Ignition Timing?
 

Would putting on a new Distributor throw off ignition timing? Also, is Clockwise on Distributor "Advance" or "Retard?"

Chilton Manual shows:

-79 is 31 BTDC

80-81 is 23 BTDC

Would the different timing be due to CIS and L-Jet?

When I put my new cap on back in Sept. it did not throw the timing off. Did you get a new rotor too?

Yup, got the set off Rock Auto. Mine had a Bosch set on it, which you can clearly see the quality difference.

The reason I am asking the timing question is that I turned the Distributor clockwise and my engine runs a whole lot smoother. I can't check timing on my own since I need it to get to 3000 Rpm and I don't have an external tach.

Can someone answer the original question about Advance/Retard?

IIR, clockwise = advance. I read somewhere that by advancing the timing a little beyond recommended, you can pick up about 10 more horsepower. That may be why you noticed a difference.

It's not the power diff, but more of an engine missing environment. My Engine really runs smoother when I turn the Dist Clockwise.

Then maybe it was out of timing before you adjusted it?
Like you, my tach is not working, so I need a timing gun with a built-in tach. They are super expensive though, so I'm going to try and borrow one (after a replace the fuel accumulator).

Actually timing was spot on, since it was the Smog Guy who I had change it last year in order for it pass smog. I do think the new setting was for an EFI 81 and not an 81 Euro CIS. If this is correct, then I should be following the 79 US setting of 31. Going to verify this later with a 928 buddy who also has a 79.

Leo,
I know this is going to sound stone ax and all,...
On my '80, the dynamic timing is supposed to be 23deg. , however, after some experimentation, I found it runs really strong at 28deg. I was curious, so I checked it at idle, with no vac advance,.... Lo and behold a static timing of 8deg.
(the same setting my old GTO, and ski boat used). Usually the smog guys will retard timing to get a lower emission level. Unfortunately, this also sucks up your power . Just my 2 cents.
-K

I actually took it for a drive and love it's current setting, clockwise a little bit (advance?). I'm gonna verify it later when I can get someone to hold my rpms at 3K. Either way, it's staying till next smog check at the end of the year.

hey mp could you turn the idle screw to get your 3000rpm?

MPDano,
IIRC, the correct timing for a Euro is 26 or 28 degrees versus 23 for a US version. There should be a timing mark on your harmonic balancer with a 26 or 28. That value would be correct at 3000 RPM with the vacuum line disconnected.

My issue with marks being on the HB is that i am unsure which one I used. My Block is US and I used my Euro CIS stuff. I will check the HB and see what marks I have on there. Although, if it isn't there, I can always guesstimate with the other marks.

Your right. The Harmonic Balancer had a 28 on it. I went ahead and set it at 28 and did a test drive and it drive a lot nicer, which was very close to what I had changed it to. I'll change it back to the Smog Passer setting, which I marked on the Distributor when that time comes. Thanks for the help!

Yes Advancing your timeing will always smooth out the idle.

Here is an old hot rodders trick

When you hot-rod an engine, change cam, compression, ect the timeing goes out the window. The stock specs are NO LONGER ANY GOOD

SO!! heres the trick
Hook up a vacuum gauge to manifold vac
Advance the timing for max smooth running, as you go to far it will get rough and pop.
NOTE the VAC ... lets say its 24 deg at idle.
retard till the vacuume is 1.25 to 1.5 inch's of mercury less (22.5) and you will be really close.
test drive under full throttle to make sure it dose not ping.
If it does, back it off a hair more.

That was my race setup and it always worked.

Just for the record, the rotor turns clockwise so moving the distributor clockwise retards the timing. Counter clockwise advances the timing.

This is exactly what I needed to now. So the higher the number is an "advance."

Yes. The 23 means the ignition fires when the piston is 23 degrees BEFORE top dead center. If you move the distributor 8 degree counter clockwise it will move the timing to 31 degrees before top dead center.

Just a reminder that the distributor turns at half the speed of the crankshaft. Moving the distributor body --4-- degrees will change from 23º BTDC to 31º BTDC at the crank.

It's easy to get a little carried away with advance at idle, since the engine seems to run smoother/faster at idle with the extra advance. If you go overboard though, you risk detonation at higher engine speeds, detonation that you may not hear over other noises until too late, when it turns into a rod knock or a serious piston slap. Depending on fuel quality, a couple (crankshaft) degrees is genally not too unsafe, but no more on good pump premium gas. Also, if you have -any- lean cylinders because of less-than-perfect injectors, you risk lean detonation with any extra advance.

Good catch on the degrees. Also, running too advanced has been known to blow head gaskets. If you are going to set the timing buy a cheap timing light and follow the WSM concerning degrees and vacuum line attachments.

Like MP, DP and Bob said :)