71 Fast Back Recommissioning

[broady_6]

Just sat in the sunshine browsing the internetprovidings and thought it was a good chance to have a ramble

[JackReddick]

Right lets see if I can unpick all of this. You didn't have the vacuum line from the left carb before this rebuild? Was the carb blanked off? If not then you had an air leak, and the fact the distributor wasn't plumbed up for advance means any old setting you had before you took it apart are now all but useless.

Which mark on the pulley are you timing it with? There is often confusion in this area. Can you post a photo? What is the part number of your distributor? Generally these engines are timed to 0 or 5 degrees. Once i know your part number I can tell you the correct timing

What points gap are you running? It should be 0.4mm

You say
"There is also a vac line from the left carb manifold but that’s plugged off"

But that doesn't make sense to me, Single vacuum distributors have a hose that connected the left carb to the distributor.
For dual vacuum distributors you have an additional hose which connects the retard side of the distributor to the right hand side carb/manifold.

Ive always found dual vac's to be much more agro than they're worth. Someone wiser than I will correct me here, but i think they were generally fitted to auto gearbox cars?

You are correct, the volume screw wound out increases fuel flow. Here is the full set up guide, Follow every step from basic settings to get the carbs operating together.

https://www.thesamba.com/vw/archives/ma ... /index.php

Thanks for this mate.

So let me try and summarise a bit better -

The distributor had the vac advance but this wasn’t connected to the left carb, there was no hose on it. I have now connected a hose from the fistributor to the left carb.
On the left carb manifold, (the pipe from cylinder head to that the carb bolts to) is a vac hose. This has been blocked off (this was how it was when i purchased it). I read this is for a dual vac dizzy as you said, but my dizzy isn’t.

Points were gapped to .4mm yesterday.

I was timing it statically to the furthest left point, believed to be TDC. It won’t fire on this. I therefore timed it to the far right notch (7.5?) and it fires on this but doesn’t idle

I’ll get photos and part numbers together of what i have later today.

Sorry i’m a bit vague - it’s like the blind leading the blind over here

[broady_6]

all good info. all done right so far. once we have a photo of the pulley we can get on. theres a few different pulleys. depending that youve got it could be a far as 12.5 btc from memory

[937carrera]

Locate the engine code and post that as well, you never know what might be in there

[JackReddick]

Right i have some photos so please see below.
i've found paper work for the distributor, it is this one linked here - https://www.vwheritage.com/043905205r-d ... e-vw-spare

The first photo shows the vacuum hose from the left carb manifold i mentioend which is blocked off. (in the background of the photo)

i'm not sure if the code is the engine code or just a part number?









I hope these are the right bits, let me know if i need to get any more photos! thanks chaps

[broady_6]

All the right bits, im just heading out. But when I get back ill go through it all with you. Only quick thing ill say its, youre using the wrong timing mark. So that's an easy fix.

[JackReddick]

Thanks mate much appreciated

[937carrera]

I'll just point you in this direction for engine codes etc, it's another part of this website,a technical web which has good info in it but a bit hidden because it's on a different URL

http://home.clara.net/hallvw/t3engnos.htm

and this one has pictures at the bottom

https://www.thesamba.com/vw/archives/in ... berst3.php

Those other numbers are crankcase part numbers / casting numbers

Have you cheated and used telescopic pushrod tubes instead of taking the heads off

I'll let broady help you more when he gets back

[JackReddick]

I'll just point you in this direction for engine codes etc, it's another part of this website,a technical web which has good info in it but a bit hidden because it's on a different URL

http://home.clara.net/hallvw/t3engnos.htm

and this one has pictures at the bottom

https://www.thesamba.com/vw/archives/in ... berst3.php

Those other numbers are crankcase part numbers / casting numbers

Have you cheated and used telescopic pushrod tubes instead of taking the heads off

I'll let broady help you more when he gets back

Thanks for the links mate, just checked my log book and it’s a “T” code engine, need to actually confirm on the engine though.

Nah they’re proper rods, had the heads off on Friday and fitted them

[937carrera]

Nah they’re proper rods, had the heads off on Friday and fitted them

Well done for that then

[JackReddick]

Nah they’re proper rods, had the heads off on Friday and fitted them

Well done for that then

Thanks! it was a hell of alot easier than my mk4 golf GTI to get the heads off

[937carrera]

Never got past doing MK1 Golfs, but have had the head off a Polo GTi that wasn't too challenging, only £8 for a new valve as well

[broady_6]

Okey doke, the engine code is on the top of the engine right next to the case join, near the throttle bell crank. I think we'll be ok with knowing its a T. T's were usually timed to 5 BTDC. But that distributor should be better suited to 7.5.

Here you can see the various different pulley markings, which is why I was after a photo.

http://home.clara.net/hallvw/type3ign.htm

Of the little cluster of three in your photo you need to be dynamically timing to the left hand one. With the vacuum hose removed at one end and plug to stop the carb sucking in air. Obviously set it statically first then run the engine to warm it up and then check with a strobe.

Also looking in your photos, the choke coil is a long way round, have you checked the chokes are both working, and working evenly?

To do this take the air filter off, ideally before the engine has run that day. Both chokes should be closed. Then turn on the ignition and watch both chokes, it wont take long for them to start moving. Ideally they should both move together and most importantly both should make it to fully open. Which is vertical.

I think thats all for now?

[JackReddick]

Okey doke, the engine code is on the top of the engine right next to the case join, near the throttle bell crank. I think we'll be ok with knowing its a T. T's were usually timed to 5 BTDC. But that distributor should be better suited to 7.5.

Here you can see the various different pulley markings, which is why I was after a photo.

http://home.clara.net/hallvw/type3ign.htm

Of the little cluster of three in your photo you need to be dynamically timing to the left hand one. With the vacuum hose removed at one end and plug to stop the carb sucking in air. Obviously set it statically first then run the engine to warm it up and then check with a strobe.

Also looking in your photos, the choke coil is a long way round, have you checked the chokes are both working, and working evenly?

To do this take the air filter off, ideally before the engine has run that day. Both chokes should be closed. Then turn on the ignition and watch both chokes, it wont take long for them to start moving. Ideally they should both move together and most importantly both should make it to fully open. Which is vertical.

I think thats all for now?

Thanks for the info dude.

Am i reading the diagram wrong? As to me 7.5 looks to be the far right mark when looking down from the back of the car, not far left.

Just been out and checked, both chokes are fully closed before i’ve touched the car, will monitor how they open/behave once i start trying to run it

[broady_6]

Yeah you're reading it wrong. This is the diagram which applys to you.



So from the left to right the 4 marks are
0, 7.5, 10, 12.5

Monitor how the open before you run it. Just turn the ignition on and watch them open up. Hopefully uniformly.

Fingers crossed we can get you there

[937carrera]

I'll chuck in some thoughts here:

Does it depend on the engine number, pre / post 1009830.

From the photo the pattern of notches looks like an early engine so timing should be at TDC, i.e the left most isolated notch (VAC HOSES ON). If it were me I would measure how far away each of those notches is from TDC and then calculate where each of those notches is, using the pulley diameter and PI.

The later engines are to be set at 7.5 BTDC (VAC HOSES OFF)

Note the difference, it's whether the vac hoses are connected or not.

For a great explanation of why vac is important and how it affects timing read this viewtopic.php?f=26&t=13771&p=63915

And of course this assumes that the advance curve of the dizzy is as standard, because the idle timing is set largely so that full advance operates to the right target when required, then advance curve giving the engine what is required at all points inbetween


ps - as Broady has just given you the answer and saved doing the maths for the other notches and I see there are actually 3 settings for T engines, but that setting would indicate a '69 or earlier engine ? Note the same difference in whether vac hoses are on or off

[JackReddick]

Yeah you're reading it wrong. This is the diagram which applys to you.



So from the left to right the 4 marks are
0, 7.5, 10, 12.5

Monitor how the open before you run it. Just turn the ignition on and watch them open up. Hopefully uniformly.

Fingers crossed we can get you there

Just double checked, my engine code is T0866514.

The chokes ARE opening fully and are now synchornised to one another.

I’ve got it to run for a bit, but then the right hand carb starts spitting/coughing, it runs a bit lumpy then dies out.

I’ve had another look at the fuel lines, i’ve lost all confidence in the previous owner and i’m going to replace them. Do you guys know the correct inner/outer diameters for the fuel lines?

We’re getting there!

[JackReddick]

I’ve uploaded the “cough” here as hopefully it gives a better understanding than my description-

https://youtu.be/E4qJLmoL7Dc

[937carrera]

OK, so it's the middle one which is set at TDC with VAC on, subject to Broadys advice

Set it at that, then take the vac off and block where necessary and I'll bet the timing is now about 7.5 ish BTDC.

That cough sounds to be nothing more than simply running out of fuel. It's not a cough and carry on, it's a cough and die. My T25 and 412LS do that when the fuel isn't getting through after they have been stood for a while of have run out of fuel.

What do you do next. Crank it over and after a bit it restarts ?

As you have already done a carb rebuild it won't do any harm to whip them off and do a quick inspection to ensure the jets are not blocked and check the operation of the float level again.

[JackReddick]

OK, so it's the middle one which is set at TDC with VAC on, subject to Broadys advice

Set it at that, then take the vac off and block where necessary and I'll bet the timing is now about 7.5 ish BTDC.

That cough sounds to be nothing more than simply running out of fuel. It's not a cough and carry on, it's a cough and die. My T25 and 412LS do that when the fuel isn't getting through after they have been stood for a while of have run out of fuel.

What do you do next. Crank it over and after a bit it restarts ?

As you have already done a carb rebuild it won't do any harm to whip them off and do a quick inspection to ensure the jets are not blocked and check the operation of the float level again.

She’s running well now i really appreciate your help!

So once shut off, it smokes quite a bit out of the right carb, i’ve also noticed when you put your foot down, the right carb makes a suction noise whereas the left carb doesnt.

Also, most worryingly, once shut off a large anount of smoke appears from what i believe is the thermostat flaps. The thermostat was stuck shut, but i have since fized that. I’ve uploaded a couple of videos of both bits, hopefully you guys have some ideas? I hope it isn’t RIP engine

https://youtu.be/5v5hMbE3lrM
https://youtu.be/NE1XcJiZ040

[937carrera]

I'm not that good with carbs, so with that out of the way:

I think you need to spend a bit of time balancing the carbs up, can you see the engine rocking,that's consistent with a different level of suction from each carb. Baisc things first, are you sure tappets are correctly set on all 4 cylinders and the balance pipe is air tight. If the carbs are like the 412LS there's an air bypass / idle screw and a volume / mixture screw. They need tweaking so that they perform the same at both side. Of course if you have a "snail" to measure airflow the job is made easier. You can get pretty close tuning by ear to how the engine sounds.

The smoke in the carb is what petrol vapour would look like on a warm but stationery engine if you opened the throttle to activate the accelerator pump, except it looks a bit bluer that I would expect.

The smoke when you switch off may be nothing more than old leaks and oily hand resides burning off with the heat. I would take it for a run round the block a few times to see how she runs under load before making further changes, that will also give you the chance to allow the oil to burn off. Don't go too far in case she loses fuel again.

[broady_6]

Daft question, got the HT leads the right way around on the left hand head? 1432 is the firing order 3 and 4 are the land hand head as you look at it from the back of the car. 4 being nearest too you.

[JackReddick]

Daft question, got the HT leads the right way around on the left hand head? 1432 is the firing order 3 and 4 are the land hand head as you look at it from the back of the car. 4 being nearest too you.

Yup, 1432 is how she’s set

[937carrera]

Alternatively, have the engine running and pull the plug leads off one at a time. The one that reduces engine speed the least is the one with the problem. Wear something that will insulate you nicely, it's easy on a type 4 but I think plug access is more difficult on type 3 so consider disconnecting at the dizzy instead

[broady_6]

Have you checked the exhaust at each head port. Ideal from cold start him up and then touch each branch, before they get too hot. Obviously be very careful. If one is cold/colder than the rest then it'll pin point the problem. But as David said, a carb off again won't hurt. I've just done a two year resto on mine. Including ultra sonic carb cleaning. It drive pretty well, but hesitates, I've just pin pointed that the right hand carb is under fueling. So either a float issue, or something's found its way in.