I'll be taking a trip with the car to the Dyno in the next couple of weeks. Would like to get some tips on carb tuning. My carburetor is a Edelbrock AVS2 800 CFM model 1913. I have a complete tuning kit for it. Any help is appreciated. Thanks.

 

Does the "complete" tuning kit include step up springs for the power pistons? If not, get those. Dyno tuning unfortunately doesn't address transients like rapid throttle movement and resulting drop in manifold vacuum. I've found that the E-brock carbs almost always need different step up springs to fix the weak tip-in problem.

 

Yes the kit has step up springs. Will the weak tip in be indicated on the A/F ratio meters? Also when tuning should I start with step up springs first then rods then jets.

 

Yes, normally you’ll see a lean spike if the transition is too quick.
Do an inventory first, then just start with that.

 

Read through the tuning section in your manual starting on page #6.

do you have an O2 set up on your car? How long is your session booked for?

plan to have 1 lean set up and 3 set up’s on the rich side for WOT .

write down the requirements for each and have those set ups ready in a marked baggy . For example on the tuning chart using #9 (2 stages rich on main circuit and one stage rich on secondaries) you would need metering rods #1431 , metering rods # 1448 and secondary jets #1431

dont worry about changing step up springs or sec air flap tension during your initial WOT runs. Get your WOT to best power first.

you CAN set up light throttle tip in response on a chassis dyno..it’s not always WOT blasts. Depending on if your car is auto or manual, start at around 1500 rpm in 2nd or 3 rd gear and gently roll into the throttle.

be prepared and use your time wisely

 

I don't have o2 sensors on my car. Guy at the chassis Dyno said he would install them on the exhaust, I didn't ask him where on the exhaust. We're going to start with 3 hrs. I do have a progression ignition hei on the car so I can change timing with the app on my phone. Thanks for all the tips guys very helpful.

 

You can do some simple set ups before going. instal a set of step up springs that come in about 2” of vac above your idle vac in gear .

use your manifold vac reading for that. The springs are colour coded and have a min opening spec…those should be permanent once changed.

set timing to 33 to 34 all in between 2500 and 3k. doing those two things will get you off to a good start. The Ebrock carbs are so simple and quick to do any changes on. What also helps to speed things up is to have a long flexible fuel supply line that you leave connected and can lift off the top of the carb and sit it to the side while making changes. If you’re getting into removing the top multiple times, you only need four screws, one near each corner to run it again.

smear a light layer of white grease on top of the air horn gasket so it releases easy

it’s also a good idea to have a fuel pressure gauge close to the carb inlet.

 

I have a 4 speed Muncie, so should the idle vacuum reading be with the car in neutral as far as the step up springs are concerned?

 

in neutral, warm, correct timing and idle speed.

i should have said pic a spring that will open at least 2” below your idle vac. How many springs choices did you get in your tuning kit and the colour?

 

I got 5 sets of springs in the kit. Blue, yellow, orange,pink,and plain. My car pulls 8 to 9 inches of vacuum at 800/ rpm idle.

 

The pink is 7” , I would stick those in. That’s if you’ve set your idle speed by getting the highest idle with the idle mix screws, and then backing it down to where you want it.

the next one down is the orange 5” which could cause a slight flat spot off idle.