early air cleaner question

I have been refurbishing my heater on my '60 bug, replaced missing flap on right side and new control cable. I noticed a 30mm spigot coming out of the left side heater box through the firewall near no.3 cylinder which seems the same size as a spigot facing down on the air-intake. Should there be a pipe joining these? there is a flap missing on the end of the air intake so am wondering how this works, is it necessary to have warm air from the heater box going to the air-cleaner and what role does the flap have? Anyone knowledge on this gratefully received😎

My understanding is that they should indeed be connected, and that the flap is intended as some sort of thermostatic device to control the temperature of the air mixture by closing off the warm air feed at a certain temperature. It's not critically important though, and I may be wrong on this. Basically, the engine will run fine without that hose, but I believe that it should be connected.

yes origionally they had a cardboard hose connecting

but yes it will run fine its really only for very cold climates but will make yr engine warm up quicker

That makes sense, thanks for your help🙂

There was also a rubber grommet where the hose came through the fromt tinware to seal the outside of the hose.

The pre-heater air hose ducts warm air to the carb when your engine is at idle (or the throttle is closed). This is designed to help stop the carb from icing-up.

The flap (missing from your air filter) is weighted so that it 'stands-up' when there is a low air flow situation (ie: idle). When it is 'standing-up' it allows the warm air from the pre-heater hose to enter the air filter. When you open the throttle the flap is 'sucked' into a horizontal position, blocking off the pre-heated air and drawing air from the larger air intake opening.

It is true that the hose can be left off and most of the time you won't notice - however it does make some difference when used in high humidity/low temp situations (like a rain storm in winter). I run the pre-heater hose on my '63 and I have never had a problem with the carb icing-up since I fitted it.

If you choose to leave the pre-heater hose off your car, make sure you block off the hole in the tinwear so that hot air from your exhaust isn't drawn into the engine bay.

R 🙂

Cheers Rossco, thank you, I intend putting the pipe back, when I can find one, also the flap too but I might have to make that maybe. There are quite a few changes to air-cleaners over the years, I just want to keep mine as it should be and if it improves the motor that's a bonus!

the carboard hose is available new from Vintage Vee Dub in sydney 02-9789-1777 they might also have a flapper valve S/H as well just measure the approx length u need to run the hose and give eum a call

the flapper valve is also able to locked in the open position for when vehicle are operating in warm climates and dont require the pre heat

vw54 wrote:the flapper valve is also able to locked in the open position for when vehicle are operating in warm climates and dont require the pre heat

true - forgot about that... but I would only lock it open in warm, dry climates as I have experienced problems with carbs icing-up during summer when it is really humid (but usually only whilst the engine is warming up) - can be really annoying when it regularly stalls at the first set of lights/intersection that you come to... my first Bug (a '74 L Bug) used to be really bad...

AnnosL, could you let us know how you get on when you replace the air cleaner pre-heat flap? I have a couple of air cleaners that are also missing this flap, but are in otherwise perfect condition...

R 🙂

Thanks for that, I am ringing vintage in a min, will let you know how it goes, also try to get the grommet Grumble mentioned.I live in Albany which has a pretty cool climate, downright cold in the winter so I reckon I will set up the pre-heat hose and flap properly and leave 'em on

just an update, Ratty63, got pipe and grommet from Vintage but they couldn't supply the flap so will keep looking for that, seems to have followed the same fate as the thermostat

Update: finally got the bits for the air cleaner to return to stock, amazingly the motor idles better and doesn't stutter when accelerating away in second like it did, cannot explain this and I thought it was my imagination but it is definately an improvement from before

annosL wrote:Update: finally got the bits for the air cleaner to return to stock, amazingly the motor idles better and doesn't stutter when accelerating away in second like it did, cannot explain this and I thought it was my imagination but it is definately an improvement from before

Great, same result as I found when I re-fitted everything that was missing. Good to hear.

I'm not really surprised that it does make a difference (despite what so many people will tell you), after-all, the VW factory wouldn't have gone to the extra expense of fitting all the pre-heating to every VW they made if it didn't do something... 🤪

Just as a matter of interest, where did you manage to find the replacement flap for the air cleaner?

Thanks for keeping us informed with your progress - more info for those who follow our path in the future.

R 🙂

Thanks Ratty63, I got the flap by having to buy another air cleaner, which was slightly different as it had a hose going to the oil filler but mine did not so I just replaced the flap only, otherwise they were identical. Got it from Vee Dub Centre in Perth, $35.00, not real cheap but I'm glad I got it as it has made a difference.