edelbrock carb tuning?

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This thread is hilarious.

I Personally Like Edelbrocks', as well.

I run a 1406 600cfm Electric Choke on a Big Block 400.

It runs pretty good., but suffers from wanting more airflow up top. I really learned alot about it as I dialed it in.

Edelbrock Carbuerators run great when ALL THE OTHER basics of the Fuel, and Ignition Systems are in top shape. Trying to dial in a Edlebrock with a issue anywhere else is a False Tune.

The Basic Idea is :

Plug the Vac. Advance Port.
Crank Engine
Set Ignition timing to highest steady vacuum.
Set Idle to 900-1000
Adjust RB Idle Air IN until you hear the DROP, then adjust out 1/2 turn
Adjust LB Idle Air IN until the DROP, then adjust out 1/2 turn


Plug back in Vac. Advance, Test Drive.
 
dodgetkboy78 said:
Dude, you can't tell someone what springs, jets, and suck to run on their crab from a computer............

AND I have had 1406's that ran pretty fat in stock form, a lot depends on the cam, manifold, head, timing, altitude, gears in the car.............................
Click to expand...

DUDE!!!
EGGGSACTLY!!!!!! That was a joke!! after reading all the prev & post advice it is even funnier!!
The only way to do it properly is to take it to a frame dyno. the o2 will tell you how rich or lean it is and adjustments are made from there.....and like someone else said EVERYTHING ELSE HAS TO BE working properly or its a false tune. SPEND THE MONEY IT IS WORTH IT!!!

NO one can accurately diagnose ANYTHING over the internet...they can get you close to an area to check out( IF the description of what is happening is accurate...BIG IF)....but tuning a car, ONE MUST be present in order to do it correctly....is it poppin back, is there a dead miss, is it hard to start....listen to it run...does it sound close? ...how do you do that stuff over the internet?
 
66cuda said:
600 cfm electric choke 1406 carbs are set up for "economy" out of the box......which means they run pretty lean (DANGEROUSLY LEAN) other can explain what that does in detail but essentially it detonates pistons ( UN-GOOD)

Move the stock front jets (95-98's I think) to the rear and put the 100's in the front with the stock meter rods...... replace the stock metering springs with the Orange ones from the kit....

remove the vacuum advance tube and plug the port at the carb........ then start dialing in your timing

OH ya moving the accelerator pump UP to the TOP most hole will give you a lil extra squirt

The counter weights on the secondary s are cast/stamped....you can shave them if you want/need to for quicker open but do it a very little bit at a time...once you go to far you are screwed.....shave a taste then try it......shave a taste then try it when you get close STOP.....typically the next shave will take you over the edge and it will open too fast and bog....

ALSO check your ignition....sounds a lil like you may be getting random spark levels..... are you running points or HEI........if points they may need replacing....if HEI have it checked....it may be failing or going "random"....

my 2 cents
good luck
Click to expand...
not on a mild teener!
 
UGH!!! The neat thing about free advice is you get what you pay for. Lotsa BS in this thread!

Let's get back to first principles. There's an old saying that "99% of carb problems are ignition related". This old saying is based in historical fact. Anyhow, your situation begs a few questions:

Is this carb new, or used? Do you know it's history? Do you have the Edelbrock manual that came with the carb? Have you read it?

Are you sure you don't have a vacuum leak somewhere? 99% of all non-ignition related carb problems are vacuum leaks. PCV system installed and functioning correctly?

Is this off idle flat spot something you can "step through?" That is, if you push the pedal down a little further, say 1/2 way will the car accelerate smoothly? Or, the more you push the pedal, the more is will bog and blubber?

If the carb is new, did you double check the float levels? Even if it isn't, this is the absolute first thing you must do when tuning any carb.

Do you have a vacuum gauge? Timing light? Tachometer? Dwell gauge (for points)?

Is your distributor functioning properly? Does the mechanical advance work? Test this by turning the rotor clockwise by hand and releasing, it should spring back all the way. Vacuum advance? You need a hand vacuum pump to test this (pretty cheap at Sears or HF). It should move the breaker plate when vacuum is applied, and hold vacuum. If it springs back as soon as you quit pumping vacuum, it's junk, and will cause an off idle stumble. Alternately you can test one of two ways: With the engine running at idle, connect the vacuum advance hose to the manifold vacuum port (drivers side) on the front of the carb. The timing should advance 10-15 degrees and the idle speed should pick up noticeably. Alternatively, disconnect and cap both ports on the front of the carb and test drive the car. If the stumble is gone, the vac advance is leaking. If you have points, make sure the dwell is correct. Static point gap will get you close if the distributor is new, but dwell is the only way to set accurately. How about the other obvious stuff like plugs new and gapped correctly, cap, rotor and wires new?

How about general engine health? What is your manifold vacuum at idle? Is it steady? Does the needle twitch or fluctuate? Internal vacuum leaks? Test this by sealing the crankcase breather with your thumb with the engine at idle. You should feel vacuum build, but the idle speed should not change. If it does, or if pressure builds you have bigger issues.

Next, we can focus on tuning the carb. Read the carb manual, it tells you pretty much everything you need to know. Seriously. Next do what Prine said above. This will get you "lean best idle" but will probably end you up with the timing a bit fast. No big deal, you can always roll it back. The big thing when setting the carb is to get the timing set to something reasonable and then leave it alone so you can get the carb dialed in. So, go richer or leaner? On an out-of-the-box 1406 at sea level, I'd start by going richer. Assuming you have the stock #1427 (.098) main jet, try a #1455 (.073x.042) rod. That will be a 6% increase. Orange springs will probably help throttle response as well.

ONLY CHANGE ONE THING AT A TIME! And then test drive. If you change 2 or 3 things you may fix one problem while creating another. You'll never know where you're at or what worked.

As for the crank damper, if the ring has slipped not only will you have a hard time knowing where your timing actually is, it isn't doing any dampening anymore. Fix this.
 
C130 Chief said:
UGH!!! The neat thing about free advice is you get what you pay for. Lotsa BS in this thread!

Let's get back to first principles. There's an old saying that "99% of carb problems are ignition related". This old saying is based in historical fact. Anyhow, your situation begs a few questions:

Is this carb new, or used? Do you know it's history? Do you have the Edelbrock manual that came with the carb? Have you read it?

Are you sure you don't have a vacuum leak somewhere? 99% of all non-ignition related carb problems are vacuum leaks. PCV system installed and functioning correctly?

Is this off idle flat spot something you can "step through?" That is, if you push the pedal down a little further, say 1/2 way will the car accelerate smoothly? Or, the more you push the pedal, the more is will bog and blubber?

If the carb is new, did you double check the float levels? Even if it isn't, this is the absolute first thing you must do when tuning any carb.

Do you have a vacuum gauge? Timing light? Tachometer? Dwell gauge (for points)?

Is your distributor functioning properly? Does the mechanical advance work? Test this by turning the rotor clockwise by hand and releasing, it should spring back all the way. Vacuum advance? You need a hand vacuum pump to test this (pretty cheap at Sears or HF). It should move the breaker plate when vacuum is applied, and hold vacuum. If it springs back as soon as you quit pumping vacuum, it's junk, and will cause an off idle stumble. Alternately you can test one of two ways: With the engine running at idle, connect the vacuum advance hose to the manifold vacuum port (drivers side) on the front of the carb. The timing should advance 10-15 degrees and the idle speed should pick up noticeably. Alternatively, disconnect and cap both ports on the front of the carb and test drive the car. If the stumble is gone, the vac advance is leaking. If you have points, make sure the dwell is correct. Static point gap will get you close if the distributor is new, but dwell is the only way to set accurately. How about the other obvious stuff like plugs new and gapped correctly, cap, rotor and wires new?

How about general engine health? What is your manifold vacuum at idle? Is it steady? Does the needle twitch or fluctuate? Internal vacuum leaks? Test this by sealing the crankcase breather with your thumb with the engine at idle. You should feel vacuum build, but the idle speed should not change. If it does, or if pressure builds you have bigger issues.

Next, we can focus on tuning the carb. Read the carb manual, it tells you pretty much everything you need to know. Seriously. Next do what Prine said above. This will get you "lean best idle" but will probably end you up with the timing a bit fast. No big deal, you can always roll it back. The big thing when setting the carb is to get the timing set to something reasonable and then leave it alone so you can get the carb dialed in. So, go richer or leaner? On an out-of-the-box 1406 at sea level, I'd start by going richer. Assuming you have the stock #1427 (.098) main jet, try a #1455 (.073x.042) rod. That will be a 6% increase. Orange springs will probably help throttle response as well.

ONLY CHANGE ONE THING AT A TIME! And then test drive. If you change 2 or 3 things you may fix one problem while creating another. You'll never know where you're at or what worked.

As for the crank damper, if the ring has slipped not only will you have a hard time knowing where your timing actually is, it isn't doing any dampening anymore. Fix this.
Click to expand...


we are pretty much on the same page, orange springs , richen it up......but this only gets you "close"... Close may be good enough...but guys dont believe the 1406 is set to "economy" out of the box...HENCE the advice to go to a frame dyno shop....
 
SirDan, Go to Edelbrock web site and print the very detailed instructions they have.
It will take a couple of times reading through it. I cured my stumbling with weaker
step up springs.
 
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