Annular Boosters

[tortuga]

Holley 750 XP, 427/535 ford racing stroker.

Butt dyno says oh yea...motor has a whole new sound and urgency

[Gaz64]

Looks good.

You have the right theory now.

Me, I would gone like the XP 850 I'm building at the moment.

Your 750 becomes about 700 with the annulars.

But I bet it is responsive with those 12 hole inserts.

How about sharing some jetting info.

[Tom Kirkham]

More info on annular boosters.

https://www.musclecardiy.com/perform...science-guide/

[joyridin']

They worked great on my Cobra when I put a new center section in my carb. Car ran like a dream and was twice as responsive compared to the old set-up.

[tortuga]

Originally Posted by joyridin'

They worked great on my Cobra when I put a new center section in my carb. Car ran like a dream and was twice as responsive compared to the old set-up.

And yes from what I have read, you do lose some WOT Flow capability, but I bet I've spent 10-15 seconds there over 19000 miles...gain HP across the board and big torque down lower, which the butt dyno verifies, and for a street car is more practical.

I jetted down 2, HSABs at 35, PVRS no change, threw in some new plugs see what happens. Idle circuits no changes.

The transition to the mains is much smoother and more urgent for lack of a better term.

It's interesting to look down the carb and see how much cleaner the gas comes out of the annulars than it did out of the down legs. Like putting yor garden hose nozzle on spray instead of jet...

[Gaz64]

Originally Posted by tortuga

And yes from what I have read, you do lose some WOT Flow capability, but I bet I've spent 10-15 seconds there over 19000 miles...gain HP across the board and big torque down lower, which the butt dyno verifies, and for a street car is more practical.

I jetted down 2, HSABs at 35, PVCRs no change, threw in some new plugs see what happens. Idle circuits no changes.

The transition to the mains is much smoother and more urgent for lack of a better term.

It's interesting to look down the carb and see how much the cleaner the gas comes out of the annulars than it did out of the down legs. Like putting yor garden hose nozzle on spray instead of jet...

You can probably go down again on the mains, another 2, then up 1 if necessary, and also pull some accelerator pump volume out.

Those pink cams deliver a fair bit.

Cams from smallest to largest :

cam color #1 #2

white 17cc - 19.5cc

blue 18cc - 20cc

red 18.5cc - 20cc

orange 19cc - 24.5cc

black 19cc - 18cc

green 24cc - 30cc

pink 30cc - 37.5cc

Some of the cams, although smaller in total volume, are more aggressive in the first third, so take care in selecting a cam.

Troy Patterson from TMP Carbs knows all about building LARGE Holleys that can go wide open at 1500 rpm. Not many can do that.
Not that anybody I know does, but shows what his carbs can do. He runs annulars on most of his carbs as a personal preference.
Once you've had annulars in a true tuned setup, you won't go back to anything else.

[tortuga]

Originally Posted by Gaz64

You can probably go down again on the mains, another 2, then up 1 if necessary, and also pull some accelerator pump volume out.

Those pink cams deliver a fair bit.

Cams from smallest to largest :

cam color #1 #2

white 17cc - 19.5cc

blue 18cc - 20cc

red 18.5cc - 20cc

orange 19cc - 24.5cc

black 19cc - 18cc

green 24cc - 30cc

pink 30cc - 37.5cc

Some of the cams, although smaller in total volume, are more aggressive in the first third, so take care in selecting a cam.

Troy Patterson from TMP Carbs knows all about building LARGE Holleys that can wide open at 1500 rpm. Not many can do that.
Not that anybody I know does, but shows what his carbs can do. He runs annulars on most of his carbs as a personal preference.
Once you've had annulars in a true tuned setup, you won't go back to anything else.

Thanks Gary!

printing this out for my man cave bulletin board.

Steve H
SPF 1764

[tortuga]

The latest tune: it has never run better or stronger, 70 pri jets, 40 pri HSAB pri, 35 sec, 75 Iab all around, 65 power valves, about 11" idle vac, 75 sec jets, 50cc pumps both ends brown cam sec, blue primary...plugs all nice and light brown, 20 deg initial 34 total, light springs. I know the 50cc pumps aren't really needed but I had them and don't need to worry about bottoming, plus it got rid of a touch of hiccup on secondary opening...good times