TheSamba.com :: View topic - 72 bus vacuum lines for dual carbs setup questions

Fri Apr 17, 2015 3:20 am

good morning everyone
getting sooo close to twst starting up my engine rebuild !!!

so a few questions about vacuum line hook ups etc..

I have found some silicone lines made for vacuum says will not collapse and super flexible easy to use , but after reading threads on samba people talking use solid plastic and or hard lines etc
has anyone used good silicone line before they are not cheap but come in all the required sizes so should hook up great

im sticking with the hard line that runs the length of the bus to the boaster its in great shape , and want to replace the flexible lines at other ends etc....

thoughts??

and I have a new check valve the common black and white one I see in a lot of threads , but not sure where it should be installed ??

I have connected both carb intakes and put in a tee to head up to the brake booster, thinking of installing the check valve right after this T which would be located directly infront of the engine tin , kinda beside the flywheel

not sure if original ran on drivers side or passenger side of tin when it comes out of the tin ( does it normally go out tin near right or left carb?)
I cannot find the correct hole in tin to go through...... I could make one but shouldn't have to

I found a thing that ma be an old check valve on the bus atteacted to old vacuum line but sure dokesnt look like the black and white one I bought ?

its about one inch in diameter , iwould describe as a really small version of my oil bath cleaner (round in middle and on top of it has the two ports on top that the vacuum connects to) thinking it must be old style check valve??
sorry I have no photos of it at the moment will try and get next couple days ,
my van in storage as I work on engine project over winter that's why lol

so three questions
silicone lines
location of check valve
and which side does the line exit engine department left or right carb side ??

thanks again folks

Fri Apr 17, 2015 7:37 am

Goodhand77 wrote: so three questions
#1: silicone lines
#2: location of check valve
#3: and which side does the line exit engine department left or right carb side ??
#1, you are the test pilot on that, the brake supply should be wire reinforced so it doesn't suck shut on a warm day and give you a suprise when you don't expect it, the brakes still work but require much more pedal force than you are used to, it usually happens in tight parking lots or bumper to bumper traffic.
#2, the check valve can be anywhere but right infront of the bellhousing tin is the best spot, it's out of danger there and leaves plenty of line ahead of it to act as a larger reservoir for vacuum.
#3, usually it's on the left closest to the metal body tube, the less rubber line the better (see #1).

Fri Apr 17, 2015 7:55 am

Hey guys this is the vacuum line I bought google it for info , I think I might try it , just not sure about long runs cause you can buy it by the roll aswell...

Check it out I bought
Vibrant performance
Silicone vacuum line
Part number 2104

Just type in that part number and brings you right to it

Some race car guys in know use it , for short drag racing applications , not vw guys at all though

Fri Apr 17, 2015 8:04 am

All vacuum isn't created equally. Where are you pulling your brake vacuum from? Can you show a picture? Is it from the intake manifolds below the carburetor? If '72 bus has the same diameter vac line to the booster, there is a gates 15/32 line that will work. Aero mech has the Gates number. I have it at home on my PC.

Fri Apr 17, 2015 8:31 am

Yup dual carb located right under the carbs on basically centre of the intake and yup I think it's the same size as the brake booster, but it does require a tee in it with a much smaller line that goes to the oil bath plentum

I will snap a photo when I get home later today
My real job getting in the way of my Vw project !!

Fri Apr 17, 2015 9:16 am

Goodhand77 wrote: Yup dual carb located right under the carbs on basically centre of the intake and yup I think it's the same size as the brake booster, but it does require a tee in it with a much smaller line that goes to the oil bath plentum

I will snap a photo when I get home later today
My real job getting in the way of my Vw project !!

Doing a T in a big line like that between the manifolds can have unexpected results. Essentially you are running a balance line between the intake manifolds. This can make it more difficult to balance the carbs. On my dual IDF setup the brake vacuum comes off the #4 intake below the carb and that's it.

As far as silicone---not my preference. It won't take gas and this line is exposed to gas. Ordinary rubber and it gets considered for replacement at the same time as the fuel lines. Not necessarily replaced mind you, but considered. You check it.

The maximum possible pressure on that line (from the outside) is 15PSI and the motor won't pull that. I don't worry about collapsing anything. I have a pump that will pull max vacuum on a line and I may test whatever I use, at heat, but I'm not overly concerned. Nice sturdy reinforced hose.

On my LHD bus the line runs through the breast tin on the left. There is a grommeted hole. Chk. valve is immediately in front of the tin. This is a handy disconnect point although not the simplest to reach---not bad. Up by the clutch wingnut.

Sun Apr 19, 2015 5:21 am

these are the photos of my intake ports for my vacuum lines,
my first attempt to hooking up but to the wrong side of breast plate i think ? but the only hole on other side of the plate i think goes to the accelerator cable?

and the vacuum kit from german supply store i bought didn't send me an elbow with for the right side carb with the correct ? rubber 90 with a port for the hook up to the oil breather (small line that goes to small port under right side of oil breather)
so this was my first attempt , thinking I'm going to give my silicone lines a try

Sun Apr 19, 2015 5:24 am

i bought these new heads and almost have engine completed for test start, but no idea what this hole is for its the same size as my head studs and in the same spot on both heads
any ideas what they are for?

Sun Apr 19, 2015 7:01 am

Air injection ports.
http://www.thesamba.com/vw/forum/viewtopic.php?p=500435#500435

Sun Apr 19, 2015 7:30 am

hey tcash

I read the link you sent but I don't think, it could be air injection ports, but not sure

unless im misunderstanding , but the holes that I have simply are threaded holes through front of both heads on cylinder number 2 and number 3, right beside the carb intake

but the hole are threaded all the way through to open cavatity on the back side (basically open to the "fins" on the head

so these holes are not threaded into any sealed locations ie exhaust ports or anything just threaded hole in both heads open to fins on back side ??

sorry if im misunderstanding the other link though ? but air injection would need to go into a sealed cavity?? I think

Sun Apr 19, 2015 8:15 am

Air injection ports go all the way through to the exhaust ports, those look like TS2 mounting holes when those heads are used with fuel injection, same hole, just not as deep.

Sun Apr 19, 2015 8:25 am

re busdaddy
hey sorry not sure what Ts2 stands for?

Sun Apr 19, 2015 8:43 am

If you don't have fuel injection don't worry, it means Temperature Sensor #2 and it tells the computer if the engine's warmed up so it can adjust the mixture accordingly :wink:

Sun Apr 19, 2015 8:53 am

ah sorry for being temporariy stupid lol
I should have guessed that !
thank you

so I could use this hole as a source to thread in a head temp sensor?
maybe the Dakota one people talk about?
not sure how it attaches ? haven't seen in person
maybe it goes over spark plug aswell?

I would like to hook up the better unit that's all

Sun Apr 19, 2015 9:04 am

It's not suitable for a CHT, too far from the action. Under the spark plug is a better location, read the tutorial on Germansupply's website regarding notching the head for the sender, even if you don't install one right now it's better than taking all the tin off when it's in the bus to do it.

Sun Apr 19, 2015 11:59 am

Goodhand77 wrote: ah sorry for being temporariy stupid lol
I should have guessed that !
thank you

so I could use this hole as a source to thread in a head temp sensor?
maybe the Dakota one people talk about?
not sure how it attaches ? haven't seen in person
maybe it goes over spark plug aswell?

I would like to hook up the better unit that's all Plug the holes with a bolts, tin allowing, or put a bit of aluminum tape over them, so you don't leak cooling air. I have the same ones and will do one or the other. Likely an allen capscrew if it will fit. Looks like a fine thread maybe M10.

Mon Apr 20, 2015 6:26 am

Can't tell from the images what carbs are being used here but, from all the information I can gather, single barrel carbs require the vacuum to be taken from both intakes through a balance tube.

Please correct me if I'm wrong here. I asked about this in an earlier post but got no reply.

Mon Apr 20, 2015 7:53 am

well im no expert but learning as I go!
I have dual solex single barrel carbs and they indeed have balance tubes ,
I have hooked up mine are painted green you can it hooked up on one intake ,
it has three steel lines one goes to the top of the drivers side carb, and the other two lines go connect to each intake located on the inside side of them , all three lines join to a small round canister looking thing

sorry I can show photo of complete thing when I get home, this is photo of line to passenger side carb intake ,

now moving on you can see located on the outside of both intakes there is a port about 1/2 inch in size that is for the vacuum up to the oil breather plentium (small line off a teeon right intake and then both intakes connect via 1/2 line approx. and tee up to the brake booster,
you can see photo off the right side intake with small red line attached to plentium etc... I am redoing the lines with different hoses and connectors though , these look like crap and driving me nuts to look at, bought some good silicone line I want to try out

hope this answers your questions , I photos off everything just not all in gallery and cant add to it from my work gotta wait til later at home sorry,
let me know if you want to see any

thx cory

Mon Apr 20, 2015 7:55 am

ps pitapan
I checked they are m10 fine thread , im going to go to Fastenal later today to look for good cap for these holes
thx though, I thought they might not be useful for me

Mon Apr 20, 2015 9:26 am

My '73 Dixie bus has Delortto frd's and still has the stock balance tube which goes through the firewall tin on the left side. The dipshit po had it connected with fuel hose and they were both kinked closed so, needless to say no power brakey.

My '72 Niagra bus has Weber 40's and all sources say only one intake needs to be tapped.