Holley Annular Question...?

Old 06-14-2010, 07:55 PM
  #1  
HamerDown
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Default Holley Annular Question...?

Holley list# 9380 annular 850 DP

1) why or what are the benefits that it's a "square" jetted carb?

2) would it be of any benefit to remove the rear/secondary PV (it has two) and jet it smaller in the primary side and fatter in the secondary's ?

3) What are the benefits of this carb being "annular" vs any other 4150 ?

4) When testing w/a vacuum gauge, will the primary power valve automatically be the same as the secondary PV?

Thanks for any feedback > I called Holley and it was like talking to someone at McDonald's drive thru :roll:
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Old 06-15-2010, 12:05 PM
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jmarksdragster
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It depends on what you want to do with it and what the specs are on what it's going on.

Assuming a street/strip or drag car, it's jetted square for even fuel distribution to all the cylinders at WOT. Even still it is not always the case as some intakes, most often dual plane intakes can have issues with even distribution and require staggering the jets or more drastic measures in some cases. Equal fuel from the primary and secondary at WOT is usually the best place to start.
And concerning equal fuel, again assuming a street/strip or drag car, there is no reason to use a secondary power valve and good reason not to. The PVCR's can come uncovered on a hard launch and make lean, even if for a moment. Also, unless you plan on cruising at 3/4 throttle it will serve no purpose, 99% of the time the secondaries are either closed or wide open. Either case needs nor PV. Jet up 6-8 to start when blocking the secondary PV, then jet up or down as needed for best MPH at the track.
Annular boosters provide the carb with a stronger and quicker responding metering signal all else being equal, but usually cut the available airflow at WOT on a 4150 carb. If you have smaller engine or run primarily on the street it is worth having, larger displacement engines or higher HP engines that keep the RPM up keeping the airspeed through the carb may pick up a little HP with a downleg booster. So it will depend on the app.
As far as the PV vacuum rating... we've determined you don't want a secondary PV most of the time, setting the PV vacuum setting is about finding the optimum point below cruise vacuum for the PV to open soon enough and not have it surge or too low allowing it to run rich too soon. You do not set the PV based on idle vacuum.

And with some of the phone tech some companies use these days you might get a better answer at McDonald's...
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Old 06-15-2010, 08:34 PM
  #3  
HamerDown
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Originally Posted by jmarksdragster
It depends on what you want to do with it and what the specs are on what it's going on.

Assuming a street/strip or drag car, it's jetted square for even fuel distribution to all the cylinders at WOT. Even still it is not always the case as some intakes, most often dual plane intakes can have issues with even distribution and require staggering the jets or more drastic measures in some cases. Equal fuel from the primary and secondary at WOT is usually the best place to start.
And concerning equal fuel, again assuming a street/strip or drag car, there is no reason to use a secondary power valve and good reason not to. The PVCR's can come uncovered on a hard launch and make lean, even if for a moment. Also, unless you plan on cruising at 3/4 throttle it will serve no purpose, 99% of the time the secondaries are either closed or wide open. Either case needs nor PV. Jet up 6-8 to start when blocking the secondary PV, then jet up or down as needed for best MPH at the track.
Annular boosters provide the carb with a stronger and quicker responding metering signal all else being equal, but usually cut the available airflow at WOT on a 4150 carb. If you have smaller engine or run primarily on the street it is worth having, larger displacement engines or higher HP engines that keep the RPM up keeping the airspeed through the carb may pick up a little HP with a downleg booster. So it will depend on the app.
As far as the PV vacuum rating... we've determined you don't want a secondary PV most of the time, setting the PV vacuum setting is about finding the optimum point below cruise vacuum for the PV to open soon enough and not have it surge or too low allowing it to run rich too soon. You do not set the PV based on idle vacuum.

And with some of the phone tech some companies use these days you might get a better answer at McDonald's...
Mark, what a informative reply > I thank you!
If I may give more detail about application...
This carb would be used on a 468 BBC Jet Boat
Max RPM is 5400 but I usually spend most of the time at 3000-4200.
10:1 compression
Weiand Stealth intake
Lunati Voodoo Roller Cam #60212
># Advertised Duration (Int/Exh): 282/290
# Duration @ .050 (Int/Exh): 231/239
# Gross Valve Lift (Int/Exh): .600/.600
# LSA/ICL: 110/106
# Valve Lash (Int/Exh): Hyd/Hyd
# RPM Range: 2200-5800
049 large oval heads w/larger valves ported etc.
Headers with performance baffles.

Soooo, with the above should I still delete the secondary power-valve and up the rear jetting...or...leave the secondary PV and keep the square jettein?
Any other advice...would be much appreciated.
Thanks Ray
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Old 06-16-2010, 08:54 PM
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jmarksdragster
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Well considering you do have a different deal being in a boat, I would opt to plug the PV in the secondary for starters. This is to make sure you have sufficient fuel to start with when the secondaries open up. You will need to take some time to tune it, to find out what it wants for fuel. I would put a vacuum gauge on it, and if you can spring for it a wideband O2 system it would make tuning a whole lot easier. If it were me, I would disconnect and tie the secondaries closed and tune the primary to start with. You need to learn to properly read the plugs. Once you get the timing and idle set up, run it for some short WOT bursts and stop quick, shut it off and pull a couple plugs to look at. As long as plugs are OK try some extended cruising, pull plugs again. Once the plugs look good (and may take a couple sets to set it up) hook up the secondaries and run some extended higher RPM runs, check the plugs again. If it looks rich you may need the PV, and the vacuum gauge will help determine where it needs to be. I would also possibly stagger the PV vacuum #'s, higher in the front and maybe a little lower in back. Finding the load point that requires more fuel will be a little more difficult without a wideband and will require some time with it the first time out. Make sure you get it up to operating temp as well.

Here is a good place to read up on plug reading.
http://www.dragstuff.com/techarticle...ark-plugs.html
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Old 06-17-2010, 04:33 PM
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HamerDown
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Originally Posted by jmarksdragster
Well considering you do have a different deal being in a boat, I would opt to plug the PV in the secondary for starters. This is to make sure you have sufficient fuel to start with when the secondaries open up. You will need to take some time to tune it, to find out what it wants for fuel. I would put a vacuum gauge on it, and if you can spring for it a wideband O2 system it would make tuning a whole lot easier. If it were me, I would disconnect and tie the secondaries closed and tune the primary to start with. You need to learn to properly read the plugs. Once you get the timing and idle set up, run it for some short WOT bursts and stop quick, shut it off and pull a couple plugs to look at. As long as plugs are OK try some extended cruising, pull plugs again. Once the plugs look good (and may take a couple sets to set it up) hook up the secondaries and run some extended higher RPM runs, check the plugs again. If it looks rich you may need the PV, and the vacuum gauge will help determine where it needs to be. I would also possibly stagger the PV vacuum #'s, higher in the front and maybe a little lower in back. Finding the load point that requires more fuel will be a little more difficult without a wideband and will require some time with it the first time out. Make sure you get it up to operating temp as well.

Here is a good place to read up on plug reading.
http://www.dragstuff.com/techarticle...ark-plugs.html
I thank you again for the informative reply...looks like I'll have my work cut out for me getting this thing right.
I won't be able to use the wideband O2 system as my headers are water injected to keep the chrome on. Headers come up and over the rear of the boat.
I can use a vacuum gauge.
Thanks
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Old 06-20-2010, 04:55 PM
  #6  
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Thinking now about blocking the secondary PV and raising the secondary jetting accordingly.
Original jetting from Holley is 78 square > but that won't apply anymore.
Any suggestions on a good Jetting starting point?
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Old 06-21-2010, 10:02 AM
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jmarksdragster
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Start with 86 in the secondary with no PV, it may be a little rich but better than being lean. Reading plugs will be your ally in getting it right.
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Old 09-14-2010, 06:38 PM
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I finally got to try my Annular 850 DP list-9380 > the below as taken as a starting/observation reference

1)Jetted out of the box 78 square

2)Two PV's 6.5 and 1/2 idle vacuum 13"

3) floats set properly

4) set idle for max RPM with vacuum gauge = 3/4 out

5) #31 discharge nozzles P&S

6) fuel psi good = 5/7 lbs

OPERATION...
*Good idle but seems a little too choppy for 900 rpm

*Holding @ 1600 rpm engine has a faint sputter/miss

*in the 4000 rpm range engine goes flat > almost like there's a rag over the carb > then it comes to life when the PV opens.

*max RPM is now only 5K and down 2/300 rpm from my little 715-vacuum secondary carb


Vacuum Gauge Observations... vacuum seems a bit high for cam

Idle = 13"

2500 = 15"

3000 = 14"

3500 = 11"

4000 = 8"

5000 = 5" and as low as it goes

*Plugs appear to be safely on the rich side and NOT heavily rich.

*As primary throttle blades open > a steady supply of fuel from discharge nozzles > as secondaries open they also receive a steady flow of fuel = smooth transition between the two

*Looking into carb at idle nothing leaking into carb > when I blip the throttle I see fuel discharging from the annular boosters.


Your thoughts?

Thanks, Ray

PS. I can tune any Weber or Dellorto DHLA-40 and my 715 VS very well but, this Annular 850 DP will be tricky.
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Old 09-15-2010, 08:44 AM
  #9  
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At 4000 RPM are the secondaries even open? I would still plug the secondary PV and jet up. Put an 8.5 PV in the primary, if it still appears flat try a 9.5. It needs to open when the load is high enough to warrant the extra fuel. And don't worry about any effect on idle, the idle jet is much smaller than the main jets feeding them. As far as the sputtering at 1600, have someone hold it there and cover one of the idle air bleeds, if it gets better try covering two. That would tell you the IAB/IJ sizes are too lean for the transition circuit and need to be changed to enrich the circuit. If it gets worse, then it is too rich. As far as the idle, pull the carb now that the idle speed is set and see how much of the transition slot is showing. should have roughly .020 exposed with the blade set for the correct idle speed. What kind of timing curve do you have? Insufficient initial timing will make tuning harder and will run poor, with that much cam I would expect a minimum of 20˚ initial, and maybe up to 25˚
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Old 09-17-2010, 02:08 PM
  #10  
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Mark- Kuudoos to you my friend for taking the time to explain these carb questions. Each time you do, people like myself learn a lot. You have a way of explaining it that makes it understandable... I have learned a lot from you & some of the others here about carbs. I knew nothing about them 5 or 6 years ago. With guys like you (& some trial & error), I wield the small flat-blade screw driver with absolute confidence as my sword now days.
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