Calibrating a Holley HP 0-80541-1

[csx7031]

..."NASCAR Approved" 650 is proving to be very challenging. Engine is 330 CID SBF, 10:1CR, solid roller cam 244/250@ .050 .616/.616 lift, 108 LSA, Vic Jr. intake. Made 502 HP @ 6900 RPM, 423 TQ @ 5300 RPM with 750 HP 80528-1. Initially had holes in all throttle blades, wouldn't idle under 1800 RPM with idle screws all the way out. Installed new throttle blades (no holes). Will idle at 1000 RPM but transfer slot is almost completely covered, maybe .008 exposed. Best mixture screw setting is 5/8 turn CCW but plugs (AR3926) read lean. Hard to start, lean surge at 2000 RPM flat cruise, WAY down on power. The calibration seems odd to me. Maybe it is the "NASCAR" calibration
Straight leg booster, all jets 71, ICR .030, IAB .072, HSAB .041, PVCR .044, emulsion top .028, middle .033, bottom .033, siphon break .026, jet block number 11978.
I'm almost at a loss on how to proceed with calibrating this carb. I can go back to the 750 HP but, I'd like to try to make this thing work if possible. Any and all input would be appreciated.

Thanks,
Chuck

[hondo383]

What is your timing setup base/total?
Are you using a pcv valve?
What fuel?
Do you have a spacer under the carb what type?
Sounds like you have an air leak

[csx7031]

Base timing is 18, 32 total (its what the AFR 185 heads liked). No spacer, just .300 insulating gasket, no PCV. Chuck

[Tuner]

The "2000 RPM lean surge" is more likely a rich blubber. What do the plugs look like?

The large .041"MAB and .033" # 2 # 3 E-bleeds are causing the main to start early and slobber. Rev it to 2000-2500 range where the main starts and put your fingers over the MABs or put some tooth picks in them, see how much less fuel flows from the boosters.

You need to plug the two lower E-bleeds, just use the single top .028" E-bleed, move the idle jet down to the bottom of the idle well (if it isn't already?), the .030 IJ is OK but it needs to be below float level, should not be at the top of the block, if it is, move it (tap 6-32 thread in passage entering idle well at bottom of well and use brass set screws) and use .029" or .031" IJ, .070 IAB, Somewhere between #65-67 PMJ, 046" PVCR, #85 PV. Secondary, duplicate the primary or plug the PV and start with #73-74 MJ . MAB .028" P and S. That should run well enough you can tune it from that starting point. If you mean the idle won't slow below 1000 you should check the butterflies to see if they are centered in the bores with the idle speed screws backed all the way off. Loosen screws, shuffle throttle shafts back and forth and rotate throttle plates to fit.

[Walter R. Malik]

..."NASCAR Approved" 650 is proving to be very challenging. Engine is 330 CID SBF, 10:1CR, solid roller cam 244/250@ .050 .616/.616 lift, 108 LSA, Vic Jr. intake. Made 502 HP @ 6900 RPM, 423 TQ @ 5300 RPM with 750 HP 80528-1. Initially had holes in all throttle blades, wouldn't idle under 1800 RPM with idle screws all the way out. Installed new throttle blades (no holes). Will idle at 1000 RPM but transfer slot is almost completely covered, maybe .008 exposed. Best mixture screw setting is 5/8 turn CCW but plugs (AR3926) read lean. Hard to start, lean surge at 2000 RPM flat cruise, WAY down on power. The calibration seems odd to me. Maybe it is the "NASCAR" calibration
Straight leg booster, all jets 71, ICR .030, IAB .072, HSAB .041, PVCR .044, emulsion top .028, middle .033, bottom .033, siphon break .026, jet block number 11978.
I'm almost at a loss on how to proceed with calibrating this carb. I can go back to the 750 HP but, I'd like to try to make this thing work if possible. Any and all input would be appreciated.

Thanks,
Chuck

The carb is probably way off because it seems you have an air leak somewhere but, I would begin by simply changing the HSB to somewhere in the .028" to .031" size and drop the main jets about 3 numbers.

[Tuner]

The big E-bleeds below float level are causing the main to dump early and erratically.

[csx7031]

ICR and air bleeds unchanged, the throttle blades are centered on the bores. No air leaks. Changed jets from 71 to 69, T-slot square at .025, best idle with 1 turn on mixture screws. I placed a U shaped .019 piece of SS safety wire in the bottom two emulsion holes. It sounded better so, I went for a test drive. No more problems with lean cruise, revs good, no transition problems, and the power is up. I only did 1/2 throttle because I don't know how lean it is now and I'm in town). Idle speed is 1200 RPM with the T-slots at .025. I need more time to tap the emulsion holes and look at the plugs. Any suggestions on emulsion sizes if I want to use all 3 holes? 24,24,26????? Thanks for the help so far. Please share your ideas and suggestions.
Thanks,
Chuck

[jmarkaudio]

Make them smaller if you want all 3, .021 is a good start.

[csx7031]

Mark, thanks for the response. Should I start with .021 in all 3 or should the top one be a bit larger? Thanks, Chuck

[BobbyB]

What happened to this thread?

[Tuner]

ICR and air bleeds unchanged, the throttle blades are centered on the bores. No air leaks. Changed jets from 71 to 69, T-slot square at .025, best idle with 1 turn on mixture screws. I placed a U shaped .019 piece of SS safety wire in the bottom two emulsion holes. It sounded better so, I went for a test drive. No more problems with lean cruise, revs good, no transition problems, and the power is up. I only did 1/2 throttle because I don't know how lean it is now and I'm in town). Idle speed is 1200 RPM with the T-slots at .025. I need more time to tap the emulsion holes and look at the plugs. Any suggestions on emulsion sizes if I want to use all 3 holes? 24,24,26????? Thanks for the help so far. Please share your ideas and suggestions.
Thanks,
Chuck

Putting wire in E-bleeds is OK for a proof-of-concept test to see if reducing or eliminating E-bleed air gives a desirable result at part-throttle, but if the wire protrudes into the main well the resulting effect on WOT flow will be unpredictable and has a 99% chance of making it much leaner than you would expect for jet size in use and very likely extremely lean at WOT. It could even be rich one time at WOT and lean the next, or switch back and forth as RPM changes.

The unpredictability is because air and fuel flow in carburetors is pulsatory and all engines manifold pressure/vacuum pulsation characteristics are not the same, even in the same engine at different RPM.

The main well and booster passage should not have anything sticking in from an E-bleed. Even though the well is .170" ID, the tip of a .028" drill bit sticking in .040" will prevent normal WOT fuel flow.