Wandering timing

[chimpboy]

Hi,

What should I be checking? The timing on my TB42 is wandering - checked it a fortnight ago and it was good, next time I checked it was out a heap. Fixed it, checked it the next day and it had moved ten degrees. Fixed again, checked it, it's moved 10 degrees again.

It's not that the bolt is loose where you adjust it - I've checked that of course. Is it the distributor rotor?

I have a vague memory that the crank pulley can move on these motors but I've searched the archives and couldn't find anything.

Jason

[chimpboy]

Any ideas?

[Vsicks Pathy]

Timing belt loose and the tensioner is no longer able to tension it?

Timing chain streched? Then as as above.

Dizzy moving, bolt not tightening down on it?

Worn gear on the bottom of the dizzy?

I am suspecting the last one. Happens on HX and HZ Holden 6's alot.

I am out of ideas. Hope this helps.

[chimpboy]

Timing belt loose and the tensioner is no longer able to tension it?

Timing chain streched? Then as as above.

Dizzy moving, bolt not tightening down on it?

Worn gear on the bottom of the dizzy?

I am suspecting the last one. Happens on HX and HZ Holden 6's alot.

I am out of ideas. Hope this helps.

Thanks. I suspected the last one too, so I've had the dizzy out. It's perfect down there, no wear on the gear at all. Gave everything a clean while I was at it, the advance weights etc.

Timing chain looks okay as well, from what I could see with the distributor out.

I'm starting to think it's human error; maybe I've just had some kind of weird brain fart when checking the timing. I will check again tomorrow; couldn't tonight as I accidentally flattened the battery by leaving the door slightly open!

Grr!

Jason

[0xyg3n]

is the dwell angle changing at all or is it just timing? Could be dwell which will adjust timing , check points if you have them fitted.
Another thing to check is that the timing mark on the harmonic balancer has not moved giving the impression the timing is changing.

[chimpboy]

Thanks for the suggestions. I don't have a dwell meter but the points gap was okay.

This is now fixed, but I am not sure what the problem was. I removed the distributor, checked timing chain, and completely disassembled and reassembled the dizzy. I didn't see any problems but it is now all working fine.

So either something was loose but not in a way I noticed when dismantling, or else I just goofed up when checking the timing.

All good now anyway, thanks.

Cheers,

Jason

[CRUSHU]

out of curiousity, what were the symptoms?

My EFI picks up and looses power for no reason, and I am unsure why. 1 minute you will be doing 100k's with pedal to spare, and other times you are flat to the floor, and have to turn off the overdrive to go over 100, or go up hills. Very frustrating.

[chimpboy]

out of curiousity, what were the symptoms?

My EFI picks up and looses power for no reason, and I am unsure why. 1 minute you will be doing 100k's with pedal to spare, and other times you are flat to the floor, and have to turn off the overdrive to go over 100, or go up hills. Very frustrating.

Rough at low revs, and occasional backfire at high revs.

Also a very rich exhaust.

In your case, how's your fuel filter?

I ran through lots of tests for mine and I still don't really know what was wrong; I can only assume it was one of the things I checked.

Is your problem heat-related at all? ie worse when cold or worse when hot? On other cars I've had coils fail after they got hot but perform okay when cool.

Jason

[CRUSHU]

fuel filter was replaced about 3000k's ago. the problem can came and go even on a long drive. I drove 3 hours at 100kph with the problem coming and going.

[mav]

Hi,

What should I be checking? The timing on my TB42 is wandering - checked it a fortnight ago and it was good, next time I checked it was out a heap. Fixed it, checked it the next day and it had moved ten degrees. Fixed again, checked it, it's moved 10 degrees again.

It's not that the bolt is loose where you adjust it - I've checked that of course. Is it the distributor rotor?

I have a vague memory that the crank pulley can move on these motors but I've searched the archives and couldn't find anything.

Jason

you say the timing is moving but is it effecting the performance? are you checking the timing with the vacuum advance disconnected and plugged, with the engine at normal operating temperature, is the idle speed and dwell angle checked before checking the timing? the other thing is remove the distributor cap and grab the rotor button it should turn a little one way (direction of rotation) and spring back when released, if this doesnt move at all or doesnt spring back you have issues with the advance springs and weights in the distributor, see how you go and let us know.

[mav]

out of curiousity, what were the symptoms?

My EFI picks up and looses power for no reason, and I am unsure why. 1 minute you will be doing 100k's with pedal to spare, and other times you are flat to the floor, and have to turn off the overdrive to go over 100, or go up hills. Very frustrating.

is it on gas as well? does it do it on gas?

[CRUSHU]

out of curiousity, what were the symptoms?

My EFI picks up and looses power for no reason, and I am unsure why. 1 minute you will be doing 100k's with pedal to spare, and other times you are flat to the floor, and have to turn off the overdrive to go over 100, or go up hills. Very frustrating.

is it on gas as well? does it do it on gas?

yes it is dual fuel, and it happens on both fuels.

[matthewK]

with my 4.2 carbie

you put your foot on the gass and the motor slow right down then 15 seconds later its pick right up

some times going up hills the car slows to a point and starts spitting 2-3 times

recont its timming then?

[CRUSHU]

no, i think your problem is a dud carby. it either starves for fuel at WOT (wide open throttle) untill the fuel system can catch up, or the accelerator pump is dead, and pouring too much fuel in, and smothering it.

[batcho101]

hey guys my dad had the same problem in his 91 4.2 dual fuel patrol and it was cause by the nut being threaded where it holds the distributor in place so as when u put down your foot it woudl twist under the torgue and the timing would go out..maybe an idea to consider with yours

[J Top]

If you do suspect your harmonic balancer, scribe a line down the front of your pulley from the timing mark to the centre of the crank and see if it moves
J Top

[mav]

out of curiousity, what were the symptoms?

My EFI picks up and looses power for no reason, and I am unsure why. 1 minute you will be doing 100k's with pedal to spare, and other times you are flat to the floor, and have to turn off the overdrive to go over 100, or go up hills. Very frustrating.

is it on gas as well? does it do it on gas?

yes it is dual fuel, and it happens on both fuels.

quite possible its a vacuum leak, try connecting up a vacuum gauge and when driving and the power starts to drop off before putting in more throttle see what the gauge does. does it surge at idle? try spraying wd40 on any areas you might suspect are leaking including hoses, if its leaking the idle speed will change. it would have to be in between the air flow meter/gas mixer ring and the head.

[mav]

no, i think your problem is a dud carby. it either starves for fuel at WOT (wide open throttle) untill the fuel system can catch up, or the accelerator pump is dead, and pouring too much fuel in, and smothering it.

you put your foot on the gass and the motor slow right down then 15 seconds later its pick right up, this would be the dud accelerator pump.

some times going up hills the car slows to a point and starts spitting 2-3 times, this would be blocked secondary jet or the power valve not opening and letting in enough fuel like what CRUSHU said.