Hey you Edelbrock guys ... listen up

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Fast79Chief
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Joined: Wed May 09, 2018 7:10 am
Location: Eastern Pennsylvania

Hey you Edelbrock guys ... listen up

Post by Fast79Chief »

So here's a quick tip for you to really dial in that carb just off idle. I'm going to use the 79 AMC 360 and 1406 example today. Pay close attention here cause it can get confusing.
First thing is check your timing with a light to make sure you are where you need to be at the specified RPM.
Next is your fuel pressure into carb. These carbs are pressure sensitive for proper functioning . Under 6 lbs. Is best.
Warm up your engine fully, I mean fully.
Shut it off. Remove your air cleaner. Loosen the two step down rod assembly cover screws just enough to slide them aside so that they are still half covering the top of the spring barrel assembly. Do not remove the covers.
Start your car. Leave it in neutral or Park.
Your engine CANNOT be idling too high for this setup to work. If you are idling too high, then you are already outside of the IDLE CIRCUIT and into the intermediate circuit of your carb. Adjust your idle so that you are NOT opening the primary butterfly too far.
Now look at the rod/spring/barrel assemblies at idle. They should be firmly planted about 1/2" down in the chambers at idle and not moving.
Now crack the throttle a shot. Not slowly open and not a wacko blast ... a small 1/8 to 1/4 primary quick shot.
If your barrel assemblies don't pop up with each crack of the throttle, then suck back down at idle ... you are NOT setup correctly and running worse than it could and should.
Shut off the engine. Now slide the little covers over out of the way enough to pull out your Rod, Barrel and Spring in each side. Careful not to drop those springs into your carb throat.
If this assembly was NOT jumping up when you cracked the throttle, you need to go to stronger setup springs.

I have around 18-19" of vaccum at idle (750 rpm in Park) and this requires the Silver (strongest) springs to overcome that vacuum when you come off of idle and are trying to tip into intermediate/cruise circuit.

Select the spring with the proper tension to operate these step-up assemblies as I described above, then further mixture tuning can go from there. Edelbrock makes a set of 5 or 6 spring pairs that are calibrated to different vaccuum strength. You can buy the set for cheap.

Until you address your engine vacuum signal FIRST ... with these carburetors you are chasing your tail with rod and jet changes.

Most people do not know that you can observe this circuit functioning with the engine running at idle in (Neutral or Park) . Saves a lot of guesswork and trial and error, when you can SEE if the step down circuit is working or not while running.

Once you have the proper springs in place, then and only then should you go onto fine tuning Rod and Jet combos for off idle and cruise response and power. There is a Tuning Chart for your specific model edelbrock online. Follow the tuning instructions in the manual and according to the Rod/Jet chart to get the response you want.

That's it. This little trick of observing the step-down assemblies work is key to initial tuning. It's easy after that.
1979 Cherokee Chief S, V8, MSD Pro Billet Distributor with New Factory Ignition Box (are these 2 even supposed to work together?), HEI Wires, Edelbrock 1406, Edelbrock Performer manifold, 3.54 gears, Tru-Trac Locker in the rear, Turbo 400, New Quadratrac, Dual gas tanks, new 32 x 11.50's, Big 9000 winch, Homemade 2.5" full length exhaust, Custom Headlight Harness, Custom front bumper working, Custom Rear Swing-out Bumper, Class V receiver hitch ... and a lot of work to do yet. :)
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