Hello Joe,

Thank you for contacting us.

You may have more than one condition giving you the issues you’re having.
The stumble or hesitation at the beginning of acceleration may be inadequate volume of fuel from the accelerator pump.
It can be adjusted by changing the linkage rod connection to the pump, to either increase the fuel shot or reduce it… it’s quick and easy to test and a good place to start.
The step up springs can be changed to give a quicker shot of fuel also.
Because your supercharger is adding air, you need to add more fuel to compensate and maintain a good air fuel ratio.
You may also need to go to a larger accelerator pump nozzle to get the fuel off idle your engine is demanding.
Edelbrock sells them in individual units or kits of 3 for tuning purposes, start by discovering what you have (numbers are printed on the nozzle assembly).
Changing the actual pump assembly can also yield a quicker fuel shot… The larger CFM carbs have a stiffer spring on the pump assembly rod.
Keep in mind that unlike tuning on a dyno, seat of the pants tuning takes time and involves taking several small steps and testing each one… check your timing as you go also… you may need to add more timing as you add fuel.

Now let’s talk about your backfire issue…
Engine backfire can be a lean or rich condition. Check your plugs to get an indication of how the engine is running… If they are black you may have a rich condition, but I suspect you are probably running lean as that is the most common with a supercharger added.
You may need to add bigger main and secondary jets if you’re too lean and/or smaller ones if you’re too rich.

On a dyno you can constantly check the air/fuel ratios and adjust accordingly, but for the home shop enthusiast, you can get there it just takes a little longer, so don’t rush it.
Edelbrock also has great tech support, if you get stuck their team can assist you in getting the most out of your car.

Let me repeat one more time… Carb tuning and engine timing go hand in hand, and when adding more fuel and air into an engine it may need a little more time to burn it so consider adding a few degrees more advance timing and testing your performance.

If you have any other questions, please chat, email, or call Customer Service. 

Sincerely,

Sarah
Classic Car Restoration Club Video Membership

Hello Scott,

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Thanks!

Hello Jerome,

Here’s what our expert had to say regarding your question:

Hi Jerome,
A nice daily driver combination would be a Edelbrock Performer #2711 intake and a Edelbrock Performer 500cfm or 600cfm carburetor.
Running the numbers, ideally you should have around 550cfm carb. of course nobody makes a 550cfm carb.
Most guys opt up to 600cfm, although it will run fine with a 500cfm carb and have better vacuum.

Sincerely,
Julia
Classic Car Restoration Club Video Membership

Best,

Jerome

Hello Richard,

Thank you for your patience while I got the answer from the expert, here is the reply:

My apologies for the long delay in response the engine expert we referred your question too experienced a sudden death in his family and has been called out of town to help settle the estate.

We referred your question to others in his absence, and here is the feedback.
Camshafts are measured in three ways: Lift, Duration and Degrees of Lobe Separation.
Using only the duration specifications you’ve listed, while helpful it fails to give us the complete story as to how your camshaft should perform.
The failure of your engine to idle without additional throttle input suggests it needs additional tuning perhaps even larger primary and secondary idle jets.
We suspect the lack of power below 3000 rpm may be cam related, but don’t have enough information to say that definitively.

Wrench Safe,

Mark
Classic Car Restoration Club

You’ll have to forgive me as I feel the need to forward your question to a few of my associates whom are more familiar with this great little sports car. It may take a few days to hear back from them, so please bear with me as I await their response.
Wrench Safe, Mark