Another Carb Question 2100

[redfishtony]

Trying to post a video but it must be too big. Well I took the carb off to remove the EGR Plate under it and discovered I needed the plate for the height. Took the round vacuum canisters off and made a plate with gasket to block the holes. Re-assembled and checked for vacuum leaks. None that I can find except for the hole in the valve cover (EGR). Cranks and runs fine but RPM's are up and down then after about 2-3 minutes engine stalls. Cranks right back up. Watching the marks with the timing light it moves from 10 to 20 as the rpms fluctuate. Any ideas? I might just be time for a new carb.

 

[blubuckaroo]

I've done the same thing by inserting a piece of .010" stainless shim stock between the EGR valve and spacer plate.
Have you tried adjusting the idle mixture screws?
By eliminating the EGR, you've increased the ratio of oxygen in your mixture.
That's at idle. To make it run right at cruise, you'll also need to re-jet.

 

[B RON CO]

Hi, if you didn't adjust the idle mixture screws I would try that. Either open each screw clockwise, a little, or gently bottom them in and come back out 2 full turns.
Did you plug the vacuum hose that went to the old EGR valve?
Back in the day, some guys used to plug the vacuum hose on the EGR valve and remove the belt from the air pump.
The EGR is not on the valve cover. The greasy one on the left side is the PCV valve. The hose on the right rear came from a little filter clipped inside the air cleaner, which is the beginning of the PCV system. Fresh air into the right side, fumes sucked into the intake manifold from the left side.
Good luck

 

[redfishtony]

Sorry for the confusion. I miss and said EGR rather than PCV. This motor came out of a 74 Gallaxie 500 which had all the smog and EGR stuff on it. My bronco is a 69 so it doesn't have any of the canisters and such. The block between the carb and manifold was giving me problems with tons of vacuum leaks. I have stopped all them up and only have the the large line that comes from the front bottom hooked up to the valve cover. There is a line on the passenger side that runs to the advance on the distributor. The PCV valve is in the valve cover but is not hooked up.

 

[redfishtony]

Oh and one other thing. I notice very little change when I adjust the mixture screws on the lower front of the carb. Seems to run the same no matter what possition they are in. They are set a 2 turns out right now.

 

[blubuckaroo]

Oh and one other thing. I notice very little change when I adjust the mixture screws on the lower front of the carb. Seems to run the same no matter what possition they are in. They are set a 2 turns out right now.

Your idle vent ports are probably plugged with gasoline deposits.
You can usually clear them without disassembly by spraying them with Chem tool while the engine is running.

 

[redfishtony]

I’m going to clean them out this afternoon. Never took them out when I rebuilt the carb.

 

[B RON CO]

Hi, I hope you didn't eliminate the PVC valve. It is important to keep the engine clean. Good luck

 

[bmc69]

What exactly do you mean by this " I have stopped all them up and only have the the large line that comes from the front bottom hooked up to the valve cover." The line coming from the plate has to either be connected to PCV or plugged. Connected to PCV being the much more preferable option.

 

[redfishtony]

What exactly do you mean by this " I have stopped all them up and only have the the large line that comes from the front bottom hooked up to the valve cover." The line coming from the plate has to either be connected to PCV or plugged. Connected to PCV being the much more preferable option.

BMC69, If you look at the picture I posted you can see where the big line is hooked to. Its hooked to the oil filler cap on the valve cover. If you zoom in you can see on the passenger side back there is also what appears to be a PCV valve there also that is not hooked to anything. I can easily hook both of them up to it if I need to. The only other vacuum line being used is the one to the distributor. I didnt get home in time to take the air adjustment screws out and clean them. I'm hoping that will help my surging and stalling. Thanks everyone for the help. TW

 

[gr8scott]

I can easily hook both of them up to it if I need to. TW

You should, as it helps keep the engine clean. Oil fill hose to base of air cleaner, PCV hose to base of carb.

 

[DirtDonk]

100% what they said. While the PCV may very well be one of those "stupid smog control devices" to some, they are in reality one of the best inventions for the internal combustion engine of that period. And still in use today because they are so beneficial all the way around.

I did not look at the picture, but in a Bronco of '71 vintage or later (sounds like yours is at least a '73 since it's got EGR? (or was that always the PCV you were referring to?) you would have a plastic elbow in the passenger side valve cover to allow filtered air to get sucked into the crankcase. The driver's side oil fill cap would have the actual PCV valve that is connected to full manifold vacuum at the base of the carburetor. Can be on the carb body itself, or the spacer. Or even in some cases a fitting drilled into the manifold itself, as long as it's only in the center common plenum area and not an individual running.

So yea, hood it back up somehow and it'll also serve to get your mixtures back in balance. Do that before you try messing with the carb to compensate.

Now after blabbering on, I'll go check out the pic.

Paul

 

[DirtDonk]

Ok, I see the open elbow in the back on the passenger side. Connect that to a filtered air source, or at least replace it with a filtered cap/cover inlet.

I see the PCV valve still in the oil fill cap, but where do you have the hose connected? Still to the intake or carburetor? Then you're fine in that regard.
The only thing I'd say is that the valve looks pretty well aged, and may be in need of replacing with a new one.
It's cheap insurance, part of a tune up anyway, and may be causing trouble.
They're pretty reliable and with a cleaning now and then do not have to be replaced every tune-up. But with one of unknown age, it's cheap insurance to replace it with a new one.

Paul

 

[DirtDonk]

And if it's not already, connect your vacuum advance to ported vacuum to see how it acts afterwards. If it runs better, leave it there for the time being.
Some prefer full vacuum, but most prefer ported so that there is no vacuum to the distributor at idle, and comes on right as you're pushing the throttle.

If it's already there, then you can try the opposite to see how you like it. Personally I always leave them on ported vacuum for best results when all other smog stuff is removed. But then, I prefer to leave the smog stuff on myself, unless I'm building a super high performance engine.

Paul

 

[redfishtony]

Thanks Paul for the information. The motor is a 351W out of a 73 Gallixie 500, that's why it had the EGR plate on it. My bronco is a 69 so it doesn't have any of the EGR stuff on it, I have the original filter housing which I think actually has a spot for the hose on the passenger side to hook up. The distributor is hooked up to the small tab on the passenger side and seems to be working properly. I took both the air/fuel mix screws out tonight and sprayed cleaner in the holes. seemed to be open. reinstalled them and still am not getting much change with them in or out. I'm ready to just order a new carb.

 

[blubuckaroo]

redfishtony,
Was the engine already having problems before you removed the EGR valve?
Did removing it change anything?
It sounds like it's got a vacuum leak.

 

[DirtDonk]

...My bronco is a 69 so it doesn't have any of the EGR stuff on it, I have the original filter housing which I think actually has a spot for the hose on the passenger side to hook up.

Should be one somewhere, but on a '69 the hose fitting would be on the driver's side.
You did not have a charcoal canister on the '69, so no extra fitting for that. And the PCV valve would normally have been at the rear of the passenger side valve cover that year, where you now have an angled elbow fitting.
A fairly large hose fitting would have stuck out of the small end of the filter housing (just to the driver's side of the carburetor) and connected via a hose to the driver's valve cover/oil filler cap. Where you now have the valve.
In '71 they swapped sides so the valve was on the driver's, and the clean air return on the passenger. Looks like you have the later configuration on yours. No problem though. As said, the engine doesn't care where the suckage comes from, as long as it's sucking.

The PCV valve itself connects to a large vacuum port on the carburetor or spacer. Yours looks like it goes down in the front somewhere, but disappears from sight so I can't see where it is connected. Does it go around to the back somewhere? It needs to be on a large port in the common plenum area.

The distributor is hooked up to the small tab on the passenger side and seems to be working properly...

Can't remember if that is ported vacuum or not, but I think it is. So you're probably right.
Full vacuum is underneath on the front of the carb, correct?
When you put your finger over the hose now, you can't feel any vacuum at idle? If not, then the carb is set up correctly.

Paul

 

[DirtDonk]

Good call to get back to that.
That was the first thing that came to mind when he said he removed the spacer. With the number of different intake, carb, spacer and gasket combinations available, it's so easy to make your own custom vacuum leaks on these things!

So Tony, you said you checked for vacuum leaks in the beginning after you made your own plate. How did you check?
And what did you mean when you said you removed the "round vacuum canisters" in your first post?
At first I just read that as the kind of stuff a later model vehicle has. But I can't think of any vacuum canisters on a '69, and normally a '73 car would have had them on the fender instead of the top of the engine. Is that what you meant though? Were there just some cans from the donor vehicle still connected to the engine?

Did you verify that you have all of your unused ports plugged on both the carburetor base and the intake manifold?

Paul

 

[redfishtony]

Thanks guys for sticking with me on this. I will post a few more pics tonight of the things I removed off the spacer block under the carb. I may not be calling them the correct name. Also I have the big hose on the front of the carb hooked to the filler cap. The other side is just open. If I unhook the hose going to the filler cap it runs rough and dies. I’m still wondering if I just need to replace the carb. I removed the air/fuel screws and tried to clean them and still no change. Runs about the same in any position. All new gaskets both manifold to spacer and spacer to carb. Not knowing exactly what the PO had done make it hard to diagnose. Stand by for more pics. BTW is there a way to post vids so y’all can hear it running. That might help. TW

 

[DirtDonk]

Yes, you can post videos. Never done it myself in all these years though, so no clue how to do it.
I think most are links to YouTube videos, so perhaps you can't actually post one up directly to the site?

Look forward to seeing it either way.

Paul