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Hot exhaust headers even at idle

EFI Tuning Fundamentals

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Having listened to this section including the effect of higher/lower compression ratio. I was wondering if it is linked to an affect I have on my Westfield kit car: It appears to run well on a mildly tuned engine (very tame 2.0lt Pinto on twin webber carburettors), however I have been surprised how hot the manifold headers get and very quickly at idle. I had previously put it down to confined space and I have often checked ignition timing. Now I am wondering if other factors can be causing it. Any thoughts?

I ran Pinto engines in our Sports 2000 race cars. Hot header at idle -- the cam belt has jumped a tooth. You need to set the crank at TDC then get the cam turned so the pointer on the cam pulley lines up with the dot on the head.

As David said, if the camshaft timing is out the engine may be burning more fuel, later in the cycle and that will put more heat into the exhaust.

As you surmise, ignition timing has a BIG affect on exhaust temperature for the same reason. many people run relatively retarded idle timing because 'it doesn't matter, I don't drive the car there', others so they can run more cold advance as a 'fast idle' tool. For the most part, I'd suggest running the timing as required for full load-full throttle.

That said, you don't mention what ignition you're using, most likely it's either an OEM based one with vacuum disconnected, or one of the aftermarket ones that used to be commonly available (haven't kept up) with default curves that you may be able to better set to your requirements.

There are 2 and 3D fully electronic ignitions available, the former simply mapping timing to rpm, but the latter also uses a TPS (throttle position sensor) on the throttle linkage/end of a carbie to give the ability to also map to the amount of throttle used - this can make a big difference in driveability, response, economy, plug life and what is applicable here, to the ability to run more idle advance. This has two big benefits from the improved combustion efficiency - less charge needs to be burned and it's earlier in the power stoke, so there is a lot less energy left to heat the manifold.

Some of the newer ignition ECUs may have other additions (not kept up) for temperature or detonation corrections?

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