Installation

Installation of a McCulloch VS57 supercharger should essentially be straightforward with three notable exceptions, modifying the carburetor, modifying the fuel pump and actually getting the system to work, however, because we nowadays have little chance of finding all the required components for an installation, it is possible that installation is going to involve a fair few problems. Hopefully, however, your installation will have no problems and this section of the web site will provide sufficient information to allow you to carry out an installation that actually works successfully.

If you intend to fabricate your own mounting bracket, and/or idler pulley and drive pulley then the only advice I can really give (due to lack of experience) is make sure you mock up with an easily worked material first (such as wood) before you start fabricating with metal. The same also applies when fabricating mounts for the relocation of engine components such as generator or power steering pump mounts.

Carburetion, Fuel Pump, and Ignition modifications are discussed on seperate pages on the site, under the Technical Reference.

Main System component  Installation

The following diagram (which is of a Kaiser installation) shows the layout of the main supercharger components as mounted upon the engine. The actual mounting position varies according to the host engine, and has to take into account hood clearance, clearance of existing engine components, and for fairly obvious reasons has to be at the front of the engine (to enable it to be driven from a crankshaft pulley) and on the upper half of the engine (to simplify ducting to the carburetor and air cleaner).

Main components mounted on an Engine

The first stage of the installation is to drain the engine of coolant and remove the radiator and any associated shrouding, this is basically to provide access to the front of the engine, which will ultimately make the job easier. The next stage is to remove the fan belt, fan and possibly the crankshaft pulley. If the engine has a front engine mount (notably Thunderbirds and Ford Trucks, but maybe other applications as well) then the engine will have to be supported using and axle stand and trolley jack and the front mount removed. Any existing air cleaner and support bracketing should also be removed as this will no longer be required.

The stock crankshaft pulley may be reused or it may be replaced by the McCulloch supercharger pulley which basically depends on the type of supercharger drive pulley you have. Some of the McCulloch supercharger crankshaft pulleys were designed to bolt directly to the stock crankshaft pulley and had only a single groove for the supercharger drive belt, others have an additional groove to drive power steering pumps, and very rarely some pulleys also have support for air conditioning. If the supercharger crankshaft pulley has only one groove then it is fairly safe to assume that it is designed to bolt straight onto the existing crankshaft pulley. If the supercharger crankshaft pulley has more than one groove then it is either a replacement for an existing accessory pulley, or it is a direct replacement for the existing crankshaft pulley. The only real way to find out is to fit it onto the existing crank pulley and see how it fits against the pulley, or alternatively remove the existing crankshaft pulley and see how the supercharger pulley fits onto the crankshaft or harmonic dampner. Once you’ve decided how it fits, bolt the supercharger drive pulley loosely to the engine as it their may be some adjustments required later to allow for correct belt alignment.

The next step is to the attach the supercharger mounting bracket and associated idler arm to the engine. It is recommended that the VS57 supercharger is attached to the mounting bracket at this stage as it allows clearance problems to be quickly identified. NOTE:- The supercharger housing is aluminum so care should be taken not to strip the threads on the housing. Also the supercharger should be positioned so that the McCulloch badge on the top of the supercharger is topmost, which can result in the supercharger outlet being in the wrong position with respect to the carburetor. In this case the supercharger outlet can be rotated by first removing the nameplate, taking care not to lose the spring underneath the nameplate, and then removing the six bolts from the row of tapped holes in the face of the supercharger. The two sections of the supercharger can then be pulled apart gently by about ½” and the outlet housing can be rotated to the correct position, and the bolts, spring and nameplate replaced, with the nameplate retaining it’s topmost position.  The whole assembly should then be positioned in it’s expected mounting position and a check of clearances made.

Typical clearance problems for the supercharger and/or mounting bracket are caused by radiator hoses, oil filler tube and/or crankcase ventilation, thermostat housings and pipework to the carburetor.  Clearance problems may also be encountered with the bracket and idler arm position with respect to other system components such as the generator or a power steering pump. Don’t forget to allow for the movement of the idler arm when the supercharger drive belt changes position on the supercharger drive sheaves. Addressing these clearance problems is easier said than done and might involve re-routing carburetor pipework and coolant hosing, modifying the valley cover to relocate the oil filler and/or crankcase ventilation, and in the case of the thermostat housing finding or fabricating an alternative housing. If the generator causes clearance problems then it will have to be repositioned, although in some cases the McCulloch supercharger brackets had provision for generator re-positioning and the actual job might just involve moving the generator forward or back using appropriate shimming on it’s mounts. The same often applies to power steering pumps and the McCulloch brackets often provided mounting points for these.  If your bracket has no provision for generator and/or power steering pump then I’m afraid you are going to have to work out new positions for these components and you may possibly have to fabricate appropriate brackets for them. In all cases you should always preserve pulley alignment against the appropriate crankshaft pulley drive groove.

Whilst checking the clearance of the mounting bracket, idler arm and mounting bracket, a check should also be made on the mounting points of the bracket. Would the mounting points on the bracket provide a rigid mount for the bracket, and if not are their spare mounting holes on the bracket that could be used to attach support braces to, an corresponding mounting points on the engine for the other end of the support braces. If you do need braces then you will probably have to fabricate them, as you can practically guarantee that you did not get them when you obtained the bracket.

Once you have established and resolved all clearance problems, and you have determined and fabricated any additional bracing, if it is required, then attach the mounting bracket, support bracing and idler assembly to the engine, and if it is not currently attached, attach the supercharger to the mounting bracket. Some system components may have to be removed or loosened in order to provide sufficient clearances for this. One the bracket is installed, reinstall any relocated or removed components and have a good look at the pulley alignments and clearances for the drive belts that need to be installed. This is where the job could get really frustrating if insufficient clearances are not available for the drive belts, as the component movement or modification is required to provide the clearance. Again allowance must be made for the supercharger ratio shifting, when the supercharger drive belt will change position with the idler arm. Pulley alignment generally tends to be less of a problem as shims and/or spacers can be used to reposition pulleys.

Once you are satisfied with pulley alignment and belt clearance tighten up the installed components and install the appropriate drive belts. If the front engine mount was removed, loosely reinstall it and check for clearances. If there appears to be insufficient clearance, or if more clearance is desired to aid for easier belt removal without having to dismantle the system then modify the mount accordingly. This tends to be not much of a problem with the majority of engines as the front mounts are generally provided as steady rests and do not take the full weight of the engine.

Reinstall the fan and the radiator. A spacer may be required for the fan and in some cases the radiator may have to be mounted forward (which can be achieved by repositioning it forward in its mount, or via use of spacers if front mounted) in order to maintain sufficient clearance between the fan and radiator. The very minimum clearance between fan and radiator should be 5/8” and the preferred amount is ¾” or more. At least 1/6” clearance is required behind the fan as well, to prevent it from chafing belts.

Plumbing and Wiring

McCulloch Supercharger Plumbing & Wiring

The above diagram shows, in a simplified form, the main plumbing and wiring used in a McCulloch supercharger installation. This can essentially be broken down into five sub-systems, these being the input air supply, pressurised air plumbing, vacuum plumbing, fuel supply and electrical connections.

The input air supply is basically straightforward and involves connecting the supercharger input (which is the central opening on the rear of the supercharger) to the air cleaner using 3 ½” diameter hose. The actual length of this hose depends upon the position of the air cleaner which, as always, is application dependant, and the type of hosing used should be a reinforced type, as the supercharger air demand can result in the collapse of standard hosing. All connections should be tight (using hose clamps), to prevent dirt ingress and to reduce induction noise. With regards to the air filter McCulloch used to supply two basic variants of air cleaners, a long thin cylindrical, and a short fat cylindrical one. Both of these air cleaners were high capacity air filters using disposal paper elements for air filtering, and can be used in a modern installation, assuming you can get replacement elements. If an original air cleaner is not available, then it is common practice to adapt a high capacity K & N air filter and install that with the supercharger. Again location is dependant upon the application, and I’d recommend looking through the photos on the VS57 photo page for examples of typical installations. Under no circumstances should the original oil bath air cleaners for the vehicle be used as these can cause excessive use of oil by the supercharger, which will try to suck air from oil reservoir inside supercharger, if the oil bath air cleaner has insufficient capacity for the superchargers requirements. In extreme cases the use of the original oil bath cleaner can result in oil being sucked into the supercharger and subsequently blown into the engine. Similarly under no circumstances should the supercharger be operated without being connected to an air filter, as any dirt or grit particles sucked into the supercharger will effectively sandblast the inside of the supercharger and permanently reduce the efficiency of the supercharger.

The act of supercharging air increases the temperature of the air being blown into the carburettor, a known fact which unfortunately cannot be avoided, unless some form of inter-cooling is used at the inlet manifold. An increase in air temperature results in a less dense air charge for a given volume, resulting in a decrease in volumetric efficiency (and subsequent decrease in power gain) for the engine being blown. If the air supply for the air filter is sourced from the engine compartment of the car, then that air will already have an increased temperature as a result of it being warmed on it’s passage through the radiator, and as a result of hot engine components within the engine compartment. This will result in a further reduction of volumetric efficiency. To avoid the use of warmed air from the engine compartment ducting should be run from the air cleaner assembly to the front of the car, allowing cool air to be fed to the supercharger. Again the intended application affects the positioning of this ducting, it is however recommended that ducting is connected to a mesh covered hole in the radiator cowling, directly behind the font grille. In some applications (such as Ford) it may be possible to tap existing ducting, which is present to provide a cool air supply to the passenger compartment of the car.

The pressurised air plumbing is basically the hose connections between the supercharger volute outlet and the carburettor bonnet (or air box), and supplementary hose connections between the air bonnet and carburettor (where required for pressure equalisation), and the supercharger outlet and the fuel pump and distributor. The connection between the supercharger outlet and the carburettor bonnet is generally made using 2 ¾” diameter reinforced (neoprene lined is the most suitable type) hosing, which is clamped using 12” hose clamps. Any bends in the hosing should be smooth, otherwise significant pressure drops can occur to the boost pressure. It is possible to use metal tubing in conjunction with hosing for this connection, as long as all inside diameters are basically the same, and all connections made are airtight using hose clamps. Small bore hosing (typically 5/32”) is used for the remaining connections, and these must also be clamped airtight using the appropriate hose clamps. If any of the pressurised air plumbing connections are not airtight, then the resultant air leaks will cause a drop in the boost pressure at the carburettor, and cause noise in the form of whistling.

When a vacuum switch is being used to switch the supercharger between it’s “low boost” and “high boost” operating modes, then a connection has to be made to the inlet manifold and run to the vacuum switch. Standard vacuum hosing can be used, although this should be wired up to provide a secure connection at the appropriate connection points. As the vacuum switch relies on their being zero vacuum for it to switch the supercharger into “high boost”, the hosing should run directly to the inlet manifold and not connected to the vacuum connection at the carburettor. If no appropriate point is available for connection then a nipple will have to be tapped into the inlet manifold. The actual vacuum switch is either mounted directly to the supercharger, using one of the supercharger mounting bolts, or directly to the supercharger mounting bracket, with it being positioned, in both cases close to both the intake manifold and the supercharger solenoid enclosure.

The fuel supply connections are straightforward and have essentially been covered in the previous sections. The fuel supply from the mechanical fuel pump is fed to the electrical fuel pump (via flexible fuel lines if the electric pump is not mounted directly on the engine or supercharger mounting bracket), and the supply from the electric pump is fed to directly to the carburettor. It may be necessary to increase the diameter of the piping used for the fuel connections, as in some cases fuel starvation can occur under high boost and high load conditions, due to insufficient fuel capacity in the stock fuel lines. If this is the case the whole fuel system should use larger bore piping, i.e. the connection from the mechanical fuel pump to the fuel tank should use this piping as well.

The electrical connections for the supercharger control system are shown in more detail in the diagram below.

Vacuum Switch Wiring

As can be seen a wire is run from the primary terminal of the coil to one post of the vacuum switch, and wires are run from the second post of the vacuum switch to the electric fuel pump and the solenoid that is enclosed in the housing underneath the badge on the supercharger. This allows the electric fuel pump to be activated at the same as time as the supercharger is switched to “high boost”, and subsequently ensures that the fuel pressure is increased to the amount required under high boost to overcome the increased carburettor internal pressure. If a mechanical switch, such as one mounted on the throttle which is activated at ¾ full throttle, then this is wired in place of the vacuum switch. If an additional switch is required to enable high boost to switched in directly by the driver (not recommended, but some people will want it), then this should be wired in separately to the vacuum (or throttle) switch, and is basically the duplicate of the wiring for the vacuum switch. Large capacity wires should be used as the load of both the solenoid and electric fuel pump is high, and can result in burn out if the wiring is adequate. I’ll try and quantify the actual load when I get the opportunity.

NOTE: It is possible that the solenoid in the supercharger is a 6 volt unit and not a 12 volt unit, in which case a resistor should be added in line between the solenoid and the vacuum/throttle switch to the drop the voltage to 6 volts, if a 12 volt supply is used. This is very likely for the early VS57A and VS57B units, and may also apply to the VS57C units. The only sure way of finding out is to remove the solenoid from the supercharger and test it using a 6 volt supply. If it actuates with 6 volts then use a resistor.

Checking the Supercharger Control System

After the supercharger has been installed a complete check should be made to ensure the correct functioning of all the installed and modified components. The follow provides the procedures used for checking.

An air-fuel meter, 0-10 lb vacuum, 0-10 lb boost and 0-15 lb fuel pressure gauges are required for the check. The vacuum gauge should be connected to the intake manifold vacuum, the fuel pressure gauge should be connected to the fuel line between the mechanical fuel pump and carburetor, and the boost gauge should be connected to the pressure line from the supercharger discharge throat to the mechanical fuel pump, with T pieces being used for the connections where required. The air fuel gauge connection should be as per the manufacturers instructions.

1.      Turn the supercharger variable ratio pulley by hand at least 12 times fast to ensure that the oil pump in the supercharger is primed.

2.      Turn on the ignition, but do not start the engine.

3.      Remove the vacuum hose from the rear of the vacuum switch and plug the free end of the hose. Add a length of hosing to the vacuum switch to enable it to reach your mouth. Blow into the hose and listen for a click which should be heard as the solenoid regulator valve closes. The electric fuel pump should be energised at this stage so a constant whirring or buzzing sound should be heard from the pump as well. Repeat the test by sucking and then blowing, making sure the solenoid valve closes and the electric pump starts each time. After repeating the tests blow for a few seconds to allow the electric pump to supply sufficient fuel to fill the float bowl of the carburettor.

4.      Check all fuel lines from the tank to the engine to be sure that all fittings are secure and that they are not leaking under pressure.

5.      Suck on the hose to open the vacuum switch contacts and to shut off the electric pump. Start and warm up the engine.

6.      After the engine is warm advance the engine speed to approximately 2500 rpm and blow on the hose. This will cause the vacuum switch to close, and the rear flange of the supercharger input pulley should move away from the front flange, causing the drive belt to move to the bottom of the pulley. Sucking on the hose should open the vacuum switch contacts and cause the pulley flange separation to close, resulting in the drive belt moving to the outside edge of the pulley. Reconnect the manifold vacuum hose to the vacuum switch, after removing the plug, and secure tight.

7.      Advance the throttle until the engine is turning approximately 2500 rpm. The rear flange of the supercharger input pulley should start closing to the front flange, moving the drive belt to the outer edge of the pulley sheave. (At idle speed the flanges of the input pulley are separated and the drive belt is riding near the bottom of the pulley.)

8.      Before road testing the supercharger set ignition timing to it’s stock settings and adjust as necessary after conducting the road tests.

9.      Road tests of the supercharger operation are covered in the section on checking the fuel system pressure.

Checking the Fuel System Pressure

McCulloch recommended the following procedure for checking the fuel pressures, which are governed by the air/fuel ration of the mix inside the carburetor.

An air-fuel meter, 0-10 lb vacuum, 0-10 lb boost and 0-15 lb fuel pressure gauges are required for the check. The vacuum gauge should be connected to the intake manifold vacuum, the fuel pressure gauge should be connected to the fuel line between the mechanical fuel pump and carburetor, and the boost gauge should be connected to the pressure line from the supercharger discharge throat to the mechanical fuel pump, with T pieces being used for the connections where required. The air fuel gauge connection should be as per the manufacturers instructions.

To conduct the check the car has to be run on the road or a dynamometer. Under sustained running (with full throttle), and over 3,000 RPM, the boost pressure from the superchargers should read 5 pounds maximum and should remain constant. Failure to read 4.5 to 5 pounds, event though the pressure rose rapidly when manifold vacuum reached zero, is an indication of a defective solenoid regulator.  Provided the electric pump has been correctly wired up, the pump will be energized at the same time as when the supercharger shifts into “high blower” and produces 5 pounds. At the instance of the shift the fuel pressure should start to increase until it reaches a pressure at least 2 to 3 lbs higher than that indicated by the boost pressure gauge.

Drive the car at road load conditions and watch the manifold vacuum, fuel pressure, supercharger boost pressure, and the air-fuel ratio at car speed increments of 10 mph. The air-fuel ratio should run from 12 to 13 off the idle circuit, and then back towards rich as the car progresses towards full throttle. The following tables will serve as a guide.

Cruise (Low Boost) Air-Fuel Check

MPH

Air-Fuel ratio

Boost pressure (lbs)

Fuel Pressure (lbs)

Manifold vacuum

20

30

40

50

60

70

80

90

12 to 13

12.5 to 13.5

13 to 13.5

13 to 13.5

13 to 13.5

13

13 to 12

12 to 11.5

0

0.75

1.0

1.3

1.7

1.9

2.0

2.7

3.5 to 7

3.5 to 7

3.5 to 7

3.5 to 7

3.5 to 7

3.5 to 7

3.5 to 7

3.5 to 7

12 to 15

12 to 13

10 to 12

10 to 10

9 to 10

9 to 8

8 to 6

5 to 3

 

Full Throttle (High Boost) Air-Fuel Check

MPH

Air-Fuel ratio

Boost pressure (lbs)

Fuel Pressure (lbs)

Manifold vacuum

20

40

60

80

100+

12 to 13

12 to 11.6

11.2 to 10.8

10.8 to 10.2

10 to 10.4

1 to 2

2 to 3

4 to 5

4.5 to 5

4.5 to 5

6 to 12

6 to 12

6 to 12

9 to 12

9 to 12

0 to 1

1 to 3

3 to 4

3.5 to 4

3.5 to 4

One thing to be aware of with regards to the vacuum values listed in the above tables is that they are only a general indication of the expected values. A “Golden Hawk” which has a powerful engine in a light chassis will cruise with a higher manifold vacuum than, for example, a heavy station wagon with a modest engine. Fuel pressure will also vary between engines, as it depends on the engine size and the number of pumps installed.