Aspen 1977 Super Six vacuum issues

1337m4723

Active Member
Joined
Apr 14, 2018
Messages
42
Reaction score
12
Location
Hanover Germany
Hi Guys,

I am back again needing some answers.

My Super Six has some issues containing the carburetor and the vacuum system.

My first question is if I am thinking correctly: when the engine is cold and I am driving, it often dies recently.
I could recreate the problem yesterday, but only when it's cold:
- I hold the throttle as if I were driving steadily.
- Then I take off the gas as if I have to stop at an intersection.
- Then accelerate to start driving again. --> The engine dies and sounds like it has choked/hiccupped.
- When the engine warmed up, I could treat it with different throttle positions in a quick change and it did not die. Even when using the brakes and giving it a lot of throttle ind R or D.

My Idea: the carburetor throttle bearing is worn. When heated, the bearing fits again and the throttle function is back to normal.
Is this plausible? I am not a learned mechanic, so maybe this question is nonsense... But maybe you can understand what I am thinking about.

My second question is: I think the vacuum system has some issues. Idling is not really nice like the engine does not run "round".
I was searching for affordable spare-parts.
Do you know where vacuum parts are available? I don't necessarily need NOS parts. I would be happy with remanufactured Asian products or something similar.

- I blieve the vacuum solenoid valve is leaking. Is there a spare part available?
- I'd like to replace some vacuum-hoses...(my engine still has all original hoses I guess.)
- Is there a spare part for the Vacuum amplifier? (I don't know if this is really necessary...)

Maybe you can give me a hint if there are shops for those parts.. Rockauto has many parts, but not everything.

Best greetings from hanover (Germany)
Matze

IMG_20170827_175613_1.jpg
 

69-

Well-Known Member
Joined
Dec 13, 2020
Messages
154
Reaction score
83
Location
Germany
Hi Matze,

I'd first replace all old vacuum lines. Normal and locally available lines are perfectly ok.
The I'd check with a handheld gauge connected to manifold vacuum the vac level and impact of different driving situations. Take a loong line to the inside with the gauge right next to you.

There are some good sites available showing possible problems based on the vac readings.

Also, old fuel lines (Rubber Parts) can be a culprit. I replaced all of them as well. :)

That's what I would do before buying replacement parts.
 

1337m4723

Active Member
Joined
Apr 14, 2018
Messages
42
Reaction score
12
Location
Hanover Germany
Hi 69- :)

Thank you for your response :)

Good to know, that other lines will fit as well! There are some "special" lines with stock connectors why I am a bit careful which line will work...
But what you write sounds like hoped, that every kind of vacuum hose can be used.

Good tipp with the gauge. Can I connect that thing at the same line as the brake booster and the vaccum amplifier? (they are are conencted to the vacuum manifold with a T-piece which has two more exits available with rubber plugs on it)

That could help to search for the vaccum problem I think.

For the carburetor issue I have the suspucion that the problem is not related to fuel or vacuum. :(
 

69-

Well-Known Member
Joined
Dec 13, 2020
Messages
154
Reaction score
83
Location
Germany
The tee is perfect for the gauge.

Re carburater throttle bushings. Yes, the could wear out and yes, thats air you dont want. Easy test: grab the throttle lever and try to move it up-down, best with air filter off, of course :).

If it is moving too much, you could get a new bushing in, but last time I had that done by a shop was in 2013. Could send you the contacts, it is in Germany, close to the border to the Netherlands. But I dont know if they are still in business.
 

Aspen500

Well-Known Member
Joined
Feb 14, 2015
Messages
5,895
Reaction score
1,980
Location
Rib Mountain (Wausau) WI
About the vacuum amplifier. It's for the EGR system and isn't vital, unless you have emission tests in where you live. It boosts the weak vacuum signal from the ported EGR hose from the carb to a higher vacuum signal that can open the EGR valve. Of course, if it leaks internally, you'd have a vacuum leak. They don't appear to be listed anymore aftermarket but I do see them on Ebay quite often.

Check the choke operation. If it only happens on a cold engine, it's possible the choke is opening too soon, and quickly opening the throttle causes an extreme lean condition and engine "cough" or stall. I only say that since you said it's fine with the engine warm. Worth a look anyways.

Some throttle shaft play is normal, especially on old carbs with lots of use. It's really only a problem if it gets beyond slight movement. Even then, it can be compensated for to some extent by adjusting the idle screws a tad richer. It won't affect off idle much, if at all (loose shaft).
 

AJ/FormS

Well-Known Member
Joined
Apr 26, 2016
Messages
1,258
Reaction score
293
Location
On the Circle of the earth, Southern Man,Canada
Some throttle shaft play is normal, especially on old carbs with lots of use. It's really only a problem if it gets beyond slight movement. Even then, it can be compensated for to some extent by adjusting the idle screws a tad richer. It won't affect off idle much, if at all (loose shaft).
What he said^^
I have never seen a carb so worn, that it would do what you say.
Much more likely is that the under-carb heater is not working correctly, or the heated air intake, or the idle-speed is too slow, closing the transfers, or the thermostat is not working right, or the accelerator pump system needs work, or and most common of all, like mentioned,
is a failing choke system.
All these systems are bandaides to a carb that is manufactured IMO, way too lean. You can fix that but it's usually easier to just restore the failed or failing systems.
BTW
the choke system, can be pretty dang fussy. The factory adjustments were set up for a new engine, back in the day, running on gas of the day, at or near sealevel. So here we are some 40 odd years later, and you got the sealevel part down pat...........
 

1337m4723

Active Member
Joined
Apr 14, 2018
Messages
42
Reaction score
12
Location
Hanover Germany
About the vacuum amplifier. It's for the EGR system and isn't vital, unless you have emission tests in where you live. It boosts the weak vacuum signal from the ported EGR hose from the carb to a higher vacuum signal that can open the EGR valve. Of course, if it leaks internally, you'd have a vacuum leak. They don't appear to be listed anymore aftermarket but I do see them on Ebay quite often.

Check the choke operation. If it only happens on a cold engine, it's possible the choke is opening too soon, and quickly opening the throttle causes an extreme lean condition and engine "cough" or stall. I only say that since you said it's fine with the engine warm. Worth a look anyways.

Some throttle shaft play is normal, especially on old carbs with lots of use. It's really only a problem if it gets beyond slight movement. Even then, it can be compensated for to some extent by adjusting the idle screws a tad richer. It won't affect off idle much, if at all (loose shaft).

What he said^^
I have never seen a carb so worn, that it would do what you say.
Much more likely is that the under-carb heater is not working correctly, or the heated air intake, or the idle-speed is too slow, closing the transfers, or the thermostat is not working right, or the accelerator pump system needs work, or and most common of all, like mentioned,
is a failing choke system.
All these systems are bandaides to a carb that is manufactured IMO, way too lean. You can fix that but it's usually easier to just restore the failed or failing systems.
BTW
the choke system, can be pretty dang fussy. The factory adjustments were set up for a new engine, back in the day, running on gas of the day, at or near sealevel. So here we are some 40 odd years later, and you got the sealevel part down pat...........
Thank you all for your tipps!!

Yesterday I had the time to play around with a vacuum pump and a vacuum gauge.

So I think I found at least one faulty part: The distributor vacuum control leaks. I tested a new one and my old one in the car with the pump. The one I have built in cannot hold a vacuum.

Other faulty parts I found (I am assuming) is that someone "killed" the solenoid for the EGR-valve. The EGR valve is functioning with my hand vacuum pump and kills the engine in idle.
But when I set vacuum to the solenoid the EGR-valve is not moving. I need to varify this the next time I am at the car. (But that problem is not causing the trouble, since the EGR is closed..)

Next thing: The vacuum tee at the intake manifold was really worn out and broke when I removed one plug to connect my gauge... -.-"
Do you know where to find a replacement for the tee? (see the pictures) It doesn't need to be original... a suitable functioning port would make me happy.

All in all the vacuum only reaches about 15 psi in idle and does not hold the vacuum evenly. The needle is "dancing"...

IMG_20211123_201054.jpg


IMG_20211123_201210.jpg
 
Last edited:

Camtron

Well-Known Member
Joined
Apr 25, 2019
Messages
1,031
Reaction score
698
Location
Here
I have an original intake vacuum tree fitting I won’t be using again. You can have it for the flat rate shipping charges at USPS if you like.
 

69-

Well-Known Member
Joined
Dec 13, 2020
Messages
154
Reaction score
83
Location
Germany
Heh, we should have combined shipping to Hannover :)

As an easy fix, plug that brocken port with liquid metal, and use a T adapter in one of the other lines, if needed.

And I would replace all old vac lines.
 

AJ/FormS

Well-Known Member
Joined
Apr 26, 2016
Messages
1,258
Reaction score
293
Location
On the Circle of the earth, Southern Man,Canada
The distributor vacuum control leaks.
Is this the one on the distributor? If yes, it depends where you are checking from. >The Vacuum advance can itself should NOT leak vacuum, If it does, then it is worthless. But if you're pulling vacuum at the OSAC, that could be normal.
>The vacuum amplifier is a pneumatic relay. The yellow line is the signal generator. The manifold vacuum is the power supply. The orange hose sends manifold vacuum to the EGR,down the blue then white-traced hoses. But it is interrupted twice; first at the vacuum solenoid valve and second at the CCEGR thermo-vacuum valve. This means that three conditions have to be met to trigger the EGR;
1) the carb has to be opened far enough to open the port, and
2) the solenoid has to be energized (usually in Top gear), and
3) the coolant has to be above a certain minimum operating temperature.(usually 195*F)
To witness your system working, you will have to plumb a vacuum gauge close to the EGR valve in such a manner as you can see it from the driver's seat; then with the engine warm enough to open the factory rated thermostat, take it for a hiway run. When all three conditions are met, the EGR valve will open, and if it happens after say 30mph, you should not even notice it.
Your engine does neither need nor want EGR, but there is no harm in running it if your system is functioning properly.
The charcoal canister in the diagram is a full-time running device, but probably gets it's signal from venturi vacuum, or a port above the throttle blades, so that it does Not operate at idle.
I feel that your vacuum could be a little higher. Besides a vacuum leak, the biggest contributors to low vacuum, in order of probability, are;
1) a vacuum leak at one of the ports, or a exhaust getting into the intake underneath the carb
2) a high idle,
3) tight valves,
4) retarded timing,
5) very low or uneven compression pressure
6) a very high "wet" fuel level
The ones most likely to cause; "Idling is not really nice like the engine does not run "round"", are numbers 6,3 and 5, and on a 2bbl; imbalanced mixture screw adjustment. As you may notice, 5 and 3 are related
A wandering vacuum needle is usually showing an AirFuelRatio problem. Thus having a low Vacuum AND wandering needle, that does not clear up with mixture screw adjustment, AND does Not "round out", is usually pointing to a vacuum leak. And since slantys are known for the occasional intake to be leaking at one or more ports at the cylinder head; I would start by looking there.
And then, if you have a Solid Lifter engine, I would definitely go there next; followed by a compression test.
Good luck.
img_20170827_175613_1-jpg.jpg
 
Last edited:

Aspen500

Well-Known Member
Joined
Feb 14, 2015
Messages
5,895
Reaction score
1,980
Location
Rib Mountain (Wausau) WI
Never thought of valve adjustment if it's solid lifter. Going by your avatar photo, I'd guess it is solid. Too loose or too tight can cause all sorts of problems, especially the too tight way. That can keep the valves from fully closing when warm. Even if it isn't causing any obvious problems, it's always surprising how much smoother the engine runs when the adjustment is correct,,,,,,,and almost more importantly, the same for each cylinder.
 
Top