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Your carb has a larger venturi size . That being the case I don't know what to recommend, as I don't work on large venturi carbs booster setups.
Right hand drive has given good info on what he has used. That sounds like it is working well for him. I would call BLP and ask them what they recommend, given your setup and of course street driving.
Booster leg ID and discharge hole is an important part of the equation, especially if you can't easily remove the booster for reconfiguration.
Mike Laws or Jmarkaudio could help here if they are still reading this forum.
Statistics: Posted by rgalajda — Sat Apr 01, 2023 10:15 am
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at this point Im going to try my carb with annular boosters , now just to understand sizing etc
I found an old post from 2015 on Yellow Bullet
" Annular Boosters ...Please educate me " jmarkaudio had some very good posts that were very encouraging to try annular boosters on street car with a large venturi carb
My current carb has no performance issues its just I now drive my car alot at low rpm on street with manual trans and my afr is very irregular between banks with dual plane intake esp after I went down in the IFR and up in bleeds to get nice clean idle and lean cruise
Statistics: Posted by CDN — Wed Mar 29, 2023 6:25 pm
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I also threaded my own boosters.
Statistics: Posted by rgalajda — Wed Mar 29, 2023 11:33 am
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https://allcarbs.com/product/down-leg-b ... ation-kit/
The thread Allstate uses is 5/16-32 UNEF. If you then source a 5/16-32 UNEF die you are then able to broaden the available boosters to try in the main body and are not locked into what Allstate supply. I purchase the BLP banjos and .600” id inserts and have also tried their machined downleg booster and Braswell style. The die can be run down any of these boosters mounting section to make the thread without needing to size first. Doing this greatly improves the tuning flexibility of your carburetor.
These are BLP 16 hole annulars that have been threaded with the mentioned die
On the left is a BLP machined downleg. On the right Braswell style I’m yet to trial.
Statistics: Posted by Right hand drive — Wed Mar 29, 2023 10:12 am
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https://allcarbs.com/product/holley-hp- ... -boosters/
Statistics: Posted by rgalajda — Tue Mar 28, 2023 6:13 pm
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Any specific annular booster I should use ??
Statistics: Posted by CDN — Mon Mar 27, 2023 5:49 pm
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On a light race car that launches at say 4500 rpm and up, the downleg booster will be adequate in a 1.56 venturi.
An annular booster has a larger inside diameter ( excluding mini annualars ) which forces more air flow through the booster, improving the signal. Plus will have multiple discharge holes for better fuel atomization.
For a street car that has to deal with a wide working rpm range, the 1.56” Venturi and a downleg booster will be poor at low main -venturi speeds. The signal drops by a sizable margin compared to a 1.4 venturi. This is where a high gain booster to amplify the main venturi signal is needed.
When converting your carb to Annular boosters the IFR can stay the same size. The IAB , maybe?
I converted my Holley carb primary boosters to annular last fall. Although I didn’t have time to finish the testing before the season turned cold, the initial tests showed better throttle response at lower rpm. And that was a 1.4 venturi carb. I used 8 hole aprox .072” boosters. Primary jet dropped 4 sizes. Also fuel mileage improved. 800 cfm carb pictured below.
Statistics: Posted by rgalajda — Mon Mar 27, 2023 11:02 am
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Statistics: Posted by CDN — Mon Mar 27, 2023 2:40 am
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Statistics: Posted by Duh — Mon Mar 27, 2023 2:30 am
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Y , the lower of two of your pictures does that have annular boosters?
I have been told the very early 850DP main body had the best designs but not sure why or what boosters or venturi size
I might consider changing main body too
Statistics: Posted by CDN — Mon Mar 27, 2023 2:15 am
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Statistics: Posted by Duh — Mon Mar 27, 2023 1:16 am
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