Pre heat ideas

[72Hardtop]

Would like to run some additional pre heat for the IDF's. I have all the tin in place and pre heat duct (72) but the duct is covered at the moment. I'm trying to come up with an easy way to duct heat from the pre heat duct on the passenger side firewall to both carb tops. It would have to split so it can be ran to both carbs. Any ideas as to what can be used? With the least amount of fabrication.

Not having any icing issues but would like to help the carbs get more heat and help with fuel atomization on cool high humid days.

[hambone]

The heat has to go away when the engine warms up, so you'd need a flappy-thermostat device. Ducting from someplace hot would be relatively easy with foil tubing.

[72Hardtop]

The heat has to go away when the engine warms up, so you'd need a flappy-thermostat device. Ducting from someplace hot would be relatively easy with foil tubing.

Yeah, I figured it would need a T-stat of some sort. But I figured if I downsize the hose from the pre heat duct that I'd be able to skip the T stat even more so given the system isn't a closed system as it is with the original set up. If not, any thoughts on what to use for T-stat? Something that could be relatively easy to install/fabricate?

[Amskeptic]

The heat has to go away when the engine warms up, so you'd need a flappy-thermostat device. Ducting from someplace hot would be relatively easy with foil tubing.

Yeah, I figured it would need a T-stat of some sort. But I figured if I downsize the hose from the pre heat duct that I'd be able to skip the T stat even more so given the system isn't a closed system as it is with the original set up. If not, any thoughts on what to use for T-stat? Something that could be relatively easy to install/fabricate?

How big are the throats to your carbs?

You could have:
* superior filtration
*take off points for fuel vapors and crankcase fumes
*automatic thermostatic preheat with pre-aligned everything.
just by sticking in a stick '73 plastic air filter with the factory ducts leading to your IDFs

Only problem I see (other than it being butt-ugly) would be if the throttle linkages are a big clumsy series of bell cranks and whatnot.
Colin

[72Hardtop]

Well they're 40mm Weber IDF's with 28mm vents. As for the linkage set up: http://images.thesamba.com/vw/gallery/pix/905279.jpg

Is it even possible to adapt a 72-73 air intake system onto IDF's? I used to have the stock stuff but did away with it years ago (after CA exempted pre '74 vehicles from smog).

[Amskeptic]

Is it even possible to adapt a 72-73 air intake system onto IDF's?

Oopsie . . . big double throats. Nope.

There is no classy solution for your request with open air filters without boxing them in who knows what.
Colin

[72Hardtop]

Just a thought...

Would it be possible to adapt/create a way to plum a hose from the pre-heat duct have it split then run to a fitting at the top of each carb filter cap. And at an early point adapt the T-stat from a 72-73 into the hose at the 'Y' where the hoses/ducting would split for each carb?

I would need to have a Y section that Id be able to adapt the T-stat to. Any ideas? How about hose/duct sizes what would be the best size to use?

I'm going to pick up one of these as well: http://www.buttysbits.com/throttle-kits.html

Very likely the last throttle linkage the bus will ever need.

[Amskeptic]

Just a thought...

Would it be possible to adapt/create a way to plum a hose from the pre-heat duct have it split then run to a fitting at the top of each carb filter cap. And at an early point adapt the T-stat from a 72-73 into the hose at the 'Y' where the hoses/ducting would split for each carb?

I would need to have a Y section that Id be able to adapt the T-stat to. Any ideas? How about hose/duct sizes what would be the best size to use?

I'm going to pick up one of these as well: http://www.buttysbits.com/throttle-kits.html

Very likely the last throttle linkage the bus will ever need.

Please understand that pre-heating the intake air is not a simple task of sticking a couple of hoses onto the air filter caps. The sheer volume of ambient air is enormous. The latent heat of evaporation is enormous. That is why we see condensation on carburetors even on a 75* day.

The air pre-heater supplies 100% of the engine's air when needed. Anything less is a waste of time. Little "breather hose" supplies of warm air are no match for everything flooding in through the air filter mesh.
Colin

[72Hardtop]

Just a thought...

Would it be possible to adapt/create a way to plum a hose from the pre-heat duct have it split then run to a fitting at the top of each carb filter cap. And at an early point adapt the T-stat from a 72-73 into the hose at the 'Y' where the hoses/ducting would split for each carb?

I would need to have a Y section that Id be able to adapt the T-stat to. Any ideas? How about hose/duct sizes what would be the best size to use?

I'm going to pick up one of these as well: http://www.buttysbits.com/throttle-kits.html

Very likely the last throttle linkage the bus will ever need.

Please understand that pre-heating the intake air is not a simple task of sticking a couple of hoses onto the air filter caps. The sheer volume of ambient air is enormous. The latent heat of evaporation is enormous. That is why we see condensation on carburetors even on a 75* day.

The air pre-heater supplies 100% of the engine's air when needed. Anything less is a waste of time. Little "breather hose" supplies of warm air are no match for everything flooding in through the air filter mesh.
Colin

I'm aware of that. I was considering the use of or adapting a different filter base for each carb (closed). Or perhaps modifying the stock set up using the filter can and air channels & T-stat. I'd just need a custom/modified base for each carb that could accept the stock air channels on top. It would be nice if someone offered something as such especially considering how many aftermarket duals there are out there.

[Amskeptic]

It would be nice if someone offered something as such especially considering how many aftermarket duals there are out there.

I see little concern for Reality from most of these aftermarket vendors.

The aftermarket industry was answering the big complaint of "inadequate power" by adaptations of other brands. They could not give less of a damn for cold driveability issues. 40 years later, the latest cars have driveability that has never been better, and we now want some for our old classics. The only acceptable driveability I have experienced is from stock induction, and the best compromise of power and driveability is a thoroughly warmed up Raby engine.
Colin

[72Hardtop]

The following would work. I just need to adapt the T stat to it.

http://www.csp-shop.com/cgi-bin/cshop2/ ... ort=0&all=

[Amskeptic]

The following would work. I just need to adapt the T stat to it.

http://www.csp-shop.com/cgi-bin/cshop2/ ... ort=0&all=

That is a solidly seriously beautiful butt-ugly option! You mu$t be very very devoted to your carburetor$ . . .
Colin
( do they guarantee to clear the throttle linkages?)

[72Hardtop]

Waiting for response back from them but it does appear it will. It's meant for duals and I'd imagine they'd of had to make consideration of linkage set up/s. Not to butt ugly. I'd get to run a paper filter as well. Now to just figure out how to hook up the pre-heat/T-stat.

The stock T-stat run off vac or was it electrical?

I know somewhere out there...there has to be someone offering something similar for MUCH cheaper.

[Bleyseng]

If you want to stay duals then I would go with that air cleaner setup and a set of IDF throttle bodies with megasquirt FI. Forget the carb warmup issues but it will cost lots more than using stock Ljet.

[Amskeptic]

Now to just figure out how to hook up the pre-heat/T-stat.
The stock T-stat run off vac or was it electrical?

Stock pre-heat thermostat was a bimetal vacuum valve in the right air horn. The *brass* nipple went to the vacuum actuator that actually pulled the flap to allow warm air up from the cylinders. The *black* nipple was connected to manifold vacuum. When cold, the bimetal allowed full vacuum to the actuator. When it warmed up, it would bleed the vacuum and the flap would close off the heated air. You could/can hear the vacuum valve "sing" when it was warm.
Colin