• Registered: 2010-10-27
  • Posts: 35

Topic: timing loves to jump.

Yeah i know... i am sure you all have seen this on thesamba... anyways my carb is great and the tuning is good. Still the timing while at idle loves to jump around like say 3 BTC to 10 BTDC not steady at 7.5 BTDC. I am using SVDA and i noticed that when i try 009 it's the same result. They jumps like if vaccum was goin nuts. I tried different points and condenser. Same results. I did plugged the vaccum ports as well while timing it. What do you guys think?

Last edited by 74Superbeetle (2010-12-13 17:30:18)

Super Beetle 74 currently restoring...
69 standard beetle
  • From: Washington, Indiana
  • Registered: 2004-03-27
  • Posts: 1,425

Re: timing loves to jump.

If you have a lot of endplay in the crankshaft it will cause the timing to jump around.....

                                                                    Yancey

Yancey's Website

  • Registered: 2010-10-27
  • Posts: 35

Re: timing loves to jump.

How do I know if the crankshaft has alot of endplay?

Super Beetle 74 currently restoring...
69 standard beetle
  • From: Washington, Indiana
  • Registered: 2004-03-27
  • Posts: 1,425

Re: timing loves to jump.

Get an expert opinion from a good VW Mechanic.....If you dont know any then while the engine is cool and shut off grip the lower pulley and push and pull back and forth front to back......if you have more than .006 thousands of movement then you have more than you are supposed to.....with the distributer cap off push and pull on the pulley, if you see the roter going back and forth then there is your timing problem.....Have someone hold the clutch in while you are checking the timing and if your timing doesnt fluctuate then thats the problem.....(the clutch being in will minimize the crankshaft back and forth movement and your timing SHOULD stay constant better if that is the problem....

                                                                Yancey

Yancey's Website

  • Registered: 2010-10-27
  • Posts: 35

Re: timing loves to jump.

so i tried your advice and the crankshaft isnt past the endplay. I pull and pushed the lower pulley but nothing so i had the clutch pressed down while timing it but nothing. So meaning my crankshaft is ok.

Super Beetle 74 currently restoring...
69 standard beetle
  • From: Washington, Indiana
  • Registered: 2004-03-27
  • Posts: 1,425

Re: timing loves to jump.

Possibly yor idle is too high causing the centrifugal advance to work when it shouldnt? Try setting your idle down low.....Also check and see if the centrifugal advance is sticking....

                                                                                Yancey

Yancey's Website

  • Registered: 2010-10-27
  • Posts: 35

Re: timing loves to jump.

so what i do i need to do to find out that the centrifugal advance is sticking? Sorry just i am still learning.

Super Beetle 74 currently restoring...
69 standard beetle
  • From: Cincinnati, Ohio
  • Registered: 2005-09-10
  • Posts: 2,336

Re: timing loves to jump.

74Superbeetle wrote:

so what i do i need to do to find out that the centrifugal advance is sticking? Sorry just i am still learning.

Just to add my 2 cents to this conversation...you may be "chasing your tail" on this problem.  There could be any number of things that could be causing erratic (non-steady) timing:

- crankshaft end-play as Yancey mentioned
- a non-steady idle caused by dirty or semi-clogged carb.
- intake manifold leaks
- vacuum leaks
- distributer issues (as Yancey mentioned)
- etc.

Or you could even have multiple issues on a 36 year-old vehicle.  Honestly...when I check my timing it's not 100% rock steady either.  If your Beetles engine is running fine...I wouldn't worry too much.  Just get it as close as you can.

- Nick

1979 Super Beetle Convertible
  • Registered: 2010-10-27
  • Posts: 35

Re: timing loves to jump.

74Superbeetle wrote:

so what i do i need to do to find out that the centrifugal advance is sticking? Sorry just i am still learning.

I read the bentley manual and i tested it by the rotor that should spring back to original position. It works fine and i tested the vaccum by sucking the vaccum hose and the breaker plate moved and when i let the hose go the plate comes back in place.
Bug in my nose, my car does runs well just i dont want small timing issue to ruin my engine after all the work i put in this car. I will probably take it to vw mechanic to fix it for me because i am not sure what else i can do. So i can be safe about it.

Super Beetle 74 currently restoring...
69 standard beetle
  • From: Cincinnati, Ohio
  • Registered: 2005-09-10
  • Posts: 2,336

Re: timing loves to jump.

74Superbeetle wrote:
74Superbeetle wrote:

so what i do i need to do to find out that the centrifugal advance is sticking? Sorry just i am still learning.

I read the bentley manual and i tested it by the rotor that should spring back to original position. It works fine and i tested the vaccum by sucking the vaccum hose and the breaker plate moved and when i let the hose go the plate comes back in place.
Bug in my nose, my car does runs well just i dont want small timing issue to ruin my engine after all the work i put in this car. I will probably take it to vw mechanic to fix it for me because i am not sure what else i can do. So i can be safe about it.

Sometimes it's a process of elimination.  The more things you test...and the results are good...the fewer things that are left that could be causing a problem.

I would hate for you to take your Beetle to a mechanic who's going to do a bunch of troubleshooting, find nothing wrong, and charge you a lot of $$$ for the troubleshooting time.  You mentioned that your carb. is good, your distributer is good, tuning is good, and end-play on the crankshaft is good.  You've already eliminated a number of items.

It's really hard to say over the internet if you truly have a problem or not.  You could simply have a rough or uneven idle in your carb. causing the timing to jump around.  And if that's true...taking it to a mechanic may not help.

Good luck,

- Nick

1979 Super Beetle Convertible
  • Registered: 2010-10-27
  • Posts: 35

Re: timing loves to jump.

yeah.... i can only hope it works. I talked to the mechanic today and he works on old VWs for a long time and have a shop as well. If it doesnt work then i dont know.

Super Beetle 74 currently restoring...
69 standard beetle
  • TomB
  • Moderator
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  • From: Austin, TX
  • Registered: 2004-03-27
  • Posts: 1,095

Re: timing loves to jump.

I've never had an engine (VW, BMW, Volvo, Borgward) going back to the 60s where the strobe timing didn't appear to jitter a few degrees. I've always set it by the position that looks steadiest, and ignored the jumps.

  • From: Cincinnati, Ohio
  • Registered: 2005-09-10
  • Posts: 2,336

Re: timing loves to jump.

TomB wrote:

I've never had an engine (VW, BMW, Volvo, Borgward) going back to the 60s where the strobe timing didn't appear to jitter a few degrees. I've always set it by the position that looks steadiest, and ignored the jumps.

Well said Tom!  I might even add that on an old air-cooled 4 cylinder VW Beetle engine...the timing can be a bit more "jumpy" than say on a 6 or 8 cylinder vehicle.

- Nick

1979 Super Beetle Convertible
  • Registered: 2010-10-27
  • Posts: 35

Re: timing loves to jump.

i came to conclusion... The rpm isnt solid when idling and not steady at all so i am leaning to vacuum leak. I used a carb cleaner but nothing. I must be missing a leak somewhere....

Super Beetle 74 currently restoring...
69 standard beetle
  • From: Cincinnati, Ohio
  • Registered: 2005-09-10
  • Posts: 2,336

Re: timing loves to jump.

74Superbeetle wrote:

i came to conclusion... The rpm isnt solid when idling and not steady at all so i am leaning to vacuum leak. I used a carb cleaner but nothing. I must be missing a leak somewhere....

I'm thinking that the non-steady idle rpm is the issue...and the non-steady idle could be related to a vacuum leak or something is worn in the carburetor.  Remind us...what is the condition of the carburetor?

If the carb. is on the older side...some sort of wear is always a possibility.  And no matter what you do...this non-steady idle rpm will be there...unless of course you rebuild the carb. or install a rebuilt or new carb.

I of course do not know how well or poorly your engine is running (can't see or hear it)...but if it seems to be running fine...and you cannot find a specific reason for the non-steady idle rpm...I really wouldn't loose too much sleep over it.  Just get the timing as close as you can to the specified setting...and see how it goes.

Good luck,

- Nick

1979 Super Beetle Convertible