Success! and thank you!

[Jeff B]

Hi, I'm a new member, signed up about 2 weeks ago.
I've got a '74 sii w/ a 304, that I've had for about 17 years, and it was my daily driver until about 5 years ago.

Haven't driven it much the last couple of years, mostly because it was running kind of rough, and I hadn't had any time to work on it. I have given up on mechanics around here, if they can't plug it into a code reader they don't want to work on it. The last time I had it into a shop about two years ago, the mechanic said the carb was fine - nothing wrong with it (even though it had a major dead spot that you had feather the pedal through). It idled fine, and wide open was fine, you just couldn't take off from a stop sign very easily.

Last fall I decided to start working on it, just doing some basic maintenance plus I installed a pertronix unit in the dist. I started looking around trying to find a different mechanic that would work on the carb, and they all blew me off, saying that they "didn't like working of carbs, go check out so-and-so, he does a good job" only to be told the same thing at the next shop. Over the winter I talked to at least a dozen mechanics and never did find anyone willing to work on it.

But I did find this site, and a lot of information. I even contemplated calling ronmc, who only lives about 35 miles away. After reading all of the relevant threads several times, I decided to give it a try myself. Found the right kit and a new float, and tore it down, taking lots of pictures. After soaking, scrubbing and cleaning as best I could, I reassembled it with lots of trips back in to look at my pictures and reference a couple of threads here.

Before I hooked the fuel line up, I thought I ought to check that out, so hooked up a piece of tubing to the outlet of the filter and ran it over to a bucket, cranking the engine, I got a very weak flow of gas that smelled like varnish and then nothing - crap! So I pull the filter off, still nothing, unhook the lines and drain the tank, flush the lines and blow them out, get 2 new fuel filters, and had to order a pump.

The pump got here yesterday. This morning I hook the pump and filter back up, fresh fuel, crank it and it fires! Still need to do some minor adjusting, but it runs! Now I have to go out and move a bunch of crap in the garage so I can get it out and go for a drive in our fresh snow!

Just want to say thank you to ihon for running the forum, and to mr. Mayben for the information that gave the me confidence to try my first carb job.

I will probably be asking some questions about vacuum lines, as the way mine are hooked up (and have been since I got it) look nothing like the routing diagrams, but it runs.

Jeff

 

[Michael Mayben]

Congratulations on doing this!

And...you have encountered the typical "response" from today's so-called "technicians" regarding carburetors! If anyone ever sez that the "carburetor is fine" on a vehicle that is old and hasn't been in use for years is fulla guapo!

If you need the vacuum hose routing information posted, just ask.

 

[Jeff B]

Thanks michael, after work tonight I will post the way my hoses are routed compared to the diagram, and you can let me know how f'd up it is!
Then I will go to the parts store and buy some new hose to replace everything!

Jeff

 

[Jeff B]

Michael, or anybody else willing to help out a poor working stiff,

okay, I'm going to attach a pdf of the routing diagram in case you don't have it handy.

To start off, on the left (drivers) side, there is no air pump,
nothing connected to the high temp vacuum control valve (red),
no tee 1,
nothing connected to the low temp vac control valve(scs system)( blue), so that takes care of everything on the left or drivers side.

Of the rest of it, there are only two hoses that are as shown on the diagram, hose m from the canister to the carb, and hose I from the egr valve to the low temp vac. Valve (egr system)( bronze).

Hose n (the other hose from the can to the carb) is missing and the port on the carb is open and sucking air. Would it be better to replace this or to cap it off? I put a piece of tape over it for now.

The distributor vacuum advance is connected by a line that runs straight back past the coil and is teed into a line that loops between and connects to two ports - the one on the right side and the right port on the back of the carb where hoses h and o should be.

H is supposed to run back to the low temp vac valve (egr), nothing is run to that connector.

O is supposed to run the choke vacuum diaphragm.

The choke vacuum is run off the back left side port. (which should run around the left side to tee 1, the vac advance and high temp vac control).

The large port in the middle of the back has a short piece of hose that is plugged, does not connect to anything, no hose l, and no place for it to hook up to (vacuum manifold?)

only one line connects to the solenoid on the firewall and runs to the air cleaner.
Supposed to be one line hose b to the low temp vac system on the left and the other hose d to tee 2 and on to the air cleaner and low temp vac (egr system)

that's it. How fooked is it? The vacuum advance and choke work, but it sure seems like the rest is a mess.

Thanks for any advice given.

Jeff

 

[RobertC]

Since no one else has replied, I will make a few comments...

Is there a vacuum manifold tee on the pass rear of intake manifold?

You should run hose n to the evap canister... Then, this system should work correctly assuming the lines still run to the gas tank.

Since the egr valve / low temp switch are not hooked to a vacuum source, I have to assume the egr is not working "correctly"... This May mean that there is a possible vacuum leak, but I do not really know.

The vacuum advance should be connected to the port where the choke vacuum is now connected - per diagram. And, the choke vacuum connected to the port for "o".

Since your vehicle does not have the the air pump, I do not know the pros / cons of running all lines correctly to the temp vac switches / etc per the diagram.

 

[Michael Mayben]

Before ya take any steps in resolving the vacuum hose issue, we need to know what your ultimate goal is.

If it's a "restoration", then simply replace every piece of soft rubber with new stuff correctly plumbed. And it seems that you will also need some replacement hardware to go with that. Most everything is available either new or used except the actual egr valve itself but we do have used ones.

If this is a playtoy to be used on occasion, then I'd treat it as a "off-road only" enterprise and simply bypass/remove everything that is vacuum connected. There is absolutely nothing under the hood that needs to actually be useable except for the carb connection to the distributor advance canister.

So let us know what you are leaning towards and we can go from there.

Again, we've delt with most all of this type information in one sub-forum or the other in the last two years!

 

[Jeff B]

Hey guys, thanks for the replies.
Been a busy week, haven't had time to do much on it.

Michael - I guess most people would say this is a toy for me. I stopped using it as a dd about 6 years ago when I got a different job that required a 60 mile (round trip) commute. Since that time it has been mostly a hunting and fishing rig, also used to haul trailer-loads of lawn clippings and leaves to the dump, or other stuff that wouldn't fit in the trunk of my buick. It could be "off-road" only, but if these things (egr and evap) are functional without the air pump then I feel they should be hooked up. If they give me problems - its history, just like the air pump for whatever reason the po pulled it.

I can't afford to do a "restoration", but I do need to fix it up some. I did some body work on it a few years back which made it 3 different colors and embarrassed the hell out of my daughters. Funny thing though, once my girls got old enough to drive, they always wanted me to take the top off and let them take it out to the lake! - they didn't mind bombing around out in the country, but they didn't want it parked in front of the house!

Anyway, back to the current project of getting it to run! It now idles smoothly, and revs with just the slightest bit of hesitation at mid throttle but will pull through it. Don't have a vac gauge, just my old sears timing light and "engine analyzer" (rpm, dwell, volts, points).

The vacuum manifold on the intake was probably taken off by whoever removed the air pump and associated plumbing. It was replaced with an elbow to run to the brakes.

I did pick up some new hose, some of them were a little stiff. I also thought that there had to be a better way to route the hoses that were on there than the way they were.

Replaced the missing hose from the can to the carb, since I had to do something there - open port.

Checked the egr valve by pressing up on the bottom while it was idling, and it wanted to die, let go and it recovered - mostly - was just a little rougher, so I pulled the egr and cleaned it up, got the part that sticks out of the bottom to move. (cracked the line coming from the fitting in the valley to the intake while pulling the egr valve - replaced it.)

I think that it had been hooked up wrong and not functioning for so long the the bottom of it was all gunked up and when I pushed it up it wouldn't return. After cleaning, put it back on and it idles fine, press up and it wants to die, let off and it returns to normal.

Assuming that this check means it is working okay I rerouted the vacuum lines to it as shown on the diagram, carb to the low temp vac valve, ltv valve to egr, ltv valve to solenoid.

Ran new line (o) to choke diaphragm, and new line (a) to vacuum advance ( did not put in tee and line to high temp vac control valve)

so far so good. I have something on all of the carb ports, and no indications of any leaks, smooth idle, no change if I spray carb cleaner around everything.

Question time.

The diagram shows the other line from the solenoid (line b) running to the drivers side (scs) low temp vac valve. ( the way it is run on mine goes to the air cleaner?? ) and then from there to the high temp vac valve (line f).
Then the teed line off the advance to the high temp vac.
And without the vac manifold there is no place to hook up line p from the air cleaner temp sensor.

Do any of these really make any difference? Mostly wondering about the line from the solenoid. What the heck are these control valves and the solenoid supposed to do?

Also while moving the air cleaner on and off several times the larger hose from the valve cover cracked, is this just a piece of regular hose or some special preformed piece?

Thanks for for putting up with the new guy with the stoopid questions!

Jeff

 

[Michael Mayben]

The entire vacuum-operated system is an add-on type emissions systems Jeff, it performs no other function on the level of vehicle we're discussing here. Ihc did not design any significant internal engine changes for emissions purposes as did chryfordrolet on their products. That is why "optimizing" these engines for off road use only works so painlessly!

Unless you have all parts of the system connected together as they were originally, the emissions system can't/won't perform...period. Sure...bits and pieces May operate, but not in a cohesive manner throughout all engine rpm and roadspeed conditions.

Egr is controlled by manifold vacuum, engine coolant temp, and road speed in the case of your fairly early adaptation. The good thing is that it's entirely a bolt-on deal and eliminating it has no affect on engine operation. The low temp and high temp switches control/modulate when and how long the egr actually "opens".

All the crapbackward vacuum operation of the vacuum-potted air cleaner is simply to prevent an overload of hc/co at cold engine start, something your eyeballs will never see. That goes along with the divorced choke actuation which is also an emissions design. The air cleaner system itself is highly restrictive to actual air flow, that was part of the noise reduction scenario that played out in the car/truck bizz back in the day.

The evaporative emissions system is to prevent admitting gasoline vapors from discharging to the atmosphere and is a passive system that has no impact at all on engine operation.

The a.I.r. System was probably the most significant actual "enhancement" to the entire engine emissions scenario and it's been eliminated for many years according to your explanation so it's doing nothing at this point other than allowing the remaining pieces to rot away.

The 7/16" hose from the air cleaner housing to the flame arrestor mounted to the valve cover is a special hose. It's an "emissions" hose and rated for exposure to hydrocarbons internally. It must be connected to the air cleaner or to a aftermarket vented cap so that atmospheric air that enters that hose is filtered at all times. That stuff is one half of the actual pcv system for ventilating the engine crankcase.

The only other real significant piece of the entire system is the distributor advance curve (emissions version) that was part of the package, and dialing in the distributor to "enhance" the timing curve is something that can go along with updating the ignition system when finances allow.

I'm here ta tell ya, unless you have everything connected with each piece operational, you are going to continue to have glitches occur in a random fashion over time. And...the engine will never maintain any state of tune for very long.