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23
Other Problems / 8v GU with Weber 32/34 DMTL AND 4-2-1 exhaust Super lean
Last post by Tetch76 -
I have a 8v GU that's been running happily on a Weber 32/34 DMTL. I have just swapped out the 4-1 exhaust for a Corrado 4-2 manifold and a Frankenstein 2-1 downpipe.

As it's a Syncro the original down pipe was narrow and squared off due to lack of room. Now it's obviously breathing much better...so well, in fact, I can only get it to run if I fix the choke 80% closed.

It massively leans out with any throttle. I have checked:

Vacuum tubes - no leaks
Carb/adapter/flange/manifold gaskets - no leaks
Intake manifold - no leaks
Exhaust manifold - no leaks
Throttle plate on primary - centred and full closes
Jets: increased the idle from 55 to 60 - no change in idle
Cleaned out carb primary circuit - clean
New fuel filter
Timing checked - 8°BTDC
Vacuum Guage 19.5 in HG
Fuel pump - pumping
Accelerator pump - pumping

I haven't had a chance to pull the plugs but I'd bet money on them looking lean.

I will check the float but it's only 6 months old and was set properly.

Maybe dirty needle valve?

I am at a loss as to what else it may be. Help me MK2 owners. You're my only hope...
25
Engine & Gearbox / Re: High rpm when cold for 20 minutes,...?
Last post by Keekster64 -
Quote from: philip on
It's obvioues to me that you know your stuff ! I've been trying to learn for the last 30 years about these cars doing my best. Your knowleged is a credit to this website and i can't thank you enaugh for everything. I have been looking for years for video's like you sent me and never found one that informative ! I hope my golf will keep going for as long as possible, i do get a lot of attention now adays with people beeping, flashing there lights, thumbs up,...that i never expected. Thanks again, until next time lol
You inspired me to do another DIY video.  This time the carb is off the car, which makes it easier to explain.
https://www.youtube.com/watch?v=Ti10QifyZTY&t=431s
26
Engine & Gearbox / Re: High rpm when cold for 20 minutes,...?
Last post by philip -
It's obvioues to me that you know your stuff ! I've been trying to learn for the last 30 years about these cars doing my best. Your knowleged is a credit to this website and i can't thank you enaugh for everything. I have been looking for years for video's like you sent me and never found one that informative ! I hope my golf will keep going for as long as possible, i do get a lot of attention now adays with people beeping, flashing there lights, thumbs up,...that i never expected. Thanks again, until next time lol
27
Engine & Gearbox / Re: High rpm when cold for 20 minutes,...?
Last post by Keekster64 -
Quote from: philip on
Hi, well it's bizzare, tested the car this morning, idles at 1100 rpm for 15 minutes then goes back around 900. After leaving it to cool down an hour, it starts and idles way too low at +- 600 rpm for about 10 minutes. I think i'm going to leave it be now and stop fiddling as there is a big improvement in any case. Thank you all for all the help and especially the video you sent me that was so usefull to learn about the cab,... the old girl got 89000 miles, first owner from new. I wanted the GTI but couldn't afford it so got the last 1600 cc Driver without power stearing lol.

Thanks again,

Phil.
Glad you found the video useful.  There is so little info on these carbs, and it took me a while to figure out how it worked, so I wanted to share the knowledge.  Its fair to say the carbs are rather over engineered, and not particularly resilient.  I had a 1990 Toyota Carina for 7 years, before I bought the 91 Driver.  The Toyota had a carb that worked so well from cold it used to surprise me that it didn't have fuel injection.  It was flawless.  It makes you wonder if the japanese could design a carb to work so perfectly, why cant the europeans!!

At the moment I'm running the supposedly better Weber.  Its not true.  Its better than a knackered Pierburg, but its a crude carb which cant deliver the fuel efficient running the pierburg can deliver.  I've done another video on it.  Its flaw, in the 1600, is the accellerator pump jet.  The web con kit has the same jet for the 1600 and 1800.  Why?  Because its the smallest one they do.  It mean it delivers too much fuel when you floor the throttle, cause it to stumble before it accellerates.  It can also cause the engine to stall at idle if you blip the throttle.  I have managed to improve it though.  There is an external arm/cam wheel, that controls the amount of fuel.  I used a dremmel to take 1mm off the cam which has the effect of reducing the amount if fuel the pump jet delivers.  Its a lot better, but its still a little on the rich side, but it does the job.  Its also harder to start from a warm start, as the idle and the choke are controlled both by the choke cable, and the idle only increase when you pull the choke out most of the way, i.e too much when warm.
28
Engine & Gearbox / Re: High rpm when cold for 20 minutes,...?
Last post by philip -
Hi, well it's bizzare, tested the car this morning, idles at 1100 rpm for 15 minutes then goes back around 900. After leaving it to cool down an hour, it starts and idles way too low at +- 600 rpm for about 10 minutes. I think i'm going to leave it be now and stop fiddling as there is a big improvement in any case. Thank you all for all the help and especially the video you sent me that was so usefull to learn about the cab,... the old girl got 89000 miles, first owner from new. I wanted the GTI but couldn't afford it so got the last 1600 cc Driver without power stearing lol.

Thanks again,

Phil.
29
Engine & Gearbox / Re: High rpm when cold for 20 minutes,...?
Last post by philip -
Well, I don't know how to explain this, may be the weather being so hot? I was up at 8 am down to the car all ready for the mission lol.
When i took off everything, i realised i didn't have the right tools to take of the waxstat. I then remembered that 20 years ago ( i got my golf from new ). I actually fiddled with the settings of the cab flap, sucking on the hostpipe turning that wheel,....So i thought, let's check the gap again that should be around 2.5 mm. It was way off ! No wonder i've been using over 12 liters of petrol per 100 K for years when it should be around 9.5 L max urban ( that's all i do ). So to make a long story short, i adjusted it as it should and then lightly gave a few hammer hits on the waxstat ( yes i know, pretty stupid ). In any case, put everything back, started the car, it idled at 1100 rpm, drove 5 minutes, when straight back to 850/900 rpm ? Must be a miracle ! But i will not know until tomorrow morning when it's stoned cold again if this did the trick ! Fingers crossed, Un-real !!!