Are you sure about this? By feedback carb we are talking about a carb with the fuel metering solenoid on it that is reacting to a computer signal and has a oxygen sensor in the system. I have never seen a holley 4bbl with a fuel metering solenoid, though I definitely have not seen everything.

 

The system is feed back, the carb itself is not , they actually bled atmospheric air into the intake manifold to control the fuel air mix under certain conditions.. Ya I know crude, it is still a feedback system it is just not actively controlling the carb but bleeding extra air in to the intake to lean the mix. The 4BBL feedback system used on the 351W is a cluster to say the least. Really the best solution to these systems if they are not functioning is just pull it all install an intake and carb. You can retain the EGR and the thematic but it requires some rewiring and plumbing to do so. The VV 7200 351W system was more reliable and simpler to be quite honest that is part of the reason it stuck around till 1991 and was able to meet emissions as reliably as the EFI 5.0L even without EEC ignition control and could do mid 20's MPG on the highway.. The VV 7200 351W kept the Duraspark II ignition right until end of production in 1991.

 

I had trouble with the one in my '83 (I think it was?) that had simply deteriorated to the point that bits of the solenoid and seals and whatever else that was made of plastic had just fallen apart inside the carb.
I cleaned it out, epoxied any open holes to seal it up (back into a regular carburetor basically) and put it back together. Ran great from then on!

Unrelated, but the biggest issue I had with that engine was that it would rarely start. That's what led me to the carburetor issue, but the main trouble starting turned out to the the little Ford-specific ECM power relay just up behind the battery. All by itself and out in the weather (and not sealed) it had just turned to dust inside the plastic cover. Almost never worked after a certain point. Decided to change the pins and convert it to a normal "Bosch" type relay and, voila! All of a sudden I had a reliable truck again!

And the carb seemed to run fine without the solenoid controlling anything.

Paul

 

I remember some of the carbs in the 60's before emissions had a little bi-metal piece in the rear of the carb. When the engine compartment got fairly hot, this bi-metal piece would flex open and open a little rubber stopper and create a air leak, to raise the idle of the engine when it was really hot under the hood. It might have been called a "hot idle compensator".

I also seem to have problems now and then when de-comissioning emissions engines and trying to keep the original emissions carb. I find after it's all said and done, that I seem to run a little rich at idle. No amount of mixture screw adjustment seems to help. What I have done on a couple of them is to take a plugged vacuum port near the bottom front of the carb (a small port), and run a vacuum line from it up to the air cleaner and let it suck air through the air filter. After I do that, it all seems to straighten out the exhaust cleans up at idle and I have plenty of adjustment on my mixture screws and my idle stop. My only theory so far is some of these emissions devices leak air all the time, like the choke for instance. I know the EGR also leaks air, but it should be off at idle, so it can't be that. But I am suspicious that the carb idle circuits are calibrated for various vacuum leaks, and when we take them away it throws the idle calibration off in the carb. Another reason to switch to a aftermarket carb.

 

Yup some of the engines in the 60's and even the 50's and was used in to the 80's on some applications. Usually it was included on the PCV system or was right on the carb .
Some emissions applications do have metered air leaks for various things some carbs will run rich at idle when ripping emissions you should figure in a new carb. Sometimes you can cheat and low the fuel level in the bowl a bit to lean things out this is generally only a problem on reverse idle circuit carbs and with normal ones you can shut the fuel right off. Also it is easier for the emissions system to deal with excess hydrocarbons and convert them to good guys than it is with a lean or even ideal mix.

 

 

Coming up from underneath could be a transmission vacuum modulator if yours is so-equipped. Is it a small diameter tube, at about 3/16" or so? Or larger?
Seeing a pic would be great. I thought the modulator tubes came up across and up more to the middle of the engine.

Regarding the fittings in the previous pics, on the TCV's if there is no single line to any of them, then you don't need to cap any fittings. They are just switched valves that open and close depending on temperature, so if there is no vacuum hose fitted to one port, there won't be any leaks.
If you do have hoses to any of them though, find out where it goes and let us know.

For the one on the top of the air-cleaner snorkel that opens and closes the hot-air intake damper, you should be ok. It's a good little device, that directs warm air from the exhaust manifold up to the air intake to help the engine run better when dead cold. Opens up the cold-air intake portion when warmed up.
You should remove the snorkel hose and peek down the tube though, just to make sure it's defaulted to the open position (open to the outside air of the snorkel) anyway. I believe that is their default position, but it never hurts to double check. If it's closed to the outside it will choke off some of the incoming air.

Paul

 

The Tube up the back of the Engine may be for the vacuum modulator for the trans if it's a C6. Follow the tube and see where it goes.
The vacuum control valves can come out the intake and thermostat housing as you are no longer using them.

The ones on the air cleaner are for the heat stove to help mitigate carb icing in cold weather. If you do not have the rise pipe or the heat shroud on the passenger exhaust manifold I would not worry about it unless icing becomes an issue.

 

I looked, he lives in Canada. I think I would anticipate carb icing if he drives it in the winter. Those really cold dry days, no problem. It's those rainy damp days in the 30's and 40's that are the worst.

 

 

Make sure you're pointing the timing light at the marks on the passenger side of the engine, past the alternator.
Also make sure your vacuum advance is disconnected and plugged.

There are two marks on the balancer: A big cutout notch and a small etched notch.
IIRC, they are a third of a turn away from each other. Make sure the small etched notch is the one you're looking for, and clean it with a rag and some WD-40 if you have to.

EDIT: This info is correct for a 300-6. Not sure about your engine.

 

351w correct? Also make sure you have your light clipped on the very front passenger side sparkplug wire.