The photo in this very post shows a HOLE in an air cleaner. Not in a carb, not in a float bowl, in an air cleaner. Points have been made to vent to the air cleaner, the vacuum and the float bowl and all 3 are different, correct me if I am mistaken.
Nope. You're correct. But each is different because each is for a different application. And it wasn't said to vent to the float bowl. You vent more fumes FROM the float bowls.
The only one that was on an EB was Doug's pic of the hole, which he said in his text, and I repeated, was supposed to have a fitting in it to fit the hose to, but it was missing.
Only missing. Still need one to make it work. But the point was that this is what Ford used to vent to the air-cleaner.
The other two are just what I said previously. Nothing gets vented to a float bowl. It gets vented
from the float bowl. And I said somewhere that the carb and the air cleaner were effectively the same thing as far as EVAP is concerned. All they mean by "venting to the carb" is that the vapors are re-introduced into the air-fuel mix through the carb venturii via a hose to the air cleaner. Same things, different words.
All carbs have a float bowl vent to atmosphere inside the air cleaner, which is a potential source of pollution. So later carbs had a vent/valve to use the CC as the carb's new "vent". This would combine vapors from the carb with vapors from the tank in the canister, then burn them through the air cleaner. Just like normal.
There was a 1-way valve in that line to keep vapors going in the direction of the canister.
The vacuum is still as stated. It can work under the right circumstances. You just have to be able to control it.
Since you can't with your setup, you can't use vacuum as EVAP. Completely different system than yours.
Second, I never, ever, in any photos or diagrams ever seen a hose connected to one of the Large Chimney vents. The only time that could even be an option is when there are no other nipples or fittings on the CC. If the CC has any nipples, either small or large, then the chimney stacks are never connected to anything. Please show me anything, anywhere to prove that to be incorrect. A photo in this very thread shows both chimneys with vented caps.
You're right. I only described it verbally because that's how it was set up on a Bronco. And in 904's photo of his '77, he shows a hose laying there on top of the canister. It's not clear where it goes unless you know. Sorry, I just happened to know where it went, but describing it was not the same as seeing it.
I don't have any pics of mine, since it's now disconnected during a retrofit, but there are hopefully some here that can post one up. Your Bronco originally had one just like described though, if it was one of the years so equipped. I think from mid '69 to early '76?
The pre-'76 Broncos would have had the low-mount canister on the frame. This had one fitting for the small hose to the evap-condensing tank behind the driver's seat, and two large "chimney" fittings. One for a hose up to the firewall with a plastic "grommet" to hold the hose open (later years had the mushroom cap) and the other large hose went to the hole on the air filter that 904 showed in his pic.
The only diff was that in his pic the fitting is missing. He was only using the hole to show you where the hose and fitting are supposed to go. The hole is usually filled with a plastic hose fitting. But the concept is valid. We just need a pic of the fitting to prove it.
As far as the tank goes, it is a BC Broncos tank. You stated "the big vents NEVER go to the tank. Otherwise you'd have a fitting that size on your tanks. And I've never seen or heard of one that size on any of our tanks.
Please look at this link.
http://www.bcbroncos.com/store/product_info.php?cPath=131_68&products_id=2024
It is the BC Bronco's tank and the fittings are 3/8 and 5/16. The canister has 2 nipple sizes, 5/16 and 1/4. I guess I found the only tank in the world with a 5/16 fitting and the hose fits perfectly on the bigger nipple of the canister which is the exact same 5/16.
If there was a 1/4 nipple on the tank then I suppose it would be obvious to vent to the smaller nipple on the CC but, since one of the fittings is 5/16 and the same size is on the CC, I thought it was obviously supposed to go there. Now I need to find a step down barb to connect a 1/4 hose to the 5/16 hose that vents the gas tank.
Ok, I was referring to stock original tanks. Sorry I wasn't clear on that. I wasn't even thinking of aftermarket, which I should have been. But I was also referring to the big fittings. By that, I meant the "BIG" chimney fittings. If you meant the larger of the two "small" fittings, then I misunderstood what you were saying. I consider all four fittings on the canister in my statements. 3 different sizes, 4 distinct fittings.
Still, with a "stock" tank, it's the smallest of the hose fittings that receives vapors from all years of EB tanks. The larger of the two small ones on your specific tanks is, I believe, still for the vapors to go up to the engine via the CANP circuit.
Still, I thought the larger of those two looked like it was 3/8" instead of 5/16" like you say it is. Thanks for clearing that up. I should be more familiar with aftermarket tanks in minute detail, since I sell them, but I've only looked at the later canisters a few times. And it's been awhile.
One thing that's been consistent over the years at least, the aftermarket tanks don't match the factory hose sizes very well. My old NWMP tank's two evap vents that are in the same place as the stock ones on the main tank were not correct either. I got some to fit, but wasn't happy about how much I had to clamp down on the 5/16 hose to get them sealed tight against the factory steel and plastic lines.
But here again, you're using a non-stock EVAP canister. So an aftermarket Bronco-specific tank and a non-stock canister might not match even if the tanks did match the stock setup.
My MSD EFI does have a ported/timed vacuum source so it appears that is where I will be venting, the confusion is all of the step up and step down fittings required to make nipples on all 4 ends of the hoses fit correctly.
Stop. Don't pass go.
Just because your new throttle body has a timed vacuum port has, in no way, any bearing on your evap system. Unless MSD says to hook it there. In which case I'd actually call them to find out why myself.
Timed vacuum is usually (always?) only for a vacuum advance distributor and has nothing to do with EVAP unless it's through other specific accessories specifically designed to control that circuit.
Which it doesn't sound like it is.
I haven't read the MSD instructions lately, so I'll try to do that tomorrow to see if there is anything I can find that would help here. Probably not, as you've got them right in front of you, but it would make me feel more in touch if I re-read them again to re-familiarize myself with what's going on.
Sorry if none of that was clear for whatever reason. All of the questions you just asked seemed to me to be the same ones we've been answering.
Ok, here's my bottom line suggestion for you then. It's just a suggestion to give my angle on this whole thing though. If you think there's a better way, or if someone chimes in and has more direct knowledge of how it would work better, then do it that way.
The bottom line is that you have an EFI equipped engine that does not have a dedicated EVAP control circuit. Therefore, you should hook it up just like you would on any non-EFI Early Bronco V8 engine.
And that is:
1. Smallest fitting on the canister goes to the tank line. If that's the 1/4" one on the canister, and 5/16 on the tank, then it's just got to be adapted like you said. That's where all vapors will enter the canister.
2. The medium fitting on the canister gets plugged/capped/closed. Not used.
3. One of the large chimney types (might as well be the one farthest from the motor) gets a mushroom cap and is the atmospheric pressure equalizer, or whatever it's called.
4. The remaining large chimney fitting will get the proper fiber hose (available at most auto parts stores I would think) fitted and routed to the air cleaner housing somewhere. This is how it will get to the throttle body to be used in the engine.
Depending on your air cleaner, you can contact the manufacturer to see if they have those plastic elbow fittings that attach to knockouts in the lower plate, or drill your own for some sort of fitting that is the right size to match the chimney on the canister.
Most of the major air cleaner manufacturers include knockouts in the lower plate for just this purpose. Edelbrock, K&N, Mr Gasket, etc. should have the spot and the fitting available. If not, you need to make your own.
If you have a stock air-cleaner housing, you could use that. I know it's not as cool or as free-breathing as a nice big aftermarket filter housing is, but it's got good hood and distributor clearance and would have a nice convenient fitting (or just a hole to put one) in a nice convenient spot.
Just a thought.
5. Forget vacuum.
Paul
