for the rebuild, it shows different measurements for 1st Type and 2d & 3d types for the 1972 500. They're different for Float level (+1/32) and front vacuum break (-5/64). There is a footnote for 1st type "These applications have a secondary metering rod of 27/32. Fig V." It has no hint as to what the measurement is on the 2d/3d types. How do I figure out which to use?

(Out of curiosity, would I get the power boost if I used the 71 numbers rather than the 72, or was that a different carburetor? Are there other differences leading to the drop in power?).

Finally, this can of carburetor cleaner says that cast iron parts should be coated with penetrating oil to prevent flash rusting. Does this apply to me?

thanks

hawk

[submariner409]

Gunk Foaming Engine Cleaner is essentially a soluble oil used for external degreasing. Spray it on, hose it off.

Not sure about the float heights and vacuum breaks for your QJ - they're all different, and probably nowhere near those same settings on one of my Olds 455 4MC setups.

I can say that, unless you're really familiar with secondary metering rods (there's a million of them, all different tapers), hanger height control, and air valve opening adjustment, stick with the factory specs. No, you won't get any more power by lifting a rod set early - just a richer secondary mixture.

Find that Doug Roe HP book on Rochester carbs - it's worth its weight in gold.

[blue_eldo]

Originally Posted by dochawk

I have the rebuild kit for the carb on my 72 Eldorado convertible, but I'm new at this.

There is a small metal "box" on the driver's side of the air filter housing--is this the egr connection?

When I had it checked out before buying it, it was blowing 2.0% CO; my limit is 1.2%. I'll rebuild the carb and give it a full tune up; is this likely to be enough?

I absolutely have to meet the standard for initial registration (the car came from out of state). I can either smog it yearly, or smog it once and get an exemption for the future (with a 2,500 mile/year limit). Either way, though, I need to get it down at least once.

I have my rebuild kit, chilton, hanes, a bottle of spray cleaner, and the can of carb cleaner. Any other advice?

Thanks

hawk

The small metal box is a crankcase breather that is taking oil vapor that the PCV is not handleing and venting to the air filter housing.
The quadrajet is a complicated beast. the most common problem is the primary power piston sticking in it's bore. the primary power piston had manifold vacuum on one side and a small spring. The spring pushes the piston up to the rich position and vacuum pulls it down to a leaner position. The piston is connected to a pair of tapered metering rods. The primary power piston can be freed up without taking the carb apart. You can see it by looking down through a vent tube in the top air horn and carefully push down on it with a small screwdriver. If it gets stuck in the down position, it will run very lean and hesitate and stall. With some experience, you can make a little tool to reach in there a hook on it and pull the piston up. If this fails you can simply remove the air horn with the card in place on the engine and get access to the primary power piston and metering rods.
For you to be happy with a 72 eldorado you need to become a quadrajet expert. There is a ton of Quadrajet information on the internet. there is information sprinkled in Corvette blogs, Pontiac blogs and Olds sites as well, So start digging before.

[awadecki]

That box in the air cleaner is definitely (as said before), the crankcase breather--the other half of the PCV system. You should probably replace it along with the PCV--it's only a few dollars.

Before you go about tearing through the carb, you should complete all of the ignition system repairs. Then--I'm surprised no one suggested this--you should change the fuel filter at the inlet on the carb. It's probably all gummed up. You might not even have a problem with the secondaries. My guess is that the carb probably isn't getting enough fuel.

[dochawk]

It's a little late to not tear through the carb



(The entire sequence of my pictures and comments [as well as future updates] is at http://dochawk.org/column.090222.html. This should continue working indefinitely, even if these links/pictures stop.)

The gaskets did not come off in single pieces, but crumbled . . .







(all little pictures here link to full size images).

I've got the little pieces in a can of chem-dip, but the three big pieces won't fit through the opening of the can! What can I safely pour it into to clean them?

There is a plastic piece that doesn't seem to have a replacement in the rebuild kit:

Should I do anything special to clean this piece , or just wipe it?

In keeping with the, uhh, bizzare electrical bungling, apparently done by someone who only needs half a chair to sit, I found this.



I'm no automotive engineer, but I'm reasonably certain that Cadillac didn't ship a couple of vacuum lines plugged with hex bolts . . .

I d have assume that these should be reconnected, but what is this line, and what would have led someone to do this? There's plenty of length to have reconnected it.


Also, another couple of connections are of concern.


The nipple circled in red is capped. Is this correct? Since it's with a cap, and not a hex nut, I could believe that this is real.

Also, the blue and yellow circled lines don't connect to anything. Should they, or is this just a way to get air below?

thanks

hawk

[submariner409]

The last pic, blue and yellow ----bowl vents........ just as they are. Red circle is a ported vacuum tap --- the cap indicates that it may not have been used in this application. The larger tube, in the base, with what looks like white tape on it, is the PCV hose hookup. The hose with screw in it is probably part of a choke or accelerator return modulator hookup (or maybe part of the secondary air valve lockout mechanism).

I think the black plastic piece is a splash/surge suppressor in the primary bowl - prevents fuel from sloshing side to side. The piston, rods, and hairpin clip in the black plastic piece cutout are the primary metering rods - careful - don't lose or bend anything - that piston should move up and down freely.

For the larger parts, carb cleaner and a toothbrush. Shoot carb cleaner through all ports and passages.

Call Frank Linster or Joe at Automotive Rebuilders in Bensalem, PA and see what a rebuilt carb would cost. 215 639 6511

[cadillac_al]

It's not a bad idea to freshen up that carb but an old mechanic told me a long time ago that " a lot of carburators get rebuilt because of poor ignition" (mostly points). It doesn't appear to be that dirty in there so it might not have been your problem. Your hands look a little too dirty for carb work in my opinion. I hope your kit came with a new float needle and seat. If not, now is the time to replace them. Make sure the primary needles are/were moving freely. If you take your time and put it all back together like you took it apart everything should be fine.

Oh yeah, if you really want to do a good job you should epoxy the well plugs at the bottom of the fuel bowls from the bottom side. If you search around the net for Quadrajet rebuilds you should find more info and pictures of epoxy dabbed on them. Those plugs frequently leak and make the vehicle harder to start after it has sat overnight or a couple days depending on the leakage rate.

[awadecki]

That rubber block holds the needle/seat assembly in. Just clean it up and put it back in.

Maybe you can help me. How did you get the fuel filter inlet nut off to remove the carb? Did you move your A/C compressor?