Snorkel "deep fording" cut off switch

Okay after installing my home-made PVC snorkel i realized, as is common knowledge, that 2.5 inch is not sufficient for every day optimal operation.
SOOOO.... i keep the original intake on the front of the airbox open as well as the snorkel.
And i added a little option to cut off the main intake when needed. Mabye it was a flash back to my Marine days in Humvees with thier deep fording switch.
but thats what i did.with minimal modification. All i had to procure was some vacuum line and a Briggs and stratton fuel cut off switch (4.00)
I intercepted the constantly there Cruise control vacuum sice the wire to the control lever for this function had been cut years ago and i have no need for C.C anyway.I junctioned the vacuum line there, ran it into the cabin, ran another line back to the vacuum motor in the airbox that moves the door to allow heated air from the exhaust into the airbox.
Now i must state that i live in an area where it MIGHT get into the 40s or 30s for two or three days a year and therefor have no need for pre-heated air.
I plugged the heated air line.If you were adusive enough to get around the
power steerign lines you could re-route the heated air line to a higher location and perhaps re-use that as well but theres little room to manuver there so i decided to NOT mess with it.
To make it short, you run in "normal operation" with air coming in from both locations, then turn the knob 45 degrees to "fording" and it pulls the door shut, cutting off the forward intake, allowing only air from the snorkel.
This might have some flaws that i will discover "in the field" but so far in "lab testing" its functional.
Only one issue so far,....when i turn it back to "normal use" the vacuum holds. So i need a "t-connected" check halve or a purge button of some type.I will work this out soon.But it has no problem running with snorkel only as far as i can tell at lower, non- highway speeds, so im not too worried.
Heres pics and a diagram.






Perhaps this will be of some use to someone.It cost less than 10.00.
1/4 inch vacuum tubing and the switch. I got all of it at Auto Zone.

I suppose us guy who run in colder climates could pull another heater airbox from the junkyard and not have to sacrifice our heat?

I don't have near the setup, I have an extra 4" tube going to the cowl, and I have a piece of plastic that fits the hole in front with a bolt I can put in by hand in about a minute.

Yours is way more user friendly! good job.

I have to say i cant vouch for the colder climates with the heater hose. I can only think that mabye if the exhaust was blocked from most if not all water coming in contact with it, which would be tough because it would mean the exhaust becoming extremely hot during regular use.Or re-routing the heater hose up closer to the hood with mabye a "Y" junction that has another vacuum motor to divert running off the same switch somehow.

I just wanted to put a write-up on the forum since ive been learning from it for so many years, i wanted to "give back"...as it were. If nothing else, to inspire someone else to make a better one then mine from my ideas.

Not to be a nay-sayer, but I see a problem here...

When you go to wide-open-throttle (WOT) your vaccume drops. So if you're in deep water and have to hit the skinney-pedal, the front flap will fall open and water will rush in.


I'm sure there's a solution you can come up with to handle that, I can think of a few different ones of off the top of my head; but you definately want to take care of that.

+

I was not aware of that. I guess the fact that it holds vacuum after i turn the valve back to regular, i can "charge" the system then turn it back to hold in its own atmosphere. Thanks for that, ive not spent much time with vacuum systems, other than making sure everything was connected.....

NP

Basically think of it this way:

The ammount of vaccume you have is the difference between what the engine is trying to take in, vs the ammount you are allowing it to have (with the throttle). When you open the throttle plates all the way, there is no difference between what it CAN use and what it IS using.

If you've ever seen an old chevelle with the automatic cowl-induction, you can see how GM took advantage of that. They had a spring loaded flap that was open, but engine vaccume pulled it closed. That way, when you stomped the peddal, the springs took over and the flap opened to allow more air in right when it was needed most.
Which is exactly opposite of what you want...
Like I said, there's a few different ways you can take care of it... it's just something you have to allow for.

Fozzy_Bear said:

Not to be a nay-sayer, but I see a problem here...

When you go to wide-open-throttle (WOT) your vaccume drops. So if you're in deep water and have to hit the skinney-pedal, the front flap will fall open and water will rush in.


I'm sure there's a solution you can come up with to handle that, I can think of a few different ones of off the top of my head; but you definately want to take care of that.

+

Click to expand...

Easily fixed with a check valve if not already in place from the factory. I believe most vehicles come that way.

-Ron

XXX said:

Easily fixed... most vehicles come that way.

Click to expand...

Yeah, but I wouldn't want to assume ... I just though I should mention it.