Ok, Holley has just sent me a replacement 68mm TB with the appropriate throttle screw in it to replace my post production unit that no one can figure out how I got it.

The problem I am experiencing is the revs stay up when I get off the gas.

This is somewhat puzzling to me considering the post production unit did not do this.

I have tried to dial the throttle screw all the way in, and all the way out. No change, in either idle or dwell.

I am wondering if this has something to do with Spec b's. Do they create enough vacum to warrant extra fuel being provided?

This is puzzling. Has anyone else had this problem with any mods they have done?

Thanx in advance...

 

You likely have a vacuum leak somewhere. Recheck your work!

 

Yeah, I thought about that. It is unlikely because the idle does come back to 850ish; it just takes a while to do so.

That is why I am curious...

 

Sticky throttle cable/linkage?

 

No, all good. I even put a return spring on the opposing side in order to ensure the throttle plate was closing.

I cannot figure it out.