Carb Preheat (to help eliminate Weber progressive icing?)

[Oil Phil-M]

Back when I had a weber regressive and icing problems I used the preheater inlet. Found that a 2 inch pvc female-female coupler fit perfectly in the opening and an aluminum heater hose from a bug fit perfetly onto the coupler. For the carb I fabricated a box out of sheet metal that encased the air filter and another pvc coupler for a "snout".

I ended up using it all year round. The engine had less hesitation and ran better with the hot air. Later I found that those black insulator spacers had been installed between the head and the runners diminishing any natural heat transfer to the runners.

[Amskeptic]

[Duncwarw]

I'd like to know why I haven't suffered with a great deal of "icing" issues.

That aside, in the UK, you can buy an IMDU (Inlet Manifold De-icing Unit) and I think there are two sizes so you might find one that fits properly.

You could also make one and as Wildthings suggests, I'd run it from a relay. As far as that "hot plate" goes, it was indeed on the Vega and I've read the small Blazers had it, among others.

I started to experiment with heat trace under an insulating material but I have no time and so for the worst icing experience I've had was a lack of idle that was at around 0F. I'll see what happens this winter.

Welcome back Bob.
_________________
“To find yourself, think for yourself”
Socrates, 470 BC - 399 BC

[Wildthings]

I personally don't like the idea of adding relays. I like what they do, but they add a level of complication that might keep you van from starting and running when you want it to. Not only are you adding a relay, but you are adding wiring and a triggering mechanism. After all the factory designed and installed double relay on the later Bays is perhaps the #2 cause of FI problems after the TII sensor.

I have in mind some kind of special fusible link that will fail quickly in case of fire. Actually just a properly positioned inline fuse might work. Set the fuse holder high in the engine bay, such as right at the top of the fire wall or where the relay is for the aux fan. If you get a gas fire then the heat and flames should quickly melt the fuse holder cutting off the fuel. There are commercial links just for this process as well.

The problem at this point becomes cutting off the flow of fuel by gravity. Sticking your plain jane fuel pump underneath the bus will not help here. You need to do one of the following.

1. Use a fuel pump with a built in anti siphon valve like the OEM mechanical pumps had.

2. Bring the fuel into the engine bay by a metal line and connect the metal line to the rubber hose near the top of the engine bay above the level of the top of the fuel tank.

3. Install a spring loaded check valve at the outlet of the tank, or on the outlet of the fuel pump if you have the pump installed underneath.

4. For my next bus I am thinking of installing the pump in the tank using a top outlet. This will leave only a very short section of hose susceptible to failure. and burn through, mostly above the level of the tank. Once the pump is depowered and the line burns though above the carb this would this would kill the flow better than anything else I can think of.

[Duncwarw]

Though I can't agree with the bit about the relays, I wholeheartedly agree about the safety issues. After all, fuel pump and fan relays are in millions of cars and rarely fail.

It's fairly common in the UK to install a fuel-shut off solenoid at the tank outlet which electrically shuts down flow when the key's off or it is otherwise triggered. Also handy to keep from getting a face full during maintenance.

Auto extinguishing systems are available at speed shops and would probably be the ultimate in piece of mind.

Metal line is a big help but you have to have a flexible bit where the line leaves the body to enter the engine room.

When we've discussed this before all sorts of ideas came up. I wonder if anybody's employed some yet?
_________________
“To find yourself, think for yourself”
Socrates, 470 BC - 399 BC

[Wildthings]

[Duncwarw]

Nice.

I mis-typed. The body is not the problem. The engine moves around sort of within the body. That's where the need for flexibility arises.
_________________
“To find yourself, think for yourself”
Socrates, 470 BC - 399 BC

[Underdog65]

EFE Page http://www.carburetion.com/efe.htm here is a site that sell the plat you show in your thread have not order one yet but will be soon hope it help some one.

[davis911s]

[barryman]

[davis911s]

Here is how mine looks

BEFORE

Top SEALED

Look at the airfilter

From the rear engine access

and good news, This modification has worked EXCELLENT!
No more stalling in cooler and wetter weather, I am VERY happy

Shawn
_________________
"I choose to use CAA on old cars with character...instead of car payments on a new car "

1973 Westfalia, Camper Special with 75 FI. Automatic 003 . Non-pop top
1977 Porsche 911S Targa, 2.7 L with 5spd
1992 Passat G60 Syncro Wagon (SOLD)
1975 Westfalia (SOLD)
1979 Westfalia (SOLD)

[brownONE]

[Wildthings]

[busdaddy]

I'm not too sure you would get much heat out of the booster fan duct under driving conditions, too far upstream to pick up much heat.

The 72-74's pick up air from below the cylinders, never tried but the early duct should work on a later bus with a bit of hole cutting.
A hose or two through the firewall tin and back into the lower tin would work great. Or down through the rear tin by the dipstick or over the coil.
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[brownONE]

[brownONE]

[davis911s]

If you look at my pictures the top picture shows the before picture. It shows the "hole" on the duct where you should be looking. If you find tin with that hole you found the right piece

I don't have an underneath picture but it has a metal "shroud" that forces air up to the hole shown in the above picture.

Shawn
_________________
"I choose to use CAA on old cars with character...instead of car payments on a new car "

1973 Westfalia, Camper Special with 75 FI. Automatic 003 . Non-pop top
1977 Porsche 911S Targa, 2.7 L with 5spd
1992 Passat G60 Syncro Wagon (SOLD)
1975 Westfalia (SOLD)
1979 Westfalia (SOLD)

[brownONE]

davis911s:

would you possibly have a pic of what the underside of that electrical box looks like? how exactly did you mount it? i see bolts with wing nuts on top of the filter, were you unable to use the clamps after you put the box in?


thanks

[davis911s]

Read this

http://ad-libs-vw-technical.blogspot.com/2007/10/long-awaited-progressive-carb-warm-air.html
He is the guy I "stole" the idea from. He shows a good pic of the inside of the box. Mine is cut out just like his. You need to cut out the bottom to fit around the carb. The bolts are there so you can change/ clean filters.

This is an EXCELLENT mod. It was -20 here the other day and it ran like a champ I know the "icing" is caused by condensation not just the cold. My mod has worked from +20 degrees all the way through to -20 degrees. IT WORKS. But I think it has brought the fuel mileage down a bit.

Good luck

Shawn
_________________
"I choose to use CAA on old cars with character...instead of car payments on a new car "

1973 Westfalia, Camper Special with 75 FI. Automatic 003 . Non-pop top
1977 Porsche 911S Targa, 2.7 L with 5spd
1992 Passat G60 Syncro Wagon (SOLD)
1975 Westfalia (SOLD)
1979 Westfalia (SOLD)

[brownONE]

thank you thank you thank you. great link.

i can't wait to gather up all the parts i need to get this thing put together.

you've been great help, davis911s
_________________
BROWN
b1originals.com

'77 automatic BUS