ignition timing

does anyone know the revised ignition timing when a car has been converted to unleaded? my car is a 90 cabby 1.8 carb(weber).i am asking as there is a sticker on the inside of my drivers door shut saying it is revised but no indication of what it should be.
thanks

Chris, Recently told by VW mech (word of mouth) 2 degrees retarded.
My 89 1.8 clipper was reset to that and it goes really well…has Weber also. keep smiling, J.

What engine do you have? The vast majority of VW carb engines can run on standard unleaded 95 ron petrol with no adjustment. The only reason for altering the timing would be if you have a high compreseion engine such as a GTI engine which requires higher octane 98 ron fuel - even then you can just use super-unleaded.

Cheers

1.8 carb engine is the same compression ratio as the 1.8 GTI.

Oh yes  ops:  , was thinking of mk1 1.5-1.6 carb engines, forgot about cabbys!

acording to auto data a 1.8 needs to be set at 18 degrees with vacume disconnected.

according to my mates book (unleaded ignition timing) it needed tio be set at 16 degrees with vacume connected?

had mine set at 16 but it seem's under powered? has anyone tried 2 deg's??

I was advised unleaded should be 2 degrees retarded from whatever the  standard setting was.
I think a 1.8 carb engine should be 17-19 degrees at 675-825 RPM with vac connected. another 2 takes it back 19-21 degrees BTDC. The smaller engines and the injected versions the vac should be disconnected and plugged. Trouble is …having got one running right, it is a hell of a job to measure what it actually is !

I think a 1.8 carb engine should be 17-19 degrees at 675-825 RPM with vac connected. another 2 takes it back 19-21 degrees BTDC

Isn't that advancing the timing (unless I'm still half asleep)? Advancing means the spark happens at an even greater point before TDC. Retarding to 2 degrees would make it 15-17 BTDC, although I had to retard my mk2 carb 1.8 to about 8-10 BTDC.

Cheers

markwon said

I think a 1.8 carb engine should be 17-19 degrees at 675-825 RPM with vac connected. another 2 takes it back 19-21 degrees BTDC

Isn't that advancing the timing (unless I'm still half asleep)? Advancing means the spark happens at an even greater point before TDC. Retarding to 2 degrees would make it 15-17 BTDC, although I had to retard my mk2 carb 1.8 to about 8-10 BTDC.

Cheers

Nope, you got it right.

As far as I know, you should only be putting super unleaded into a 1.8 carb engine, due to it being a high compression. Super unleaded is the same (near enough) octane as 4 star, so no timing adjustments are required.

You can use regular unleaded if you don't use all the performance of the car, eg not more than 3/4 throttle, no high speed motorway journeys, keep revs well below maximum.

Isn't it ok with the ignition retarded (bar the performance drop off)? Been running that way since I got it a couple of years ago, no pinking noticable. It's just a work hack and I don't want to buy 98 ron, plus it's an auto so hardly a drivers car

Remembering from way back when 4 star disappeared and the only unleaded was the 95 RON lots of 1.8 MK11 Golfs had their timing altered to suit and lost a few hp in the process.

My Cabrio has the dealer sticker on the slam panel and I've been looking to find out what the timing should be to put it back to orginal and get my missing horses back.

The two MK11 Golf Haynes manuals I have both quote 17-19 BTDC (doesn't mention vac connected or disconnected).

I have a Haynes databook on CD and that says Golf Cabrio/Scirocco 1.8 1983-93 should be 18+/-1 BTDC at 750+/-50 RPM vacuum connected and for 95 RON 14+/-1 BTDC.

Mark, Many thanks and you're absolutely right. I should stop posting on the forum after midnight. keep smiling J.

so what setting is everyone going for?? mines currently at 16 but it's not got the power it had when i first got it? an i havent got a clue what it was??

Pete, I should go for 14+/-1 degree BTDC. with vac connected.That
just about takes care of the 2 degrees retarded comment. Don't
forget it needs to be set at idle speed (about 750) rpm.
I think "Early-1800"s post has summed it up. While you're about
it , I would check your distributor advance / retard mechanism and weights and make sure it is all free. If you have a Weber, check that
the secondary throttle is opening properly. J