Over the last few months, I have messed about with lost of things in an attempt to cure this rough running engine, and I have decided to back to absolute basics and work through it methodically. So, the first place to start I guess is the engine block itself, or more importantly, the valve train. Its possible that if the vales are not adjusted correctly, then popping and banging could indeed occur. My problem here is that I am bloody hopeless at adjusting valves and have never yet managed to get it right.

Earlier this year, following everyones advice at the N.E.C. I bought myself one of the Gunson Tappet adjusters, which is supposed to make valve adjustment quick and easy.





The theory behind it is sound for sure. You adjust one tappet as normal, and then rotate the outer part of this tool to calibrate it, and then by a series of clicks on a ratchet, the rest of the tappets are easily and quickly adjusted to be exactly the same.





It was certainly quicker and easier to go through them all with this tool, and my conclusion at the end of it all is that I still cannot adjust tappets, but at least this tool only took ten minutes to work that out compared with the usual hour swearing at the engine. Would I recommend this tool if you were a competent mechanic? Most definitely !! Did it work for me?  No, I`m still crap at adjusting tappets.




OK then . . .  Plan B:
Some of the T25 engines had self adjusting hydraulic tappets fitted, and there is much debate over which is best - Hydraulic or solid lifters. The biggest disadvantage for us with Buggys, is that the tappets can drain their oil if left parked up for a while, making the engines quite noisy and rattly when they are first started, but they do quickly quieten down as oil pressure comes in to play. I know that my engine originally had hydraulics, but were changed to solids for increased performance when Farmer Rob owned it. I have also learned that not all Type4/25 engines  can run hydraulics either, as there was a 1700 variant fitted to the Bay Window that did not have the correct oil galleries for the tappets to operate.

Seeing as I still cannot adjust Tappets, I have decided "sod it" and to revert back to hydraulics, because at the end of the day, its one less thing I have to worry about. VW Heritage supplied a set of tappets and pushrod seals, and Farmer Rob sent over a set of longer 262mm pushrods that were also need for the conversion.

It is very easy to replace them. The rocker arms are removed, along with the pushrods, and this allows you to pop the pushrod tubes out through the front of the cylinder head. With the lifters now exposed, they withdraw very easy with a magnet. In fact it was all so easy to do, I didn`t have time to grab the camera.

Before you install the new tappets though, they do need to be bled with oil to remove all of the air, and this can make the initial start up much easier. Looking round on the net, I found many different approaches to this, most of which look horrifically messy. I did find a very easy and unconventional way to do it though, and that was by taking them apart, and its not as daunting as you might think.

A side view of a Hydraulic tappet showing the small oil hole that is used to pressurize them in situ.





And this is the end that the pushrod sits in. I dismantled these on a little tray with a bit of rag in, as we will be playing with oil in a bit.
The first thing to do is remove the small circlip at the end, it comes out fairly easily.





Once that is out, remove the two plungers - they should also slide out very easily.





Before we add any oil, have a quick look inside at the big spring and make sure it is sitting centrally in its recess.





Then add a few drops of clean engine oil until the spring is completely covered.





Next, refit the larger of the two plungers. It probably won`t go any further in than the picture shows, and this is due to the oil that we have just added in the chamber behind it. If you look in the middle of the plunger, you will spot the top of a small ball bearing in a hole.





The next stage requires a bit of delicate brute force as we now need to expel all the air from the chamber. You need to depress the ball bearing downwards with enough force that the plunger starts to move downwards but not so hard that you dislodge the ball bearing. I can guarantee that at least one of these will go "TWANG" and the ball bearing along with its holder will push through. Do not panic if it does, the ball bearing sits on a little spring inside a cup, which is clipped to the underside of the plunger. If you have got this far, then it really is not rocket science to work out how to put it back together again.





When the top of the plunger passes that little oil hole on the side, you need to insert something to hold the plunger in place. Here I used a spike tool, although a nail will probably work just as well.





Very important not to pick the tappet up, nor move it, as whilst the excess oil is now running down the sides we do not want any escaping from the chamber. Drop in the top plunger and refit the circlip.





Once the circlip is in place, you can pull out the spike - and thats it, they are now bled and ready for use.





Once they are refitted back in the holes, (not forgetting a splodge of cam-lube on the ends if they are new) the tubes and pushrods can be put back in place. Always use new O-Rings on the tubes, because this is a VW after all, and they are known to leak from here. The valve settings could not be easier. With the engine rotated in the correct position for adjustment, turn the valve adjusters so that they just touch the face of the tappet, and then wind them in by 2 full turns. Lock the nut, and thats it - never touch them again.


As a result of fitting these, and getting the adjustments correct, my engine block now sounds very different and feels a lot smoother.


The downside is that I can now rule out incorrect valve adjustment as the cause of my problems, as the popping and banging is still there.

Whilst messing about, I spotted a little hole in the Vaccuum line. I`m usually pretty careful with stuff like this, but its right above one of the Carb balance outlets, so its entirely possible that I could have caught it with a spanner at some point. Could this introduce extra air into the system and cause the banging and popping noises?





Nope - replaced the pipe and has made no difference whatsoever.

What do you mean by banging and popping? Is it all the time, just on over run when?

If it is backfiring or fuel exploding in the exhaust then it has to be overfuelling and/or not burning properly and/or air getting into the exhaust

Sounds like you might need your carb balancer back, if you do then PM me quick and I will get it in the post Monday, miss that and it will be a week as I will be away.

It fires up on the button, ticks over and idles just fine - try and accelerate, even really slowly, and the exhaust sounds like it is going to explode, with quite a few chuffs back through the carbs too. I haven`t got is fast enough to hear what it does on the over-run.

I have driven cars on three cylinders, even two, and very used to how misfiring sounds, but this is so severe, it really frightens you into doing anything because it just sounds so loud and so wrong.

Don`t worry about about sending the balancer back quickly mate, I have another here I can use if need be, but to be honest, I am a long way from that point at the moment. Are you doing any of the Pier Pressure legs? If so, that may be small enough for a hump / dump around the country. Failing that, I`m sure we will catch up soon somewhere else.

With the valves sorted, next on the list is fuel and ignition.

This is where diagnosis becomes problematical, because unlike trying to fathom out why something will not start, in this instance, I do have fuel, and I do have a spark.

As I understand electrics more, I`ll have a play here first. Now, if I had something breaking down, such as rotor arm or distributor cap, spark plugs or leads, then I would expect the engine to shake violently as sound as though it were firing on three or less cylinders. But this is not the case, as mine actually sounds as if it is running on five,with an extra firing sequence thrown in for good measure.

Although I have a Vacuum distributor fitted, I always have a spare Bosch 009 to hand, fitted with electronic ignition, that can be a godsend when trying to eliminate problem engines. It took but a matter of minutes to fit it, and block off the vacuum.

Nope - still exactly the same, and to be honest, it kind of rules out anything on the ignition system.

Can't be certain but after the elimination of ignition and things my thoughts would turn
to a blockage in the carb...

The rubber pipe, could it be possible that the hole used to contain a tiny piece of
rubber that has since been sucked inside and is now blocking things up...

An airline into the take off tube might shift it, maybe 

Peter

Time to inspect the fuel system then.

So far, I have been less than impressed by the 2 pieces of Dellorto junk that Eurocarb have sent me, but one of the nice features of these carbs is the ease in which you can remove and inspect the jets. Now I am fully aware that my tank is not the cleanest, never has been - but I have so many in line filters in place that I am often surprised that any fuel manages to get through. I was very surprised though to see that I had blockages on all four jets - all of the small holes were blocked and around half of the next size up were blocked.





This just didn`t seem right - I was prepared for a blockage, but not to this extent. Rater than just clear the blockage, it was also important to know what it was made of, and hence where it had come from, and this made me very annoyed. In fact, if you heard a very loud roar this afternoon and wondered WTF ? It was me. You see, the blockage inside my jets were made of brass, and looked remarkably like bits of swarf that Eurocarb had left in there when they supposedly refurbished these carbs. Inspecting the jets under a microscope revealed even more. If you imagine mechanically punching a hole in a piece of metal, where it hasn`t quite gone to plan, and you end up with a disc that is hanging by a small bit on its circumference, well that is how some of the larger jet holes looked. The quality here is just disgusting.

Out with the small tools, into the ultrasonic bath, and rather than being as good as new, they were now what I deemed as acceptable.


Trouble is, when I put them back into the carbs, it made absolutely no difference whatsoever - still the banging and popping.

But that was a good thing, because having that much blockage can never be a good thing, and I figured that if the blockage I had found had not made any difference, then there must still be another blockage causing the problem.

Rather than strip the carbs down any further, I found a quicker way to prove / disprove the theory, and here you can see my quick lash up of a pair of Weber 34 ICT`s - its not pretty under there, with all the pipes in the wrong places and the wrong lengths, but it was enough for me to press the starter button to see what would happen this time.





The result is best expressed as


DAMN YOU  -  EUROCARB

I took it for a quick spin around the block, it was very heavy traffic, and it felt like the carbs had just been thrown on with no settings or balancing being done, and in the hour I was driving, not once did it backfire or pop.

Bloody Dellorto`s   

Actually, that is unfair, I know the Dells are a good carb, its just the idiots that put them together, filled them with swarf, didn`t test them, had them back for repair and returned them in a worse state than when they went away, and call themselves experts.

I have lost all faith in Eurocarb, their Customer Service may be friendly, but their technicians are obviously incompetent. 

This time around, I am going to send them to an expert that I trust, someone who I know will get to the bottom of things and hopefully get them to perform as Mr Dellorto had intended.



Farmer Rob - You have incoming   

I'm glad you have found the issue!! 

It is worrying when some supposed experts 'fix' things!  Hence why I try to do absolutely everything myself!

Won't be long till you are back on the road?

Blimey!

I hope you do have a chat with whoever has control of this refurb stuff...

Somehow all this 'selling things' now, is way too easy for them!

Peter

One thing I will add is that I would be very concerned that the jets themselves had been
through some sort of 'refurbish' attempt. And my first direct question would be for an explanation
of why they have been re drilled, a refurb or 'anyfurb' should use new ones, nobody should attempt to
modify jets as that's just absurd!

Your description of a disc hanging from the edge of a hole inside is that of the drill
not cutting clean when it broke through, the little 'disc is a classic sign.

All in all, yet another f**k up from a supplier. It's just unreal!

Peter

I totally agree with you Peter, but my communications with Eurocarb are at an end, because this is what would happen.

If I phoned them, I would get a very pleasant person on the other end of the phone that would listen and agree with my problems. They would offer to do whatever I wanted and would even pick the stuff up at their cost. This person would be so nice on the phone, that despite how annoyed I was, it would just be impossible to shout at them, because on the face of it, they were doing everything I wanted them to.

But to what end?
There is no point sending these back (yet again), because I do not trust that they will return in a better, let alone fixed condition.

I am hearing very similar stories across a few forums now of people with carbs being returned that have not been thoroughly cleaned out after various machining processes and this is appalling, give the four figure price tag that is often applied. This seems to be their policy and procedure, and they are unlikely to change for a lone customer or two ranting down the phone. I do hope that they read this though (across the several forums I am on) and realize that I actually have quite a following in the Automotive Industry, and to pee off the person that sponsors and hosts a number of Vehicle Enthusiast forums will be viewed over time as a huge PR disaster.

No, my advice for anyone wanting to deal with them, is when you get your goods from them, strip them down carefully and thoroughly clean and inspect every item very carefully. Get a magnifying glass and inspect every single hole in the jets. Find someone with an airline and blow through all the galleries, making sure everything is scrupulously clean and free from debris BEFORE you even think about fitting it.

My immediate concern with my own pair is knowing that they are full of swarf, I am hesitant about putting an airline anywhere near them as I do not know which way to blow - knowing my luck with these, I would probably end up ramming the swarf further up a hole than blowing it clear.

Hence why I am sending them to a real expert, Farmer Rob

Dave not knocking Rob but have a word with gower and lee ltd they did a twin choke weber for me about 6 years ago came back like new fitted it a minor tweek to set up and untouched since after thousands of miles which made a change from previous years of intermittent running rough.
I would give them a highly recommended star.

Do you have any contact details for them Keith ?

I do try and take a lot of pictures as I am going along (you must know that by now) and I have just blown up one of the pictures I took of those jets when they first arrived with me, because I wish I had inspected them as closely then as I am now.

Have a look - what do you see?





Looking at the top jet. The small hole (4th one along) is completely blocked by a bit of brass swarf. The holes at the lower edge of the bottom jet, numbers 2 and 6 have some swarf still attached on the top edge that is just waiting to drop off. Generally, the holes are fairly roughly cut with no care taken at all.


And Eurocarb were happy to send these out as brand new and ready for use,
No wonder I have never got these carbs to run as they should.

Gosh Dave I work to low standards but even I would hope to get more clean drilling and finished surfaces to each of these holes, especially for a precision part of the carb. Also I would have visually looked through each hole and ensured it was clear and smooth before using the piece myself let alone charging someone else for my skills/services.

But you obviously need to clean through every channel and pathway from this point to the cylinder to now insure none of the swarf is lodged elsewhere.

Things can only get better...