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Old 06-06-2010, 08:06 AM
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edelbrock carbs

when changing the metering rods on the model 1412 800cfm, does increasing the size of the metering rods eg .71-.48 to .73-.52 increase or decrease the amount of fuel going through the jets. AS well I changed the metering rod spring which are controlled by the drop in engine vaccum from lightest to most stiff also went from a K&N 14 by 14x2.5 filter to a system flow 14x3 and the xtreme lid which lets an extr 500cfm of air if neede so they say but when my air inducion flaps open there right above the carb with no choke horn and I picked up .88 sec in the 1/4 and 11mph, its a .60 over 010 block with 397041 heads fully ported xe268 hyd cam 1.6 roller rockers m21 with 3.73's in it.Its mainlly for the street but man is it fun to drive its a 1980 Z28 that I just finished working on after 4and a half years.nights weekends Thanksgiving I'm sure more than someone out there has been there and done that or is still there.
Well getting back to my question about the metering rods any help would help. Please anyone your advice will be thankfully received and faithfully applied.

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Old 06-06-2010, 08:40 AM
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Quote:
Originally Posted by sapsz28
does increasing the size of the metering rods eg .71-.48 to .73-.52 increase or decrease the amount of fuel going through the jets.
You leaned it out on the cruise and power mode.
http://www.telusplanet.net/public/gi...d/carb_jet.htm
There is a chart on the bottom of the linked page that may come in handy. It doesn't cover all jet/rod combinations but it's a start. I prefer to figure the area of the combo rather than use edelbrock's calibration charts as they are skewed in places.
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Old 06-06-2010, 08:43 AM
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Quote:
Originally Posted by sapsz28
when changing the metering rods on the model 1412 800cfm, does increasing the size of the metering rods eg .71-.48 to .73-.52 increase or decrease the amount of fuel going through the jets.
The fuel flow through the jet is DECREASED, i.e. a LEANER air/fuel ratio will be the result.
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Old 06-06-2010, 09:46 AM
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edelbrock carbs

However At Wot The Springs Are In There Upmost Position Leaving The Rod At Its Highest Point Therefeore The Jet Has No Blockage And Is Letting In As Much Fuel As The Motor Will Pull In According To The Calibration Book.
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Old 06-06-2010, 10:09 AM
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That's not exactly correct, the primary side will either be on the thicker or smaller side of the rod depending on vacuum and spring used, it won't pull all the way up and out of the jets.
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Old 06-06-2010, 11:00 AM
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Quote:
Originally Posted by sapsz28
However At Wot The Springs Are In There Upmost Position Leaving The Rod At Its Highest Point Therefeore The Jet Has No Blockage And Is Letting In As Much Fuel As The Motor Will Pull In According To The Calibration Book.
If you swap a 0.071" x 0.048" rod to a 0.073" x 0.052" rod, the amount of fuel through the jet will be DECREASED. There is no point where the rod is retracted from the jet.
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Old 06-06-2010, 11:51 AM
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The rod moves up as manifold vacuum decreases.
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Old 06-07-2010, 05:03 PM
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edelbrock carbs

I have the strongest spring in there to help the rod lift up as high as possible to let the most amount of fuel pass through the jets as the callibration book instructs.
Thanks very much everyone for your help.

Last edited by sapsz28; 06-08-2010 at 12:06 PM. Reason: forgo to add
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