Got An Idea - Technology for Tuning

[matt63]

The reason I bought this unit was because plug reading sounded too time consuming and requires alot of experience.  The idle mixture was adjusted to maximize intake vacuum and seems to be right according to the A/F ratio.  When i brought the engine speed up the A/F went rich so I suspect the jetting is still fat even though I have dropped it 3 sizes from the the stock jet size.  The whole idea that carbs "should be close out of the box" never made any sense to me considering the variations in intake vacuum, etc.

[HP2]

The whole idea that carbs "should be close out of the box" never made any sense to me considering the variations in intake vacuum, etc.

cam overlap, altitude, ignition capability. Yup, I hear ya. "Close" in this case seems to mean that it will allow gas to be ingested into you engine.

[matt63]

I took the Cuda on it's first jaunt this spring as it had to go to the shop for a front end inspection.  I was watching the meter off and on during the short trip.  The cruising air/fuel mixture is pretty close at around 14.  The idle mixture is a little fat but not bad at high 12's.  I'm sure the secondary jet is way too big as it drops fast under moderate throttle.  I'll have to get a volunteer or use the logging feature to check that out.  I'll get a full test done after I sort a few things out.

[KellysCuda aircard]

Hey, I bought one too, cant wait to get it figured out.

[matt63]

Hey, I bought one too, cant wait to get it figured out.

It's very easy to use.  Once the bung and sensor are installed just follow the quick start guide.  An initial self calibration routine runs and then it's operational.

[matt63]

I finally got to the start of my tuning project after dealing with a bunch of other issues, some of which aren't dealt with yet (see my rad post).  The initial log shows that my idle and primaries are just fine at around 13.5:1 idle and 14.5 cruise.  I think I will do a test with the secondaries wired closed to make sure.  I did get a 3/4 throttle run and logged it.  I'm scratching my head a little on this one. The AFR went way lean momentarily and then drops to 10 -11 when I get back into the throttle after shifts.  It then gradually leans out to somewhere around 13 -14:1.  I'm kind of suspecting that the secondaries (vacuum) are kicking in too early.  I think I'll use the heavy black spring (Holley HP Street 750) and see if it makes a difference.  I haven't looked at the plugs lately but I'll probably change them once the AFR's are looking better.  One thing I do know for sure...seeing the data log sure raises alot of questions!  I'll do some more experimentation tonight.

[Jacksboys]

The AFR went way lean momentarily and then drops to 10 -11 when I get back into the throttle after shifts.

Just remember that with a carb, there will be a moment when the air will be traveling faster than the fuel when you put it to the floor.  By a moment, I mean maybe a second (+/-).