Edelbrock Carburetor Tuning
For starters, should I just change the two plunger springs to the strongest ones?
I disagree with most of the questions above.
For starters you need to isolate the issue.
By breaking up the different situations, the circuits that need adjusting can be isolated.
On these carburators, many of the systems interelate. Because of that the sequence of isolating is important.
heres how to break it up and check each situation.
0. Warm up. The choke system and fast idle system changes everything. With a new carb, get it idling and come back this later.
Once its warmed up.
1. Slow idle. Slow idle in gear if on an automatic. Goal here will be slowest rpm that will idle strong and smooth in gear. On a stock engine this should be anywhere from 500 rpm to 750 rpm on some smogged engines. it will take several tries. Get it close. Come back to it again later when the engine has been driven.
2. Low speed system. Slowly accelerating from stop or low speed. Specifically opening the throttle slowly. This reduces or eliminates the need for pump shot.
3. Low speed cruising. Driving at a steady speed and rpm on fairly flat ground or slight uphills. Anything 45 mph and under.
4. High speed cruising. Driving at a steady speed and rpm on fairly flat ground or uphills. Anything 65 mph and over on flat. Less on uphills. Exactly where the main system fully takes over is hard to know without testing for it.
5. High speed system response. Firmly part throttle acceleration at highway speeds (like interstate passing) or uphill.
6. Step up system. Increasingly open throttle at speed. Probably best from at least 35 mph. Every increase of throttle opening should result in a corresponding increase in power.
7. Rapid acceleration from stop or very low speed. This is testing pump shot. it can only be settled upon after the steady and slowly acceleration tests are good.
8. Full throttle acceleration at high speed. This is the test for secondary opening characteristics.
This will make ALOT more sense if you watch the video and/or read Chrysler's late 60s Master Tech on Carburetor Fundementals
Master Technician Service Conference - Chrysler's Training for Mechanics