Quadrajet jetting

[schweng18]

Does anyone know what size the original jets are in the stock '81 Quadrajet?

I removed all of the smog contol equipment and think I need to install larger jets.

Any advice?

Thanks

Dave

 

[Yoda]

Dave,

I know nothing about this subject but... we have several L81'ers that have done some fabulous things to their engines and carbs... hand tight one will be along with some advice and suggestions..

Bud

 

[GerryLP]

Does anyone know what size the original jets are in the stock '81 Quadrajet?

I removed all of the smog contol equipment and think I need to install larger jets.

Any advice?

Thanks

Dave

Dave,

I am at work right now, but tonight I could send you the E4ME maual. It is about 8 megs, so let me know if you can receive it. I also believe I have it broken-down into four parts (this would then require 4 emails at about 2 megs each).

Generally speaking, the primary jets do not need messing with, since the L81 has the closed-loop mixture control (M/C), and the computer is going to adjust that as it is needed.

The secondary jets (aka metering orifice plates) are not removable. To effect a change in the metered fuel on the secondary side, one must change the metering rods which are designed to change their relative position within the metering orifice plates.

You shouldn't have a reason to mess with these unless you have a change in the engine's compression ratio, or basic deviation from original design. Perhaps your "problem" is just a matter for adjustment of key factors (TPS, M/C).

 

[schweng18]

Dave,

I am at work right now, but tonight I could send you the E4ME maual. It is about 8 megs, so let me know if you can receive it. I also believe I have it broken-down into four parts (this would then require 4 emails at about 2 megs each).

Generally speaking, the primary jets do not need messing with, since the L81 has the closed-loop mixture control (M/C), and the computer is going to adjust that as it is needed.

The secondary jets (aka metering orifice plates) are not removable. To effect a change in the metered fuel on the secondary side, one must change the metering rods which are designed to change their relative position within the metering orifice plates.

You shouldn't have a reason to mess with these unless you have a change in the engine's compression ratio, or basic deviation from original design. Perhaps your "problem" is just a matter for adjustment of key factors (TPS, M/C).

Thanks Gerry

I can receive the emails.

Dave

 

[schweng18]

Got it fixed! With a litttle guidance from my uncle the mechanic. It wasn't the carb at all, somehow the harmonic balancer must have moved a little bit and the timing mark is off. We set the timing by ear and kept adjusting it until the hesitation was gone. What an incredible difference, it's a totally different car. Thanks for al of the information though, I really appreciate the help.

Dave

 

[Peer81]

Good to hear Dave!
But if the harmonic balancer has moved, I think it's time to replace it. You don't want that big round metal disc getting lose at 3000 rpm!

Greetings Peter.

 

[schweng18]

I concur Peter. How is your project coming along?