1406 metering rod swap

[Slantsix64]

i got a 318 with a 600 cfm edelbrock carb ld4b intake trying to improve throttle response. My Question is if I change my metering rods from 0.75x0.47 to 0.71x 0.47 would that lean out the carb or rich it up?

 

[rumblefish360]

Enrichment

 

[Slantsix64]

Enrichment

What would be a size to lean it

 

[rumblefish360]

Anything larger than the .075.
It is fatter there by taking up more room in the jet for less fuel.

Anything lower is thinner and allows more fuel past the jet.

 

[Slantsix64]

Okay I think I understand how it works now so If I added a 0.95 jets with those rods 71x47 then it would be leaning out?

 

[KindredSpirit]

Check out the 1406 owners manual from Edelbrock. It contains a graph of different rich/lean combinations and an accompanying chart of rods and jets. I think it's on the Edelbrock website.

 

[rumblefish360]

Is the jet bigger or smaller?
Is the rod bigger or smaller?

It’s all math from here!

If you make it leaner with a smaller rod, then a smaller jet will also lean it out more.

Go to Edelbrock. Ok and there automotive section and find the instructions to down load.

 

[j par]

I've been doing this on my 360 recently. Actually today I was looking at the smaller diameter rod. Somehow I got some odd jets that were 100? The throttle response was an improvement over the 98 but I'm going to try a smaller-diameter rod next and obviously see if I can get it any better or if it gets bad again.

 

[65Val]

The easiest way is to subtract the rod size from the jet size to get the"open" or "flow" area of the jet, eg: .95 jet - 71 rod = 24, and, .95 jet - 75 rod = 20, so the .95/75 combination will be leaner than the .95/71 combo.

Easy peazy.....

 

[MichaelSullivan]

Do you know what the AFR is or can you meter the AFR? The metering rod might not necessarily be the problem. The spring that is installed with the metering rod might be to strong and overcoming the vacuum at part throttle and allowing the rod to move into the secondary metering (0.047).