Hi. I recently bought a 1978 Trans Am. It has the original driveline in it ( pontiac 400 ).
The Qjet was in bad need of a rebuild, so I took it apart and cleaned all orificed and channels with breakecleaner and compressed air.
The baseplate was really bad. the primary plates where pretty bent, so I had to do some serious tweaking to get the plates to close tight and evenly right and left.
I replaced the needle and seat with a new set, and trimmed the floatheight to the usual specs.
The APT is about 3 turns from bottom and the primary needles hang nice and even.
Acceleration pump is working as it should.
The car runs and pulls fine, it seems to only have idle problems...
The choke is hot-air type, and I have adjusted it so it snaps to fully closed position when I press the accelerator with cold engine.
mixture screws moves fine, and will make the engine stall when turned in further than ~1.5 turns. other than this they dont really affect idle quality at all...
That was a little info on the setup.
If I crank the engine cold with choke applied engien will fire right up and idle at 1500 rpm. purring like a kitten.
After about a minute or so the choke plate will start to open up slowly, and this will cause idle to fall and a minute later the engine stalls.
When engine is at operating temperature idle is impossible to get lower than 1000 rpm, and it is going up and down a lot, like it is just about to stall all the time.
Idle by-pass is working, and the idlechannels supply fuel.
I am thinking vacuumleak. Then intake has the original metalgasket between the intake and the baseplategasket. I am not really sure what purpose this metal gasket serves?
I have rebuild and adjusted lots of Qjets over the years. Never lost a battle with one!
I have a lot going on at work and my mind must be pre-occupied, so I must be missing out on some detail. Help guys! What am I missing???
:-)
