What manifold for a Holley Bugspray?

[xavier]

Guys,

plenum or isolated runner type? What is best with a Holley Bugspray?
Thank you.
Xavier

[Zach Gomulka]

If the carb has balance port between the barrels use an isolated runner.

[rick m]

I ran a plenum style on the first one I had in 1970/71.  It worked well but then again it was on a big motor (92x72) with Norris cam.  Later switched to duals.

RM

[Dave Rosique]

                                                          ^^^Yep^^^
Way back when I was a wee lad, the rule was "plenum with a Holley, isolated tube with a Zenith"
Around '75 or so, I ran a Holley Bugspray on a high compression 1835 that did pretty good (for a Holley  )

[xavier]

OK. For what I have seen and read both style were used(more of the isolated type).
What would trigger the decision? CC, cam, heads(single/dual),...
Thank you
Xavier

[Sarge]

The way I remember it was Holley on isolated manifold.  Zeniths were a little different... you could buy a new carb from say Auto Haus that was "set up" to be used as a single.  These worked best on a plenum style manifold.  There were plenty of Porsche Zeniths around, too but these came with different emulsion tubes and seemed to do better on an isolated style manifold.  The Porsche style emulsion tubes are marked S1... the others were marked K4.