Furious Fastback

[Rhysos]

Thanks Peter, I know my existing leads were compatible with the standard screw-on nipple of the B5HS spark plugs, so I will have a look for the same fitment with the replacement leads.

I have a plan of action now and will essentially service the ignition system; new leads, coil, rotor arm, dizzy cap and spark plugs. I shall report back in due course…

[Rhysos]

I had the whole afternoon yesterday to troubleshoot the car. I pragmatically went through a list of things in the hope of resolving the terrible running issue and got some encouraging results.

First up, I removed the carbs to get access to the spark plugs, whipped those out and then performed a compression test. Results were: cyl 1: 117psi, cyl 2: 85psi, cyl 3: 102psi and cyl 4: 100psi. The good news is that none of the cylinders have degraded since I last tested them, phew! So, compression was verified and checked out. Rather than refit the old spark plugs (which were already coked up, despite only cleaning them just the other week and covering 0.1 miles!), I fitted some fresh ones:

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I wasn’t able to get a replacement rotor arm (parts store didn’t have it in stock), but I did have a replacement dizzy cap in my spares trunk, so I switched that over:

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Car started willingly, but still sounded a bit rough a first with smokey emissions. It smoothed out once warmed up and the chokes fully opened. Using Peter's suggestion, I used my timing light to verify that signal was being sent down each HT lead. It was all good and sparking at each cylinder, excellent news, now getting somewhere!

Next was to check the ignition timing and I discovered that this had drifted from when I last set it. For my particular distributor, it should have been on the 10 BTDC mark whilst idling at around 900rpm (vacuum line plugged), but it was actually closer to my big white mark denoting TDC. Not sure what has caused the timing to shift, but the difference once the distributor was rotated by a smidge was instantly noticeable.

I buttoned everything back up and went for a spin around the block. The car was so much happier; more power, less hesitation and no misfires! I will get out soon for a longer run, but I am relieved that things are improving and the car moves under it's own steam again.

I need to dig into the reason why the car is rapidly carbon fouling the spark plugs. It is possible that the poor ignition timing has been a factor, but I suspect that it is also running rich. I get poor fuel economy, which further makes me think this. Could it be as simple as the volume adjustment screws not being set correctly?

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Hmmm, I will read up and perform a more comprehensive set-up of the carbs. Truth be told, things are mostly as they were when I got the car, but that doesn’t mean that they were set-up correctly.

[broady_6]

DId you check the points gap? It tends to be that points close up and thats what alters the timing. If you havent got a carb flow meter, I would highly recommend getting one. It will help you with the balance no end.

[Rhysos]

I did check the points gap and it was still at 0.04mm. I had the thought earlier on that I should check the dwell measurement using my Gunson Sparktune. It measures the dwell whilst the engine is being turned over (not running). However, I got a bouncy reading that rapidly fluctuated between 41 - 54 degrees when performing the test (I did it several times and ensured the tool was calibrated):

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What would cause this unstable reading? Could it indicate a worn-out distributor?

On the question of balancing the carbs, I do have a Gunson Carbalancer, but haven’t got around to using it yet. I have ‘acquired’ a traffic cone to make the adapter to fit on the top of the carbs and over the protruding threaded pieces. I will read up on the balancing procedure and see if I can work it out as this sounds like it should be my next step.

[broady_6]

Worn lobes on the dissy can cause dwell to wander. Which can cause rough running, because it effectly alters the timing slightly on each cylinder. You can measure the lobes if you mic it up in a similar way to measuing run out. But its a bit of a fiddle to do on the car. Thats quite a bit swing on yours, so maybe that goes some way to explaining your issues. Whats the part number on your dissy? Bosch or VW numer is fine. Sorry if youve already supplied.

Make sure you read the itinerant VW, it turns out balancing the carbs is likely a waste of time until you get the chokes and fast idle cams sorted.

[Rhysos]

Thanks Broady, makes sense and your description backs-up what I was starting to hypothesise. The car has always been rough on start-up, in a way that sounds lumpy (you can even see the engine ‘juddering’ at lower revs) – it smooths out when the engine has warmed up and/or when the idle speed picks up. You may well be right about the worn lobes and presumably the inconsistent firing of the cylinders could be at the root of the problems that I have been chasing.

The distributor installed is a VW 311 905 205 F (Bosch 0231 137 013), which is an earlier SVA type dating to the mid 60’s. We have discussed options before, so I know that the 113-905-205T is a close match (SVA type), but it may be a good idea to go with a SVDA type instead? However, my PDSIT carbs also date to the mid 60’s and sit on single port manifolds, so I would need to source a replacement dizzy that would work for this ‘unique’ set-up.

Thanks for highlighting that I need to look at the chokes and fast idle cams before balancing. I tried to read the Itinerant VW guide last night, but I think I was too tired to digest the information. I will make sure I read, read and read before I start fiddling with the carb settings. Better to do it right and do it once.

[purplepeter]

I wouldn't get too hung up on the sooty plugs, especially if you're only doing short journeys.
Be prepared for the likelyhood of carb adjustment being a pain the first few times you attempt it, you need to do the bench settings first as in the Haynes manual- My first attempts resulted in the car being un driveable (with all the symptoms you've been experiancing) but you'll get there- When it's right, you'll know!
I'm sure Dave will have a stash of dissys, or I'm happy to lend you one

[Rhysos]

Morning Peter! The sooty plugs are frustrating me as I suspect they are part of the cause of inefficient ignition. They get so fouled that they struggle to spark, thus compounding my running troubles. You are correct though, the car has only really been doing short test drives and driveway idling lately – it would be great to get things to a reliable point and travel further afield soon (eg: the Stanford Hall show, but that will probably have to wait until next year).

The carb adjustment is a steep learning curve, but I am keen to learn the correct procedure. I will preserve, even if it means two steps back and one step forward! Thanks for the encouragement, I will consult the Haynes and start with the bench settings as you suggest. The Itinerant guide will hopefully fill in the blanks.

I’ll reach out to Dave to see if he has an old distributor stashed away. It would be a good reason to swing over to him for a visit and to go for a longer run out in the car. I’ll come back to you if I cannot get hold of one.

Quick q: which distributor do you run, Peter? Your car is the same era as mine (same factory paint colour originally as well), I just have a lot of backdated parts on my engine. I reckon I should start moving back to period correct parts as and when I need to replace stuff.

[broady_6]

Thanks Broady, makes sense and your description backs-up what I was starting to hypothesise. The car has always been rough on start-up, in a way that sounds lumpy (you can even see the engine ‘juddering’ at lower revs) – it smooths out when the engine has warmed up and/or when the idle speed picks up. You may well be right about the worn lobes and presumably the inconsistent firing of the cylinders could be at the root of the problems that I have been chasing.

The distributor installed is a VW 311 905 205 F (Bosch 0231 137 013), which is an earlier SVA type dating to the mid 60’s. We have discussed options before, so I know that the 113-905-205T is a close match (SVA type), but it may be a good idea to go with a SVDA type instead? However, my PDSIT carbs also date to the mid 60’s and sit on single port manifolds, so I would need to source a replacement dizzy that would work for this ‘unique’ set-up.

Thanks for highlighting that I need to look at the chokes and fast idle cams before balancing. I tried to read the Itinerant VW guide last night, but I think I was too tired to digest the information. I will make sure I read, read and read before I start fiddling with the carb settings. Better to do it right and do it once.

The idle speed picks up? The id speed should be dying away. On start up, high 1000s for a few seconds, then dropping to 13-1500 or a few minutes an then down to 8-900rpm.

As Peter says, plugs tend to show you the last running conditions, so if you ran at idle and shut down, or were doing short journeys. It would get hot enough, these engines like to rev. If you rung the engine for long enough the exhaust valves will be so hot that the spark isnt required to keep it running. Which is why we have the idle cut off valve to kill the fuel supply. Otherwise the engine would be self sustaining. And as peter also says, brace yourself to be annoyed. These carbs can be a pain. A combination if that guide I sent, and the one on the samba you sent will get you there.

[Rhysos]

The idle speed picks up?

Yeah, sort of... basically, I need to hold the revs up with the accelerator pedal when the car starts from cold or it will stall after a few seconds. After a minute the car needs no further assistance and will idle by itself (the chokes have mostly opened by this point).

On start up, high 1000s for a few seconds, then dropping to 13-1500 or a few minutes an then down to 8-900rpm.

Clearly the idle doesn’t behave as it should either, which could be fundamentally down to the carbs being incorrectly set-up

I find that I need to run with just one carb return spring. The combined tension of having two installed pulls the idle speed down too low. They are aftermarket springs, which I assume are appropriate for this application:

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Having one return spring enables the car to idle initially without stalling (after accelerator pedal assistance). Once out driving around with the engine warmed up, the idle is more than twice what it should be (just over 2000rpm). It sounds like I’m sat impatiently at the traffic lights all revved up. If I put the spring back in place after driving for a few miles then the idle revs are closer to where they should be (around 950 - 1000rpm). It’s just a quirk that I’ve lived with up until now.

If you rung the engine for long enough the exhaust valves will be so hot that the spark isnt required to keep it running. Which is why we have the idle cut off valve to kill the fuel supply.

Ah, yes, this explains the ‘dieseling on’ issue that I understand these engines can be prone to if the cut-off valves fail.

A combination if that guide I sent, and the one on the samba you sent will get you there.

Thank you – it is my bedtime reading this week!

[broady_6]

Not sure if you are familiar with the correct procedure. But to start just about any aircooled VW. Press the throttle pedal too the floor and release it. This has the action of allowing the choke to move freely and the bimetalic coil will move it to the correct position for the temperature.

Then turn the key and crank the engine, it should catch and start at the idle the choke has set it too. I will do you a vide of mine later.

The spring should have zero impact. They are unrelated to the settings. They are purely for return the carburattor butterflys back to their idle/least open position. They cant "over close" or as you set the butteryfly valve gap with the stop screw. So when it hits that stop, its not moving. You could use the strongest springs ever made, all you would find is, youd need some serious leg power in order to operate the throttle pedal. But the engine would still sit at idle all day.

I do wish you lived closer, id love to go through this with you on the car, I find it stupidly interesting

A basic thing which may help, wined your mixture screws all the way in. And count the turns and make a note. Then turn them out 2 turns.

Disconnect the throttle linkage at the carb ends. Then back out the throttle stop screw, again counting and making note. Then turn it back in until it just touches the paddle. then give it half a turn more. Crank the engine and see if it shows any sign of life.

[broady_6]

It not perfect, but I havent fine tuned it yet. But here is a cold start on mine. As you can see it will start but it still needs a blip to stabilise. Then it largely does as required. I didnt film it all the way off the chokes, it would take too long.

https://youtu.be/HLj09m_3H5c

[Rhysos]

Not sure if you are familiar with the correct procedure. But to start just about any aircooled VW. Press the throttle pedal too the floor and release it. This has the action of allowing the choke to move freely and the bimetalic coil will move it to the correct position for the temperature.

Then turn the key and crank the engine, it should catch and start at the idle the choke has set it too.

Thanks Broady. This is basically the same as I remember for my Beetle, although that has been off the road for 20 years so it is a vague memory!.

It not perfect, but I havent fine tuned it yet. But here is a cold start on mine. As you can see it will start but it still needs a blip to stabilise. Then it largely does as required. I didnt film it all the way off the chokes, it would take too long.

I appreciate you taking the time to film and upload a video of your cold start. Makes me realise that mine needs some time and patience to get it in a similar ballpark, but I have a solid reference point now.

I get my Fasty started anyway that I can; typically depress the pedal a couple of times and then crank. If it doesn’t take straight away (which is common) then I pump the accelerator pedal until it catches. I assume the squirt of extra fuel from the carb(s) accelerator pump(s) helps get it going when it has been sat for a while. I will also grab a video of my cold start tomorrow when I have a moment – it can then serve as a ‘before’ comparison to sit alongside an ‘after’ video once I eventually get the carbs dialled in.

The spring should have zero impact. They are unrelated to the settings. They are purely for return the carburattor butterflys back to their idle/least open position. They cant "over close" or as you set the butteryfly valve gap with the stop screw. So when it hits that stop, its not moving. You could use the strongest springs ever made, all you would find is, youd need some serious leg power in order to operate the throttle pedal. But the engine would still sit at idle all day.

The explanation of the return springs makes sense to me now. If the car’s revs are too low for a stable idle when both springs are on, then the issue must reside with the carb settings.

I do wish you lived closer, id love to go through this with you on the car, I find it stupidly interesting

I hear ya! That would be awesome, but I’m just grateful that we have this forum to communicate and share knowledge about keeping these old cars going. It is all a continuous quest of problem solving and learning, which I also find very engaging.

A basic thing which may help, wined your mixture screws all the way in. And count the turns and make a note. Then turn them out 2 turns.

Disconnect the throttle linkage at the carb ends. Then back out the throttle stop screw, again counting and making note. Then turn it back in until it just touches the paddle. then give it half a turn more. Crank the engine and see if it shows any sign of life.

I will do exactly this and report back before diving deeper down the PDSIT rabbit hole

[Rhysos]

I will have time later this afternoon to get out on the car and start navigating the PDSIT carb settings. I've just created a video of the car cold starting, prior to making any adjustments. This will be my 'before' video to compare progress against: https://youtu.be/WWWfXK3zl7U

The car hasn't been started for a few days, so I was happy that it came alive so quickly. Clearly the new dizzy cap, spark plugs and ignition timing adjustment have made a significant difference. Plus, it seems that I no longer have to keep my foot on the accelerator for the first minute to stop the engine dying. In this case it just need a couple of revs to get stable.

As you can see from the tach (not 100% sure of it's accuracy), the idle speed picks up as the chokes start to open. However, this is only with one return spring on and towards the end of the clip you can see me moving the linkage back further than it naturally settles, which lowers the rpms (in other words, I'm effectively pulling the throttle levers back manually against their stop screws). I put the second spring on after this video clip and it started fine. It idled at around 1000rpm (according to the tach), but it sounded lumpy, unstable and eventually stalled.

Let's see where I get to later after some tweaking...

[Rhysos]

Well, I am no further forward in terms of a breakthrough, but I am getting familiar with how the parts of the carbs interrelate and how local adjustments have a global affect. Starting to appreciate why setting up and balancing these carbs is a challenge. I need more time to tinker, but decided this evening to make an adapter for my Gunson Carbalancer, as per Peter’s design. This involved the decapitation of an ‘abandoned’ traffic cone:

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Using the top section as a spacer with the fittings sealed in one end:

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All fitted up and in operation, it looks like this:

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Initial results were promising, The little float sometimes gets stuck and the seal around the carb could be improved with some refinement to the design, but it works! Alas, at this point I was starting to loose the light, but hopefully I will find time over the weekend to have a play.

[purplepeter]

To answer a previous question, I think my dissy is a T, but can't confirm at the mo, as my boot is full of Torsion arms!
On the shelf I have a T, K & a german 009, but I'm fairly sure I've got a couple more.

Back to your tinkering Today, Have a delve around your pedal cluster, Don't be tempted to remove them, (its a bugger of a job), but do remove the build up of detritus & get the throttle bar running freely- lubricate it, as it's important that you have the full range of movement. Also, make sure the carpet mats aren't hindering the throttle

You really do need the second carb return spring- The idle circuit & balance pipe won't function properly unless the throttles are fully on the stops

[Rhysos]

To answer a previous question, I think my dissy is a T, but can't confirm at the mo, as my boot is full of Torsion arms!
On the shelf I have a T, K & a german 009, but I'm fairly sure I've got a couple more.

Thanks Peter, having looked it up I have seen that the T distributor is a DVDA type, which makes sense with our cars being manufactured in 1972. If I was able to find one, I’m not sure if the double vacuum element would work with my earlier (mid-60’s) PDSIT carbs? Anyway, I’ve been in touch with Dave and he thinks he may have something, so I will see if we can locate it and more importantly if it will work with my set-up.

Have a delve around your pedal cluster, Don't be tempted to remove them, (its a bugger of a job), but do remove the build up of detritus & get the throttle bar running freely- lubricate it, as it's important that you have the full range of movement.

Good recommendation. I actually did this not so long ago and had to order some new parts to get the linkage working correctly. All good in that department. What I did notice at the other end was that the barrel nut was clamped down on the actual wire strands of the accelerator cable, not the end cap (for lack of a better term). I figured this was probably incorrect, so adjusted so that the barrel nut clamps onto the end cap. This has added a bit more slack and as a result has enabled the idle (when warmed up) to settle lower than it was. I have full throw on the pedal, so I think this is an improvement.

The other thing that helped was following Broady’s advice to wind in the volume control screws and then to wind them out 2 turns. I found that my engine wasn’t happy with 2 turns, so screwed them back by half a turn. So much better (Incidentally, the ‘Look, Listen, Do it Better’ guide recommends 1 ½ turns out as the initial setting).

Before obsessing over the idle settings and the addition of the second return spring (jobs for another day), I thought I should go for a proper drive out. Happy to report that these adjustments have improved smoothness of the car no end. I covered about 15 miles and took a verity of routes. Runs up through gears really nice, no pops, no backfires and no hesitation.

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On the ring road I got her up to 60mph and she was cruising happily without any lumpy judders. Got back home, parked up and I am delighted to say that I was able to hot restart the car, which was a welcome experience!

Thanks again for all of the support and advice that you fellas have given me these past couple of weeks. It has enabled me to work the problem and as a result I had a smile on my face this afternoon as I cruised about like I didn’t have a care in the world!

[broady_6]

First of all I am please you have a huge improvement! If I were you I would now take a step back, especially as its forecast lovely for a week and just so a bit of driving and enjoy the car again. Obviously monitor the engine for temperature ect. Before you think about doing any more work.

Im glad you spotted the bellcrank, it jump straight out at me in that video. someone had used it to pull the carbs off the stops to get the car to idle. I certainly seems like a fundamental engine set up with get you at least 95% of the way there. If youve got a good SVDA dissy, it will run more than well enough of that. Its what ive run mine on for years. And ive got 2 or 3 DVDAs in the garage. Id never felt the need to fit one though.

[purplepeter]

I'd concur with Broady, Well done on getting to this stage
Now just leave it alone & take pains to avoid disturbing the carbs

[Rhysos]

Exactly, I think the old adage ‘if it ain’t broke, don’t fix it’ applies here. I would like to start progressively getting some miles on the car and carefully monitor how the car performs. I need to build my trust in the car and gain confidence that it can cover distances reliably.

[937carrera]

20-30 miles a day should suffice.

You're guaranteed to get up to temperature, having gone through the warm up cycle, you get comfortable with the car, and if you do have problems, you're never that far from home

After that 200 miles is only a weeks worth of trips

[purplepeter]

Have a chat with Dave & Larry- they are both good at giving pep talks to encourage you into longer trips!
Have a think about 1st June- It's stonor show (100 miles from Bristol), even if the Fasty isn't up to it by then, have a day out in your sensible car, & just come & meet people whilst enjoying an old school vw show

[Rhysos]

20-30 miles a day should suffice.

You're guaranteed to get up to temperature, having gone through the warm up cycle, you get comfortable with the car, and if you do have problems, you're never that far from home

After that 200 miles is only a weeks worth of trips

It is a good way to frame it! You cannot argue with the maths.

Have a chat with Dave & Larry- they are both good at giving pep talks to encourage you into longer trips!

I do need to give them a shout at some point and see if they have any plans to get out in their notch. Really enjoyed our mini-convoy of Type 3’s last year after the VW picnic. They are good people, so I will have a chat.

Back in the day with my Beetle I used to go everywhere. In my late teens and early 20’s was my daily driver and I depended on it to get to work. When I was a uni student, I used to travel back and forth to visit my folks and cover 100+ miles without even thinking about it. I just knew it would go the distance and being my first car it t was all I knew. I didn’t overthink it, I just cracked on. Good times!

The Fasty has the potential to become a solid driver, but it has been a journey to even get it up to this point. So many parts were either on their way out or needed adjustment. It has been value hands-on experience though and eventually I will get to a similar point where I don’t have to overthink and it will just be an enjoyable driver.

Have a think about 1st June- It's stonor show (100 miles from Bristol), even if the Fasty isn't up to it by then, have a day out in your sensible car, & just come & meet people whilst enjoying an old school vw show

Stoner could be a good one to aim for. However, if the car is not quite ready at that point, then there is always Bristol Volksfest the following weekend!

[greenfyregirl]

great thread you lot

Broady…. how do you know if yr dissy is worn? are there correct measurements for the lobes?

[Rhysos]

great thread you lot

Here's hoping that it will one day be a great car

So, there I was, out enjoying an evening cruise at sunset with my lad. The car now pulling well and the engine feeling more alive. Unfortunately, the good times were short lived as my bliss was interrupted by the car pulling quite hard to the left. I pulled over and felt a lot of heat radiating off the passenger side front disc and brake dust coating the rim. Pretty conclusive evidence that the pads were not releasing. Couple of taps with the end of my wrench seemed to help alleviate some of the drag and I turned back and head for home.

Next day, I jacked up the car removed the wheel to get to the calliper:

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I drove out the retaining pins and carefully pried back the brake pads (ie: coaxed back the slave cylinder). The pads themselves still have plenty of meat on them, so I cleaned up the area and reinstalled. Wheel span freely, so thought I may have cracked it with just a little TLC. However, as soon as I pumped the brake pedal the wheel clamped up again. Bugger!

I opened the bonnet to check fluid levels and to my surprise the right chamber of the reservoir was dry – and not a lot the left side either! Damn, where has all the fluid gone?!

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I pulled the driver’s side wheel to get access to the master cylinder and it didn’t take long to spot the problem. The plastic feed pipe connection had broken:

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I pulled out the broken connection and rubber bung and will get replacements on order along with some DOT4 brake fluid. The flexi hoses seem to be in good condition, but I don’t know how old they are. I’ve heard that as they age they can swell internally leading to brake drag. Because I am going to have to fully bleed to the system, it might be worth replacing all my flexi hoses whilst I am at it.