Harv's McGee injection thread

[Harv]

I've been stashing away McGee info for a while, so figure I will post it here so it doesn't get lost. I've also managed to pick up a later model McGee set, so will also post here what I learn as I pull the thing apart.

To kick it off, an article from Australian Hot Rod November 1966:

Optimized-Australian Hot Rod November 1966 1.jpg (570.17 KiB) Viewed 2858 times

Optimized-Australian Hot Rod November 1966 2.jpg (643.54 KiB) Viewed 2858 times

Optimized-Australian Hot Rod November 1966 3.jpg (771.95 KiB) Viewed 2858 times

Optimized-Australian Hot Rod November 1966 4.jpg (643.72 KiB) Viewed 2858 times

Cheers,
Harv

[Harv]

Some photos:

This was taken at the 2006 Vintage Speedcar Spectacular:

2006 Vintage Speedcar Spectacular of a Repco Holden engine 1.jpg (560.59 KiB) Viewed 2857 times

This is Dave's grey motor set, posted elsewhere on the forum:

Dave Paganos angle drive.jpg (126.88 KiB) Viewed 2857 times

Dave Paganos mcgee injection.jpg (154.63 KiB) Viewed 2857 times

This is a set that was sold on eBay a while back:

eBay McGee 1.png (191.24 KiB) Viewed 2857 times

eBay McGee 2.png (212.26 KiB) Viewed 2857 times

eBay McGee 3.png (230.78 KiB) Viewed 2857 times

eBay McGee 4.png (228.32 KiB) Viewed 2857 times

eBay McGee 5.png (220.11 KiB) Viewed 2857 times

[Harv]

eBay McGee 6.png (195.46 KiB) Viewed 2856 times

This set was posted on FaceBook:

FaceBook midget project mcGee injection.jpg (43.61 KiB) Viewed 2856 times

This set was also posted on FaceBook:

FaceBook photo 1.jpg (571.57 KiB) Viewed 2856 times

FaceBook photo 2.jpg (547.98 KiB) Viewed 2856 times

The Frank Brewer speedcar:

Grey perhaps..PNG (294.98 KiB) Viewed 2856 times

The elusive grey motor angle drive for dizzy and pump:

McGee fuel pump and right angle distributor from Michael Bresnehan.jpg (73.81 KiB) Viewed 2856 times

Cheers,
Harv

[Harv]

Warren Greve's speedcar:

Warren Greve's speedcar.PNG (479.45 KiB) Viewed 2856 times

Red motor from eBay (apologies for the late model ):

Red motor eBay 2018 1.jpg (257.46 KiB) Viewed 2856 times

Red motor eBay 2018 2.jpg (259.27 KiB) Viewed 2856 times

Red motor eBay 2018 3.jpg (263.72 KiB) Viewed 2856 times

Red motor eBay 2018 4.jpg (284.75 KiB) Viewed 2856 times

Red motor in a very tidy early Holden engine bay:

Red motor in green car.jpg (76.21 KiB) Viewed 2856 times

[Harv]

Another red motor set:

red motor McGee injection 1.jpg (74.67 KiB) Viewed 2856 times

red motor McGee injection 1.jpg (74.67 KiB) Viewed 2856 times

red motor McGee injection 3.jpg (61.18 KiB) Viewed 2856 times

red motor McGee injection 4.jpg (62.19 KiB) Viewed 2856 times

Cheers,
Harv

[Harv]

Some starting info on the nozzles from my McGee set. It was originally on a 6-cylinder Holden motor. Seller suggests blue motor, though I suspect red motor based on bolt pattern. Will check via a gasket and confirm either way.

The Mcgee set has six injectors as per the photo below:

Optimized-Nozzles.JPG (623.7 KiB) Viewed 2852 times

There were four blue nozzles (feeding cylinders 1, 3, 4 and 6) and two red nozzles (feeding cylinders 2 and 5). Not sure why the larger red nozzles are on 2 and 5. This was allegedly from a Holden 12-port head, so siamesing should not be the issue. Having said that, the bolt pattern looks suspicously like the earlier 9-port head… I need to check against a gasket. The red nozzles have a slightly longer overall length, and are slightly different in the thread machining to the blue nozzles

The nozzles are an all-aluminium item, with a mild-steel mesh screen in the discharge end (in the photo, the “right hand” end is the discharge, with the cylinder end open and meshed). I have heard of nozzles being described as “mesh tip” before, and assume this is what they mean. I know that some nozzles (perhaps Hilborn) have a removable mesh prior to the nozzle to prevent dirt entry. In the McGee nozzles the mesh is on the discharge side and appears fixed. The blue mesh is 0.23” diameter and the red mesh 0.206”. I need to connect the garden hose up to them… assume the spray pattern is a mixture of flow through the mesh, and flow out the holes near the tip end.

The blue nozzles have four 0.041” radial holes at the discharge, each sitting in a 0.104” countersink. The red nozzles have two 0.102” radial holes without countersink. The red holes have three times the area of the blue holes.

Both nozzles have two air bleed holes drilled into the nut face (0.060” in the blue, 0.055 in the red). The red holes have 20% more area than the blue holes. These holes are used to introduce air into the nozzles (from outside the manifold) to assist idle. The internals must be venturi shaped to do this, otherwise they would squirt fuel out. I need to take a closer look at the venturi setup.

Both nozzles are tapped 1/8”-27NPT to screw into the manifold, and 3/8-24UNC on the inlet side to connect to the fuel pipes. Each nozzle has an ally adaptor (left side of photo) to allow them to adapt to 3/16” pipe (45º double flare). The adaptors are solid aluminium, bored to 0.108” on the discharge side and with a tiny 0.034” hole bored on the inlet side. The 0.034” hole must act as the restriction to determine fuel flow through the nozzle.

Cheers,
Harv

[Harv]

Some photos of the barrel valve, which is machined from a sold block of aluminium:

Optimized-Barrel valve 1.JPG (250.04 KiB) Viewed 2836 times

Optimized-Barrel valve 2.JPG (494.25 KiB) Viewed 2836 times

Optimized-Barrel valve 3.JPG (467.22 KiB) Viewed 2836 times

Optimized-Barrel valve 4.JPG (503.8 KiB) Viewed 2836 times

Optimized-Barrel valve 5.JPG (481.1 KiB) Viewed 2836 times

The larger ports are tapped to 9/16-18UNF (-6AN) o-ring boss (ORB). The smaller pill port is tapped to 3/8-24UNF (-3AN) ORB. The cross-drillings are tapped to 3/8-24UNF, with the female threads cut to a tapered thread. The mounting bolt holes are tapped to 1/4-20UNC.

Barrel valve plumbing schematic.png (14.03 KiB) Viewed 2835 times

More photos to follow once I clean up the internals.

Cheers,
Harv

[Harv]

Photo of the internals below. Note that i have the spool oriented incorrectly - the spring bears on the larger end of the spool, not the thinner shaft end.

Optimized-Internals.jpg (558.79 KiB) Viewed 2808 times

The plugs are an o-ring boss (ORB) design, with the threads of each plug having a bleed hole. Mechanical fuel injection can run at 100-200psi. There is a risk that the high pressure is trapped in the fuel system by shut valves. When you go to take a plug out, the high pressure throws the plug at you at the speed of light . The bleed holes let you unscrew the fitting, and vent the fuel pressure whilst the plug is still retained by the last few threads.

Plug vent holes.jpg (259.34 KiB) Viewed 2808 times

The spool is an interesting one. It has a normal fuel ramp, but also has a secondary bypass hole. When the throttle is slammed shut, no fuel flows out the ramp. Fuel is instead diverted into the secondary bypass hole, and through the secondary bypass poppet back to tank. This helps even out fuel pressure and prevent rich running when the throttle is opened again.

Spool.jpg (826.32 KiB) Viewed 2808 times

Spool operation for secondary bypass.jpg (680.97 KiB) Viewed 2808 times

The primary bypass spring is made from 0.014" wire, the secondary bypass spring from 0.027" wire whilst the spool retaining spring is made from 0.031" wire. The pill is of the screw-in type with a chamfered inlet, and is 3/8-24UNF. Similar, but not identical to Enderle pills (which are 7/16").

Cheers,
Harv

[Harv]

The McGee injection set that I bought came with had an Enderle 80A pump. I've bought a McGee pump, and when I pull it apart I'll post it here. For interest, I'll post the workings of the Enderle pump here too so it can be compared to the McGee.

My Enderle pump has had an interesting life. Someone has machined down the main body (probably to clear something - see the shiny bit in the photo below), which means I can't tell what size 80A pump it is without wet testing it. The inlet and outlet though are clearly marked. The inlet is ¾-16UNF ORB (-8AN), whilst the outlet is 9/16-18UNF ORB (-6AN).

Optimized-Enderle 80A pump overhead view (1).JPG (515.75 KiB) Viewed 2792 times

The pump shaft has a round end with teeth cut into it. This meshes with a gear mounted inside the front pump cover:

Enderle 80A pump gear mesh.JPG (910.15 KiB) Viewed 2792 times

The fuel is moved from inlet to outlet by the meshing gears. The fluid can pass through the volute side of the front pump cover, but not the other side.

Optimized-Enderle 80A pump internals.JPG (425.03 KiB) Viewed 2792 times

To change the pump rotation, the front pump cover can be rotated 180º. This moves the volute from one side of the pump to the other. A notch is cut into the front pump cover to tell which way the pump is oriented:

Enderle 80A pump notch.JPG (1.07 MiB) Viewed 2792 times

Cheers,
Harv

[Harv]

Ladies and Gents,

As flagged over on my meth monster project thread, I have been fortunate enough to pick up a set of McGee injection to suit a Repco crossflow head. Basic photo below:

injector and angle drive.JPG (622.6 KiB) Viewed 2758 times

I’ll work through the gear over the next few weeks… lots of reverse engineering to do. I’ll share what I find here. It’s going to be interesting because the injection set comes with some additional bits (nozzles, pump, shaft stops, metering valve) that would suggest it may have had a few different lives.

One thing that caught my eye is that the injection set came with some additional plumbing. A “normal” system is similar to the first three diagrams below.

vacuum controlled idle.png (71.97 KiB) Viewed 2758 times

When the vehicle is cranked, the poppet in the primary bypass is shut and all the fuel flows to the injectors as per the top diagram. The fuel pump speed is very, very low, so not much fuel gets there. Not uncommon to see either an additional electric priming pump, or a “squirty bottle of fuel down the injector hat” to help fuel up on cranking. Once the vehicle fires, the fuel pump spins faster and more fuel goes to the injectors. The primary bypass poppet opens, and excess fuel gets spilt back to the tank as per the second diagram. When you step on the loud pedal, the barrel valve opens, letting more and more fuel go to the injectors. The barrel valve is pretty rough though… it does idle and WOT, but in-between is pretty rough. With the car at full noise, you can take your foot off the throttle (gear change in drag racing, cornering in speedway). The pump is still spinning madly, so the secondary bypass opens to spill the excess fuel back to the tank as per the third diagram.

Where my McGee setup is weird is that an additional vacuum operated valve has been added (see picture below):

vacuum pressure regulator.jpg (482.24 KiB) Viewed 2758 times

The injection set came with a plumbing diagram that suggests a lineup like the fourth diagram. At idle and cruise (high vacuum signal) the vacuum valve opens up, providing additional fuel. Once you stand on the throttle (no vacuum), the valve shuts and the system goes back to being normal injection. So why have this additional valve? Firstly, it gives the injection a cruise circuit. This would be useful on the street, because at cruise the barrel valve is part open and doing a crappy job of metering fuel. Not so useful on the drag strip or speedway, where the vehicle is never at cruise. It also means that at idle the primary bypass does not need to supply as much fuel. The primary bypass pill can thus be a larger diameter. This will allow for a leaner top-end. I need to think this one through a bit more as I pull apart the metering valve plumbing.

The other unusual item that the injection set came with was an electric solenoid:

shutoff solenoid valve.jpg (485.78 KiB) Viewed 2758 times

This is an on/off valve. Most mechanical injection set have a shutoff valve before the barrel valve, as per the blue box on the fourth diagram above. It acts as a positive way to shut off fuel to the engine, and stops fuel syphoning into the engine. The weird bit about my setup is that the shutoff is an electric solenoid valve – normally this is a manual ball valve, sometimes driven by a cable. The electric solenoid again would suggest that this injection set may have spent some time on a road car.

Cheers,
Harv

[Harv]

A post for today on nozzles. Nozzles are the lumps of brass that screw into the manifold and do the actual fuel squirting. The McGee grey motor injection set came with six nozzles installed, and eight spare nozzles. Good opportunity for me to learn about how the McGee nozzles are identified.

McGee nozzles are made to have a -3AN fuel inlet fitting. This suits 3/16" tube, and has a 3/8"-24UNF straight thread. The thread that screws into the injector manifold is 1/8-27NPT.
The nozzles are made in five different styles:
1) X style (both Left and Right),
2) R style,
3) C style,
4) Shower Head style, and
5) Straight style.
The different styles are shown in the image below:

Nozzles.png (554.47 KiB) Viewed 2730 times

X, R and C styles are near identical - the fuel squirts out at 90º to the nozzle body, but in a different direction for each style. Each McGee nozzle is also available in six different sizes - #8, #10, #12, #14, #16 and #18. Part numbers for the different nozzles are given in the table below:

Nozzle part numbers.PNG (13.08 KiB) Viewed 2730 times

The grey motor injection set came with three XL nozzles and three XR nozzles (plus a spare of each). A nozzle can be seen peeking into the inlet manifold below:

nozzle in manifold.jpg (484.53 KiB) Viewed 2730 times

nozzle screwed into manifold.jpg (437.21 KiB) Viewed 2730 times

These are stamped X18, as per the lower image below (this is a Right-hand X style):

McGee nozzles from grey motor injection set.jpg (387.82 KiB) Viewed 2730 times

I suspect the X18 is similar to the Kinsler coding, and that the internal fuel control orifice is 0.018” diameter (looks to be, but I need to get hold of my fine pin gauges to confirm). They are not Kinsler nozzles though, as Kinsler run either 1, 3, 4 or 6 vent holes – these have two 0.134” external vents (cant see them in the photo above as I have the nozzle turned the wrong way).

The injection set also came with six spare Straight nozzles, as per the upper image above. These have a 0.121” internal bore (massive compared to the 0.018” nozzles), and two external vent holes (0.093” and 0.063”).

The bit I am not sure of is whether these are #8, #10, #12, #14, #16 or #18 nozzles. I’ve sent a query over to McGee in the states, and see what response I get.

The 0.018” holes in the nozzles make me understand why there are so many warnings about keeping mechanical fuel injection systems spotlessly clean, and why they run such intricate filtration.

Cheers,
Harv

[Blacky]

Harv, just had a look at this one thought I would grab a couple of pics for you, think they are being a bit loose with the truth horsepower wise but the bloke swears it's true -















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[Blacky]

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[Errol62]

Teasing us blacky. Nice stickers.


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[Harv]

Thanks Blacky - much appreciated. It looks like one of the later McGee sets. The early ones had separate throttle bodies, the later ones had a single manifold. The barrel valve photos are particularly useful... someone has stuck an Enderle barrel valve on my set, though I still have the original McGee one to piece back together.

Agree that 265BHP is a bit funky for an older, stock-headed, naturally aspirated grey. Possible, but improbable. Best I have seen is John Douglas' Repco headed EFI naturally aspirated FJ (196HP) and Mark Riek's turbo'd EFI FX ute (226HP). Assuming a 30% driveline loss, those would be 280BHP and 322BHP.

Cheers,
Harv