? about metering rods

[clarkja]

what diference is there likely to be when changing the metering rods in an ebrock 1406.I changed the main jets from .098 to .101.what about the metering rods?stock they are .075x.047,the closest size in the calibration kit is .073x.047.I'm not real sure as to what exactly will come from changing them.can anyone explain it laymans terms?

[Wesdog]

Did you read the info in the Edelbrock booklet about carb tuning? There is a chart that shows what effect the different recommended combinations of rod/jets will have. The rods have 2 steps or diameters and when combined with different size jet openings will change the cruise and power curve areas by different amounts, rich or lean. Don't blindly change these parts. If you run overly lean you risk serious engine damage, trust me on this. Start with the stock rods/jets and ensure all the other areas that affect A/F ratio and engine performance are set correctly such as checking for vacuum leaks and ensuring your timing curve is reasonably correct in all areas initial/mech/vac. Egr affects A/F ratio so make sure it is functioning correctly if one is so equiped. Don't try to fix a vacuum leak by changing carb A/F metering parts. Take a look at your spark plugs also as they can tell you a lot about how the engine is setup. If all other things are correct and you are running rich or lean then refer to the table in the booklet and move as small a step as available in the cruise or power curve toward rich or lean as applicable. Once again, if you operate your engine overly lean you risk serious damage to pistons and valves.
I have a wideband O2 sensor monitor that displays my actual A/F mixture in realtime. This is very different from the narrowband A/F mixture meters commonly available. The narrowband sensor based setups ONLY provide info relative to stoich which is 14.7 to 1. They will tell you if you are above or below, (rich or lean) but not by how much. They are useful for getting fairly close but will not tell you what your actual A/F ratio is. The good thing about them is they are cheap. All O2 sensors setups require the installation of a bung in the exhaust for mounting the sensor. The sensor must be before the CAT close to the exhaust manifold and should be installed in a vertical orientation if possible.

Here's a link to the manual:

http://www.edelbrock.com/automotive/eps_sect2.html
http://www.edelbrock.com/automotive/eps_1406.html

[ August 23, 2003, 04:02 PM: Message edited by: Wesdog ]

[clarkja]

what kind of 02 sensor do you have?part #,name,etc..?Is your gauge one that uses the led bars or does it have a needle like normal gauges?

[clarkja]

Oh,thanks for the link to the manual.I did not have one,but now I do.

[Chevelleguy]

The .073 rod is smaller at the large section and will make your fuel curve a little richer at part throttle but the same at full throttle.

[Wesdog]

Originally posted by clarkja:
what kind of 02 sensor do you have?part #,name,etc..?Is your gauge one that uses the led bars or does it have a needle like normal gauges?I got my wideband O2 meter from these guys:

http://www.techedge.com.au/

The sensor can be obtained from various places but it won't work with a narrowband O2 setup. You have to have the proper electronic circuit to interface with it. You can get the Bosch 13246, NTK L1H1 sensor from AutoZone for around $169.95.

Here's a photo showing the A/F ratio display:

http://www.fullsizejeeps.com/jeeps/files/Misc-Pictures/401_gauges1.jpg