Red 72 Explorer Sport Patina Rebuild

[gunnibronco]

Excellent. Thanks for going to the trouble!
I wonder if the parts changed, or my memory is faulty.
Or both!

Would not be the first time for either one!
I forget if you said, but what month was this '72 built in? I see the extra support link to the throttle linkage screwed to the firewall, but what looks to be a later carburetor.
The extra linkage, and the two holes in the firewall, disappeared in very late '72 if I remember. After the cold-air opening started to appear in the core support near the battery. And that new feature of the core support was usually accompanied by the power steering bump-out on the driver's side. Before cold-air intake and power steering were available.

Paul

It was built at the end of April 1972. That's interesting I wondered about the extra linkage on the throttle. I didn't think it was on my 74 before I changed everything. I'll look at the core support, I'm not sure about either feature.

I would not use this:
View attachment 951395

Install this:
View attachment 951396

Here:
View attachment 951397

Connect this:
View attachment 951398

To this:
View attachment 951399

I'm going to order the part tomorrow. Hopefully it will be here in time for Super Cel but I kind of doubt it, coming all the way from the east coast.

When I started this project in the spring, I didn't know what I was missing and just assumed the Wix filter fit. It's listed as a crank case breather filter, not the EVAP filter (I assumed it was for the EVAP just because it fit the hole, kinda). So it makes sense it was maybe just an error in the Rock Auto catalog and it doesn't belong to the 72 V8.

I wonder if someone will have a very stock set up for you to look at next week?

That has crossed my mind. I know there is a very original Sport model that lives up in Reno, I can't remember what year, but it could be the right one to look at.

 

[DirtDonk]

It doesn’t show the finer detail on the V8 filter diagram on the previous page, but if you look at the six cylinder air cleaner, you can see exactly how mine was set up on the V8. Clip on the outside and a fitting inside the hose.
Looks like the V8 version in the diagram is more like you guys are talking about with that extra snap in fitting. Or twist-in, I should say.

 

[gunnibronco]

I've been fine tuning what I can and finding new problems on each drive. LOL.

I reset the carb to better baselines after finding a carb rebuild instruction sheet that addressed many of the specific functions on my 72 carb. And it ran way worse. Figures. It particularly set the carb to pull the choke off way too early. So I've of adjusted most/all of the choke pull off (the expensive, hens teeth part I sourced) out and made a major adjustment to the dash pot in the carb. I also put a bunch of "extra" adjustment into the thermostatic choke to keep it closed longer. It now starts up and will stay running until it is warm. It runs great warm, the idle kind of hunts but not too bad.

My neighbor came over and helped through a few checks. We found one diaphragms (it's dual vac/diaphragm) in the distributor advance is bad, so I'll need to order one. Then I'll spend more time on the carb set up. Until then it runs and drives and that's pretty ok. It does seem to get terrible gas mileage, but that's based on the dramatic drop in the fuel gauge while test driving it. I need to actually go fill it up and keep track of mileage and the gas it takes to refill, the gauge is obviously wildly off.

The "clean" FoMoCo aux tank I had is cracked, to I removed it, cleaned the original and reinstalled it. It's fine now. I couldn't pull from the aux tank so I put some compressed air through the lines and it must have pushed something out of the selector valve because it is working now.

The speedometer was bouncing around like crazy so I pulled the cable out and put some Triflow teflon lube on it. The next drive the speedo was smooth as silk. About a mile down the road I looked again and the damn needle broke off and was laying in the bottom of the gauge. Really? So yesterday was spent disassembling the original speedo and my "spare" and checking things out. The original has a scrape mark where the needle must have been riding on the face before it broke. So I cleaned up the spare, changed the odometer to match the original mileage and installed it into the original gauge cluster. After reinstallation is was hunting around and noisy but a couple miles into the drive it settled and quieted down and seems to be fixed (fingers crossed it stays that way).

I had a local locksmith figure the key code and cut me some brand new keys. I only had one very worn copy of a copy of a copy.......

I half assed the EVAP line into the filter housing with a brass fitting until the new fitting arrives from NECFP. I doubt it will be here by Super Cel. But otherwise it all seems ready and I'm down to fine tuning and minor stuff.

I did coat the truck with Meguiars #7 a couple times and let it sit for about 48 hours, then waxed it and it looks great. I've also spent a lot of time on cleaning the glass and interior and gone over some of the trim with some polish just to give it a light cleaning. Pictures don't do it justice, but it's super clean and looking great!

 

[SLOWnEASY]

I did coat the truck with Meguiars #7 a couple times and let it sit for about 48 hours, then waxed it and it looks great. I've also spent a lot of time on cleaning the glass and interior and gone over some of the trim with some polish just to give it a light cleaning. Pictures don't do it justice, but it's super clean and looking great!
View attachment 951520

I'd say it looks great, it actually inspires me to try to clean mine up.

 

[Chiclassics]

I also put a bunch of "extra" adjustment into the thermostatic choke to keep it closed longer. It now starts up and will stay running until it is warm. It runs great warm, the idle kind of hunts but not too bad.

Nice!

We found one diaphragms (it's dual vac/diaphragm) in the distributor advance is bad, so I'll need to order one. Then I'll spend more time on the carb set up.

makes sense.

 

[gunnibronco]

Last pre-Super Cel update:

• Gauge issues
  • Swapped IVRs with no change.
  • Swapped water temp sensor with no change, so I guess that means it's the gauge.
  • Swapped oil pressure sensor and now have a working oil pressure gauge.
  • Mileage is not as bad as the gauges indicate, I'm hoping that getting the advance and carb right will help.

I'm struggling with the carb. I'm not really trying to get it perfect, just reliable to start and run (cold & hot). It's mostly choke & idle issues. It's hard when you only get 1 cold start each day to play with things. It does run nice (despite timing advance issues) once warm. Occasionally it will stall while coming to a stop. Idle is not smooth, bounces about 1000 rpm, trying to idle at 800 rpm. Any input is appreciated.

• Timing notes- 4700' elevation
  • Initial timing set at 18* BTDC- seems high but don't get any pinging under load (this could change with a new vac advance I suppose).
  • I don't get vac through the line feeding the leaking vac advance diaphragm. This is fed through the blue valve/72 only trans/ambient temp system. So I don't know when I should see vacuum. It's not a problem until I tackle the vac advance.
• Carb notes
  • Idle smooths and raises from around 800 rpm to about 1100 rpm if I pinch off the PVC hose. I've sprayed brake cleaner & carb cleaner around the PCV valve, grommet, and oil fill cap with no change. So I'm *thinking* this is not a vac leak, but a symptom of drawing crank case vapor into the intake below the carb. Thoughts/ideas? PCV valve? It seems to be free in the direction it should be.
    • Idle mixture screws are backed out further than I expect. Most advice says start around 1.5 turns out and close in 1/4 turn increments, but I can't go much below 1.5 turns out without stalling. I think I'm out about 1.75 turns to get it where it is.
  • Choke wants to open early unless choke is over adjusted and choke pull off is basically adjusted off completely. I've been able to get it to cold idle closer to spec (1100 rpm- it was up around 1600 rpm) so that helped with the vac choke pull off. Hopefully it will start up cold, but I'm just not confident. This is frustrating. I keep thinking I know what to adjust, but it seems like one thing throws another adjustment out of whack and I end up chasing my tail and making too many adjustments.
• Could this all be a symptom of the PCV issue? It runs so smooth with the PCV pinched off, it feels like a better starting point and all my adjustments would be closer to "normal". IDK.

 

[Chiclassics]

• Initial timing set at 18* BTDC- seems high but don't get any pinging under load (this could change with a new vac advance I suppose).

10 degrees without connecting vacuum advance for sea level. Start adding 1 degree for each 1000 elevation. So in your case ideally 15 degrees when your advanced vacuum port is disconnected. So at 18, I would say you have 3 degrees extra.

I don't get vac through the line feeding the leaking vac advance diaphragm. This is fed through the blue valve/72 only trans/ambient temp system. So I don't know when I should see vacuum. It's not a problem until I tackle the vac advance.

Does your carb has "ported" vacuum line. You need ported one to connect to vacuum adv on dist. This creates zero vacuum at idle and only starts creating vacuum when you give throttle.

Idle smooths and raises from around 800 rpm to about 1100 rpm if I pinch off the PVC hose.

typically when you close pcv engine dies(becoming richer)...as carb is designed to have pcv -which is "controlled vacuum leak". Is your PCV valve in good condition(does it rattle if you shake it..) may be change that first and see if it lets you bring idle down. Sorry I haven't been following your post from the beginning are you manual or automatic/if automatic you need 200 rpms extra at idle for it to idle well in drive as there is the torque conv load.

 

[bigmuddy]

Man that "patina" just looks right!

 

[gunnibronco]

Here are a couple pics to help describe the system.

Vac hose diagram. I have not found a diagram for the 72, but this is all new hose based on the routing of the old hose I removed.

• To be clear I do not know how the following should work:
  • blue valve
  • ambient temp/transmission switch
  • 2 line vac advance - parts descriptions mention "with vacuum retard".

Blue arrow: "Blue vacuum valve"
White arrow: ported vacuum off carb
Yellow arrow: manifold vacuum, good diaphragm
Red arrow: no vac, from blue vac valve, bad diaphragm

10 degrees without connecting vacuum advance for sea level. Start adding 1 degree for each 1000 elevation. So in your case ideally 15 degrees when your advanced vacuum port is disconnected. So at 18, I would say you have 3 degrees extra.

Both advance vac lines are disconnected & plugged when setting timing. I just jumped it to 20* BTDC with no issues, I expect this will change when I get working vac advance.

• The inner "good" diaphragm sees manifold vacuum at idle.
  • Connecting the manifold vacuum to the good vac advance port does not change the timing at idle.
• The outer "bad" diaphragm is getting no vacuum at idle, or at higher rpms. Unless something is happening while I'm driving.
• I should probably just wait to get a good vac advance installed, but I'd like to know what SHOULD be happening.

Does your carb has "ported" vacuum line. You need ported one to connect to vacuum adv on dist. This creates zero vacuum at idle and only starts creating vacuum when you give throttle.

Ported vacuum is off lower passenger side of carb, but runs through "switch" and "blue valve". I see no vac beyond the switch. I don't know when it should open or what it does inside the "blue valve". It's probably good it isn't getting vacuum to the dizzy, as that diaphragm is bad.

typically when you close pcv engine dies(becoming richer)...as carb is designed to have pcv -which is "controlled vacuum leak". Is your PCV valve in good condition(does it rattle if you shake it..) may be change that first and see if it lets you bring idle down. Sorry I haven't been following your post from the beginning are you manual or automatic/if automatic you need 200 rpms extra at idle for it to idle well in drive as there is the torque conv load.

It's a manual transmission. PCV valve rattles and acts as a check valve as I would expect. There is a little oil in the hose to the carb, which was new. The PCV enters a plate that is sandwiched between the carb and intake, not really into the carb.

Thanks for your input.

 

[Oldtimer]

 

[gunnibronco]

View attachment 951628

That's great, thanks.

The only difference with mine is the Transmission/Ambient Temp vac switch. It interrupts the ported vac from the carb to the blue valve (12a111). I checked my switch and it works. It opens in 3rd gear. I could delete it and get advance in all gears. I'll see once I get the new vacuum advance.

 

[gunnibronco]

I don't know why it says "With A/T Only" it's definitely on the 72 3 speeds.

 

[Chiclassics]

To be clear I do not know how the following should work:

• blue valve
• ambient temp/transmission switch
• 2 line vac advance - parts descriptions mention "with vacuum retard".

Got it! I can explain now i forgot you still have stock setting. Most of these are reduced in modern carb lines to make it simpler..So in your diagram the diaphragm thats closer to dizzy (which you noted as Good)is actually a timing "retard" that helps reduce timing when you decelerate- this reduces emissions. The other one (which you indicated bad) is the timing "advance" one which seems to be not working right now. Which explains you had to advance the mechanical timing to compensate for this for better driving experience but that also means you have this extra timing at idle you dont need.

The way "advance" diaphram is fed also further fine tuned in stock it looks like. Modern carbs we directly plug the carb ported vaccuum to dizzy's adv port(no blue valves). Based on the diagram you put, it looks like its switching between manifold vacuum and carbs ported vacuum-perhaps based on cold engine vs hot engine perhaps further fine tuning the advance.

Just do this. Disconnect the input lines at blue valve. start engine. While engine is idling -

1)check vacuum at the input lines to blue valve(by putting finger at end). You should get vacuum from manifold line, no vacuum on ported vacuum from carb
2) have someone give it a little throttle : Now you should see some suction(vacuum) at the carb ported line.
3) Now switch off engine. Connect the lines back on. And start engine again. Now check vacuum at the output of blue valve I believe you should see no vacuum at idle but should see vacuum when throttle . Its possible you might have vacuum at idle probably the reason why they are taking manifold vacuum here...it wont hurt having that. But whats important to test is it should switch to ported vacuum at throttle as its a "dynamic" vacuum where as manifold vacuum is mostly "static vacuum".

I would recommend above tests to make sure all other stuff is good before you get the new diaphram. Once you get new one...reduce mechanical advance to 15 and see how the idle is..

 

[Chiclassics]

Ported vacuum is off lower passenger side of carb, but runs through "switch" and "blue valve". I see no vac beyond the switch.

Once you perform above tests , if you still see no vacuum at throttle at the output of blue valve then its bad

 

[gunnibronco]

Once you perform above tests , if you still see no vacuum at throttle at the output of blue valve then its bad

Thanks. After Super Cel I'll dive back into it and see what I find. Considering it's mostly original and hasn't run since about 2009 it's doing pretty good. I've never done much with carbs so this is mostly new territory, so I have a lot to learn.

Sent from my Pixel 7 using Tapatalk

 

[gnpenning]

Pcv valves are calibrated vacuum leaks basically. They need to be the right size for your application.

You have very specific wants for your choke to operate. Have you considered a manual choke. You will be able to adjust on the fly for your needs. Early broncos came with them and aftermarket ones are available as well. Do you have others that will be driving it?

I have several vehicles with manual choked and I'm very happy with doing the work myself. It takes a little more driver thought.

 

[DirtDonk]

It takes a little more driver thought.

Something that is much needed, but seems to be in short supply sometimes!

 

[gunnibronco]

Pcv valves are calibrated vacuum leaks basically. They need to be the right size for your application.

You have very specific wants for your choke to operate. Have you considered a manual choke. You will be able to adjust on the fly for your needs. Early broncos came with them and aftermarket ones are available as well. Do you have others that will be driving it?

I have several vehicles with manual choked and I'm very happy with doing the work myself. It takes a little more driver thought.

I removed a manual choke that the PO had installed and installed a new thermostatic choke. It started pretty good cold this morning, and it's starting very nicely hot, so I'm pretty close. My goal is as close to stock as possible. I'll consider changes, including vacuum routing as needed. I'm going to wait till I get the new vac advance installed, then see. I picked up a new PCV valve today and will install it, I don't think it will help, but for $2.35 I figured it was worth a try. Regarding size, there are 2 listed for my 72. One with 1/2" hose and one with 3/8" hose. Mine appeared to be original hose (1/2") and has a 1/2" barb on the plate under the carb, so I assume it's correct. I have a 3/8" PCV valve that was on my 74 and it doesn't fit the grommet in the oil fill cap, so again I'm assuming 1/2" is correct for this 72.

 

[gunnibronco]

New PCV valve made a difference. Idle smoothed out and now RPMs don't rise when line is pinched off. $2.35 well spent.

 

[DirtDonk]

Great news! And that’s why they were always part of the general tuneup and maintenance. Sometimes you can get away with cleaning them, sometimes you need to replace them.