Club 80-90 Forums

I have a 2ltr Aircooled 1983 T25 with a SVDA 034 electronic distributor. My garage is telling me i need special spark plugs for electronic ignition because the current is now too much for the standard ones. Is this right?

ermm, no

only upgrade advice I've ever come across on spark plugs is moving from Bosch to NGK and that was a much more highly stressed engine than a T25

What plugs are they saying you need? Have you considered changing your mechanic?

VW originally fitted a high powered electronic ignition, aftermarket ones aren't any better. It is the coil, compression ratio and the spark plug gap that determines the spark plug voltage the current is actually negligible. You just need the standard spark plugs VW recommend, Bosch W8DC or equivalent where the ambient temperatures are mainly below 25 deg C or W7C when they are above.

thanks for the advice. The problem is he hasn't told me which ones i need, just that they should specifically be for electronic ignition. I'm in france so its a bit hard to argue the point, Basically i think he's stuck trying to find the problem and clutching at straws!! is there even such a spark plug specially for electronic ignition?

Non !

Non electronic ignition systems operated at something like 6-10,000 volts. Electronic systems came out and operated at around 30,000 volts. Porsche introduced their CDI system in the sixties which generated about 35,000 volts. Saab introduced Trionic in the nineties, which is one of the first with an ignition cassette, one coil per plug, and uses ion measurement in the non firing cylinders to determine which cylinder to fire dispensing with the need for a camshaft sensor. That operates at 35,000 volts, and the plugs are cleaned when the engine is switched off by inducing a spark across the plugs. Current is negligible as Bigherb says.

Guess what, they use the same type of plugs as our humble T25's, nothing special. (heat ratings vary, but that's nothing to do with the way the spark is generated or the voltage)

Rob's second question is the best.

What problem are the garage struggling with ?

Can someone post you the right ones, just to end that issue?

Hello,

Serial Kombi....



Link in English:

https://www.serial-kombi.com/en-GB/tran ... 983-n33243" onclick="window.open(this.href);return false;

If you ever get that van running right, you should bring it over here...

Cordialement,

I was wondering when you would pop up on this thread - you're only about 140km apart aren't you ?

Those plugs you linked to are standard Bosch W7CC aren't they, nothing special ?

i would love to be able to bring the van over to see you if i could ever get it running right!!!

quick update on the problem..........Carbs have been balanced and everything is set up as it should be, but there's something we just can't work out..........when you do the timing you disconnect the vacuum advance pipe and plug it........but when we then connect the air pipe back up the engine advances, revs increase instead of decreasing!! also when i took him for a drive he ran like a dog with the vacuum advance connected but pretty well without.......all very bizarre!!



Basically the guy is saying that it's already advanced when idling, but can't understand why....any ideas?? it looks like the dizzy is turning the wrong way!!

It's a powerspark 034 SVDA dizzy

From another post

937carrera wrote:According to Mr Haynes:

7.5 degrees BTDC if it's got points with vacuum disconnected or 5 degrees ATDC with vacuum pipe connected and idle stabilisation plugs connected together.

Retimed mine a couple of weeks ago, it has electronic ignition with lots of air intake bits missing while it is a project, set it to 7 degrees BTDC idle plugs connected. Better idle, better throttle response than before so good enough for me, even though it isn't going anywhere.

I suggest the timing should be set with vacuum connected and idle stabilisation plugs connected together.

Where is the timing set now ?

matthew13 wrote:i would love to be able to bring the van over to see you if i could ever get it running right!!!

quick update on the problem..........Carbs have been balanced and everything is set up as it should be, but there's something we just can't work out..........when you do the timing you disconnect the vacuum advance pipe and plug it........but when we then connect the air pipe back up the engine advances, revs increase instead of decreasing!! also when i took him for a drive he ran like a dog with the vacuum advance connected but pretty well without.......all very bizarre!!



Basically the guy is saying that it's already advanced when idling, but can't understand why....any ideas?? it looks like the dizzy is turning the wrong way!!

It's a powerspark 034 SVDA dizzy

The dizzy should turn clockwise. It sounds like you have the vac pipe connected to the wrong port on the engine or the throttle stops are adjusted open too far.
Can you put a picture up of the vac pipe connections.

937 carrera.........its an electronic dizzy so it doesn;t have points or idle stabilisation plugs to connect together.

bigherb......the vac pipe that comes out of the dizzy goes to left hand carb. Not sure about the throttle stops as the van is still at the garage at the mo. Migth be able to put a pic on here once i get it back.

matthew13 wrote:937 carrera.........its an electronic dizzy so it doesn;t have points or idle stabilisation plugs to connect together.
.

I know, the quote was there for completeness, the setup being different for points / electronic ignition setup which is important. I would be most surprised if your CU didn't have idle stabilisation, it's a green box with two plugs on the left hand wall of the engine compartment. Go have a look

Bigherb knows his stuff, from what I understand I think your engine has been timed as if it has points, - you said

"when you do the timing you disconnect the vacuum advance pipe"

that's not how an electronic ignition CU should be timed, without getting into setting timing by using maximum advance.