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

Tue Dec 5 13:15:35 PST 2017

 I connected the timing light and let it warm up and plugged the AAR line to 
the oil bath because it will not close fully yet enough where it does not 
affect the idle speed much at all .

 I looked through the gen belt cover and when idle was 950 the timing was at 
7.5 BTDC if I slowed the idle down it sat at 5  BTDC.

 Now if I opened the throttle I could see it advance and even though the 
idle speed dropped to 950 the timing was still advanced pretty far past the 
7.5 BTDC mark and very slowly would return to 5 BTDC . Took at least 2 or 3 
minutes without timing it to drop back to 5 BTDC .

 I know it used to drop right back to 5 BTDC right away and even making 
certain the throttle was fully closed . Now doing the same thing the advance 
is still far to much and it does not have a decell deal on the throttle 
juast the spring and it does return fully .

 I pulled the Dist and am now ready to remove the advance plate to see what 
could be going on .

 If I don't find anything hanging up what else could cause this. I checked 
for any loose tin and found nothing .

 When you close the throttle the timing should return to 5 BTDC right away 
shouldn't it?
----- Original Message ----- 
From: "William J" <catnine09 at dslextreme.com>
To: <type3 at vwtype3.org>
Sent: Monday, December 04, 2017 9:24 PM
Subject: Re: [T3] On a 73 T-3 SB fuel injected aut trans pinging .

>
> ----- 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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