This page is an article from Hot Rod Magazine, June 1986, an article called "Family Ties" that compares the Ford / Holley 4180 to the generic Holley 4160 600 CFM vacuum secondary carburetor. It also shows how to modify the carb with a metering block and jets for the secondaries and talks about other hop up tricks.
If you want to down load a full size scan (it looks much better than this page) of this article to print, click here: Holley 4180 ZIP file .
I used this article to sucessfully modifiy my 4180 to run well (even
passes emissions) on my 5.0 Mustang with Edelbrock Performer Heads,
Performer Intake and Crane 2031 cam. The only mods I performed
to open the secondary idle stop about one half turn so I could shut the
primary idle stop enough so the idle transfer slots were not uncovered.
I also exposed the idle mixture screws on all four barrels by cutting
the casting (used a cut off wheel in my Dremel tool) around the
plugs. Forget trying to drill those plugs out, they're made out of
or something equally as hard!! I adjusted the four idle mixture screws
until I had maximum vacuum at idle. I also used the lightest vacuum
diaphram spring and removed the check ball as described in the article
(it made a big difference!). That's all I did. I would probably convert
to a secondary metering block as described in the article if / when I
to the track and try to change jetting for maximum performance. I kept
the stock two stage power valve since this is a street driven car and I
have enough vacuum to prevent opening the power valve at idle.
Page last updated February 26, 2006