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MG Distributor swap

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L

lesingepsycho

Jedi Warrior
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I was at the annual British Field Meet at PIR here in Portland this Labor day and while I was there I had my eye on a used Mallory dual point dizzy for relatively cheap. I talked to the guy for a while and he told me that there was a Datsun or Nissan or some sort of asian pickup truck distributor that was a direct replacement for the lucas so I wound up passing on the Mallory but now I've forgotten what the substitute distributor was and can't find any info on the web. /ubbthreads/images/graemlins/frown.gif If anybody out there knows about this, I would like to replace my dizzy with something a little better. I currently have the stock lucas with a shot vacuum unit and now I can't go with the mallory because it isn't compatible with the MSD-6AL ignition box I'm using (although I'm told if you just remove the trailing set of points it will work. Still, it's a bit expensive for the application). Any info will be greatly appreciated.
 
Yes the Hitachi and/or Isuzu Trooper 4 banger dizzys work fine in an A or B series engine.
You do have to make a couple of work bench mods with a grinder, file, and drill, but they are simple mods.
Both the Hitachi and Isuzu turn counter clockwise as does the A and B series engines. I prefer the Isuzu dizzy because it has a clip on cap and look more like the stock dizzy.
The Hitachi has a screw on cap and it's tough to get to the bottom screw with the coil where it is on a Spridget.
Fro the Hitachi, go here https://members.tripod.com/~mini_digest/dizzy.htm
For the Isuzu, I figured that one out myself.
You need a dizzy from a Trooper or Pup 4 banger, Not sure what year, they all look the same to me /ubbthreads/images/graemlins/wink.gif
It has a clip on cap, and only 2 wires coming out of the side. (+ & - to the coil) You will have to cut down the shaft. I measured the Lucas shaft and cut the Isuzu shaft the same length from the base of the body. You will have to swap drive dogs too. I played with the position of the dizzy until I had the vacuum advance in about the same spot as the Lucas and then drilled a hole in the shaft for the drive dog pin. I did not take notes, or pictures and that was a couple years ago. I do know it worked great, electronic igntion for the cost of a $10 junk yard dizzy and about an hour on the work bench. DO get a new cap, rotor and wires after you know the dizzy works. (I did get a bum electronic unit on my first junk yard dizzy)
The vac advance on the Isuzu dizzy is on small ball bearings and is silky smooth. Noticable on accelleration.

Frank
 
Thanks guys, that is just the info I was looking for. That link is really helpful too. Thanks again.

JACK
 
Hello LSP,
if you drive your MG as it should be driven, you don't need that vacuum advance to work. It is purely an economy device to allow the running of a weaker mixture at cruise.

Alec
 
piman, are you saying that the MG should spend less time at steady RPM's? Here in the US the cars must frequently cruise long distances to get anywhere of interest (shows, rallys, scenic tours, etc)
 
Hello TJ,

it was a bit of a tongue in cheek response.
Wouldn't it be so much simpler to replace the vacuum assembly? Why mess about with distributors that need a lot of fiddling to get the correct characteristics, realistically it needs a dynamometer and a lot of time to match. In other words, why re-do what the original manufacturer has done for you.

Alec
 
The problem, Alec, is that it is near impossible to find a replacement vacuum unit. Most of them have had the diaphrams disintegrate long ago and they are no longer available from any parts warehouse that I know of.

I think this may all be a moot point however since yesterday, I pulled my spark plugs and I have never seen such beautiful examples of pure clean combustion. /ubbthreads/images/graemlins/laugh.gif No oily residue, no fouling, no scorching, just a nice beautiful brownish-gray. I've never seen plugs that actually looked that way before. I'm still amazed because the car runs great but the timing was only set by feel and same with the mixture. I guess after all these years, I finally have the touch /ubbthreads/images/graemlins/laugh.gif
 
Jack:

Alec's point was that you really don't need the vacuum unit.
It's nice to have the vacuum advance for more moderate driving and slow-speed puttering, but it basically does very little after about 2500 RPM (vacuum advance is sort of an "assist" to the centrifugal advance). Sporting drivers wouldn't notice a non-functioning vacuum advance.
My race car and my last street Spridget both had the vacuum advance units removed....with Pertronixs units replacing the points.
One thing: spritenut is correct....the newer Asian distributors are real well made and would likely have a lot less slop than a 25 year-old Lucas unit.
Also, congrats on getting the touch ....soon we'll teach you the secret handshake /ubbthreads/images/graemlins/grin.gif

(..but for what it's worth, I never do igniton timing without a timing light)
 
Yeah, that's what I have decided is that the Lucas dizzy is doing its job even without the vac.adv. I'm still glad to have gotten the info about the Isuzu/Hitachi and appreciate everyone's help on that.

Now, as far as using a strobe to set the timing, I have never found a method that works on a Midget because the timing marks are on the bottom side of the car and even with it jacked up, I have never found a way to get the strobe in there because of the crossmember that is directly below and in front of the timing marks. I asked the guys down at the local brit-car parts store and they said it wasn't possible to use a strobe, the best shot is to just set static timing and call it good or guess and check. Perhaps you hold the "secret" info on how to use a timing-light on a Midget? I assume it must be the same on your Sprite.
 
I have something fancier on the racer, but on the street car, I place the front pully so that the original mark is down (at "6 Oclock") and I make a small punch mark on the top of the pully. Then I put a dab of paint on the timing chain cover that lines up with the new punch mark. The new punch mark doesn't have to be at "12 Oclock"....it can be at "2 Oclock" or wherever is convienient (and then put the paint dab adjacent to it).
If you don't want to put a punch park in the front pully, you can use a paint dab or even a thin strip of duct tape (but it won't last too long).
 
I believe I saw rebuilt vacuum advance units for sale from Scarborough Fair. Also, they have rebuilt dizzys with new bushings that have been dyno tested. I like to use parts that look original on the outside but are something quite different on the inside. I get a kick out of looking totally stock with titanium con-rods, carbon fiber lift rods, LSD & all sorts of other exotic go-faster-goodies hidden inside original housings. Did you know that you can adapt an original oil canister to accept Canton Mecca filters? When someone asks me if I did any mods, I say... Yea! I just got those K&N filters and the chrome exhaust tip at the zone. They scratch their heads and suspect a cam when it idles all cattywompus. ( I say that " these funny looking carbs are really hard to adjust") Something of course smells fishy to the old guys but the youngsters buy it every time.
 
Jeff,
It was one of you Bugeye guys that finally caught me. I showed up at an auto cross and they told me to remove my hubcaps "for safety reasons". The guy in the sprite started asking a whole lot of questions about the rear axles and became real curious about some other "inconsistencies". Fortunately I was able to pay him off with a couple of quarts of Redline.
 
[ QUOTE ]
The problem, Alec, is that it is near impossible to find a replacement vacuum unit.

[/ QUOTE ]

New vacuum units are still available for most Lucas distributors; Moss and others just can't be bothered to stock them I guess and then tell you that they are no longer being made. I replaced the vacuum advance unit in my 73 MGBGT with the correct vacuum advance that I received from Christian Hollum Imports, Montreal, Quebec, 514-639-4639. Just a suggestion. I have no financial interest, yada, yada, yada.
 
Hello all,
as most distributor parts are small and light so transport cost should not be excessive. The company in U.K. that specialises in Lucas distributors (and anything else Lucas) is Holden, www.holden.co.uk. they do rebuild distributors and also supply parts.

Alec
 
[ QUOTE ]
Fortunately I was able to pay him off with a couple of quarts of Redline.

[/ QUOTE ]
Dave,you got off cheap. My Sprite holds nearly 10 quarts, so I would have held you up for at least enough to do an oil change!
Jeff
 
My 79 MG midget 1500cc engine is easy to time with a light from the top..Dont know what all the commotion is about using a light.
 
Don, the A series engines have the timing marks located on the bottom of the timing cover. It can be an adventure trying to see them with a timing light. There is a very small notch on the pulley, and even if you paint it, it can be tough to see.
Jeff
 
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