Bummer Dave, got to be the complete fuel system next or is it doing it on a test bed too?

When Ollie played with the dells on it, he had it pulling like a train, but still backfiring and popping like a good un - I`ve checked fuel pressure and its good, and the fact that the Dells were pulling would indicate that there were no starvation issues. Gone back to ICT`s for no other reason that I trust them, and fault remains. Rob seems to think that its rough running on two cylinders on opposing sides, and that kind of rules out a lot of things.

Have you changed the rotor arm and cap lately? I had a spare in my shed for ages. When I took it out the box the contacts inside were corroded and the centre pin had fell out with the spring.

Consigned it to the bin...

Cleaned up my old one and the rotor end ......worked fine.

Leads, plugs. rotor arm, cap, distributor, electronic ignition module, ever gone from Vaccuum to non vaccuum dizzy - no joy

Perhaps a strange question but was there a 'first' thing you changed (months/years ago) to try and solve the rough running ?

Or put another way was there a time when the engine set up (carbs, electrics and of course steering wheel) actually ran OK without the rough running ie is there living memory of whether a smooth running combination is achievable ?

Sometimes I tinker and soon find I've gone one step forward and two back so wish I'd just lived with the, by now, relatively minor previous configuration.

It such a cruel truth that your time/energy/blood/sweat/tears have been thrown back at you although I have to admit, even despite it being green, you do have an amazing looking buggy to tow, put on a recovery truck or just park outside your house...

Bummer but I would go for the carbs your dellortos were just crap and the solex on there now are worn and a rebuild would help,  another option is a type 4 injection manifold and a set up or a mega squirt box and ford pick up sensor

Hugh makes a very good point. My experience on British motorbikes taught me to change one thing at a time. I often say that all my carb problems have turned out to be magneto problems.

Do you know anyone with exactly the same engine. Can you try swapping components one at a time until you infect their engine? :-D
Seriously I have done this with a mate on bikes.

Similarly I'm always wary of brand new components. Duff batches of spark plugs etc. I like to be able to pull a part off something I know is working.

Have you tried rigging up a gravity fed temporary petrol tank above the engine? maybe an old bike tank or something strapped to the cage as an experiment.

Good luck. It will be something small and annoying.

This is always the most frustrating thing to be happening and Campbell is absolutely right

The engine has had a lot of work and issues have been attended to, and as it turns out, isnt helping.

I know there is advice coming from every direction, and will add my thoughts.

Go back to basics, one by one, test, one by one again, test...

My first port of call would be the distributor cap, hair line cracks appear even in new ones, dont buy
cheap, get original. Rotor arm, I know all this is new, but it has to be done.

Then swap the leads for new or known to be good, one at a time, and test. You will be working backwards, one step at a time
and eliminating each component as you go. Spark plug caps, one by one...
Backfiring is most often a result of fuel mixture, but issues like this can mean that something else, probably electrical is breaking down
in the sequence of events, one part alone is playing up, the coil, swap it out when you have done the other stuff.

I hope it gets resolved, but absolutely know, you must change each component in the system one by one and then test.

If the entire electrical system thats attached to the engine still doesnt sort it out, then at least you know and can start to focus
elsewhere.

Dont get cross, have a plan, and stick to it

Good Luck :-)

Dave know you must be frustrated, but more thoughts to add to the mix. Can't remember but are you running electronic ignition. If so perhaps try returning to points and condenser, just to remove the possibility that the electronics are breaking down. I've had all sorts of issues with my Petronix in a 'good' svda distributor, never resolved. Points have made a massive improvement. Frustration has been not making good with the Petronix kit.

Paul

Update:

A huge thanks to everyone that has pitched in with ideas and suggestions, and an even bigger thanks to those that came up to me at Stoneleigh to say that they had analysed my entire build thread and reckoned the problem seemed to manifest itself about the same time I fitted the hydraulic lifters.

Funnily enough, I had been thinking along the same lines, and at Stoneleigh had a full set of solid lifters and pushrods to hand over to Farmer Rob, only to find out that as always, the engine guru is one step ahead of us and had just fitted a set himself with a significant change in the way the engine is now behaving. After chatting with him today, unbeknown to him, it transpires that VW also had a few issues with the hydraulics, and only ran with them for a very short length of time.

The engine backfire problems seemed to originate from cylinders number 1 and 3, (which are on opposite sides), and they share an exhaust cam lobe. This meant that the problem was either caused by an oil pressure issue in that vicinity (on both engine blocks) or that we had multiple hydraulic follower failure, with erratic valve timing as a result, which I think is more likely.

There is still a little way to go, as Rob is now trying to make sure that everything else is up to his very high standards, but I am really hopeful that I now have a summer of fun ahead of me, and should know for sure in a few days

That's good news Dave Iv got my fingers crossed for you that it's ok n good 👍

Great to read.

So the steering wheel isn't to be changed yet ?!

 

The steering wheel (only thing not yet changed) is being kept in reserve . . .  Just in case 

 

Wsome good news at last then

The steering wheel (only thing not yet changed) is being kept in reserve . . .  Just in case 

Don't change the wheel, you will only break it again

Good news Dave