AFR and VACUUM values

[cobra 53]

- cam was installed at engine (comp cam *cam quest online* recommended)
- engine no vacuum ignition advance
- PV 4.5 at the Moment

New experiences

Ignition 18° total 34° / springs 1x silver H, 1x silver L
Idling still too lean. Afterwards I restricted IAB with a wire of 0.041". At idle 850/900 the AFR drops to 11.5. Once the revs moves to 2000, AFR up to 12+, accelerating AFR 12.5. Engine sounds better than before.

On the test drive the feeling has been better than before. Sec. vacuum valve working with purple colour spring, opens at approx. 4000 RPMs.

I replaced the wires on both IAB with the wire tubes. Hole Diameter 0.067" (Foto).Idling at 850-900 AFR is 13-14. Vacuum 6-6.5, idle mix screw 1 3/4 turns open.

How can I adjust the idle mixing without the plastic tubes on the IAB? Opening the IFR?

SBF 302 - YouTube

[lippy]

If your AFR is rising to 20, that is a lean condition, not rich. It would not be caused by a missed spark or a power valve opening early. Those would cause rich conditions. Brent tells me sometimes you get a quick transient lean spike, and that may be ok. But if it is more than that, you could cause some damage running for extended periods at a lean AFR.

[cobra 53]

Back from test drive

Wat a difference!!!! Runs from idling to 1800 / 2000 rpm without
stumbling. Smouth and with good acceleration.
Roll start in 2. gear, reving up the engine and change to 3. gear, the rear wheels are spining
A totaly new feeling.
Cruising at AFR 13. I have to Change the jets for cruising and maybe WOT.
The spikes up to AFR 20 are now on intervals betwen 1 min to 2.5 min.

[Gaz64]

A misfire DOES show up as lean, high oxygen from no combustion.