From the beginning, the plan with my Magnette has been to add forced induction. Originally I was drawn to the historical significance and cool factor of a period Judson blower. I looked for over a year and considered a few different units, but the more I learned about sliding-vane blowers and their inherent shortcomings I began to realize that a Judson would not suit me. I like driving my car and plan to do it a lot. I'm not saying that a Judson is a bad choice, but for me I decided to go with the new Moss MP45 Eaton blower. Learning that the new version is sold with a beautiful HS6 bolted to it made the decision an easy one, as that was going to be my carb of choice for the Judson anyway.

So, I placed my order with Moss and their lovely unit showed up in early May. My beautiful new daughter was born a week later, so progress has been slow as I focus on more important things I decided to keep the car at home so that I could tinker between diaper changes and as of last night, I have a running supercharged Magnette!

Rich McKie and Kelvin Dodd have paved the way on many of the tricks to putting one of these in a Magnette, but being the new version I knew there would be some minor variations. The use of an HS6 instead of an HIF44 moves the throttle arm to the other side of the carb, so I plan to keep the quirky mechanical throttle linkage intact. This is probably a bad idea, but so is supercharging a 1500

I originally planned to fabricate a header before the installation, but decided to get the car on the road first and upgrade the exhaust later. I think I'll actually use an MGA manifold with the output flange angle changed matched to a bigger bore pipe, but for now the stock manifold and pea-shooter exhaust will have to do! The Magnette manifold is the same thickness as the blower intake, so no shims are needed.

So, on to the modifications needed to get things to fit. When I restored the engine bay I made the clutch pipe to the exact shape of the original. This had to be re-bent to clear my velocity stack. It will need even more room to clear whatever filter I choose to run over the stack but being cupro-nickel it should be OK. I also plan to reverse the master cylinder top to move the fill to the rear. The original fuel pipe needed a slight jog bent in it to reach the float bowl at a reasonable angle. The fuel line Moss provides is luckily the same thread so I could retain the original fitting on the feed pipe. The lower radiator hose provided in the kit fits perfectly, you just have to trim it differently than the instructions recommend for the MGA installation. The idler pulley bracket retainer bolts have Nyloc nuts on the backside, but the lower one will not fit because of proximity to the engine mount bracket. I used Loc-tite on that one instead. The blower pulley touches the bonnet release return spring, but once I relocate it further back down the rod it will have 1/2" of clearance. I also re-used the original heater pipe instead of the provided unit because I wanted to retain the correct fitting tabs.

Besides that, it is the same as an MGA. In other words, easy! If you can put on SU's you can install a supercharger. It started on the second crank after I adjusted the choke, and had it idling @850 with some slight timing and mixture adjustments. After I figure out the throttle and clean up some of the vacuum routing it will hit the road. I'll be sure to report back once I have some test miles. Here are the photos:

Tearing it down:


First test-fit, proximity to bonnet release and clutch pipe:



Coolant hose routing:



Installed!

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How did you find the time to do that with a newborn in the house???
Pretty sweet, and congratualtions!

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jeff@advanceddistributors.com

That looks nice, let us know how you like the performance.

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1958 ZB Magnette, White over Burgundy, 3 main, twin SUs.
1962 MGA MkII Red, stock 1622, dual SUs
1963 MGB Rdstr Dark blue, stock 3 main, dual SUs with OD.
1976 MGB Rdster BRG, Weber 45 DCOE, OD.

Ed.

You make it look so clean and easy. Great shots.


Kelvin.

Very nice work. I like the look of the ram tube, but would worry about unfiltered air or a stone ruining all that lovely work. Remember Murphy's law.

Well, Ed, it all looks gorgeous. I understand the attraction to the Judson, for sure, but have to agree for similar reasons that you made the right choice. I can see why you no longer needed the air-filter-housing bracket!

I will be interested to see how the carburetor linkage works out and am also interested in your selection of exhaust manifold. I would like to get away from stock Magnette to get better power, but headers typically are quite a bit noisier than cast manifolds. Is the reangling of the MGA piece a welding operation?

Curious about your ignition timing curve and how it would change from naturally aspirated to forced induction.

Can't wait for the driving report.

P.S. Love your hose clamps...

looks great, any issues with fuel affecting the coating or bearings of the blower with the suck through carb?

Looks nice and as usual I am quite impressed with your clean engine bay... definitely library quality photos!

I do find it interesting that I have a cable for my bonnet release and you (all ZB?) have a rod there... should I decide to install a supercharger I won't have that little issue, at least

Thanks for the comments guys!

I'll be sure to give a full performance report when I get the linkage worked out. I have all the necessary parts (I think) so the next few days should yield results. One of my favourite shows is on Sunday so that is the goal. The key will be getting a nice ratio so my pedal can sit at a good level and still get WOT. I dug out and cleaned a bunch of SU throttle shaft brass arms so I can play with ratios until it looks/feels good.

Based on measurements I intend to run a K&N RU4410 filter which should clamp on the velocity stack perfectly.

The MGA manifold mods with be done with brazing. Classic Motorsports recently ran an article with manifold dyno testing results. The MGA manifold had some of the best mid-range performance numbers so it seems like a good choice.

In regards to the supercharger vs. fuel, it is comforting to know that Moss did the R&D on this one and unlike Judson they are still around for any warranty issues

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Ed.

Good luck on the mechanical linkage. I found that the original short linkage arm gave the correct amount of ratio to fully open the HIF44 throttle arm. Your mileage is going to vary though.

Kelvin.

engine looks great I see you have been busy,have you heard from our Reno bound buddy? call me if you get a chance Mark

Hi Ed,

Looking good! Did Classic Motorsport test the original Magnette manifold too? Maybe its actually a sleeper. Don't run too much boost or you may melt that brazing off that modified MGA manifold! I'll look forward to your performance report in the not too distant future. Ed

Ed, Your car couldn't look prettier --- unless it was mine! Congratulations on a job well done! Arch

Well, I drove the Magnette to work every day this week and it's running absolutely perfect! The blower adds power right where you want it in the rev range, and the car has never idled smoother. The mechanical linkage was a bit difficult to get working smoothly throughout the entire travel, but now it's flawless. I'll post pictures soon, too busy driving right now!

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Here are the photos of the linkage, and the completed install. For now I'm running the air filter that comes with the kit, and will figure out a suitable filter to work with the velocity stack later on.

The linkage is made up of two brass throttle arms, one about 3/4" and the other 1" which gives me nice progressive travel. The rod is made from a Healey 3000 bonnet prop - BMC must have bought in bulk! The link between the carb and end arm is the link from the original ZB carb choke assembly. The end of the rod is supported by a bracket I made from junk around the shop. It's a steel piece with an Oilite sleeve pressed into it. I used my throttle shaft reamer to make it fit on the shaft properly. The support bracket mounts to one of the blower case bolts with a 1/2" spacer behind it. Check it out!

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That's beautiful stuff right there.

I was considering your comment about great idle quality and it occurred to me that my very historically and technically oriented friend Kevin points out that with supercharged piston aircraft, a great boon to even fuel distribution was the mixing effect exercised on fuel and air by the supercharger itself. Can't say this is the case for you, but it certainly appears plausible and sounds great.

Mark

Ed.

Lovely job on the linkage.

Kelvin

Hi Ed,

Likewise, first class job on the linkage. I like the idea of working out angles to get some progression in the system as it makes for smoother take offs. Regards, Ed

Man. I have been thinking of doing this with my Riley (same engine) and wrote supercharging the 1500 off as insane. Makes more sense to put a 3-main 1800 in. That is, until I saw this thread.

I am so tempted. Maybe I can get it in by Stowe?

Tom

PS: Does anyone have any experience with running the Supercharger with the Mikuni carbs, as shown here: http://www.v-performance.com/products/air_fuel.html ?

Tom.

Loads of experience with the Mikuni carburetor on the Moss supercharger, but so far none of it has been successful.

We have not been able to get a carb from VPD to try, so we don't know if their claims are true, but all our efforts with modified float bowl capacity and accelerator pump design have failed to get an acceptable transition from normal running to WOT.

We ran into the same problems with the Weber DGV even after building Frankencarb which was a DGV with a Holley 390 pump and lever assembly.

The SU works well because it has a slower transition controlled by engine vacuum, so doesn't bog when the throttle is opened. No instant throttle response, but no bogging either.

The most fun carburetor setup we built had a direct injection nozzle from the fuel line controlled by a solenoid, vacuum operated switch and a garage door timing circuit. When you put your foot down, full line pressure fuel was squirted downstream for a set time period. Fantastic response and power, but it was hell if you were doing snap accelerations as the fuel just kept running even if you let off.