It's pretty hard to hear detonation in a HotRod; everything else is louder.
Because of that, I bought a G-tech-ProSS , which is a windshield mounted accelerometer synchronized to time. With this tricky little unit, you can do speed tests at various PowerTiming settings. When the car slows down, she's complaining. Catch it early.
It has some other useful features as well. If you measure out a quarter mile, and follow the prompts, it will calculate your ET and estimate your power and even spit out a downloadable, dyno type graph.
Save your engine, install an accelerometer. Nice tool.
You can even use it to establish a PV tip in, the effectiveness of your vacuum advance, stall timing, etc. I find it to be an excellent tuning aid.
Quick tip;
The more Idle-timing you give it, the more closed your throttle can be made, to maintain the same idle-speed. The more closed the throttle is, the less the fuel that the transfer slots can supply and the more sluggish they will become, which leads to tip-in sags and hesitations. You can enrich the idle with the Idle-Mixture screws, but this will enrich the entire low-speed operation, cuz the idle screws never shut off. And you can overcome the sag with pumpshot.
This is all messed up.
If you have a manual trans;
For a manual trans. I highly recommend as little idle-timing as possible, consistent with a properly sized Transfer Slot exposure.
Too-much idle-timing is easy to spot;
> As the engine picks up Idle power from the timing, the gas pedal will begin to feel like an on/off switch, at tip in. This is especially annoying when going from closed-throttle deceleration to back-on, but at a low throttle opening.
>Sometimes, on deceleration, it can feel like the engine has been shut off.
>Another thing that can happen, with hi-way gears, and in First gear, is that, as the car is forced to drag the rpm below the Neutral IdleSpeed, excessive timing will make the car begin to jump, and the only cure is to toe the clutch. This makes parading as good as impossible.
The cure is simple; with the T-Slot properly sized, just retard the timing until she either quits doing that, or, she stalls in gear while pulling herself, then add back a couple of degrees.
>All of this can be directly traced back to the lack of Transfer Slot exposure, underneath the closed primary throttle valves.
>To satisfy a need for retarded idle-timing, you can run a 2-stage curve that is very fast to some arbitrarily chosen rpm like somewhere between 2000 and 2800, and then slow it down to your "all-in-by such and such" rpm. To get the Part Throttle timing back you can use a fast-acting Vcan that you modify to bring in the missing degrees.
>Another tip for a manual trans, is to map out your advance curve every 200 rpm from idle to about 3600 rpm. You can't know where to go unless you know where you are at.
These tips together should solve all your manual-trans ignition timing problems.
