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TR6 PI starts with a bang, then dies


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Have you got 6 lobes on the distributor cam?

Get #1 cylinder at 12 degrees before TDC

rotate the distributor body so that the points are just about to open, this will be the firing position of #1 cylinder,

check that the rotor arm now points to the #1 spark plug lead, and reset if necessary and then set the others 5 3 6 2 4 in an anticlockwise rotation in the cap.

If you have just put on the MU it may be better to make sure all the injectors are bled before you try and sort the ignition side. To bleed them, take all the plugs out, disconnect the + wire to the coil, we don't want any sparks setting off the petrol fumes!

Put all the injectors into a large jar so you can see the they are all spraying, and crank the engine. if they are all spraying properly replace them and carry on with the ignition issue.

John

Edited by John L
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.

 

On the cam on the distributor. When the lamp goes on (turning clockwise), the plastic thingy touching the rotor, has just passed the heel of the rotor. Rotor turning ccw.

Not like that. The points should open as the cam lobe approaches the plastic tip. Not after the peak of the lobe has passed. In other words the points open when the cam lobe diameter is increasing not decreasing.

You'll see it better with rotor arm removed.

Yes it rotates ccw.

I use this circuit for the test bulb and it needs the igntion to be on:

http://www.howacarworks.com/ignition-system/adjusting-the-static-timing

I think the operation of the light on/off will be the opposite of yours.

Peter

 

Quick method: Try setting the disy so the connector is at 10 oclock. Clamp the disy so you just turn it by hand...not completely loose. Get a helper to operate the starter. Wear gloves, and keep hands away from disy cap and leads. Slowly turn the disy backwards and forwards until the engine fires best at tick over.

(NB No-one with heart issues should attempt this!)

Edited by Peter Cobbold
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Is that turning the distributor, or trying to help diagnose what the problem is :)

 

Alan

:D

Alan, I'm hoping we haven't got a really rare condition:

http://rarediseases.org/rare-diseases/dextrocardia-with-situs-inversus/

:)

Peter

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Peter, I moved the distributor body anti-clockwise; connector to coil now at about 10 o'clock. With the engine set at about 12dgr BTDC #1 firing , I set the static timing by having a lamp between the battery + and the cable (disconnected from coil) going to the - on the coil. I rotated dist. body anti-clockwise until the lamp shuts of. Then I rotated it clockwise until the lamp just goes on? I've tested so many things now that my head is getting messed up. It's supposed to be the other way around?

I tried to start it up in this position - and pretty much same result. Sounds like some petrol is firing with a mild boof, and some smoke comes out of the air manifold.

 

On the cam on the distributor. When the lamp goes on (turning clockwise), the plastic thingy touching the rotor, has just passed the heel of the rotor. Rotor turning ccw.

 

That sounds right, the rotor arm goes anticlockwise so you time it by advancing the distributor by turning the distributor body clockwise until the light comes on.

Just make sure the rotor arm is pointing to number one plug lead and the ignition timing should pretty much there.

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That sounds right, the rotor arm goes anticlockwise so you time it by advancing the distributor by turning the distributor body clockwise until the light comes on.

Just make sure the rotor arm is pointing to number one plug lead and the ignition timing should pretty much there.

Andy,

Apologies for 'shouting' in what follows...am just trying to emphasise the bulb circuits work in the opposite sense

Morten #49 has his bulb connected to battery live to points and then to earth. I connect it from ignition feed to coil and to earth. So my bulb comes on as the points open - like yours I think. Mortens should go out at the same position.But he is timing it coming on. Which I think is when the point close at the start of the dwell period after the lobe has passed the plastic follower.

It will be a whole cam-lobe of timing out, roughly 50 crank deg. So.....static at 60 BTDC...no wonder it barely runs.

 

Pete

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i read all the things you have tried but not the simple suggestion I made of moving the plug leads around by 180 degrees. takes 30 seconds to do, a minute to check then 30 seconds to put back if necessary.

 

got to be worth a try for 2 minutes work

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Hi - back again :) Was down with a little cold.

1) grumpy2 - sorry I haven't replied, I did try out 180 off early on, but that was not right. Just an unhealty clonk from the engine. I also checked valves etc, that they are according to timing.

2) Peter - you were absolutely right. Due to other problems, I started at some point to set the static timing as the point were closing (!) not opening. I totaly went blind on it, so the static timing was set as right after the peak/lobe on the rotor. I static timed it now as right before the peak (is lobe the proper term for it?) of the distributor rotor, and I got it started !!!!

Thanks a million for all suggestions and advices - finally got there.

It still runs very rough. It won't idle. Can't get the strobe to indicate that the leads actually fires the spark all the time. The strobe is strong on the signal on the lead from the coil to the dizzy.

I was thinking if the rotor on the dizzy just barely touches the right point in the cap when the spark goes, that might be it. Think my rotor position is not 100% what it states in the workshop manual yet.Need some testing.



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Hi - back again :) Was down with a little cold.

 

1) grumpy2 - sorry I haven't replied, I did try out 180 off early on, but that was not right. Just an unhealty clonk from the engine. I also checked valves etc, that they are according to timing.

 

2) Peter - you were absolutely right. Due to other problems, I started at some point to set the static timing as the point were closing (!) not opening. I totaly went blind on it, so the static timing was set as right after the peak/lobe on the rotor. I static timed it now as right before the peak (is lobe the proper term for it?) of the distributor rotor, and I got it started !!!!

 

Thanks a million for all suggestions and advices - finally got there.

 

It still runs very rough. It won't idle. Can't get the strobe to indicate that the leads actually fires the spark all the time. The strobe is strong on the signal on the lead from the coil to the dizzy.

 

I was thinking if the rotor on the dizzy just barely touches the right point in the cap when the spark goes, that might be it. Think my rotor position is not 100% what it states in the workshop manual yet.Need some testing.

 

 

 

Morten,

At last !! Well done. 10/10 for perseverance.

 

Do leads first - as Neil says.

 

I wonder if the disy is not at the correct height or the pedestal.? Simplest check is to cut a hole in a spare disy cap and see where the rotor arm is at 12BTDC in relation to the cap contact. Then check there will be enough overlap to take around 30deg of extra crank advance , which is 15 deg on the disy. At full centrifugal advance the spark will happen 15 disy deg clockwise of the 12 BTDC position, of course. If they don't mate up OK then adjusting the disy height might be needed....not sure how...I think the pedestal is shimmed off the block.

 

 

As you have rebuilt engine once its running I think you need to run in the cam. Its not done at tickover apparently. The skilled engine builders will tell you how. And make sure the oil has a good level of ZDDP, as that is what is coating the cam lobes during running in.

 

Peter

Edited by Peter Cobbold
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And check the carbon brush inside the cap, is it moving freely ( it should).

Also check the cap for (hairline) cracks.

With a strobe each lead should give a bright flash.

Good luck, you are getting closer.

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Hi guys,

thanks :)

1) I've checked and replaced the leads (I've three sets, no change). The cap is new (tested with a few), and the rotor etc is new and been test replaced as well.

2) Good tip regarding cutting away a bit of an old dizzy cap. I did (I'll attach a picture - it's not obvious from the picture which point is #1, but the rotor is approaching it). When the engine is at 12 dgr BTDC, and the point in the dizzy is just about to open (trigger-point of the bulb test - and I've done it right this time, Peter :)), the rotor has not reached contact point for #1 inside the cap. It is actually half way between #4 (just left) and #1 (approaching). That can't be right? Isn't the coil producing the spark more or less exactly when the point opens?

 

I was thinking a) as you mention, Peter, the shaft/pedestal is to low and needs shimming (seen this explained in the workshop manual, but don't quite understand the details I must admit) or B) should be possible to remove the rotor, unscrew from shaft so I can advance the actual rotor a bit but keep the cam position. I've never tried it, and it does seem weird as the car has been running with the distributor unit like it is.

3) Regarding running-in; I'm using a running-in oil right now, high on zddp. Normally I'm leaning towards Castrol 20-50 or Penrite 20-50/60; they are also good on zddp. Wrote a small article about classic engine oils some years back, interviewing the larger oil companies about classic car oils. Love to learn, so go a bit nerdy on "insignificant" details ;)

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post-13303-0-98441400-1471423178_thumb.jpg

Edited by MortenHoyseth
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Morten, You've found the fault. The spark is made the instant the points open so if the rotor arm tip is not yet on the cap contact the spark has to jump across that gap too, as well as the plug's. So firing is poor, as is the signal for the strobe pick-up.

You need to adjust the height of the disy or pedestal with a shim ( I forget excactly how) so the the disy shaft and rotor arm moves anticlockwise in relation to the disy body. Such that at 12BTDC firing point the rotor arm overlaps the contact, with enough extra overlap left to allow for 15 degrees of advance of the spark. You can feel that extra advance in the spring- loading of the rotor arm: twist it to get to the full c/f advance position. There's plenty of overlap to spare as it also has to fit the vacuum advance, which the PI cannot use.

 

I learned on here that a new cam should be run in at 2000rpm continuously for 30 minutes. Makes sense, to deposit the ZDDP film.

Got a link to your article? Apologies for 'teaching granny to suck eggs' :)

 

Peter

Edited by Peter Cobbold
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Ah, closing in on this now :)
I do understand the principle of this - well, most of it anyway. The adjustment I'm not sure about.

If I shim (with gaskets) between the MU/dizzy pedestal and the block, I elevate the pedestal (obviously). That by itself I cannot understand has an impact on the rotor location.
However, as the distributor drive shaft is fully located on the oil pump drive dog, wouldn't the right thing be to shim the drive shaft itself (and potentially the pedestal to prevent them from touching)? Maybe that is what you are suggesting :) But seems drastic? should be any loose shim at the bottom end of the distributor drive shaft, should it?

What I could do is to grind of a bit of the bottom end of the dist. drive shaft, to lower it a bit. Then the rotor should rotate slightly cw. If I do that I could potentially make the end float to big, causing other problems.

Trying to get a hold of the engine rebuilders now. Really missing the sound of a healty engine running.

post-13303-0-15560500-1471434730_thumb.jpg

Edited by MortenHoyseth
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Can't you reposition the drive shaft a little so that it picks up on the next tooth of the drive gear and as you lower it into position it rotates to the ideal position?

Edited by peejay4A
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Hi peejay, If i remove the dist. drive shaft, move the oil pump drive dog anti-cw or cw, put the dist. driveshaft back in - settle - the rotor always seem to end up just between two points in the dist. cap. As the contact point is just about to open that is. So just by looking at the result (no calculations made), when I move the drive shaft a thooth or two left/right, the rotor ends up between two points, when the coil produces the spark.

Edited by MortenHoyseth
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I guess that explains why the suggestion is to shim the pedestal. I just can't remember having any trouble at all when I rebuilt my TR6 engine but that was a long time ago.

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Neil, yes I've driven the car after rebuild. Not more than 5 km or so. Due to multiple other problems (too loose belt alternator/pulley, defect battery, and worn butterflies), it took it in for more fiddeling. And now all this mess. But it has run, and it runs now as well, if the rev are a bit up (dunno exactly, but from 1500 rpm or so - still not very nice running).

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