Timing help please
 

Ok so my research on this board says timing is at 17 BTC. So I put in my new distributor (see previous thread) and I cannot get it to time anywhere close to that. The engine runs best at about 28 BTC. Based on position, it appears as if the previous distributor was about the same. At 17 BTC it runs bad.

Can anyone chime in on this?

My thoughts are: vacuume leak? AFM problem?

The engine runs ok but I know it can run better. It has a slight miss upon acceleration. Idles ok but shakes a little at times. At 3000 rpm it runs smooth.

We did play around with the AFM while timing the engine and it seems to run better when we opened the flap slightly at idle.

Any insight on this would be greatly appreciated. For now, I am running the car as is.... my assumption is that is ok!?!?!

The rubber on the harmonic balancer may have allowed the outer ring with the timing marks to shift with respect to the inner hub that is keyed to the crankshaft. If it slipped, then the timing marks are no longer accurate. I assume you disconnected the vacuum line from the distributor to disable the vacuum advance during setting of base timing.

Many people prefer to set timing using a vacuum gauge, do some research on that technique, it is perfectly valid and works well. It is possible to re-mark the balancer using a timing tape after setting cylinder 1 to top dead center on compression and marking that as 0 degrees on the balancer using a timing tape or make your own timing tape and transfer the marks. I think it is probably easier to do what you have done so far, just add in the vacuum gauge to make it a little more scientific.

There are a lot of places for vacuum leaks if the original vacuum lines are still in play. I recommend replacing all of them, and check under the intake manifold, directly beneath the throttle body-- there is a drain port there that is supposed to be plugged, and it may be missing the plug. On mine I used a length of vacuum line and a small bolt to form a plug.

Once you have done all the vacuum lines carefully and assured no leaks, then suspect a possible injector issue. The seals on the injectors can allow vacuum leaks, and the injectors themselves can become clogged or develop poor spray patterns. At the least, use some good quality injector cleaner for a few tanks in a row. At the most, the injectors would benefit from removal and professional cleaning/refurbishing.

CrossheartXJ6 found this was causing a vacuum leak, rough idle and misfiring:
One of the big hoses connecting the throttle body to the elbow. Check all these too. Replace them if they are rock hard or old looking.
Attachment 175672

Oh yes, you may need a vacuum diagram:
http://public.blu.livefilestore.com/...ram.jpg?psid=1
That image was made by Alex Cannara.

http://public.blu.livefilestore.com/...tem.jpg?psid=1
Also by Alex Cannara

http://public.blu.livefilestore.com/...ing.jpg?psid=1

http://qumyjw.blu.livefilestore.com/...uum.PNG?psid=1

This is a great start for me to work on finding a problem. Did not even think about the possibility that the timing mark was off.

The injectors and o rings are all new (had them sent out and cleaned). I sprayed carb cleaner around them with the car running and it did not change the engine sound so I think they are all seated properly.

My next job will be to replace all the vacuum lines and see if that has an effect.