Racing Fuel Systems

So on the weekend I decided to install annular boosters on the primary side ( was stepped dogleg ) in my 3310-1 780 cfm holley. See picture.
These boosters have 8 holes aprox, .072” .I left the calibration the same to see the effect.

PRIMARY
PMJ 69 --- PVRC .060---- IFR .036 ---- EMULSION .028 .028 – 6.5 PV

SECONDARY
SMJ 72---PVRC .068-----IFR .036------EMULSION .027 .027-- 6.5 PV

MAIN BODY
PIAB .078--- HSAB .027
SIAB .028----HSAB .024

Here is what happened
40 mph went from 14 AFR to 12.4
60 mph went from 14.5 AFR to 12
70 mph went from 14.5 AFR to 11.5

The question is , where do I go now. Thinking dropping PMJ to 64 ,test and evaluate.

454/500+ hp BBC camshaft 227 @ .050” LSA 107
Intake manifold Professional Products single plane ( Victor Jr replica )

I will preface this with the fact that I am in no way qualified to help you out in this endeavor, and I don’t want to muddy up the thread. That being said I do have questions.

1) are you running 1:1 linkage? And if not why the secondary PV?

2) curious as to why the large difference the IAB’s primary vs secondary?

3) noticed no secondary squirters?

Just wanting to gain knowledge.

"The question is , where do I go now. Thinking dropping PMJ to 64 ,test and evaluate."

A major function of the emulsion system is to emulsify (atomize) the fuel. Most 4150 Holley's use D/L boosters, therefore need heightened emulsion for atomization. Annular boosters atomize better than D/L boosters and therefore do not rely so much on the emulsion circuit for this. I suggest that you decrease the amount of emulsion in the E-circuit & HSAB relationship and reduce PMJ volume. I would do the same on the secondaries.

For steady state level cruising as outlined I’d start with the 64 jet to lean all points as tested. Retest for new AFR data set and then work on IFR and iab for lower speeds. You will find how far into the rpm (mph) IFR/iab is influencing fuel delivery and then that would lead you in the direction for changes to mains outlined by Mike above as rpm and therefore mph go up when it’s predominantly operating on mains. When you find AFR trend your looking for change PMJ up or down if required. Then onto pvcr and secondaries for load conditions.

Good luck

Seems like a good test result about how important atomisation is to power production & it is suggesting the same power can be obtained with less fuel [ smaller MJ ]. Certainly, on THIS engine, others might be different.

So i went ahead and made changes yesterday before I read the responses from you guys.

First I reduced PIAB from .078 to .076 and IFR from .038 to .036 ( my first post had incorrect IFR size )
Also I dropped the PMJ from # 69 to # 65
Cruise AFR went from generally 12:1 to 13.5:1

Next I dropped the PMJ to #62
Cruise AFR went to 14.5 fairly consistent at each 40mph 50mph 60mph and 70mph
On light acceleration the AFR leans a bit, which I am comfortable with.
WOT went to aprox 13:1
I failed to mention that I have a .068” TSR ( not sure if this is effecting anything , based on size )

So the question is , do I reduce emulsion size as Mike has recommended?

Thanks for taking the time to explain. I suppose if I was on the computer and not the phone I would have seen the vacuum pod and the metering blocks better. Interesting stuff about the PV on the secondaries from the factory and nice work on the blending to improve flow. Thanks again for the reply.

Right hand drive wrote
Have you had to do anything with the primary acc ct yet?

You could start by removing 2nd .028” emulsion leaving one at the top. When checking effect on AFR also check effect on throttle response.

Primary acc ct : .025 with 218 ( white ) pump cam as original I believe, works fine.