Setup for popular Hilborn Barrel Valves
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Hilborn w  #54 Spool – 8 Stack injections

Unblown Alcohol

Small engine  16%-20% with  .002” Butterfly 30 lb  secondary

Big engine  20%-24% with .002” to .002” Butterfly 30  lb secondary

.020” Wire spring in main by pass –  2-3 lbs

 54 barrel valve

Unblown Nitro

The higher the %, the more leakdown and larger air gap in the butterflies  

IE: 10% nitro = add 10% to leakdown % – Reduce the secondary pressure by 10%

Butterfly gap gets widened as nitro % increases –

use  .002” for up to 10%
.003” for 15% to 20%   30# secondary
.004” for 20% to 30%  10# secondary
For more Nitro than 30% – use a #56 Spool

54 barrel valve

Unblown Gas

Small Engine  10%-12% leakdown with  .004” Butterfly  30 lb secondary

Big Engine  12%-14% leakdown with .004” Butterfly 30 lb secondary

Spring in by pass =  .016” 1 lb pressure

Blown Nitro-   4 port or Shotgun

#56  #61 Spool

30% Nitro =  50% leakdown with .013”  Butterfly 12 lb secondary

40% Nitro=  60% leakdown with .015”  Butterfly 8 lb secondary

50%-60% Nitro = 70% leakdown with  .015” Butterfly 5 lb. Secondary

Blown Alky:  4 port or Shotgun

With 54 Spool:

30% leakdown  .008” B Flys 5 lb. secondary

With 56 Spool

35% leakdown  .008” B Flys 5 lb. secondary

Blown Gas  w 54 spool:

25% leakdown with .010”  B Flys 30 lb secondary

Blown Gas w 56 Spool:

25% leakdown with  .010” B Flys 35 lb. Secondary