Harv's McGee injection thread

[Harv]

Finally managed to source a new thrust bearing for the angle drive. Its a NSK FT1/2 bearing, 1/2"x15/16"x1/4". Its a $40 bearing

New one on the bottom of the photo, old one on the top.

Angle drive thrust bearing.jpg (609.99 KiB) Viewed 3532 times

Cheers,
Harv

[59wagon]

Good work Harv. Great that you got to chat with the McGee guys.

Cheers, John


Sent from my iPhone using Tapatalk

[Harv]

Finally managed to get the McGee pump screwed together. The bearings are quite sloppy in the housing, allowing the shaft to cant. This ieads to the top of the rotor contacting the pump lid (the clearance is pretty fine to start with). A few "love taps" with a copper hammer and it was back to square again. Attached below a photo of the pump with the lid off. With a standard rotation (ala grey motor, as per the green arrow) the inlet is at the top, and the outlet at the bottom. The purple arrow shows the volute - the gap in the pump that the fuel gets squeeeeeezed in. Forgive the dark looking stuff - it is antisieze that I used on the stainless bolts.

volute.JPG (119.23 KiB) Viewed 3497 times

Also got the angle drive screwed together, and mated up to the pump and magneto:

Angle drive 1.JPG (129.21 KiB) Viewed 3497 times

Angle drive 2.JPG (108.54 KiB) Viewed 3497 times

I fitted some black AN fittings (-8AN suction and -6AN discharge), and covered them with the red plastic caps to keep crap out. That is one damn heavy assembly... 5kg. No wonder that the angle drive has a tendency to crack off the "tang" in the block.

Cheers,
Harv

[FJWALLY]

Very cool bit of kit Harv - almost need a sling bracket to carry some of the weight

[Harv]

Very cool bit of kit Harv - almost need a sling bracket to carry some of the weight

That's the plan. Scintilla made a hefty ally ring that clamps around the maggie body. They were originally used to mark magneto rotation (timing). I bought a couple in a job lot of maggie parts a few years back. I plan to use one of them with a short tab to take the magneto weight onto an engine sideplate screw... something like this:

Angle drive 3.jpg (151.59 KiB) Viewed 3491 times

Cheers,
Harv

[FJWALLY]

Nice - probably should look at something like that myself.

The head of your Mag will be about middle of the timing plate once it's laid over and should be fairly close to the bottom edge of the side plate if I'm thinking right?

I haven't trial fitted either of mine to see if the Clutch slave is going to be an issue or firewall for that matter - any suggestions?

Very cool bit of kit Harv - almost need a sling bracket to carry some of the weight

That's the plan. Scintilla made a hefty ally ring that clamps around the maggie body. They were originally used to mark magneto rotation (timing). I bought a couple in a job lot of maggie parts a few years back. I plan to use one of them with a short tab to take the magneto weight onto an engine sideplate screw... something like this:


Angle drive 3.jpg



Cheers,
Harv

[Harv]

The layout will be interesting.

Injection and supercharger live on the drivers side. The injector is likely to be pointing skywards... no way it is fitting under the bonnet.
Angle drive sits into the dizzy hole, then runs the magneto forwards towards the fuel pump. Maggie head will be ~9" forward of the dizzy hole, pointing towards the grille.
Dry sump tank will live on this side too, on the subframe step.
Passenger's side has the headers only.
Front of the engine will get complex - need to sneak in the supercharger drive belt, plus the dry sump pump hanging off the end of the cam (through the timing cover). May have to move the radiator forward of the radiator top support.

Lots of brackets and adapters to make.

Cheers,
Harv

[Harv]

Small update on the injectors... minor stuff, but useful if someone else is trying to overhaul a set of McGee gear without spending a fortune. The McGee injectors for the Repco head are a two-piece brass construction, soldered together.

assembly.jpg (17.42 KiB) Viewed 3475 times

Inside the body of the injector is a tiny drilled orifice (in this case 0.018"). To allow access to the orifice, a #10-32UNF capscrew is fitted to the injector end. The capscrew is sealed with a fibre washer (you can see the washer hiding in the shadow of the photo) . You would think that the washers would be a simple thing to buy... sadly not. I hunted far and wide locally, but all the washers with the correct bore are waaaaaay to big in the OD. In theory I could cut some washers, but they are quite fine... and have 100psi of fuel pressure behind them. Not something to bugger up with my fumble fingers.

You can buy the correct washers from Hilborn or Alky Digger in the US, but the postage is prohibitive (like $30 ) unless you engage a freight forwarding company.

I managed to get a set from a modelmaker in the UK (https://eileensemporium.com/) and paid pennies for the postage:

washers.jpg (58.98 KiB) Viewed 3475 times

I know it's fiddly stuff, but very time consuming nonetheless.

Cheers,
Harv

[Harv]

A little bit more info on the ally pullies that McGee made (see earlier post of my damage, shiny black painted pulley). My red motor set has a similar pulley on the fuel pump (more on the pump later). The McGee pullies are a 32-tooth unit, 1 7/64“ wide, trapezoidal profile with 3/8" pitch.

A suitable belt is the Gates PowerGrip® timing belt. These have a part number specified by:
1. Length - the length is shown in the first part of the belt designation. The first number is the pitch length, in tenths of an inch. The belt pitch length is normally the length at the belt pitch line (located at the neutral axis near the cord line and varies with cross section and construction). Pitch length should not be confused with:
• Outside belt length (measured with a tapemeasure under no belt tension),
• Inside belt length (measured with flat pulleys or a tape measure and varies with the manufacturer),
• Belt effective length (measured at specified pulley diameter), or
• Nominal belt length (a designated belt length).

Confused? Me too. Often the best way to determine belt length is by trial and error (handy if the belt shop is nearby, friendly and has a good stock of belts… difficult if you are ordering a belt online). As an example, a belt with part number 270L050 has a 27.0" pitch length. Length will vary considerably depending on how the McGee pump is mounted.

2. Pitch - The pitch is the distance from center to center of the teeth (in inches). It is shown in the second part of the belt designation by a letter or letters. The letters correspond to pitches as follows:
• MXL = Mini Extra Light = 0.080" pitch
• XL = Extra Light = 0.200" pitch
• L = Light = 0.375" pitch (this is the pitch that the McGee pulleys use)
• H = Heavy = 0.500" pitch
• XH = Extra Heavy = 0.875" pitch
• XXH = Double Extra Heavy = 1.250" pitch
From our example, part number 270L050 has the correct 0.375" pitch.

3. Width - The width is shown in the last part of the belt designation. Light pitch belts suitable for McGee injection pulleys are available in ½”, ¾” and 1” widths. From our example, part number 270L050 is 0.50" wide. The belt that was supplied with my unit was ½” wide. As this is very much less than the 1 7/64“ pulley width, you can probably get away with not running flanges on the pulley. If the wider ¾” (or 1”) belts are used, the risk of the belt walking off the pulley increases. To counter this when using the wider belts, at least one pulley should have flanges. If the belt is short enough, each of the pulleys can have a flange on one side. When the span (center distance between shafts) is eight times or more the diameter of the smaller pulley, both pulleys should have flanges.

Similar replacement pulleys are available from Naismith Engineering:
https://www.naismith.com.au/list_products.php?m=42
The table below shows their L-profile belts:

Naismith Engineering L profile pulleys.png (289.2 KiB) Viewed 3460 times

Cheers,
Harv

[Harv]

A little bit more thought about the magneto horizontal installation. There is another very good reason to support the magneto (in addition to preventing it from snapping the spigot out of the angle drive). There is a distinct warning in the Vertex Magnetos Instruction Manual:

The VERTEX magneto is installed in the same way and in the same place as a battery-ignition distributor. However, it should not be inclined at more than 30º to the vertical. For greater inclinations or horizontal fitting special types are made, in which the plain bearings in the housing are replaced by ball bearings.

Vertex are wary of flogging out the plain bearings (bushes) that are in the drive end of the magneto. The other end (cap end) has a ball bearing, and will take some sideways loading (the diagram below shows the balls in red). The simple bushes at the drive end (circled in green) will be a lot more susceptible to wear when loaded sideways. Installing the support clamp will take this load off the bushes, allowing me to run the magneto horizontally.

Magneto support.png (226.74 KiB) Viewed 3447 times

Cheers,
Harv

[Harv]

I think I have the linkage nutted out. The linkage was a hodge-podge of nut sizes and types, some stripped. I've replaced the lot with stainless capscrews (there were a lot of funky fine UNF and UNC threads in that lot). I've retained the W-clip - none too happy, but little choice given the shaft misalignment. The el-cheapo pressed-steel throttle arms have been replaced by Stromberg SuperLink Throttle Arms (part number 9090K - https://www.stromberg-97.com/product-in ... kage-parts). The arms are diecast zinc (a lot lighter than the similar Hilborn brass arms), and closely resemble a H-beam conrod. They needed to be drilled out slightly to suit the McGee shafts.

I'm not quite happy with the hex-link (the piece with a rose joint at either end). The hex-link is pretty much extended out, and I can't quite get the throttle arms parrallel. This give a tendency for the arms to want to go over-center. When the arms go over-center, there is a tendency to want to not come off idle (bad idea during a drag race). I think I can swap out the guts of the hex-link for a longer rod (it is a funky rod, LH thread one end, RH thread the other). Need to check my linkage spare parts department and see what I can cannabalise... suspect the guts out of an old Redline Performance hex-link will do the job.

linkage.jpg (111.29 KiB) Viewed 3417 times

throttle arms and hex-link.jpg (75.8 KiB) Viewed 3417 times

W-clips and throttle stops.jpg (101.41 KiB) Viewed 3417 times

With the arms in place, I need 1.5" (~37mm) of throttle arm travel to move from idle to WOT. The original GMH firewall lever (attached to the accelerator pedal via linkage) only moves some 12mm. It's kinda on the wrong side of the engine too for a Repco head. Chances are I will need to remove the firewall linkage, and move to a cable setup. By extending the lever that pokes from the pedal through the firewall (by welding or bolting on some flatbar) by an extra 40mm I can get a cable pull of 35mm - perfect.

Cheers,
Harv

[Harv]

Some more assembly photos. First one is another McGee belt drive. This is a little different from the one posted earlier, as it is hex drive (earlier one was a tang drive to suit the earlier fuel pumps). The hex is 3/8”AF.

Belt drive assembly.jpg (132.85 KiB) Viewed 3393 times

A: Drive pulley
B: Drive pulley retaining setscrew (1/4-20UNCx37/64”, square head)
C: Bearing retaining circlips
D: Bearings (R8LL, ½”x11/8” x ¼”)
E: Brass bearing spacer
F: Brass bearing spacer retaining roll pin
G: Body
H: Shaft

The second assembly photo is a McGee “hex head” pump.

McGee hex head pump assembly.jpg (335.13 KiB) Viewed 3393 times

A: Body screws (#10-24UNCx1.75”)
B: Inlet nipple (-6AN to 9/16-18UNF ORB)
C: Outlet nipple (-8AN to 9/16-18UNF ORB)
D: Body sealing rings
E: Inlet/outlet cap
F: Gear retaining body plate
G: Volute body plate
H: Base assembly
I: Drive gear
J: Driven gear
K: Bearing retaining circlips
L: Bearings (R8LL, ½”x11/8” x ¼”)
M: Steel bearing spacer and grub screw
N: Shaft
O: Lip seal, radial dual lip (TC) oil seal, ½”x11/8” x ¼”, part number RS05011225LNC made in Buna-N.
P: Pump to drive retaining capscrews (1/4-20UNCx0.75”)

The pump is a gear pump (different to the earlier McGee sliding vane pumps), and is reversible. If the pump is driven clockwise looking onto the drive pulley (e.g. driven by belt from the crank), then the fuel flows as per the red lines in the diagram below. If the pump is driven anticlockwise looking onto the drive pulley (e.g. driven by belt from the camshaft or direct driven off the dizzy), then the fuel flows as per the green lines in the diagram below.

McGee pump circulation.jpg (101.39 KiB) Viewed 3393 times

As the pump inlet/outlet cap only goes on one way, this means that the pump inlet and outlet depend on pump rotation (as per the diagram below):

McGee pump flow.jpg (96.08 KiB) Viewed 3393 times

Cheers,
Harv

[Harv]

Got the ram tubes done, with base plates and TIG work by a local sheetmetal mob:

Ram tubes side view.jpg (88.69 KiB) Viewed 3364 times

Ram tubes top view.jpg (75.07 KiB) Viewed 3364 times

Jim Henson would approve

Honkers.jpg (6.41 KiB) Viewed 3364 times

Cheers,
Harv

[FJWALLY]

Saw this on f book this morning Harv


You’ll find me lost somewhere!

[Harv]

That's Hedley McGee's Shell Trackburner speedcar. It took out the 1964-1965 Australian National Championship.

Cheers,
Harv