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Alright Let me start off by saying I'd already done plugs. And wires just put on a new water pump now. I can't even drive the damn thing without it sputtering, killing itself at anywhere from just an idle up to 45mph it'll start sputtering I've found s suspicious hose leading nowhere an i can't find its home im but to do the filter an fuel pump here later today tho Mystery hose without a home?
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
that hose is a rather large vacuum leak, while it needs to find its home again I would at least plug it and see if it fixes your sputtering issue and then find its home and put it back where it goes.
The hose on the front of the carb going off behind the alternator looks to be broke also, may just be the picture not sure.
Sorry its probably listed but I don't see it, what year is your car?
Neal
Last edited by chevymans 77; Sep 21, 2025 at 10:01 AM.
I find it interesting that the end of the hose is painted corporate blue, but not the rest of the hose.
So, must be a bare metal port somewhere. But I don't have a clue. Way too much smog garbage for me.
I noted you said, "new plug-wires". After you get your vacuum issue sorted out, make sure plug-wires #5 & #7 are well away from each other.
Starting at the cap, through the looms and on down to the plugs. They should not run beside each other.
Due to the firing order, those two cyl will misfire. This known as Inductive Crossfire.
that hose is a rather large vacuum leak, while it needs to find its home again I would at least plug it and see if it fixes your sputtering issue and then find its home and put it back where it goes.
The hose on the front of the carb going off behind the alternator looks to be broke also, may just be the picture not sure.
Sorry its probably listed but I don't see it, what year is your car?
I find it interesting that the end of the hose is painted corporate blue, but not the rest of the hose.
So, must be a bare metal port somewhere. But I don't have a clue. Way too much smog garbage for me.
I noted you said, "new plug-wires". After you get your vacuum issue sorted out, make sure plug-wires #5 & #7 are well away from each other.
Starting at the cap, through the looms and on down to the plugs. They should not run beside each other.
Due to the firing order, those two cyl will misfire. This known as Inductive Crossfire.
That vacuum line goes the thermal switch on the air cleaner that regulates the flow of pre heated air from the stove on the drivers side exhaust manifold versus outside air on a cold start.
Since all of that has been removed on your car you don’t need that line. It can be capped off. Alternatively you could run the vacuum advance line to that nipple on the carb instead of its ported vacuum source on the front. This will add your vacuum advance to your ignition timing at idle making the car run better.
Alright Let me start off by saying I'd already done plugs. And wires just put on a new water pump now. I can't even drive the damn thing without it sputtering, killing itself at anywhere from just an idle up to 45mph it'll start sputtering I've found s suspicious hose leading nowhere an i can't find its home im but to do the filter an fuel pump here later today tho
That’s your heat riser. Another device that’s used to help the car warm up quicker. They are notorious for getting stuck shut and blocking exhaust flow though.
If you plan on removing its function like most people do you can wire it fully open, or better yet get a spacer that takes its place completely.
That’s your heat riser. Another device that’s used to help the car warm up quicker. They are notorious for getting stuck shut and blocking exhaust flow though.
If you plan on removing its function like most people do you can wire it fully open, or better yet get a spacer that takes its place completely.
If the heat riser is stuck shut, it absolutely could be one of your issues.
Do you have a vacuum pump, like a Mity-Vac? If you do, you can apply vacuum to that actuator. With vacuum applied, it should shut, without, it should open. If it actuates, you know it isn't stuck. You can then delete that line, and plug everything north of it, because I doubt you are driving your car in the snow. The same goes for most of your vacuum lines, but start with the ones that are leaking.
If you find an image of a 77 heat riser, you should be able to tell by the lever position which way is open, and which way is closed. If it is closed, you are forcing half of your exhaust through a narrow passage in the intake, and out the other bank.
If the heat riser is stuck shut, it absolutely could be one of your issues.
Do you have a vacuum pump, like a Mity-Vac? If you do, you can apply vacuum to that actuator. With vacuum applied, it should shut, without, it should open. If it actuates, you know it isn't stuck. You can then delete that line, and plug everything north of it, because I doubt you are driving your car in the snow. The same goes for most of your vacuum lines, but start with the ones that are leaking.
If you find an image of a 77 heat riser, you should be able to tell by the lever position which way is open, and which way is closed. If it is closed, you are forcing half of your exhaust through a narrow passage in the intake, and out the other bank.
it definitely moves freely and doesn't feel like it's stuck when I move that little lever.But that little arm isn't attached to the lever, and it won't stay attached
Here's the thread I was thinking of, which had images of the heat riser. Reference the open lever position, and wire it that way. You can then remove the plunger bits.
The positions of the Heat Riser Valve
Left photo Engine Temp Below 180*
Right photo Engine Temp at or above 180*
Notice the finger stops in relation as to valve open or closed...
Stumped big time
