How to properly time a 76 912e engine.

[hsysfan]

Hello everyone, I am working on a 76 912e. The main complain is that it has a hesitation on acceleration at higher RPMs. When you shift gears at about 3000rpm, you can feel the hesitation. The distributor had had petronix electronic ignition instead of points and condenser. I removed the distributor, installed new points and condenser, adjusted points to .015" (once engine was running checked dwell is 49 degrees), installed distributor back onto the engine, the engine will not start or had a very hard time starting and runs very rough. The distributor was installed roughly on the same position as it was before removal.
If timing is advanced the engine will start, run ok, drive ok, but idle sticks very high at times.

My research indicates to time the engine to 27 degrees BTDC @ 3500rpm with engine at operating temperature and vaccum hose disconnected.
There is a plug in the air fan shroud, if you remove it, there is a V shape notch in the case and there is a groove cut along the fan.
When they line up:
1.) Is it TDC for cylinder # 1.?
2.) Should both marks line up 27 degrees BTDC @ 3500rpm at operating temperature with vaccum hose disconnected?
I tried timing it with 1.) , but can not achieve it and idle is very high.
I timed it with 2.) idles fine, but it has a serious lack of power on acceleration and it is hard to start (the distributor in this position matches original location when it had the petrinix installed).
The distributor has 2 vaccum hoses attached to it, should I disconnect both of them when timing it? (I disconnected them both when timing it).

If anyone can shine some light in my path it'll be appreciated.

[Jaems]

Are you running FI or carburetors?

Is it the correct Distributor for the engine?

When given BTDC, ATDC, or TDC it is always for # 1 cylinder.

BTDC means before top dead center. You should have been given some degrees like 3 degree, 5 degrees, or etc. BTDC. If there is none then it would be TDC always at # 1 cylinder.

You turn the pulley until the mark on the pulley matches where it should be for BTDC, TDC or ATDC degrees (this is always #1 cylinder).

Then loosen the distributor clamp, hook a test light to #1 terminal on the Dist and one to the ground. Then turn the Dist. left or right until the light just starts to come on. This is static timing and the engine will start find and run good.

However, if you want the best timing, you will use a timing light . You will set the degrees on the light to, in your case, 27 degrees. then run the engine up to the 3500 RPMS. Then turn the dist left or right until the the marks on the pulley and engine match up. The vacuum lines are usually removed from the dist. before timing with the engine running.

If you still have the flat spot and are running FI. Then you have to have the distributor re condition. If you are using carburetors. Then they may need to be matched to the engine with different jets emulation tubes air correction jets and etc.

[HarryDude]

The still unanswered question is: Is the "V" mark under the timing inspection cover TDC or 27° BTDC??

[inaminit]

Hi Harry
The v is a reference spot in the housing to line up with a mark on the fan. I have 2 of these fans-one has 1 mark, which looks like a chisel mark, and the other fan has 2 marks, the chisel mark and a center punch mark about 4 fan blades to the left of the first mark when looking at the front of the fan. I used a bore scope to determint no1 tdc-that turned out to coincide with the punch mark. So-my conclusion is that the chisel line is the 27 degrees before tdc, used for 3500 rpm timing, and the punch is tdc, used for adjusting valves and static timing. Let me know or post here if you learn a different interpretation.