TR2/3/3A It was running great....until

[GTP1960]

At long last I have my tr3a back together and was tuning the engine.
i noticed the distributor post was not tightened down & in the process I accidentally raised the distributor up and unseated it.
after that..... nothing. Could not restart & I don't think I have the distributor seated correctly.
So my question is: Is there a trick to reseating a distributor ?


Appreciate any advice.

guy

 

[TR3driver]

Sounds like you let it get high enough for the tang to pop out of the slot. Try taking the cap off and turning the rotor until the tang lines up again. Push down lightly while turning so you can feel it drop into the slot, then push the distributor down where it belongs.

 

[Geo Hahn]

If trying to do this by feel a photo may help you visualize what you're trying to do.

The slot for the drive dog is asymmetrical, i.e. crosses the shaft slightly off-center so the distributor shaft only fits one way. Looks something like this when #1 is at TDC on the compression stroke:

Inserted at that point should have the rotor pointing at the #1 spark plug:

Of course, yours may be slightly or even completely different if someone has messed with the usual set-up - can still work but will look different.

If you can't get it to seat by feel you might remove the distributor, move the engine to TDC #1 compression and see what it looks like - then go from there.

 

[GTP1960]

"Of course, yours may be slightly or even completely different if someone has messed with the usual set-up - can still work but will look different."

thx Geo & Randall,
i was able to seat it once I turned the rotor.
However, I realized the fixing clamp is not raised enough to secure the base of the distributor.

( the PO's three zip ties securing & stabilizing the vacuum line to the fuel line should have been a red flag, I guess)

any reason not shim the fixing clamp collar a half inch, so it can snug the base of the distributor?

Thx again.

Guy

 

[TR3driver]

I think if you open the clamp up, you'll find that the distributor body will slide down where it belongs. If not, I'd look for the reason why as it may indicate something else wrong.

Don't get carried away when retightening the clamp. The body is just pot metal and not very strong. I've seen people crush that flange where the clamp is supposed to grip.

 

[GTP1960]

I think if you open the clamp up, you'll find that the distributor body will slide down where it belongs. If not, I'd look for the reason why as it may indicate something else wrong.

Don't get carried away when retightening the clamp. The body is just pot metal and not very strong. I've seen people crush that flange where the clamp is supposed to grip.

Maybe I did over tighten: I was cranking away before I realized I wasn't getting anywhere.

 

[TR3driver]

Maybe I did over tighten: I was cranking away before I realized I wasn't getting anywhere.

The flange looks OK in your photo, so I think you're probably OK on that score. But you'll probably need to take the bolt out and pry between the ears to get it to open back up far enough. Maybe loosen one of the nuts as well.

 

[Geo Hahn]

FWIW - That appears to be a distributor for a 1971 Sprite or Midget.

 

[GTP1960]

FWIW - That appears to be a distributor for a 1971 Sprite or Midget.

Don't know about that, ( how can you tell?) but it works pretty well, when it's tightened down properly.
( Randall was right, I had the collar cinched down so tight the base of the distributor was Teed up like a golf ball......it made for some impressive backfires for some reason). No telling what damage I did!

It's not timed & tuned just right, but it sounds 100% better & my belated "winter projects" are finally starting to meld.
i'm beginning to see the hi-beam at the end of the tunnel.

 

[Geo Hahn]

Don't know about that, (how can you tell?)...

From your photo...

...and a chart of Lucas Distributors:

https://www.sterlingbritishmotoringsociety.org/files/Lucas_Dist_Chart.pdf

Differences are in the advance, both mechanical and vacuum (which is pretty much what distinguishes one Lucas 25D4 from any other).

 

[TR3driver]

So you're reading that last digit as a '9' ? Looks more like an '8' to me.

And while the housing is obviously wrong for a 3A (though it would work more or less); that doesn't mean that someone hasn't swapped around the internal parts to be more appropriate. The surface looks bead blasted to me, which suggests some rebuilder may have been at it. Internally, only the springs & point cam are different between different versions of 25D4 (plus the vacuum module of course).

 

[Geo Hahn]

So you're reading that last digit as a '9' ? Looks more like an '8' to me...

It is hard to read, but 41228A would have originally been a 25D6 (6 cylinder engine) though, as you note, any 25D distributor body could be reworked to almost any other configuration if internals are changed.

I was surprised to discover that the spare base plate and points I carry for my 4 cylinder TR will also work in the distributor of my 6 cylinder Jaguar. Obvious once I thought it thru but initially seemed amazing the differences between a 4-cyl and 6-cyl distributor are so small.

 

[GTP1960]

I dbl checked that model # is 9.


do you think there is any advantage with changing back to the correct distributor, or a "flame thrower" type?
Though this car has electronic ignition.

thx

 

[TR3driver]

No way to answer that question, until we know if it has been modified. But even if it hasn't, I don't think you'd notice a big difference. The Sprite advance curve is less aggressive than the TR, but you can compensate for that by bumping up the initial timing (if you don't use the hand crank). Here's a quickie plot of the centrifugal advance curves.

 

[Geo Hahn]

And on a distributor that old the curve may differ from the original anyway as springs may have been changed or at the very least gotten weaker.

A friend has a Sun machine and last week I was able to see the advance curve I am really getting on one of my distributors. It was at variance from the factory spec though the engine runs quite well -- no change will be made but good to know what I have:

A key number you can find out (and possibly tune for) is what advance you see 'all in', i.e. the advance at high RPMs. Set that about right and the rest may fall into place.

 

[Geo Hahn]

Randall - What application did you use to produce that graph? I suppose I have something that would do graphs if I took the time to dig into it. Thanks!

 

[TR3driver]

Randall - What application did you use to produce that graph? I suppose I have something that would do graphs if I took the time to dig into it. Thanks!

It's just an Excel spreadsheet. Probably not the friendliest/easiest software to use (and certainly not the cheapest) but I kind of got used to it at work. If I were starting over, I'd probably go with something like Open Office's Calc
https://www.openoffice.org/product/calc.html

 

[Geo Hahn]

Thanks, that pretty easy to swipe (I've got the intro version of Excel (aka 'Bill wants you to buy the real one') and will set it up.