I've got an '83 300 six. Just bought a remanufactured Carter 1 barrel for it. There are 3 vacuum ports on the left side (viewed from front of engine) of the carb.

One goes to the throttle bore below the throttle plate, one above.

The other one, about halfway up the carb, I'm pretty sure is the EGR port.

Any help anyone could give me on what exactly the 2 ports above and below the throttle plate are would be much appreciated.

 

The upper one-on the pass side should go to the lower heat tube coming off the exhaust manifold-- for the choke [this is ussually a steel tube that has rusted out by now]. The other -I'm not sure-my carb has several others that go to the hard plastic lines for the vac operated stuff--look on the vac diagram sticker on the radiator support.

 

This comes a little late but it may help you in the future: Whenever you tear anything apart that has a bunch of crap hooked up to it (i.e. a carb) label the hoses with masking tape--use a permanent marker. Assume you have the memory of an 'end stage alzhiemers patient'.

 

I've got the heat pipe plugged.

The 2 ports I was wondering about are immediately above and below the throttle plate.

Yeah, I tried the duct tape labels, but this thing has been rebuilt before and I'm not sure they were right the first time.

Also, when I turn the idle mixture screw in/out there is no change in manifold vacuum or rpms. It IS sensitive when it gets close to the seat (enough to shut the engine down) and when it close to being fully out, but no change at all over 80% (or so) of the screw length. I thought it might be because the throttle was opened up to the transition slot, so I slowed the hot (unchoked) idle speed to around 650... same results. Does everybody agree with me that this is due to a vacuum leak somewhere? I've been looking and listening and have replaced a bunch of lines with no improvement. The only thing I can think of is that the EGR spacer-to-intake man. gasket got hosed when I put the new Carb on.

Also, getting some nasty knockage under load. I found my vacuum diagram in Mitchell's book (the underhood sticker is under 300 ft of garbage in a landfill somewhere) and hooked up my distrib. vacuum advance right (I think, still not sure about those carb ports). So, I'm assuming it's a lean mixture problem and not an over-advanced problem. I set initial timing to 10 deg.

Thanks for your help.