Looking for wireing Diagram!

[missatoria]

Greetings all My latest challenge.... I am hoping someone out there has a wiring diagram for 1948 MGTC that can be emailed.I cant locate Dads.. This is my problem; The wire that conects to the side of the distributor has no electricity with the ignition switch on or off. The coil has power to the switch side (multible wires,) but not the other side. I seem to get no fire from the spark plug wires. The fuel pump works, we have fuel. New plugs, new wire, new points, condenser, rotor and cap. There seems to be no electricity going to the distributor from anywhere! I Tried the number 1 wire in both positions (possible 180 degrees out.) It doesnt seem to be trying to fire at all. No miss fires, no back fires...The engine does have compression. A diagram would help me double check to see that I have the right path of electricity...Any Ideas Do all Mg's have one color wire under the dash? thanks for all the support.... Victoria Smith McKenna MGTC5839

[Jennifer and Hugh Pite]

Hi Victoria, here is how it works: Power comes in from the ignition switch to the SW terminal on the coil. To complete the circuit the other coil terminal (CB) is connected to ground through the points of the distributor when they are closed. That is, each time the points close the CB terminal is grounded, the coil is energized and a high voltage is induced in the secondary of the coil. This high voltage is sent to the center terminal of the distributor and then sent to the spark plug wire on the distributor that the rotor is pointing to and finally to the spark plug. Dead simple! With the ignition turned on and the small wire to the dist. disconnected see if you have voltage between CB and ground. If you do not, I suspect the coil is shot. If you do, make sure that the points do not have oxide on them. As a crude check, turn the engine over until the points close, remove the dist. cap, turn on the ignition and open the points with a small screwdriver. You should see some sparking if the points are clean. (Make sure the screw driver has a plastic handle!) Best Regards, Hugh Pite

----- Original Message ----- From: "missatoria" vmckenna@inreach.com> To: mg-tabc@yahoogroups.com> Sent: Monday, April 15, 2002 4:00 PM Subject: [mg-tabc] Looking for wireing Diagram! > Greetings all > > > My latest challenge.... > > I am hoping someone out there has a wiring diagram for 1948 MGTC that > can be emailed.I cant locate Dads.. > This is my problem; The wire that conects to the side of the > distributor has no electricity with the ignition switch on or off. The > coil has power to the switch side (multible wires,) but not the other > side. I seem to get no fire from the spark plug wires. The fuel pump > works, we have fuel. New plugs, new wire, new points, condenser, rotor > and cap. There seems to be no electricity going to the distributor > from anywhere! > I Tried the number 1 wire in both positions (possible 180 degrees > out.) It doesnt seem to be trying to fire at all. No miss fires, no > back fires...The engine does have compression. > A diagram would help me double check to see that I have the right path > of electricity...Any Ideas > Do all Mg's have one color wire under the dash? > thanks for all the support.... > Victoria Smith McKenna > MGTC5839 > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > >

[Dave & Diana Dwyer]

Hi Victoria You say that power is present on one side of the coil: that means there is no problem in the feed. However, you could be fooling yourself about what happens next. Disconnect the wire from coil to distributor, at the distributor. With ignition ON, check for power on each side of the coil and at the free end of the wire. Use a test lamp or meter with the other end connected to the block or other ground/chassis point. If you now read power both sides of the coil and at the wire end, all is well so far. If there is power on only one side of the coil, it's probably failed. Try another known good one. Once you have power to the free end of the wire, reconnect to the distributor, and connect the lamp or meter from the wire at the distributor to ground. With ignition on, turn the engine on the crank handle. The lamp should go on and off twice per rev of the engine. If it does, the distributor points are working. If not, there is a short to ground in the distributor (look for missing insulating washer under the moving part of the points, or maybe a whisker of brass torn from a washer). Find the firing stroke on number 1 as follows. Remove no. 1 plug, remove rocker cover and watch the valves while the engine is turned. When no. 1 piston is right up (look down the plug hole) and #both# valves are closed (feel free play in the rocker) you are at TDC no. 1 firing. The timing mark on the crank pulley will now line up with the finger on the timing cover. Leave the engine in this position. Check which spark electrode the rotor points to, and connect no. 1 plug lead to this. The others follow, 1-3-4-2, COUNTERclockwise. With the ignition ON, and lamp connected from coil/distributor wire to ground, rotate the distributor a small amount til the lamp comes on/off. You are now set approx TDC and the ignition should start the engine. Good luck. Regards Dave Dwyer J2, TA, TC

[Dave & Diana Dwyer]

Victoria Just a small clarification to my previous post: the spark happens when the points #open#, not when they close. You need to set the timing so the test light comes ON (that is the points have opened and are no longer shorting out the test lamp) at TDC on the firing stroke. Regards Dave Dwyer J2, TA, TC

[i.thomson@talk21.com]

Sounds like the coil to me, or the connections to it. If there is power (approx 12V) to the coil but not out of it (I assume you are measuring on the small wires Victoria - not the large one to the centre of the dist. cap) then there is a break somewhere in the coil itself. You can try opening the points with a screwdriver if you like (I just use my fingernail Hugh; it's only 12V and can't be felt. Under normal circumstances you should get a small spark at the points if they were closed (i.e. not being held open by the cam when you did it), but if you have no power to the dist. that's not going to happen. It sounds as if you have a fair idea of what you are doing Victoria so just borrow a ciol to try it and good luck. Let us know how yopu get on. Ian Thomson. -----------

> Hi Victoria, here is how it works: Power comes in from the ignition switch >to the SW terminal on the coil. To complete the circuit the other coil >terminal (CB) is connected to ground through the points of the distributor >when they are closed. That is, each time the points close the CB terminal >is grounded, the coil is energized and a high voltage is induced in the >secondary of the coil. This high voltage is sent to the center terminal of >the distributor and then sent to the spark plug wire on the distributor that >the rotor is pointing to and finally to the spark plug. Dead simple! > With the ignition turned on and the small wire to the dist. disconnected >see if you have voltage between CB and ground. If you do not, I suspect the >coil is shot. If you do, make sure that the points do not have oxide on >them. As a crude check, turn the engine over until the points close, remove >the dist. cap, turn on the ignition and open the points with a small >screwdriver. You should see some sparking if the points are clean. (Make >sure the screw driver has a plastic handle!) > Best Regards, Hugh Pite > >----- Original Message ----- >From: "missatoria" vmckenna@inreach.com> >To: mg-tabc@yahoogroups.com> >Sent: Monday, April 15, 2002 4:00 PM >Subject: [mg-tabc] Looking for wireing Diagram! > > > Greetings all > > > My latest challenge.... > > I am hoping someone out there has a wiring diagram for 1948 MGTC that > can be emailed.I cant locate Dads.. > This is my problem; The wire that conects to the side of the > distributor has no electricity with the ignition switch on or off. The > coil has power to the switch side (multible wires,) but not the other > side. I seem to get no fire from the spark plug wires. The fuel pump > works, we have fuel. New plugs, new wire, new points, condenser, rotor > and cap. There seems to be no electricity going to the distributor > from anywhere! > I Tried the number 1 wire in both positions (possible 180 degrees > out.) It doesnt seem to be trying to fire at all. No miss fires, no > back fires...The engine does have compression. > A diagram would help me double check to see that I have the right path > of electricity...Any Ideas > Do all Mg's have one color wire under the dash? > thanks for all the support.... > Victoria Smith McKenna > MGTC5839 > > > > > Your use of Yahoo! Groups is subject to http://talk21.btopenworld.com/redirect.html?http://talk21.btopenworld.com/redirect.html?http://docs.yahoo.com/info/terms/''>[url=http://talk21.btopenworld.com/redirect.html?http://docs.yahoo.com/info/terms/'http://talk21.btopenworld.com/redirect.html?http://docs.yahoo.com/info/terms/'>>http://talk21.btopenworld.com/redirect.html?http://docs.yahoo.com/info/terms/'>[url=http://docs.yahoo.com/info/terms/http://docs.yahoo.com/info/terms/> > > > > > > > >Your use of Yahoo! Groups is subject to http://talk21.btopenworld.com/redirect.html?http://talk21.btopenworld.com/redirect.html?http://docs.yahoo.com/info/terms/''>[url=http://talk21.btopenworld.com/redirect.html?http://docs.yahoo.com/info/terms/'http://talk21.btopenworld.com/redirect.html?http://docs.yahoo.com/info/terms/'>>http://talk21.btopenworld.com/redirect.html?http://docs.yahoo.com/info/terms/'>[url=http://docs.yahoo.com/info/terms/http://docs.yahoo.com/info/terms/>

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[i.thomson@talk21.com]

Dave/Victoria, Just a small point. Although it is correct to say that the firing stroke is when both valves are closed there is an easier way than taking off the rocker cover). Just put you finger firmly over the plug hole, when it trys to push you finger away that is the firing stroke. Of course you need someone to turn the starting handle while you are doing this ...but it does avoid all that messy oil under the cover. Ian Thomson. ---------

> Victoria > >Just a small clarification to my previous post: the spark happens when the >points #open#, not when they close. > >You need to set the timing so the test light comes ON (that is the points >have opened and are no longer shorting out the test lamp) at TDC on the >firing stroke. > >Regards > >Dave Dwyer >J2, TA, TC > > > > >Your use of Yahoo! Groups is subject to http://talk21.btopenworld.com/redirect. ... s/' Target='_new' Href='http://talk21.btopenworld.com/redirect. ... ms/>

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[Donald Wilkinson]

Uh, Ian, beg to differ. As Hugh cautions, when points open, collapse of magnetic field generates approx. 300 volts at hot point. One can damn sure feel that. Don TC 7993

>From: i.thomson@talk21.com >To: mg-tabc@yahoogroups.com >Subject: Re: [mg-tabc] Looking for wireing Diagram! >Date: Tue, 16 Apr 2002 08:52:54 BST > >Sounds like the coil to me, or the connections to it. If there is power >(approx 12V) to the coil but not out of it (I assume you are measuring on >the small wires Victoria - not the large one to the centre of the dist. >cap) then there is a break somewhere in the coil itself. You can try >opening the points with a screwdriver if you like (I just use my fingernail >Hugh; it's only 12V and can't be felt. Under normal circumstances you >should get a small spark at the points if they were closed (i.e. not being >held open by the cam when you did it), but if you have no power to the >dist. that's not going to happen. It sounds as if you have a fair idea of >what you are doing Victoria so just borrow a ciol to try it and good luck. >Let us know how yopu get on. > >Ian Thomson.

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[R. Zwart]

You get compressed air, when your finger is over the plug hole, during the compression stroke before firing. BOB i.thomson@talk21.com wrote:

> Dave/Victoria, Just a small point. Although it is correct to say that the firing stroke is when both valves are closed there is an easier way than taking off the rocker cover). Just put you finger firmly over the plug hole, when it trys to push you finger away that is the firing stroke. Of course you need someone to turn the starting handle while you are doing this ...but it does avoid all that messy oil under the cover. > > Ian Thomson. > > --------- > > Victoria > > > >Just a small clarification to my previous post: the spark happens when the > >points #open#, not when they close. > > > >You need to set the timing so the test light comes ON (that is the points > >have opened and are no longer shorting out the test lamp) at TDC on the > >firing stroke. > > > >Regards > > > >Dave Dwyer > >J2, TA, TC > > > > > > > > > >Your use of Yahoo! Groups is subject to http://talk21.btopenworld.com/redirect. ... s/' Target='_new' Href='http://talk21.btopenworld.com/redirect. ... ms/> > > -------------------- > talk21 your FREE portable and private address on the net at http://talk21.btopenworld.com/redirect. ... k21.com> > > -------------------- > talk21 your FREE portable and private address on the net at http://www.talk21.com > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

[i.thomson@talk21.com]

Yes, Don, as you say "at hot point" - which is nowhere near where your fingers are. At least I don't put mine inside the distributer cap which I have removed and put safely to one side in order to get to the the points. AAMOI if the voltage at the "hot point" (on the dist. cap "king lead" is only 300 Volts the car will not run. It will in reality be somewhere from 8-12,000 Volts (though only for a fraction of a second). If you don't believe me that the points don't bite try it. Go on, live dangerously. I've been doing it for 30 years and I'm still here. Ian T. ---

> Uh, Ian, beg to differ. As Hugh cautions, when points open, collapse of >magnetic field generates approx. 300 volts at hot point. One can damn sure >feel that. > >Don >TC 7993 > > >From: i.thomson@talk21.com >To: mg-tabc@yahoogroups.com >Subject: Re: [mg-tabc] Looking for wireing Diagram! >Date: Tue, 16 Apr 2002 08:52:54 BST > >Sounds like the coil to me, or the connections to it. If there is power >(approx 12V) to the coil but not out of it (I assume you are measuring on >the small wires Victoria - not the large one to the centre of the dist. >cap) then there is a break somewhere in the coil itself. You can try >opening the points with a screwdriver if you like (I just use my fingernail >Hugh; it's only 12V and can't be felt. Under normal circumstances you >should get a small spark at the points if they were closed (i.e. not being >held open by the cam when you did it), but if you have no power to the >dist. that's not going to happen. It sounds as if you have a fair idea of >what you are doing Victoria so just borrow a ciol to try it and good luck. >Let us know how yopu get on. > >Ian Thomson. > > >_________________________________________________________________ >MSN Photos is the easiest way to share and print your photos: >http://talk21.btopenworld.com/redirect.html?http://photos.msn.com/support/worldwide.aspx'>[url=http://photos.msn.com/support/worldwide.aspxhttp://photos.msn.com/support/worldwide.aspx> > > > > >Your use of Yahoo! Groups is subject to http://talk21.btopenworld.com/redirect.html?http://docs.yahoo.com/info/terms/'>[url=http://docs.yahoo.com/info/terms/http://docs.yahoo.com/info/terms/>

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