Jump to content

Why was the distributor turned so much?


Recommended Posts

Dear Forum,

Need some advice! Just got my TR6PI ('74) back from the workshop for new rear shocks. They also adjusted the ignition. And this triggered the following question:

As I noticed low rev pre-detonation, I decided to check the ignition timing. Some time ago I had done this using both a 12V test lamp as well as the standard timing light (I hooked up the timing light probe to cylinder #1 cable, front of the engine). I found then that the static timing was ~2 BTDC and static dynamic at some 700 rpm around ~4 BTDC (I now know this a too late, should be ~11).

However, today I could not make a sensible reading using the timing light and the probe to cylinder #1.

I also noted that the distributor was in quite a different position compared to the past, it seemed to be turned counter clock wise something like 40 degrees (this is not an exact figure).

When put back in roughly the same position as before: it would not start at all.

Why was the distributor turned so much?

Why can't I get a sensible reading from cylinder #1 on the timing light anymore?

Should all TR6 distributors roughly point in the same direction (+ or minus the ignition timing) – picture someone?

 

W.

Edited by Agile
Link to post
Share on other sites

Picture this. When you got the car back the distributor was positioned so that the rotor was pointing to the spark plug wire on the distributor cap for the spark plug whose piston and valves was in the correct position for combustion. Then you rotated not only the distributor but also the spark plug wires attached to the distributor cap. However, the rotor which did not rotate is now pointing at the spark plug wire for a combustion chamber that does not have it's piston and valves in position for combustion.

You will have to rearrange the spark plug wires on the distributor cap if you want to keep the distributor in that position.

Make sure #1 piston is at TDC with both vales closed and that the rotor is pointing to the spark plug wire contact in the distributor cap that goes to #1 cylinder.

Then wire up the cap in proper firing order. 5, 3, 3, 6, 2, 4 in a counterclockwise direction.

To really make it simple, If you rotate the distributor 40* clockwise, you need to move the spark plug wires 40* counterclockwise to compensate.

 

I thought about correcting the posted firing order but it just looked so interesting.

An old mechanic told me this is how he remembered it, with the fairer sex in mind.

15..too young

36...too old

24...just right

He, like myself, is now into his 60's so I suspect his opinion at least may have changed

Edited by poolboy
Link to post
Share on other sites

Digesting the feedback, thanks!

 

For the record: it is 1-5-3-6-2-4 -right?

Luckily I had made a picture before the workshop visit and I just made an 'after':

BEFORE

IMG_9571DistributorpointingtoCyl6.jpg

 

AFTER

IMG_9793Dystributorafterworkshopadjustnotspecificallypointingatxx.jpg

 

In fact, it is more like 60* different.

 

If the wires where just all moved one position (why would you do that anyway??), this does not explain why I cannot get a reading from my timing lamp anymore... or?

 

two notes:

- the rotor was replaced as you can see from the pictures

- workshop connected the vacuum hose from the distributor to a small rubber hose on the metering unit, which in my view is merely an opening of the MU to the outside pressure, not intended to be used for the distributor vacuum. Moreover: TR6PI does not use any vacuum advance - correct? Why would this hose been added??

 

W.

Link to post
Share on other sites

Agile

 

Your first photo is correct. The second one not so.

 

The rev counter cable will be under severe strain, you should put it back as photo one and follow the firing order as it should be. Not poolboys! :lol::lol::lol: I would also suggest you try another cap and leads

Edited by ntc
Link to post
Share on other sites

And ask the workshop if you can have your proper Lucas rotor arm back (or get a red one from Distributor doctor) and throw the one that is in it now in the bin ;) Connecting the A/R vacuum unit to the MU is totally wrong as its not used on a PI. So remove it.

Stuart.

Link to post
Share on other sites

Thanks for the information. I also was worried about the rev cable.

 

There is not a clever 'lead-to-cylinder-one-spark-plug-goes-here' marking on the distributor(-cap) I'de guess as nobody ever mentioned such. Meaning I need to figure out TDC of compression stroke for cylinder 1 and next follow PoolBoys advice.

Or...

Would someone have a picture of the distrubutor in the 'normal' position as well as which wire goes to which plug?

Or...

As the engine runs at the moment, just swap all wires one position and turn the distributor 360/6 = 60*

 

Nobody reacted on the timing light no longer providing a sensible reading. That's probably a polite way of saying 'stupid question'. I just checked figuring that if cyl.1 would give non-sense reading, connecting the inductive probe to cyl.6 should do the same. Anyhow, both read the same, about 17* BTDC. Which is too early I learned. No idea why the earlier measurement failed. While fixing the wires, I will set it according the answer I got from post http://www.tr-register.co.uk/forums/index.php?showtopic=24915&st=20 and out of curiosity also (try to) check if the advance curve still makes any sense.

 

As to why the wires got swapped in the first place, I'll never know.

 

Closing remark: I've learned again and I should be able to fix this with the information PoolBoy and others provided - Thanks forum!

Link to post
Share on other sites

Update: Followed PoolBoy's instruction, just moved all cables one position CCW, rotated the distributor to roughly the right positions, started the engine, used timing light to set to about 10 degrees and corrected idle speed to some 700 RPM. Used the fine-tune knob on the distributor to get to 11 degrees. All OK and predetonation gone. Up to the next issue :)

Here is a reference picture

IMG_9795Correctwiringsparkplugleadslegend.jpg

W.

Edited by Agile
Link to post
Share on other sites

Hi Agile,

What remains is the question of why the distributor in the wrong position stood!

I think they lifted the complete pedestal and drive gear and misplaced them, so how are your MU timing now?

BTW are this firm. H again?

Regards,

Rien

Link to post
Share on other sites

Rotor arm: checked, but they are on leave... :mellow:

MU timing: how can I perform a simple check on the MU timing? What should I experience due to bad MU timing? I was quite satisfied with moving all HT leads one position CCW; the puzzle fitted perfectly.

W.

Link to post
Share on other sites

Rotor arm: checked, but they are on leave... :mellow:

MU timing: how can I perform a simple check on the MU timing? What should I experience due to bad MU timing? I was quite satisfied with moving all HT leads one position CCW; the puzzle fitted perfectly.

W.

 

Hi W,

 

Simple, turn engine so that cyl 1 are in TDC AND valves are closed rotor arm pointed to the centre of the lh front wheel. Now disvconnect on the MU the outlet no. 6, blow with clean air the port in the housing, now you must see (by a CR engine ) a true the rotor a closed or a very little opening in the top of the circle. I hope I make things clear now but maybe it is better that you call me, it is very simple in Dutch :D

 

Cheers,

 

Rien

Link to post
Share on other sites

Hi W,

 

Simple, turn engine so that cyl 1 are in TDC AND valves are closed rotor arm pointed to the centre of the lh front wheel(if teh gear shaft are not rotated 180 dec). Now disvconnect on the MU the outlet no. 6, blow with clean air the port in the housing, now you must see (by a CR engine ) a true the rotor a closed or a very little opening in the top of the circle. I hope I make things clear now but maybe it is better that you call me, it is very simple in Dutch :D

 

Cheers,

 

Rien

 

Link to post
Share on other sites

Thanks!

 

The Brown-Book describes two procedures

- up to engine CP77609E - which is what Rien described; with your voice over the text starts to make sense to me!

- from engine CR1E (mine is CR3800HE): (quote)

 

(3) turn the engine in a running position until No. 6 piston is at TDC, induction stroke, i.e. No. 6 inlet and exhaust valves on the rock

 

(4) using a thin steel rule, mark off lines from the TDC line on the crankshaft pulley 29mm and 67mm on the ATDC side of the pulley. The mark off lines should be sufficiently clear to be observed as timing marks and represent 20* and 45* ATDC respectively

 

(5) Remove the number six outlet union from the metering unit body. (No portion of the rotor hole should be visible in the outlet port)

 

(6) Turn the crankshaft in a running direction until the leading edge of the hole in the rotor just appears on the upper side of the outlet port (the 'cracking' point); note the crankshaft angle at which this occurs. If this 'cracking' point appears between the lines marked in (4), i.e. 20* and 45* ATDC, the injection timing is satisfactory, if not proceed as follows:

 

(7) ... (unquote)

 

Although this sounds different from the CP engine procedure, isn't 'TDC compression stroke cyl 1' the same as 'TDC rocking position cyl 6' ?

 

@Neil: it runs quite OK at the moment (actually, nothing to compare it to...).

 

I will try this check when back home, so I might not follow up on the post soon, however I do want to make sure all is as it should be before moving to the 123ignition. It just takes more time than planned. Never a dull moment with a TR6PI :)

W.

Link to post
Share on other sites

Hi Neil,

I agree that I should not expect a miracle. Alternative is have the distributor reworked to get the advance right. I also would like to say goodbye to breaker points ('pointless' indeed). And... perhaps for me an important one: I like electronics... :)

Rgds, W.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.