Mailbag: Can I Use an EFI Kit to Control Ignition Timing?

Q: Can I use a fuel injection system to control my ignition timing?

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A: Yes. Most fuel injection kits will work with your existing ignition system. All they really need is a tach signal. Ignition timing advance can be handled mechanically and/or with vacuum, just like with a carburetor.

However, there are advantages to computer controlled timing. If you’re planning on nitrous or forced induction, timing control-compatible EFI is a must.

What are the benefits?

Fuel injection delivers fuel more precisely than a carburetor. This lets you run more ignition advance before detonation occurs. It’s basically free horsepower you can pick up when switching to EFI.

The ECU can retard the timing too. This allows you to accurately dial back advance with boost or nitrous. There’s no need to get an ignition box.

Idle stability can be improved by slightly advancing the timing when idle speed drops and retarding the timing if it’s too high. Starting is also easier with less advance while cranking than at idle.

What do I need to make it work?

You’ll need a two-wire distributor with a magnetic pickup and an adjustable rotor. Mechanical or vacuum advance must be disabled and locked out. Although not required, some kits can work with an ignition box. Per usual, it’s best to check the instruction manual.

Is there a downside?

Unfortunately, timing control is not self-tuning. It has to be programmed by the user. Adjustments need to be made gradually with timed runs or on a dyno.

Should I buy a timing control compatible EFI system?

If you already have an ignition box or are happy with your current ignition system, you can save a few bucks by buying a kit that isn’t timing control compatible. However, if timing control or power adders are part of the plan now or in the future, buy a compatible kit from the start. You don’t have to use the timing control function right away, and you can’t add timing control to a non-compatible system later.

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This is another in a series of weekly Q&A Mailbag sessions with Summit Racing‘s tech department, in which there are hundreds more. Click here to see them all.