Annular boosters effect

[cat herder]

I think the insert probably goes all the way through the banjo, it looks like it's swaged over (outwards) on the top. Without that it's depending solely on a press fit to not fall out the bottom and hang the throttle open.

[CDN]

Been following this since you started as was considering changing to annular boosters since I no longer take car to track
Has been very helpful Thankyou
Just had annular boosters installed on my 80513 HP1000 carb - still working on getting my cruise afr in high 14’slow 15’s
consistently
But so much better low speed response and cool weather drivability Very happy I changed to annular on this large benturi carb for street use I also changed to a heavy flywheel from lightweight and low speed response is still better
As has been said amazing how much jet you can take out ( in my case 6 sizes !! and gonna try houng down one more size ) and still make same power with better fuel atomization

Idle AFR IS 13.9 / 13.6 was never that even between banks before
.035 IFR .073 IAB mix screws 1 turn out
I thought .035 a bit big but at 1 turn out I assume it close ??

[cat herder]

[GTO Geoff]

The # of turns out the mixture screw is also affected by how much T slot is exposed at idle. If the T slot is barely visible, then the mixture screw[s] will be out further than if 0.060" of T slot is visible.

This is why the sequence is so important to setting up idle/transition:
FIRST thing: get the idle timing right [ Could be as much as 50* for big cams ]
2nd thing: T slot position. Zero to 040" below blades is best. Get it correct with bypass air.
3rd thing: off idle/transition rich or lean condition. Adjust with TSR to get it correct. If still lean, enlarge IFR.
4th thing: adjust mixture screws.

[CDN]

Great Tuning Guideline GTO Geoff
Thanks for posting !

[rgalajda]

The boosters were knocked out with a punch that I sized for the application . The boosters were then threaded to accept the special nuts. Barry Grant designed this system of removable boosters. You can buy this kit from " All carbs " in New York. The main body then gets machined with these tools to accept the special nuts to hold the boosters in.

https://allcarbs.com/product-category/castings/

[57 210]

Great pictures and good information as usual.

[jmarkaudio]

The primary reason for an emulsion system is to fix the curve that using a booster creates. Emulsifying fuel is a benefit, but not the primary use. With down legs you can improve performance a little with the right amount, but on a street car the fuel curve will suffer. Unless it's on a higher end race engine I would avoid it and then sparingly.