Racing Fuel Systems

Dec '12 date [3452], but like new. Holley "tech" said that they came out around then, but could not tell me differences between it and the -1. Afaik, they called them "HP ultra" until the -1 version came out, which was named "XP". This first version of the 80804 has HP cast on the bowls, but has the longer 9.750" inlet C/L to C/L. Notched drop leg boosters. Adjustable bypass air. T-slots are .190" Dark gray. [I still like the zinc carb old look better]. Has two options on progressive throttle linkage.

Stock is 84/84, 4.5 PVs w/.059" pvrc. High .035" ifr, .036" MABs, .067" IABs. emulsion is all 5 at .028". I studied at the old board, and decided on;

#76 pmj, .081" pvrc [richer to start than tuner's #76/.076" pvrc on a HP1000]. Moved ifrs down, .035", MABs .025", IABs .070". Emulsion from top .028"_'028", _, _. The boat guy was advised to try swapping 3 and 4. I'll do same. TSRs in front, .081".

Feel free to critique. I'll report back. It will replace a QFT RQ 850 that has too long T-slots. [for sale]
Thanks.
Dave

With brand ‘D’ 850, same 1.56” venturi and 1.75” throttle blade on mild 383 (~500hp) I had success with stable AFR set as below

IFR - .031” low
IAB - .070”
MAB - .028”
E-bleeds - .028” x .028” x x
PVCR - .063”
MJ - Pri 80 / Sec 89

You have TSRs so .031” might be too small but I guess IFR, IAB, PVCR and MJ would all be individual engine specific. For an experiment I added a .028” to the bottom e-bleed for a noticeable response improvement with a small penalty to AFR stability.

So that’s another baseline to reference from.

Thanks!