Tuning the 1300 in my bug couple of days back because it is pining whilst accelerating and going up hills and around corners, which i'll get to soon...

But on inspecting the timing it was off... no worries timing light out and set it a 7.5 BTDC. take it for a spin round the block still pinging but power is good.

come back home and quickly check the timing again just to make sure before I call it quits and it has moved to way BTDC, go through it all again and check it again and it's ATDC,

a. do you know what could be moving or affecting the timing to not remain set?

b. Pinging and popping, is it bad fuel/air mix, old carb.. fuel filter, or something I havn't even thought of, but it wasn't doing it before..

Any help would be sooooooo good it's powerless and pops I really feel like i'm driving chitty chitty bang bang...

Check the bracket that holds it in place may not be going tight and allowing the disy to turn even thought you have tightened the nut and bolt.

Marc

when its pinging... its very much usually TOO far advanced (retard the ignition timing by heading closer towards TDC rather than before), or simply BAD fuel.

the more retarded then the more gutless its suppose to be. So if its getting more grubby when being advanced... then far out! I'd be suss its a fuel issue then. Check that hte distriutor clamp is firm on the dissy body itself, as well as on the engine block.

heat can cause pinging as well, so running lean would be a major contributor of such. The hotter the motor gets, the sluggish it runs. They say if you can't touch the dip stick cause its too hot, then you know its overheating. It should be warm enough for you to grasp and pull out without burning yourself.

So!

1) get some PREMIUM petrol from a decent servo... like a Mobile rather than 7 Eleven... (greater octane rating naturally cures pinging half the time.)
2) time the motor for factory specs
3) make sure distributor hold down bolts are crazily firm without killing it
4) Rich it up a bit on the carb [IF THE ABOVE DOESN'T WORK]
5) If its overheating check the fan for rubbish in it like leaves, make sure the tin wear looks alright and seams firmly sealed. make sure the cooling fins on the barrels and heads aren't gunked up with oilly mud or anything. If no luck here then post another thread if shes overheating.



heres some good info:

http://en.wikipedia.org/wiki/Engine_knocking  (knocking, detonation, pinging... all the same term for same phenomenon)

QUOTE:

"Detonation can be prevented by any or all of the following techniques: the use of a fuel with high octane rating, which increases the combustion temperature of the fuel and reduces the proclivity to detonate; enriching the fuel/air ratio, which adds extra fuel to the mixture and increases the cooling effect when the fuel vaporizes in the cylinder; reducing peak cylinder pressure by increasing the engine revolutions (e.g., shifting to a lower gear, there is also evidence that knock occurs easier at low rpm than high regardless of other factors); "

Did this happen only once after you filled it up? (with fuel)?

As you said about your fuel filter... do check, cause it might be chockin and then running it lean if clogged...

chris. fuel cant alter the timing..........

I think he is saying that the pinging might not be caused by a movement of timing but from poor fuel

yeah that's what he was getting at. Fuel can't change the timing, but fuel can cause pinging. Which would seem like a timing problem

hows your endfloat?

ive got a 1600 twinport somewhere from one of my old bugs
its absolutely f**ked but in typical vw fashion still ran with 6mm crank float
everytime u put the clutch in the crank moved enough to throw the timing out and made it stall

if the clamps nice and tight i'd also be checking your drive gear for wear

sander288, The timing changing erratically could be from faulty, worn or damaged points. Or worn/loose distributor shaft or advance mechanism. IF it has a mech-advance distributor (yours 'should' be vacuum - if orig.), you can rotate the shaft via the rotor button: it should rotate just slightly, and spring back when released. If it flops back & forward, it needs repair. If it has vac. advance, the points-plate may be sticking. The mechanism can be checked by sucking on the vac. hose; plate should snap back when vac. removed.
If you are checking the timing with a strobe lamp, the dist. might start to 'advance' when the rpm goes over about 1000rpm, so initial advance must be set at a proper idle speed (not critical, say 600 - 900rpm). And use no.1 HT lead. It may be better to set the timing with the engine off - very easy.
If you have a dwell meter, check the dwell (should be within 42 - 58 deg.). If it's VARYING at all at idle, or with small speed increases, the points/distributor shaft area is the problem.

cheers for the replies

1. I'd just filled it up with a new tank of 98 octane from a Caltex... which has been done before without any pinging.
2. The ignition components minus the distributor are all new, and the dwell angle is stable and where it needs to be
3. Tinware fan etc.. are all fitted correctly and gunk free, as are the barrels etc... because I recently took the motor out to clean it.
4. The tigntening screw on the dizzy was tight, but I havn't checked the actual clamp itself so will do

Questions.

How do I measure endfloat?
How do I check the drivegear for the dizzy?

But i'll do all the other stuff when I get back home, so it will be a week or so...

Cheers
Shaun

Timing changes as the motor gets hot.

Set the timing at 7.5deg BTDC when the motor is COLD.

DO NOT TRY AND SET THE TIMING WHEN ITS HOT

why not set it hot ? we usually drive with the engine hot .

I set the timing when the motor is just able to idle,

the tappets I still havn't mastered, I get my mechanic to do that and it's always done cold i drop it off the day before so he can do it first thing in the morning

just pull it out and take a gander at it be the best way to start

Finally back home, and have fixed the problem...

First off I took the dizzy out to have a look, and checked the drive dog, which is a bit worn but ok, so I put the dizzy back in made sure it was all the way in a did the clamp back up, it seemed to be in better than before.

reset points, timing and carby again, and cleaned the fuel filter screen in the fuel pump, started her up and went for a drive,

result is perfect running, with full power again!