INNOVATE DLG1 Wideband O2 Oxygen Sensor Tuning Diagnostics Logging Air Fuel Ratio etc

[AnotherWs6]

Originally Posted by Gregski

Finally got through to Holley Tech Support today and spoke with Tony about adjusting the secondary butterflies and exposing the secondary transfer slots on my 4160 carburetor to lean out the idle mixture some more.

He said that the secondary transfer slots sit higher than the ones in the primaries and should NOT be exposed.

However I could crack the secondary butterflies open a bit more to lean out the mixture further than the 13.5 at idle I am getting now.

We also discussed advancing my ignition timing from 10° to 12° or even higher as an alternative or in addition to.

He used a phrase that I have heard from tech support guys like ProForm the makers of my previous HEI distributor, it goes like this "see if your truck likes it" or "and if your truck likes it".

Now that's kinda subjective to me, and its like asking your three year old what they would "like" for dinner, I mean my truck will run and drive with the distributor anywhere from 0° to 18° and AFR anywhere from a rich of 9 AFR to 15 AFR, anywho just getting that off my chest

10 degrees is pretty tame. My truck "likes" about 15-16.

[Gregski]

Originally Posted by AnotherWs6

10 degrees is pretty tame. My truck "likes" about 15-16.

I hear you and I used to run it as high as 16° myself but since I built (technically rebuilt my 1974 engine with 1999 Vortec heads) according to the GM Chevrolet Performance 350HO Deluxe Engine (19210008) Specifications


"Set initial spark timing at 10º before top dead center (BTDC) at 650 rpm with the vacuum advance line to the distributor disconnected and plugged. This setting will produce 32º of total advance at wide-open throttle (WOT)."

So I decided to time it according to their instructions, (at least to have a baseline) and then adjust accordingly. Just thought you all should know where I am coming from as I am a stickler for doing things by the book, within reason of course.