[ap72]

just tune the carb you have. Edelbrocks deliver some of the best mileage you can get from a carb, and are dirt simple. Even with it in perfect tune at best you're only going to se about 9 mpg's with your combo.

[chevydragster83]

Originally Posted by bentwings

In order to make the AFR work or better yet to use it properly, you must have a very good understanding of how the carb works. You need to know how the idle circuit, transition power and cruise circuits affect the AFR.

Best bet is to get the Holley book with the cut away view of a 4500 on the cover. I don't have mine handy but just check Amazon.

Above all don't get "drill happy" before you understand what you are doing.

The AFR gage simply tells you what is going on. It can be misleading if you don't understand the carb. It's not hard learning you just have to put your mind to it.

I have read the manual that came with the carb and I have some understanding of how it works maybe. It show's how to calibrate it 1 stage lean, 1 stage rich etc. I would think I could at least get it to stob loding up on gas and smelling like its flooding with the manual, calibration kit and a AFR gauge couldn't I? Even if I can't get it right my self and have to take it to someone who can it would still be a nice thing to have.

[chevydragster83]

I got an Innovate MTX-L wide band AFR gauge. I installed it yesterday and let the engine warm up. It was staying in the low 12s then it dropped as low as 11.3 at idle after it had gotten warmed up. Looks like I have a pretty major rich condition. I am going to change the oil and take it out and see what it does at different driving styles this week before I do anything to the carb. That probably explains the terrible MPG and low power wouldn't you think?

[F-BIRD'88]

Ya at idle it is richer than it needs to be. You need to get the ignition curve in order first, before you dig into th4e carb.

Is the PCV hooked up and functional.?

What is the AFR at different part throttle cruise conditions say 30mph, 45mph, 60mph steady driving.

Once you have recurved the distributo as I outlined earler, the carb will want readjustment Idle speed and idle mixture screws. This itself will be a big clean up.
Use a manifold vaccuum gauge. THE ENGINE MUST BE FULLY WARMED UP before any real meaningfull assesment and adjustments.

Best to take it out and drive it around to get it all warmed up, then set the carb
idle up using the vac gauge and AFR meter ( the vac gauge is the priority at idle.) .

Next is to get the part throttle cruise dialed in. ( primary jet and rod choice.)
Then tune the step up spring tension ( start with the 4# spring)
Take it one step at a time.

The idle spark advance is critical. 24ish+/- BTDC base timing at idle is required
This does not include vacuum advance (yet)
This distributor curve needs modification first. You cannot get the desired curve by just swappping advance springs.

Get a manifold vacuum gauge.

[F-BIRD'88]

Initial "free air" calibration of that innovate gauge is critical. Tell me how that wide band gauge works for you. electrical Grounding is critical too. Watch for false - funky readings.

[chevydragster83]

Originally Posted by F-BIRD'88

Ya at idle it is richer than it needs to be. You need to get the ignition curve in order first, before you dig into th4e carb.

Is the PCV hooked up and functional.?

What is the AFR at different part throttle cruise conditions say 30mph, 45mph, 60mph steady driving.

Once you have recurved the distributo as I outlined earler, the carb will want readjustment Idle speed and idle mixture screws. This itself will be a big clean up.
Use a manifold vaccuum gauge. THE ENGINE MUST BE FULLY WARMED UP before any real meaningfull assesment and adjustments.

Best to take it out and drive it around to get it all warmed up, then set the carb
idle up using the vac gauge and AFR meter ( the vac gauge is the priority at idle.) .

Next is to get the part throttle cruise dialed in. ( primary jet and rod choice.)
Then tune the step up spring tension ( start with the 4# spring)
Take it one step at a time.

The idle spark advance is critical. 24ish+/- BTDC base timing at idle is required
This does not include vacuum advance (yet)
This distributor curve needs modification first. You cannot get the desired curve by just swappping advance springs.

Get a manifold vacuum gauge.

I have not driven it yet. I plan to test it out tomorrow.

The guy that installed the heads and cam for me installed a curve kit in the distributor when he done the swap.

I calibrated the gauge as the instructions explained to do. I ran a ground directly to the battery to avoid any noise.

I have a manifold vacuum gauge also.

I'll update after I do some test driving.

[bentwings]

It takes a good half hour of driving to get the motor completely warmed up to operating temp. The AFR reading will be all over the place so do be too concerned.

Be sure to get the dist setup correctly first. By all means use a vac adv if you want good mpg.

Download the Logworks program and make some runs to establish a base line. Make sure you note what you did on each log.

You will need a set of number drills from about 40-80 to measure the restriction and bleeds and jets.

Mark all of these down so you have a base line here too. Make sure you do not have any exhaust leaks before the o-2 sensor.

Also make sure yo

[chevydragster83]

I took it out today and drove about 12 miles at different speeds and the gauge showed to be in the 11s at idle and just off idle. It staid in the 12s until I got up to about 55 and it leaned down a little. It seemed to be staying right on 14 to low 15 between a quarter and half throttle, like pulling a small hill. At WOT it dropped into the high 10s for a second and then staid in the mid 11s. From what I could tell it was showing rich everywhere but at moderate throttle.

[F-BIRD'88]

Rich idle and just off idle:

is the PCV installed and functional?
If not , get one.
No PCV creates a rich idle.

What is the idle base timing and max mechanical advance?
May have to slow the motor down to read the base timing. (no vacuum advance)

[chevydragster83]

Originally Posted by F-BIRD'88

Rich idle and just off idle:

is the PCV installed and functional?
If not , get one.
No PCV creates a rich idle.

What is the idle base timing and max mechanical advance?
May have to slow the motor down to read the base timing. (no vacuum advance)

The PCV is installed and functional.

I don't remember what the timing is set on, but the guy that installed the curve kit set the vacuum advance and the timing when he done the heads and cam swap. I haven't messed with it because I don't seem to be very good with the ignition system. As soon as I get a chance I'll check to see what it's set on.

What about the WOT, is it pretty much safe to say it needs leaned down, or should I double check the ignition first?

[F-BIRD'88]

Originally Posted by chevydragster83

The PCV is installed and functional.

I don't remember what the timing is set on, but the guy that installed the curve kit set the vacuum advance and the timing when he done the heads and cam swap. I haven't messed with it because I don't seem to be very good with the ignition system. As soon as I get a chance I'll check to see what it's set on.

What about the WOT, is it pretty much safe to say it needs leaned down, or should I double check the ignition first?

Worry abut the WOT jetting last.

Get the mechanical spark advance curve corrected first. I guarantee it ain't right.
You cannot get the required curve by just throwing in a curve kit.
You must set up the mechanical curve stop limit to allow the increased base idle timing and correct curve and max advance.

vac adv is a separate issue.
Then work on the idle and low speed- part throttle jetting.

re read post #15