Everything I'm reading on here calls the valve at the rear of the intake manifold that attaches to the carb spacer the EGR valve. What is the valve on the driver's side exhaust manifold collector? This doesn't seem to connect to the EGR system up by the carb. The reason I ask is I'm getting ready to install headers on my 302 and I'd like to know what to do with the vacuum line that attaches this valve.
Another thing....the prior owner also disconnected the smog pump, so there is a line that is blocked off, but still bolted to the driver's side cylinder head. What's the best way to plug this port on the head to get rid of the ugly pipe? A bolt and washer?

 

Part in upper pic with bolt stuck in it:

This is the T/E (Thermactor Emission-smog pump) check valve.

See 9A487 in pic:

 

Thank you Bill. Do you have the same type of diagram showing the EGR system layout and that valve on the exhaust manifold?

 

Is it like a choke blade which would close off the driver side manifold? Referred to as a flapper valve over at foureyedpride, it serves to route the exhaust mainly out of the passenger side manifold, where it can get scrubbed by the light-off cat (the small one close to the pass side manifold) during warmup, when emissions are higher.
Almost certainly cap it off. It should lead to/come from a Temperature Controlled Vacuum Switch, in order to allow it to open upon warm up. TCVS could be on the intake manifold near cylinders 7 and 8, or I guess it could be threaded into the thermostat housing.
Getcha a set of Explorer heads!
I've also heard a spark plug. There are plugs available which you can get online, as the Fox Body crowd deals with these regularly. Alternately, you could get some from a 'mid '70s to mid '90s 255/302/351W at the junk yard. Look under the front accessory bolts which thread into the fronts of the heads, exactly opposite the thermactor ports at their rears.
Check the rear of your other head too. I'm betting that there's a port there as well.

 

That is all I can figure is that the driver side exhaust manifold houses some type of flapper valve as you stated. I don't think my truck had any cats that I'm aware of (1976, 49 state truck), so I have no idea what this valve blocking off one manifold would accomplish.

 

D4TZ-9A427-A .. Heat Riser Valve / Obsolete

1974 F100 & Econoline 302 with T/E (Thermactor Emission).

EGR pic: Does your truck have A/T or M/T, with or without factory A/C?

Upper (lower) pic shows the 360/390 heat riser valve, 302 will be similar.

 

Hi Bill, it is a m/t truck, no a/c.

 

No pic of 1974 F100 302 with M/T, T/E without A/C

This pic with A/T & T/E without A/C will be very similar.

 

Thanks....this is for a '76, if they show one for that.

 

Truck parts catalog: Pics for 1973/74 & 1978/79. No pics for 1975/77.

Here's the pic for 1975/76 Bronco 302 from the car parts catalog:

 

Thanks Bill. That last diagram looks like what I have. Interesting though, as it shows the item on the manifold I was wondering about as part of the EGR system, even though it in no way attaches to the egr valve.

 

Well apparently very little is known about how the EGR system truly works, but I've done a bit (actually, a lot) of research the past couple of days to try and clarify for those who were wondering much like myself. The exhaust valve on the driver's side collector is indeed part of the EGR system and not a heat riser. Heat risers were used on certain vehicles to direct warm air up to the air cleaner to be ingested before the carb to assist with warm up, but that is not the case here. The exhaust valve shown above closes when the EGR is in operation, forcing the exhaust back up toward the cylinder head. The exhaust gas takes an internal route back toward the intake manifold through passages inside the head that pass through to the intake manifold, and then into the EGR valve located behind the carb to be ingested back into the intake stream. So in essence, one cannot put headers on and leave the EGR operational, unless the egr exhaust flapper could be incorporated into the collector. Hopefully this clarifies for anyone reading about what is required to maintain the EGR system and what mods would require deleting it.

 

EGR valves introduced in 1973, were mandatory in sold new in CA vehicles, but some states didn't require EGR until much later.

This heat riser valve has nothing to do with the EGR system:

D3TZ-9A427-A (replaced C5TZ-9A427-B): 1965/67 F100/350 352; 1973/74 F100 360/390.

When looking up heat riser valves for F100 & E100 (none listed for F150/250/350 or E150/350) in the 1973/79 truck catalog, it makes no mention of the EGR system.

 

I am looking for a similar diagram that shows the vacuum line routing for a 1974 302 Bronco. Thanks !