Did you check the main jet wells to make sure they are not leaking?
Did you check the main jet wells to make sure they are not leaking?
re; post #25
No, not ported vacuum. I believe thats a line for the vapor canister. It doesn't pull vacuum in the usual way. It's a calibrated feed that starts flowing at a fairly wide throttle opening.IIRC. It could also be used for an EGR signal.
Ah, that would make some sense right there! Yah I guess being mid venturi would suggest it is a wider throttle opening at which it would see some vacuum.
As to timing, if you crank in more idle-timing, as you have found out, it begins to spark-knock under load or rpm, due to being over-advanced under those conditions. The cure is to modify the mechanical advance system, to limit the power-timing, and/or to delay the vacuum advance cut-in point.
Temporarily disconnect the vacuum advance, and drive it that way for a few hours to see if its load or rpm that is causing the spark-knock.
I have the vacuum advance disconnected permanently right now, as there is no safe way to be able to drive it. If I wanted to have the vacuum hooked up and not knock base timing would need to be in the ATDC marks. So I think you have slightly misunderstood what I am saying, unless I misunderstand you right now about this ? LOL. With the vacuum advance disconnected I still get the SLIGHTEST knock but only under severe acceleration and WOT.With the vacuum advance hooked up, it does seem to be load that does it and not RPM. You could be just starting to move in 1st gear and give it a bit more throttle and the diesel knock comes on strong under the hood.
Limiting the power-timing is accomplished by reducing the slot length in the advance plate, that sits in the bottom of the dizzy. Putting stiffer springs in there will delay the rpm when the full advance is reached. Heavy cars with tall gearing do not like too much advance at lower rpms, and generally don't want it early. Most/all sbms like more idle-timing than factory supplied, but that's not always possible if it gets into spark-knock just off idle.
I was thinking about getting some of these dizzy tuning rings to help with the mechanical advance matter actually.
Why are there so many throttle return springs on there. There should be just two; a regular one, a lite back-up/safety one and no others. The back-up one is a safety, in case the main one wears out and fails.There should be another lite one returning the KD mechanism. It goes backwards towards the firewall.
There is one extra throttle spring on there to provide a more firm feeling pedal, and to provide a sure return to idle when I let off the pedal. Beginning of this week had the throttle sticking on just off idle, which I think was just weak old springs not bringing it back securely every time. So you say there is supposed to be a spring on the trans kick down arm as well? Now there is some other lines of questioning I have actually, because this is a 2bbl kick down arm on a 4bbl carb.. it doesn't necessarily work properly. It is supposed to be held with spring pressure towards the firewall?
If your fuel fill-ups are far in-between, water can accumulate in the system. Eventually that water finds its way into the carb, from where it, passes through the jets. This can/does cause driveability issues, especialy as it likes to settle in the lowest place in the bowl, you guessed it, the mainwells. It seems to be much worse with alcoholized fuels which are hydroscopic,that is, they attract moisture right out of the atmosphere. Perhaps a stabilizer can help you, or, a gas-line antifreeze. These agents work by binding the moisture to the fuel molecules, preventing them from accumulating in puddles. They then go through the jets in the normal way and are hardly noticeable under anything except the occasional hiccup at idle. If your EGR valve is still functional, it too could be the source of your woes. Temporarily defeat it,when the engine is idling well. And roadtest for a few days/ miles.
I run through roughly 1.5 tanks per month, but the car does sit idle for 3 weeks while I am gone.. There is no EGR anymore, I bought a used EDDIE intake that was EGR-less.
A lot of good info here but I would still like to see a couple plugs. I have always looked at them as a carb tuning tool.
The beauty of timing chains are there inexpensive price tags.
1)No to your KD spring question.If you have the 2bbl KD link on the TQ, it will be too short, and you risk burning out the transmission. The carb linkage must push the KD link, waaay back as far as it can go. This is best figured by disconnecting the link from the throttle lever, then pushing it as far back as it will go, holding it there, and then with the Carb at WOT, the KD link should just barely be able to be reinstalled. Then a spring should be installed onto that same link rod,and connected to the throttle lever, in such a way as to return it to its parked position with the throttle lever also parked at idle. This spring ,however, must have little to no tendency to open the throttle lever, when the other springs are removed. A tiny bit could be normal,as the linkage is somewhat weighty. This behavior is not possible with the too-short 2bbl linkrod. So fix that first.
I know the 2bbl rod is not ideal, never assumed or said it was. I do have it so that it literally moves with the throttle right now, with the use of zipties. More or less functioning the way you say it is supposed to. It gets moved back as far as the throttle will take it, and then when the throttle is let off the rod will go back to idle with the throttle arm. But yes, I have plans to modify this one to work correctly. FWIW, there was no spring on the KD lever before and everything worked as it should when the car was a 2bbl. ??
2) timing chain stretch is easy to estimate.Just rock the crank back and forth against a parked-by-spring-pressure, cam. There is a spec for that,but I forget it. I'd guess the crappy silent chains start out with a degree or so when new and just run in. So I'd guess they're good for at least 3 to 5 degrees, before you might notice a performance change.I've seen them run so loose they were hitting the case.
random interwebz guy said:If the linkage is lengthened, the WOT downshift will come sooner in the throttle travel and it will make the light throttle upshifts come later.