MK IV engine vacuum

[AC Ventura]

I wonder if anybody knows how many inches if vacuum the 302 5.0 EFI produces at idle? Im considering an engine change and would like to know what is required for the brake servo.

[Paul Mundy]

Hi , My Haynes manual for the Ford Mustang 302 efi states 17-22 inches Hg at idle. My Superblower certainly idles in this range.
   
   Regards
   Paul

[AC Ventura]

Thanks for that helpful reply Paul. You say your s/b idles in this range. Can I presume you've actually tested that?

[Paul Mundy]

Yes I have indeed.
   
   Paul M

[silty]

I don't know if it helps but my Lightweight has 14" of vacuum at a 1000rpm idle.  It had a cam change and head work by Uniclip back in the day.  I do notice that heavy braking at low speed drags the revs down below normal idle speed and it actually stalled once.  Considering I don't brake heavily from low speed very often my view is that this minor inconvenience is worth it for the performance gains.