Weber carbs on 1970 Fastback ??

[OZ1970FASTBACK]

Hello from Australia, I’m restoring a 1970 Fastback Type 3, I had the 1600cc engine rebuilt early this year, the solex carbs were shot so I ordered the twin Weber 34 ict carb kit along with all linkages & throttle arms installed them last week it runs fine but when taking it for a drive it labours & has a slight backfire…… I followed instructions that came with the kit, mixture screws 2 turns out to start but blew a lot of black smoke so I’m thinking it’s running rich so I went in half a turn on both mixture screws, running much better but still missing under load, I’m wondering do I need to adjust both floats in the carburettors ? I live in the Country so not much help out here on VWs. I’m also thinking maybe timing is out a little so can I move distriburator to advance or retard the engine, like on the old Ford V8 engines ? I don’t really know much on how these engines work as I was brought up with Fords & Holdens, any advice would be of great help, Many Thanks Jamie - Australia.

[broady_6]

Its a real easy fix, take all the jets and emultion tubes out and throw them in the bin. They are desgined for a beford CF van. Replace them with the following. It isnt the "right" answer. But it gets you somewhere close. You may need slighly bigger or small jets from these sizes. Depending on many factors.

F6 Emulsion tube
140 main jet
55 idle jet
170 air corrector jet

I hope these helps. Ive done this many times and its sorted the problem.

[OZ1970FASTBACK]

OK Many Thanks, what is the Emulsion Tube ? is that the pipe that runs from one Manifold to the other ? Is it possible to get those Jets from Ebay.com in America as that is where i purchased the Weber Kit From, Thanks again for the information.

[broady_6]

It's inside the carburettor. All of those parts are. I will find you a diagram later. I buy my parts from euro carb. But that probably isn't much use to you on the other side ise of the world.

The tube you describe is the balance pipe, for future reference

[OZ1970FASTBACK]

OK... got it, i did a search on youtube last night it showed me where the parts you mentioned are. If im right i replace the F6 Emulsion tube with the 170 Air Connector jet, the main jet is inside the Carb & The idle jet is on the outside, Ive rebuilt Holley Carbs in the past so once i looked youtube it seems a easy fix fingers crossed !!!!! Once i get those parts i will work out how to post some pictures of the Car, its on Historic rego so i can drive it on the road once i change out those parts, i did find a company here in Australia that sells those parts so i sent them a email if he can supply me 2 of each

[broady_6]

You're pretty close. But you change your current emultion tube with thr f6 tube, and the current air corrector jet with the 170.

Sounds like you've got the right idea though. And yeah, it's not particularly hard to do, just a bit fiddly. Let's hope that company can help you out.

We have a photo posting guide at the top of every page, it will be great to see your car.

You may find those jets aren't perfect for your car. But it's what I fit as a starting point here in the UK. I then do an emissions test, and drive the car to see what performance I'm getting. Then adjust the mains and or idle jets accordingly. Usually all the other bits remain the same. It's will certainly get you up and running though

[OZ1970FASTBACK]

OK i fully understand now... Replace the Emulsion Tube with a F6 Tube, Im heading off to Victoria tomorrow to visit friends for Xmas for a week & do some fishing, I will order the parts You have listed before i leave & hopefully here soon, I will try to post some pictures tonight of the fastback when my wife wakes up ( my wife is a Nurse working night-shift this week ) Have a Safe & Merry Xmas Mr broady_6. ( 3 hours later ...... Just got off the Phone to a Weber Dealer here all parts now ordered 2 x F6 Emulsion Tubes, 2 x 140 Main Jets, 2 x 55 idle Jets & 2 x 170 Air Corrector Jets -

[broady_6]

Enjoy your trip! Have a merry christmas.

[OZ1970FASTBACK]

Hello, im going to change out all those parts this weekend so i will do a Google search to know exactly what to do, i was looking at the Emulsion tube does it need to go in a certain way due to all the holes in it ??? ( it looks like a minature flute ) Do you know of a Diagram i can look at that shows me what is what e-g... Main Jets, Idle Jets & Air Corrector Jets, I know where the F6 Tube goes, Thanks again.

[broady_6]

Luckily all the parts only fit one way round, the Emuulsion tubes become obvious once you see them.

https://www.carbparts.eu/exploded_view/WEBER_34_ICT

Hopefully this helps. Let me know if you need any more help.

[OZ1970FASTBACK]

Hello, i changed out all those parts , idle jests were the same 55. i took it for a drive & it started to Miss then back fire again , it runs much better at idle no smoke or fumes what so-ever. After lunch im going to check points and advance or retard the timing then take it for another drive as it did a little blow up the carbs when i turned it off so im thinking Timing- Hopefully. I have searched the web there are 2 VW specialists around 2 hours from Me Canberra or Orange but i will have to arrange for a car trailer to take it there, i will post again in a couple of hours in regards to how it went with adjusting the Timing .

[OZ1970FASTBACK]

Latest update..... found out you cannot move the Distriburator on a fastback e-g to Retard or Advance it, im also doubtful the wires to the coil are wrong as it was put back in by a so-called local VW Expert LOL , there are 2 wires that go to Negative a green from the Dizzy & a Orange that comes from front of car, there are 3 wires on the Positive side 2 thick black wires & 1 purple, it did have electric choke on the Factory set-up twin carbs & these 2 wires are now not connected to anything is this right ??? Any ideas would be of great help as the Specialist in Canberra is not open till the 9th of January so i have a week to try and figure out whats wrong, Oh & Happy New Year to All.

[broady_6]

Glad to hear the running has improved,

When you say you found out you cannot move the distributor, what do you mean? Yours is stuck? Because you can advance and retard it. It it sounds rather like your timing does need adjustment.

Coil wise, you should have a green wire on the negative to the condenser. The otherwise may be for the diagnostic socket, which is no longer needed, or at some point your car has had an RPM gauge, and that is the signal wire for it

Postive, you will have a thick black wire that is the power supply to the coil, as you have identified, another which supplied the chockes and fuel cut off valves. You can/should remove this wiring, as it is live when the engine is running and could cause a short.

The otherwise is likely to be a power supply for the reversing lights, it will run to a fuse in the engine bay and then to the gearbox.

[broady_6]

One of these two diagrams should help you

https://www.thesamba.com/vw/archives/in ... 3_6870.jpg
Key https://www.thesamba.com/vw/archives/in ... 70_key.jpg

https://www.thesamba.com/vw/archives/in ... pe3_71.jpg
Key https://www.thesamba.com/vw/archives/in ... 71_key.jpg

[OZ1970FASTBACK]

Ok so i can turn the Dizzy to advance or retard the engine, i will wait till it cools down and give it a try in a few hours as its very hot here at the Moment, we went from 10 months of Rain & Floods then Bang 38 degrees.... No spring this year very crazy weather indeed, ill post again with my findings.

[OZ1970FASTBACK]

Latest update……. sorry I have been busy at work, I did find the nut to loosen the Dizzy I had no luck with the timing, I turned it back to where I marked it at the start of retarding & advancing it, I let it cool down for 2 hours then decided to take it for a drive & low & behold the Engine came good, no missing or sputtering what so-ever, maybe I got lucky with moving the dizzy or those changes to the Weber carbs that I did, I did phone one exhaust shop to see if he had a exhaust annaliza but no luck as of yet but I will find one, So with the Mixture Screws on these Weber Carbs is turning the Mixture screw out to Richen it & Turning it in to lean it ( less Fuel ) Once again Many Thanks for the Information You have given me.

[broady_6]

Thats great news! So happy we can help!

You are correct regarding the mixture change.

If you want to get adventurous, there is a further improvement you may need. Where are you now venting the crank case too?

[OZ1970FASTBACK]

Hello there is one large black hose that i think went to the original air cleaner..... Is that the Crank case Hose you are talking about ? Its not joined to anything at the Moment so where can i join it to and is it important ??? Any information on what i can join it too & pictures would be a great help, Thanks again - Jamie , Australia.

[broady_6]

Yeah thats the crankcase breather. A good rule of thumb, if VW thought it was worth fitting one. its important.

As your engine gets hot, the gas an oil inside the crankcase expands, this causes high pressure and will force oil to leak out. That hose connected to the airfilter, the cars are sucking, and as such they suck the high pressure out of the crank case which helps to reduce oil leaks among other things.

So one way or another you need to connect that breather point to one of the air filters on your new carbs.

[OZ1970FASTBACK]

Hello i purchased a Champion 90 degree Brass fitting for the Half inch hose , one end is threaded & the other end the hose slides on, i will drill a hole into the closet air filter underneath & pipe it to it, so it should do the Job . I did also buy a meter of half inch hose so ill work out the hose length & cut it to size.

[OZ1970FASTBACK]

Hello, well we took the Fastback to a Car show yesterday a round trip of around 150km it did run fine & no problems with the engine, i was following my wife who was driving it & around half way home i noticed some oil smoke coming out from the Left rear or the car, when we got home i inspected it for any leaks and all was good, i lifted the engine cover & on top of the block the plastic cap was sticking up and attached to it was a spring, im taking this is a safety device for Crank-case pressure ? it was a very hot day around 38 degrees Aus, i dont think the set-up i made to the air filter is good enough as its a Pan-Cake air filter & sucks in air from all around it not like the steel factory intake, so is there a better place to attach the hose too ?

[broady_6]

Youre right, thats the crankcase releif valve, the breath pipe should be connected to it, and as long as that connected to one of the airfilters, it should be hooving out the case. If its not working, it could be that a piston ring is leaking and pressurising the case. I assume you have the standard exhaust which exits at the left rear? Check your oil level, it sounds like its burning oil.

[OZ1970FASTBACK]

Hello the Exhaust is standard & the pipe exits the rear right hand side of the car, i did do a oil change the day before & checked the level twice & all was good. Is Hooving another word for sucking ??? i used a Mineral oil in 20/50 grade i have read some Fastback owners run straight 30 grade engine oil in there motors ? As our summers out here can reach 40 to 45 degree's and winter we get down to minus 5 , i will monitor it for leaks & oil consumption as hopefully nothing is to much wrong with it !

[broady_6]

Yeah, just me using slang.

I always use 20/50. It been over 10 years and its never caused any issues. All the standard exhausts exit on the left hand side when you are looking from the back of the car. There is even a notch in the body wory for the tail pipe. If yours is on the right, I would guess its been modified in some way.

[purplepeter]

Check that the plastic cap on the breather is a tight fit? It's thermoplastic, so heating it in water will allow you to bend the lugs out if it's gone loose ( should be fairly tight)