AirtekHVAC

Just got the 82 perfectly timed, at least by spec and the timing light...

When I hooked up the vacuum advance, she idles rough and backfires and cuts off when I give her throttle. I rechecked my vacuum lines and corrected a couple errors. now I can hook up the vacuum advance at idle, with no ill effects, but when I give her throttle, she spit sputters, shakes violently, backfires through the intake, and cuts off.

Any ideas?

Secondary, on her 2nd road test, this afternoon, when I give her throttle, she bucks and stalls, like loosing all power, and pops back to life as soon as I release the pedal. If I am very easy on the gas, increasing steadily, no problems....

Any ideas there? Could the issues be related? I can give her throttle as hard as I want sitting in neutral, and there is no drop in power, and she is smooth as a sewing machine ( with the vacuum advance disconnected)

GlenL

This doesn't make sense. When the throttle is opened the manifold pressure increases and there's less vacuum advance. Disconnecting the hose gives less vacuum advance, too. One works fine and one doesn't?

What are you doing when you disconnect the vacuum advance? What else have you done to the car recently?

mark kibort

thats not a vacuum line issue. check the timing belt marks.
something else

mark kibort

Glen, the vacuum advance is on the airfilter side of the throttle plate, you might be talking about the vacuum retard, which is on the intake side of the throttle plate. more throttle lss, retards, higher RPM and more throttle, and there is a "air moving across the hole " vacuum effect for "vacuum advance"

GlenL

I opened the manual because my Friday night is packed.

I see a US '82 has both advance and retard. I'm not seeing which source (ported or manifold) is for which side of the advance diaphragm. But... It looks like there's advance at idle so the advance is on the engine side of the plate.

mark kibort

glen.... no, the advance is the vacuum effect of fast moving air over the port.
its on the AFM side. this gives a little vacuum at idle, and a lot at high RPM

the engine side has (intake side) has the vacuuum which is equal to manifold pressure and it goes away with moderate to high throttle.

AirtekHVAC

I had it backwards at first...had constant suction on the advance side , and it would not start or run with it connected, once corrected, I could hook it right up, and no issues at idle.

I posted info and video in my great white thread, but no one responded....

My gut is that the engine has jumped time, perhaps a tooth on the timing belt, which is why the original owner parked it, and all I did was get it running better by rotating the the distributor. I bet my cam timing is off....

Flinstigator

Just bumping this thread. Ron did you ever figure out what the root of the problem was with the backfiring while under load? Did your engine jump time or did you find something else?