How Often Do You Set Your Timing

[Gordo2]

My car was running rather poorly, low idle/stalling, hesitation and in general feeling a rather weak. Last tune up was about a year ago/5k miles.

Replaced plugs, cap and rotor, adjusted idle today and went for a ride. Still feeling kind of doggy. Came home and adjusted the timing and went for another ride, it was like a different car. The accelleration was noticably better (got some rear end slide gunning it in second around a turn, haven't had that since shortly after my last tune up ).

Can't tell exactly how far it was off, but it seems to me a minor adjustment in timing on this engine makes a huge difference.

Think I'm going to add timing adjustment to the list of must do's around the 3 month mark from here on.

Gordo

Additional:
When I adjust to 5 deg before top dead center as recommended I've noticed slight knocking under full load. I backed it down a hair to where it sounds smooth. Do you think if I run higher octane gas (93 vs the 87 I put in it now) I can advance it back to 5 deg without the problem?

[kstylianos]

Gordo,

87 bad...espically when it starts getting warmer out here.

Use 93 octane and you should be able to set the timing to at least factory specs (5 btdc), if not more (10-12 max). If you want to advance the timing more (10-12 degrees at idle not exceeding 35 degrees at 6K RPM), make sure to richen the idle CO to 2.5-3.5% and disconnect the O2 sensor.

[bigchillcar]

my technical spec book for my '74 calls for 5 degrees atdc at 900 rpms, vacuum connected, but mine ran awful at that setting...posted the other day...driveability fine but no power, especially no peakiness areound 4k as usual.

i set mine to 5 degrees btdc and everything seems normal again. i routinely run 87 octane here in arkansas. at any rate i didn't have any knocking either way.
ryan

[Gordo2]

Originally posted by kstylianos
Gordo,

87 bad...espically when it starts getting warmer out here.

Use 93 octane and you should be able to set the timing to at least factory specs (5 btdc), if not more (10-12 max). ... make sure to richen the idle CO to 2.5-3.5% and disconnect the O2 sensor.

I've never had the mixture adjusted/tested. Guess I'm going to have to hit up the NoVA gang for the tester. How much of a process (time) is it to adjust the mixture using a teste? I assume it should be a little easier on my car now that I've removed the A/C and backdated the heater.

Wow, 10-12? Would it still have a solid idle?

I'm fairly confident my O2 sensor doesn't work which might contribute to a lean condition (the wires to the brain are melted together... good indication it doesn't work). No intent on fixing that one.

Gordo

[kstylianos]

>>Wow, 10-12? Would it still have a solid idle?

Yep. The idle will still be solid. As you advance the timing the idle will increase, so just bring the idle back down after you set timing. Dont recommend this unless you are sure all is well with your CIS.

>>I'm fairly confident my O2 sensor doesn't work which might contribute to a lean condition (the wires to the brain are melted together... good indication it doesn't work). No intent on fixing that one.

That's probably not a good thing and may be causing a lean condition. The lambda brain controls the frequency valve depending on O2 input. If the O2 sensor is disconnected the FV will go into a pre-programmed duty cycle, making the mix richer. If the wires to/from the box are suspect, the FV may not be functioning at all, causing a lean mix throughout the rpm range. The Bentleys has a good/decent CIS troubleshooting section.