Assembly

When assembling the carburettor, the bolts and fittings may be torqued. Whilst not absolutely essential, torqueing to a set value can prevent stripping threads (most of the screws are into alloy), or uneven tightening (leading to leaks). The following torque settings should be applied during assembly. Note that the values are in inch-pounds (not foot-pounds!).

Application Fastener Size- Threads Per Inch Torque Range Minimum-Maximum (inch-pounds) Dry Oiled

Fuel bowl screws 12-24 25-30 19-22

Main metering jets ¼-32 30-40 20-30

Fuel valve seat lock screw ¼-32 50-60 40-45

Float shaft retainer screws 6-32 3-5 2-3

Fuel bowl inlet fitting 7/8-20 200-250 150-190

Power valve ½-28 40-50 30-38

Accelerator pump cover screws 8-32 6-10 5-8

Choke vacuum restrictor grub screw 10-32 10-15 8-11 Fuel level check plug 5/16-24 55-65 40-50

Choke housing screws 8-32 6-10 5-8

Pump discharge nozzle screw 12-28 25-30 19-22 13. Install the pump cam and slot-head pump cam lockscrew into position #2 of the throttle shaft.

14. Install the accelerator pump adjustment screw, nut (3/8” AF) and spring to the pump operating lever,

leaving them loose for now.

15. Install the throttle stop screw and spring into the throttle body.

16. Fit and tighten the slot-head choke vacuum restrictor grub screw into the base of the throttle body. 17. Using the new throttle body gasket from the kit, fit together the main body and throttle body. Take

care that the correct gasket is chosen from the kit. Tighten the five phillips-head throttle body to main body screws.

18. Fit some spare ½” AF bolts into the throttle body flange holes. The bolts act as “legs”, supporting the carburettor off the workbench.

19. Install the pump discharge needle valve. Using the new gasket from the kit, install the pump discharge nozzle and tighten the phillips-head pump discharge nozzle screw. Set aside the throttle/main body assembly for now.

20. Screw the two main metering jets into the metering block with a wide-blade slot-head screwdriver. 21. Using new cork seals from the kit, install the two slot-head idle needle valves into the metering block.

Screw them in gently until they seat (do not overtighten!) then back them out 1½ turns.

22. Install the power valve and gasket (both from the kit) into the metering body with a 1” AF socket. Set aside the metering block assembly for now.

23. If the pump non-return valve is the “plastic umbrella” type, install a new “umbrella”. Wet the umbrella nipple with some spit, then insert the umbrella nipple from the outside of the fuel bowl and gently pulling it through from the inside. You will feel the nipple “click” as it seats. Cut the top off the nipple, leaving a small amount protruding into the fuel bowl (if the whole nipple is left it will interfere with the float at low float level).

24. Place the new diaphragm return spring into the accelerator pump housing. Fit the accelerator pump diaphragm from the kit over the spring, taking care to select the 30cc diaphragm from the kit. Fit the accelerator pump cover then install and tighten the four phillips-head accelerator pump cover screws.

25. Reassemble the float shaft retainer, float lever shaft, float spring and float assembly as one unit. Install the assembly into the fuel bowl, tightening the two slot-head float shaft retainer screws. 26. Install the new fuel valve assembly from the kit, using the adjustment screw and locknut gaskets

from the kit. Install the fuel valve seat adjustment nut and the slot-head fuel valve seat lock screw. 27. Note that there are three types of float construction: hollow brass (left image below), solid black

 For brass and nitrophyl floats, turn the fuel bowl upside down, then adjust the fuel valve seat adjustment nut until the float sits in the middle of the fuel bowl (as per the image to the right). Tighten the slot-head fuel valve seat lock screw.

 Duracon floats ride higher on the fuel than either the brass or nitrophyl float and, therefore, a higher setting is in order. For Durcon floats, turn

the fuel bowl upside down, then adjust the fuel valve seat adjustment nut until the float sits 5/16”

from the bottom of the float bowl (the side with the adjustment nut), measured at the middle of the float (a drill bit is handy to measure with). Tighten the slot-head fuel valve seat lock screw.

28. Install and tighten the slot head fuel level check plug, using the new check plug gasket from the kit. 29. Assemble the main body assembly, metering block and fuel bowl, using the new fuel bowl gasket

and metering block gasket from the kit. Whilst the fuel bowl gasket is normally symmetrical, the metering block gasket is not, and care must be taken that it is not put in back-to-front – check the alignment of the holes in the gasket with those in the metering block.

30. Install and tighten the four slot-head fuel bowl screws, using the new plastic bowl screw gaskets from the kit.

31. Fit the pump operating lever, screw, spring, locknut and retainer.

32. Ideally, the accelerator pump operating lever should just be in contact with the short pump arm (mounted on the accelerator pump cover) at idle. This absence of slack

gives sharp accelerator pump response. However, the accelerator pump operating lever needs to be set such that it does not overflex the pump diaphragm. To set the operating lever clearance, tighten the locknut such that the pump operating lever is just in contact with the short pump arm. Next, hold the throttle fully open, then move the pump arm until the pump

diaphragm is fully flexed. Measure the gap between the pump arm and the pump operating lever adjustment screw with a set of feeler gauges. If the gap is less than 0.015”, back off the locknut to suit. This will mean that there will be a slight throttle response delay (due to the operating lever having to move a little bit before it contacts and starts to move the pump arm), but this is preferable to overflexing (and tearing) the pump diaphragm.

33. Reassemble the three separate choke assemblies (fast idle pick-up lever, fast idle cam lever spring and fast idle cam lever as one unit, back-up plate and stud assembly, choke rod lever and bushing assembly and choke spring as a second unit and choke lever and swivel assembly, fast idle cam plate and fast idle cam and shaft assembly as a third unit.

34. Install the fast idle pick-up lever, fast idle cam lever spring and fast idle cam lever as one unit and hold it in place with the phillips-head fast idle cam lever screw.

35. Fit a new paper circle gasket from the kit to cover the choke vacuum passage. Holding the gasket in place, fit the back-up plate and stud assembly, choke rod lever and bushing assembly and choke spring as one unit. Install the choke link hairpin clip to the choke link.

36. Install the choke lever and swivel assembly, fast idle cam plate and fast idle cam and shaft assembly as one unit. Install the single slot-head screw to hold it in place, then fit the choke cable holder bracket with it’s two slot-head screws.

37. Adjust the fast idle screw with the choke fully open such that the gap between the throttle plates and the throttle bores is 0.020”. This is pretty small to measure with a set of standard drill bits, so again a “bent and narrowed” feeler gauge is handy.

38. Set the throttle stop screw such that the throttle plates are closed, then back the screw out 1½ turns. 39. Install the fuel filter spring, new sintered bronze filter and fuel filter gasket from the kit. Install and

tighten the fuel inlet fitting (1” AF), using the new gasket from the kit.

40. Before putting the carburetor onto the vehicle, it is wise to double check (triple check) that the parts that can fall through into the carburettor throat are staked and/or tight:

 pump nozzle screw tight. Although the screw and nozzle cannot pass into the engine (won’t fit past the booster venturi), the pump check valve “needle” certainly can.

 hot air choke restrictor grub screw tight.  Choke plate screws tight and staked.  Throttle plate screws tight and staked.

41. Install the carburettor to the manifold using the new gasket from the kit. Do not tighten the flange nuts just yet as the ability to move the carburettor slightly makes some of the connections easier. Note that the throttle bores are not centered on 350 Holley carburettors, and are offset 0.17” (~11

/64”)

to the back of the flange. If the carburettor flange gasket is put in back-to-front, it may catch the throttle plates, causing them to jam open

42. Connect the choke control cable to the choke actuation lever, and mount the outer sleeve to the cable clamp. Actuate the choke cable through its full range of motion to ensure full choke operation and adjust as necessary.

43. Connect the fuel line to the carburettor fitting.

44. Connect the manifold vacuum hose at the rear of the throttle body base, and the timed spark vacuum hose at the side of the metering block. Note that in some cases either or both of these hose connections may be not used, and must hence be capped off at the carburettor with plastic caps. 45. Install the throttle cable to the clamp and to the carburettor. Refit any throttle return spring(s)

required.

46. On automatic transmission vehicles only, install the transmission kickdown adjustment screw and black retaining clip, as correctly indicated. Failure to attend to this detail may

result in a sticking wide-open throttle or dangerous uncontrolled engine speed.

47. Tighten the manifold flange bolts to 15ftlb in the pattern shown in the image to the right. Do not overtighten the nuts, as a warped or cracked throttle body may result.

48. Check that the throttle operates smoothly and returns to idle. Check that wide open throttle (WOT) is achieved.

49. Start the engine and check the fuel lines and inlet fitting for possible leaks.