[T3] On a 73 T-3 SB fuel injected aut trans pinging .

[William J]

----- Original Message ----- 
From: "Jim Adney" <jadney at vwtype3.org>
To: <type3 at vwtype3.org>
Sent: Monday, December 04, 2017 8:05 PM
Subject: Re: [T3] On a 73 T-3 SB fuel injected aut trans pinging .


> On 4 Dec 2017 at 13:35, William J wrote:
>
>>  Does it sound like the mechanical advance weights might be sticking ?
>
> I've never seen a distributor where it was the weights that were sticking. 
> The
> thing that sticks is the relative motion between the upper and lower 
> shafts.
> There's a felt pad in the top of the upper shaft that should get a drop of 
> oil
> once a year. If you do this, it will never stick.

 Yes I've oiled it before.
>
> There are 2 ways to test your mechanical advance:.
>
> One is simply with a timing light and the vacuum hose removed, so the only
> advance that's active will be the centrifugal advance. Just watch the 
> timing
> marks with the timing light as you speed up and slow down the engine. If 
> the
> marks move, your mechanical advance is working.

 I tried to see it advance with a timing light and it was difficult to tell 
since I couldn't get a good aim in that small hole , I could see it was on 
the 5 dergee mark , didn't see it advance when I opened the throttle.
>
> The other way to check is to simply twist the rotor CW and see if you can
> feel it turn against some spring pressure and then release it and watch to
> see if it snaps smartly back. If it does, it's working.

  I never really tried to twist the rotor clockwise with any force just 
enough for the rotor to stop yet when I release it it moves back yet has a 
bit of free play , meaning I can move it back a bit more than the springs 
take it back.


 The thing is this ping just came out of the blue , no warning . It never 
did this until last friday and only after I drove 11 miles I stopped 3 
places and the 4th place on the way home once in second gear I pushed it a 
bit and heard the ping . Today I drove about a mile . Shut it down 3 times 
and after that one the way home when I felt it shift into 2nd and I pushed 
it a bit it pinged twice yet not in a row . Most times I try it again in 2nd 
and I hear no ping at all ,with the same fuel before this happened.

 it's a pretty distinct ping sound a good rattle that stops as soon as I let 
of the gas .

 I'm just guessing yet the way it just pings and then won't it sounds like 
you have the timing at least 10 degrees more advanced than it should be for 
the load on the engine .

 I didn't drive it around a lot and I didn't hear it in 1st , it seemed to 
need more of a load and stood out in second gear and I didn't have to crack 
the throttle hard just a bit more than I would normally .

 This distributor has never been apart and it was out of a 72 auto trans had 
the dual advance can. . I have no idea how may miles it had when I got it 
yet I do know I installed it in the original 73 X engine trying to pass smog 
in 97 and it's been in this engine I rebuilt since then.

 I looked down in it a few weeks ago just to see if the 2 springs were on 
,wanted to compare which spring heavy and light was on which adjust post to 
the 73 AH I rebuilt . There is a large hole and a small hole on the upper 
shaft where the spring posts are , the ones one would bend to set the curve. 
I wanted to know if I placed then the same on the one I rebuilt even though 
I have photo's of the AH before I took it apart . All that really matters to 
me is they are one the post they were because if not that would screw up the 
curve. Both posts are the same and this wouldn't matter if I had someone 
setting the curve they are the adjustment as you know.

 I don't know what else it could be to cause it to ping then not all of a 
sudden . I didn't do this by me just looking and turning the engine over via 
gen nut to see the springs . I did move one spring just a tiny bit because I 
wanted to see if it was on the post and it seemed sort of slack yet on the 
post. The springs hook on the upper removeable part what they call a cam and 
the other end hooks on the main shaft on  the pivot pins for the 2 weights . 
Isn't it possible that a weight could have warn on it's pivot enough to bind 
then let loose? Or a fiber washer under one cracked and left the building?

 I'm open to any suggestions . I think I will just take a good look tomarrow 
to see if I can see anything off in there . I may pull it and remove the 
advance plate just to see if I can find any binding in the advance. I really 
don't know where else to begin  looking .
>
> The vacuum advance on the FI engines is just there to give a bit better 
> gas
> mileage at cruising speeds. It does nothing at idle or at full throttle. 
> You
> won't notice any change in performance if it's not working.
>
> -- 
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
>
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