MorTec

HOLLEY CARB INFORMATION

HOLLEY 4 BARREL CARB LIST NUMBERS
AND STOCK JETTING

One of the things we noticed over the years is the lack of information concerning Holley List #'s and the specifications for individual carbs and their stock jetting. Many folks buy a used carb at a swap meet or from an ad and find out that it wasn't what they thought they were buying. An 850 cfm "double pumper" turns out to be a 650 cfm with vacuum secondaries. In an effort to help our viewers identify which Holley carb they have or what carb they want to buy, we've put this list together. Holley itself has a huge site on the Internet with all of their products listed. Holley can be found at www.holley.com.

Holley also has a catalog of all of their "Performance Products" and services. It is updated yearly. If you need one, contact Holley for a copy. Among many other things, the catalog lists every performance and race carb they make and the indivdual specifications for each carb. Such a list would be too big on our website, so we are going to list the most popular Holley four barrel carb List #'s and their cfm size and stock jetting specifications. When you buy a used carb always check the jetting. Over time folks are always changing the various parts in a carb and it can be far from the original baseline stock setup. Once you know the baseline setup you can make appropriate changes to improve the carb's performance.

Most square flange Holley carbs have the "List #" stamped on the front, driver's side of the choke horn. Dominator carbs have no choke horn and their list # is stamped on a flat portion of the venturi area on top of the throttle body. The newer "HP" line of four barrel carbs have the "List #" on the driver's side of the throttle body.

Keep in mind that the stock jetting listed is for applications at sea level and at 70 degrees carb inlet air temperature and is meant to give you the baseline calibration. If you live at a higher altitude or in warmer or colder climates, changes can then be made appropriately. Likewise, the power valve calibrations are stock baselines. If you have a longer duration performance or race cam you may need to change the power valves to handle reduced engine vacuum signal to the carb. These carb tuning aspects are discussed on our "HOLLEY TUNING TIPS" webpage.

 

THE FOLLOWING IS A PARTIAL LIST OF HOLLEY LIST #'S FOR SOME OF THEIR MOST POPULAR CARBS. IT IS NOT A COMPLETE LIST OF ALL CARBS MADE BY HOLLEY OVER THE YEARS.

LIST #  CFM     STOCK JETTING           POWER VALVE     TYPE

1850-2  600     (F)66,(R)plate 134-9    6.5             4160

1850-3  600     (F)66,(R)plate 134-9    6.5             4160

1850-4  600     (F)66,(R)plate 134-9    6.5             4160

2818-1  600     (F)65,(R)76             6.5             4150

3124    750     (F)70,(R)76             8.5,8.5         4150

3247    750     (F)70,(R)76             8.5,8.5         4150

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3310    780     (F)72,(R)76             10.5,8.5        4150

3310-1  780     (F)72,(R)76             10.5,8.5        4150

3310-2  750     (F)72,(R)plate 134-21   6.5             4160

3310-3  750     (F)72,(R)plate 134-21   6.5             4160

3310-4  750     (F)72,(R)plate 134-21   6.5             4160

4118    725     (F)68,(R)78             8.5             4150

4224    660     (F)76,(R)plate 134-12   ---             4160

4295    585     (F)69,(R)71             6.5             4150

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4455-S  850     (F)80,(R)80             6.5             4150

4548    450     (F)57,(R)plate 134-30   6.5             4150

4555    780    (F)70,(R)76             8.5             4150

4575    1050    (F)84,(R)84             6.5             4500

4776    600     (F)69,(R)71             6.5             4150

4776-1  600     (F)66,(R)76             6.5             4150

4776-2  600     (F)66,(R)76             6.5             4150

4776-3  600     (F)66,(R)73             6.5             4150

4776-4  600     (F)66,(R)73             6.5             4150

4777    650     (F)71,(R)76             6.5             4150

4777-1  650     (F)67,(R)76             6.5             4150

4777-2  650     (F)67,(R)76             6.5             4150

4777-3  650     (F)67,(R)73             6.5             4150

4777-4  650     (F)67,(R)73             6.5             4150

 

 

 

4778    700     (F)66,(R)71             6.5             4150

4778-1  700     (F)66,(R)76             6.5             4150

4778-2  700     (F)66,(R)76             6.5             4150

4778-3  700     (F)69,(R)78             6.5             4150

4778-4  700     (F)69,(R)78             6.5             4150

4779    750     (F)75,(R)76             8.5             4150

4779-1  750     (F)70,(R)80             8.5             4150

4779-2  750     (F)70,(R)80             6.5             4150

4779-3  750     (F)70,(R)73             6.5             4150

4779-4  750     (F)70,(R)80             6.5             4150

4779-5  750     (F)70,(R)80             6.5             4150

4779-6  750     (F)71,(R)80             6.5             4150

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4780    800     (F)72,(R)76             6.5,8.5         4150

4780-1  800     (F)70,(R)76             6.5,8.5         4150

4780-2  800     (F)70,(R)85             6.5             4150

4780-3  800     (F)71,(R)85             6.5             4150

4780-4  800     (F)71,(R)85             6.5             4150

4781    850     (F)80,(R)80             6.5,6.5         4150

4781-1  850     (F)80,(R)80             6.5,6.5         4150

4781-2  850     (F)80,(R)80             6.5,6.5         4150

4781-3  850     (F)80,(R)78             6.5,6.5         4150

4781-4  850     (F)80,(R)78             6.5,6.5         4150

4781-5  850     (F)80,(R)78             6.5,6.5         4150

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4788    830     (F)80,(R)80             6.5,6.5         4150

4788-1  830     (F)80,(R)80             6.5,6.5         4150

4800    780     (F)70,(R)76             8.5,8.5         4150

4801-1  780     (F)70,(R)76             8.5,8.5         4150

4802-1  780     (F)70,(R)76             8.5,8.5         4150

4803-1  780     (F)70,(R)76             8.5,8.5         4150

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6109    750     (F)75,(R)76             8.5             4150

6129    780     (F)70,(R)82             6.5             4150

6214    1150    (F)95,(R)95             ---             4500

6238-1  780     (F)68,(R)73             6.5,8.5         4150

6239-1  780     (F)68,(R)73             6.5,8.5         4150

6262    800     (F)62,(R)85             8.5,6.5         4165

6291    600     (F)62,(R)plate 134-39   8.5             4160

6299-1  390     (F)50,(R)plate 134-34   ---             4160

6361    650     (F)72,(R)84             8.5             4150

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6407    450     (F)58,(R)plate 134-5    8.5             4160

6464    1050    (F)88,(R)88             ---             4500

6520    600     (F)62,(R)plate 134-39   8.5             4160

6647    600     (F)68,(R)70             8.5,8.5         4150

6708    650     (F)552,(R)752           6.5,3.5         4150

6708-1  650     (F)542,(R)85            6.5             4150

6709    750     (F)652,(R)76            6.5,3.5         4150

6710    800     (F)63,(R)86             6.5,3.5         4165

7010    780     (F)662,(R)plate 134-42  6.5             4160

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7320    1150    (F)95,(R)95             ---             4500HP

7320-1  1150    (F)95,(R)95             ---             4500

7410    340     (F)50,(R)62             8.5             4150

7411    370     (F)50,(R)62             8.5             4150

8007    390     (F)51,(R)plate 134-34   6.5             4150

8082    1050    (F)84,(R)84             6.5             4500HP

8082-1  1050    (F)88,(R)88             6.5,6.5         4500

8082-2  1050    (F)84,(R)84             6.5,6.5         4500

8156    750     (F)70,(R)83             6.5             4150

8159    450     (F)59,(R)plate 134-32   8.5             4160

8162    850     (F)80,(R)80             6.5             4150

8181    600     (F)80,(R)80             6.5,6.5         4160

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8207    600     (F)622,(R)plate 134-39  8.5             4160

8572    715     (F)72,(R)84             8.5             4150

8804    830     (F)80,(R)80             6.5,6.5         4150

8896    1050    (F)88,(R)88             ---             4500HP

8896-1  1050    (F)88,(R)88             ---             4500

9002    600     (F)632,(R)plate 134-37  208             4160

9013    600     (F)64,(R)plate 134-44   6.5             4160

9015    750     (F)76,(R)plate 134-27   10.5            4160 Marine

9022    800     (F)72,(R)87             6.5             4150 Marine

9023    800     (F)61,(R)86             8.5,6.5         4165

9029    715     (F)75,(R)84             8.5             4150 Marine

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9188    780     (F)72,(R)76             6.5,8.5         4150

9375    1050    (F)92,(R)92             ---             4500HP

9375-1  1050    (F)88,(R)88             ---             4500

9377    1150    (F)94,(R)94             ---             4500

9377-1  1150    (F)92,(R)92             ---             4500HP

9379    750     (F)68,(R)81             6.5             4150

9380    850     (F)78,(R)78             6.5,6.5         4150

9381    830     (F)78,(R)78             6.5,6.5         4150

8645    750     (F)80,(R)80             6.5,6.5         4150

9646    850     (F)92,(R)92             6.5,6.5         4150 Alcohol

9776    450     (F)582,(R)plate 134-6   8.5             4160

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75010   1150    (F)92,(R)92             ---             4500 Marine

75011   1250    (F)97,(R)97             ---             4500 Marine

80145   600     (F)68,(R)70             6.5             4150

80180   850     (F)92,(R)92             6.5,6.5         4150

80186   750     (F)70,(R)70             6.5,6.5         4500HP

80186-1 750     (F)70,(R)70             6.5,6.5         4500

80309   715     (F)72,(R)80,90          2.5             4150

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80311   850     (F)84,(R)88             6.5,3.5         4150

80311-1 850     (F)84,(R)88             6.5,3.5         4150

80311-2 850     (F)84,(R)88             6.5,3.5         4150

80330   850     (F)88,(R)94             6.5             4150

80330-1 850     (F)88,(R)94             6.5             4150

80340   1050    (F)84,(R)84             6.5,6.5         4500 Marine

80340-1 1050    (F)88,(R)88             ---             4500

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80378   750     (F)59,(R)72             2.5,2.5         4150

80378-1 750     (F)56,(R)73             2.5,2.5         4150

80431   550     (F)60,(R)plate 134-9    6.5             4160

80432   550     (F)60,(R)plate 134-9    6.5             4160

80436   850     (F)80,(R)80             6.5,3.5         4150

80443   850     (F)88,(R)96             6.5,6.5         4150 Marine

80444   850     (F)88,(R)94             6.5,3.5         4150 Marine

80450   600     (F)622,(R)plate 134-39  208             4150

80457   600     (F)69,(R)plate 134-39   6.5             4160

80457-1 600     (F)64,(R)plate 134-39   6.5             4160

80496   950     (F)78,(R)78             165,165         4150HP

80497   950     (F)78,(R)78             165,165         4150HP

80498   950     (F)144,(R)144           155,155         4150HP Alcohol

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80507   390     (F)65,(R)65             3.5,3.5         4150HP

80508   750     (F)72,(R)plate 134-21   6.5             4160

80509   830     (F)86,(R)86             6.5,6.5         4150HP

80511   830     (F)84,(R)84             6.5,6.5         4150HP

80512   1000    (F)84,(R)84             6.5,6.5         4150HP

80513   1000    (F)84,(R)84             6.5,6.5         4150HP

80514   1000    (F)84,(R)88             6.5,6.5         4150HP

80519   1000    (F)84,(R)88             6.5,6.5         4150HP

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80528   750     (F)72,(R)84             6.5             4150HP

80529   750     (F)72,(R)84             6.5             4150HP

80532   1250    (F)97,(R)97             134-265         4500HP

80533   1250    (F)97,(R)97             134-265         4500HP

80535   750     (F)132,(R)132           5.5             4150HP Alcohol

80537   750     (F)73,(R)81             6.5             4150 Marine

80540   600     (F)70,(R)70             6.5             4150HP

80541   650     (F)70,(R)70             6.5             4150HP

80542   650     (F)90,(R)90             6.5             4150HP Alcohol

80776   600     (F)66,(R)73             6.5             4150

80777   650     (F)67,(R)73             6.5             4150

80778   700     (F)69,(R)78             6.5             4150

80779   750     (F)70,(R)80             6.5             4150

80780   800     (F)71,(R)85             6.5             4150

80781   850     (F)80,(R)78             6.5,6.5         4150

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81850   600     (F)66,(R)plate 134-9    6.5             4150

83310   750     (F)72,(R)plate 134-131  6.5             4160

83310-1 750     (F)72,(R)plate 134-131  6.5             4150

83311   750     (F)72,(R)plate 134-21   6.5             4150

83312   750     (F)72,(R)plate 134-131  6.5             4150

84010   600     (F)67,(R)75             6.5             4010

84010-1 600     (F)67,(R)75             6.5             4010   

84010-2 600     (F)67,(R)75             6.5             4010

84010-3 600     (F)63,(R)75             6.5             4010

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84011   750     (F)75,(R)75             6.5,6.5         4010

84011-1 750     (F)75,(R)75             6.5,6.5         4010

84011-2 750     (F)75,(R)75             6.5             4010

84011-3 750     (F)73,(R)75             6.5             4010

84015   800     (F)64,(R)90             6.5,6.5         4011

84015-1 800     (F)64,(R)90             6.5,6.5         4011

84015-2 800     (F)60,(R)90             6.5,6.5         4011

84015-3 800     (F)60,(R)90             6.5,6.5         4011

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84776   600     (F)66,(R)73             6.5             4150

84777   650     (F)67,(R)73             6.5             4150

84778   700     (F)69,(R)78             6.5             4150

84779   750     (F)70,(R)73             6.5             4150

84780   800     (F)71,(R)85             6.5             4150

84781   850     (F)80,(R)78             6.5             4150

89834   600     (F)68,(R)plate 134-39   6.5             4160

 

 

 

 

 

CARB CFM SIZING

One of the first things to determine is what size carburetor do you need? A number of factors come into play. What cubic inch size is your motor? What do you do with it? Race, street use, towing, street use with occasional trips to the track? What type of intake manifold do you have, split plenum, open plenum, tunnel ram, individual runner? How fast do you spin the motor? What is the volumetric efficiency of the motor? Do you have a manual or auto transmission? What is the rear gear ratio? Do you want to get the best gas mileage possible or do you want to develop the most power possible? Keep in mind that a carburetor is just one part of the engine combination. All of the parts need to work together. Putting a larger carburetor on is NOT going to immediately put 100 more horsepower at your disposal. The carb needs to work with the other parts you have chosen and your intentions concerning how the vehicle is going to be used.

One general rule of thumb uses a formula to determine the CFM requirements of your engine. It goes like this: You need to know the CUBIC INCHES of the motor. You also need the maximum RPMs the motor will be spun to. Finally you also need the VOLUMETRIC EFFICIENCY PERCENTAGE (VE%) of the engine. The first two items (CUBIC INCHES and RPMs), are relatively easy to determine. The engine VE% is another matter. If an engine could use all of the air it ingested, it would have a VE% of 100%. Many performance engines reach this level. Certain race engines can actually exceed this and reach a VE% of over 100% at certain points in their RPM range. Most production engines and most street performance engines have VE levels below 100%. In fact, stock, production, low performance motors will fall around 75%-85% volumetric efficiency.

The math formula is:

CARB CFM =

So if you had a stock, low performance production motor of 350 cubic inches and you wanted to spin it to 5000 rpms max and it had a VE% of 80%, the formula would determine a required carb CFM of 405 CFM. If you had a warmed over street performance motor of the same size, but it was capable of 7000 max rpms and it had better heads, camshaft, headers and a performance intake that raised the VE% to 95%, the formula would give you a minimum required carb CFM size of 673 CFM.

In a controlled situation on an engine dyno, the amount of air actually ingested by the motor can be measured. Since most folks don't regularly have access to a dyno, the above formula will get you in the ballpark. There are some exceptions of course. Using a split plenum type street manifold allows the use of a larger than "normal" carb CFM. This is because the plenum volume is cut in half by the divider, so each cylinder only has half of the total plenum volume and carb CFM to draw thru. Likewise a carburetor with vacuum secondaries will only open the secondaries enough to feed the engine what it needs. Consequently, on a street driven vehicle a split plenum intake with a vacuum secondary carb is the way to go. The vacuum signal stays high for good throttle response at low and mid range rpms. Fuel mileage is good. An "open" plenum intake, generally speaking, has opposite effects. Low rpm throttle response is decreased, but high rpm breathing is improved because of an increase in available manifold plenum volume to each engine cylinder. Consequently, open plenum intakes are a little more sensitive to the CFM size of the carb. If you are drag racing, most folks are willing to sacrifice some low end power for high rpm horsepower. Fuel mileage isn't a concern and the engine spends most of it's time at full throttle. Open plenum race intakes and "double pumper" carbs are the norm.

 


JET CHANGES AND ALTITUDE AND TEMPERATURE

Holley carbs are calibrated for sea level operation and an inlet air temperature of 70 degrees Fahrenheit. Once you know the correct stock jetting for your particular Holley carb, you can determine whether you live or race at an altitude above sea level. For every 2000 foot increase in altitude, you can reduce the jet size by one size. If you had a carb which has a stock jet size of 80 and you live or race at 2000 feet above sea level, then you would use a #79 Holley jet in the carb. Similarly, a change in the carb's inlet air temperature may require a change in the jet size from the stock calibration. Many racers go a step further by combining all of the weather varibles, temperature, barometric pressure, dewpoint and humidity with the altitude of the track they are racing at to determine the "density altitude". This is a "corrected" altitude above sea level. From there they can determine whether a jet change is necessary to maintain performance or whether to change their "dial in" (if they are bracket drag racers).

You can look at MorTec's HOLLEY CARB INFORMATION page to find the stock, standard, sea level, calibration jets for your particular Holley four barrel carb.

 


DRAG RACE JET CHANGES and MPH

Drag racers should try to optimize jetting by looking for the jet size that gives the best MPH, rather than best elapsed time (ET).

 


ACCELERATOR PUMP CAMS AND SHOOTERS

Accelerator pump cams come in various sizes and are color coded and number coded by Holley. The cams have different shaped ramps that the arm from the accelerator pump rides on. By changing the size and shape of the arc on the cam, the pump shot can be tailored to start early or later as you go from off idle to full throttle. Changing the cams can have an effect on the way a vehicle leaves the start line in a drag race. If you leave the line off idle or at a higher RPM (while foot braking or when using a trannie brake or when using a clutch with a manual transmission) experimenting with the pump cams can help. There is no set rule for use, you just have to experiment with the different cams and the different cam positioning holes in the throttle linkage of the carb. Holley sells individual cams or you can buy their kit which includes an assortment of cams to choose from.

Pump shooters are another area of experimentation. Holley carbs come with a standard shooter size which differs by carb list#. If you are experiencing a bog or hesitation off idle, you can try a larger, higher # shooter size. The bog or hesitation may be caused by a momentary lean condition when the carb goes from the idle throttle postion to the main metering system. The shooters help richen this momentary condition and eliminate the stumble. Keep going up in shooter size until a puff of black smoke comes out the exhaust, then go back one or two sizes. Playing with the shooter sizes is particularly helpful, when you have an intake with a large plenum area, such as a large open plenum or a tunnel ram. Keep in mind that as you increase the shooter size, you may also need a "hollow" screw to hold the shooters in the carb. At shooter sizes over .039, Holley recommends that you use the "hollow" screw (PN-26-12) which allows more fuel to flow to the shooters.

 


POWER VALVES and ENGINE VACUUM

There is a lot of misunderstanding concerning power valves in Holley carbs. Many 4-barrels come with a particular power valve depending on the carb list# and application. Some carbs have two power valves, while others only have one. The power valves are numbered by the amount of engine vacuum in inches at which they will open and add additional fuel to the power circuit. In other words a 6.5 power valve will open when the vacuum signal on the engine drops below 6.5" and will remain closed above that amount. One of the misconceptions is that they can't be trusted to work because an engine backfire or "belch" can "blow out" the power valve. Many Holley performance carbs models and list#'s now come with built in power valve "blow out" protection which eliminates this problem. If you have an older model carb you can purchase a small, inexpensive, easy to install kit from Holley (PN - 125-500) that will also protect the power valves in case of an engine blowback thru the carb. CENTEK in Redmond, Oregon, (see their website at www.powervalveshield.com ) also sells an inexpensive Holley power valve blow out protector, "Power Valve Shield", which takes about two minutes to install and does not require any drilling.

 

Many tuners will automatically remove the power valves and use a "plug" thinking this is the "hot" ticket. However, if the power valve is removed and plugged, the main jet size must be increased 6-10 jet sizes to make up the required fuel amount lost by the removal of the power valve. In addition, when the power valve circuit is plugged, the part throttle fuel economy is worsened and may become overly rich. Plug fouling may become a problem at part throttle.

Stock engines can have high vacuum readings (10-18 inches at idle) and the Holley power valves with higher readings like 6.5 to 10.5 will work correctly. Long duration non-stock camshafts and other performance related parts can cause a problem, because engine manifold vacuum may be lowered with these performance parts and the power valve, if incorrect, will always be open, even at part throttle, leading to an overly rich air/fuel mixture. The solution is to choose the correct power valve and to do that you need a vacuum gauge. On a manual transmission vehicle, hook up the vacuum gauge and take the reading with the engine at idle. Then use a power valve that is rated 1-2 inches below that amount. For example, a motor that shows 7" of vacuum at idle should use a 6.5 or 5.5 rated power valve. If you have an automatic transmission, take the vacuum reading at idle in "Drive" (with the emergency brake on and the wheels blocked) and chose the power valve 1-2 inches below that figure. You can get a little more detailed information by driving the car with a vacuum gauge hooked up with a longer hose so you can read it while driving. Drive the car at medium loads and while cruising and note the various vacuum readings. Then chose the appropriate power valve rating.

Holley makes performance style "standard" flow or a "high" flow power valve which has a large opening. "Single stage" power valves are available in 1" increment sizes from 2.5" thru 10.5". There are "two stage" power valves available that are more for "economy" minded users rather than "performance" enthusiasts.

 

 

 

 


ADJUSTING THE OPENING POINT OF VACUUM SECONDARIES

There are a number of ways to tune the moment when the vacuum secondaries open on a Holley four barrel carb. The vacuum secondaries are controlled by a diaphram and a color coded spring. Holley makes a number of different springs with different tension on the springs. You can change the springs and change the opening moment. The color coded springs run from light tension to heavy:

White - Lightest

Yellow (Short Spring)

Yellow

Purple

Plain (Steel grey)

Brown

Black - Heaviest

If there is a bog or hesitation when the secondaries open, the spring tension is too light, go to the next heavier spring. Holley offers a kit (PN-20-13) which contains one each of the above color springs. When you change springs you'll note that the stock cover over the spring and diaphram is not all that easy to get to. Holley makes a special cover (PN-20-59) that makes spring changes quick. Finally, Holley also makes a completely adjustable thumbscrew operated diaphram cover (PN-20-99). This cover limits the travel of the diaphram and therefore limits how far the secondary throttle plate can open. It makes secondary throttle opening adjustable. It's very nice to have if you are a bracket racer and are using a carb with vacuum secondaries. You can adjust the throttle for changes in weather and track conditions or for changes in your "dial in".