how is it done, with the vacuum line atached or detached?

The only way I've heard and done it was with the vacuum line disconnected and plugged.

-Kevin

so you set it at idle to 43.5psi then attach the vacuum line?

Yep. unplug the vac line, plug the leak on the manifold, set press, stick the line back on. All pressure references are set like this. Are you tuning with your afpr or just trying to get back to stock settings?

I just grab the vacuum hose with a pair of pliars and squeeze.

Pulling and plugging got to be a real PIA for me. Guess I'm getting lazy in my old age.

Jake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

If there's vacuum in the line when you crimp it, you'll get an inaccurate reading because it's still trapped in there.