On Sun, 26 Mar 1995, Jon N Swanson wrote:
> I recently purchased a 1973 MGB Roadster (my first MG, I'll try not to ask
Great car! I am finding mine is more of a 72-73-76 but it's registered
as a 73. <g>
> the symptoms. The way that I know it is running on #2 only - I removed all
> plug wires except for #2 and had no change in the running. If I leave
> 1, 3, and 4 connected and disconnect #2 it will not run at all.
#2 cylinder is the only one getting spark, OR the only one in the right
position for valve opening, OR the only one getting fuel (in order of
likelyhood).
> So what is the problem? I don't have any history on this vehicle - it looks
> like someone else tried (unsuccesfully) to get it running, but I have tried to
> clean up all of their messes and make everything as simple as possible.
Been there, done that <g>
> I have the plugs wired up 1-3-4-2 firing order, with #1 at the position
> immediately to the right of the key on the distributor cap, and counting
> in the counterclockwise direction. My compression tests out at
> 110, 115, 115, 120 (it is supposed to be 120 for a low compression engine,
> right?). I am obviously getting spark, I even got a nasty shock from 1,3,4
Using a clean shop rag or other insulating material, hold a disconnected
spark wire near the block and crank the car. You should get a nice fat
spark. Shocking yourself doesn't count, because you COULD be providing a
ground path from the distributor cap which does NOT pass through the
spark wire. (Mine does this to me too. I'm to scared to adjust the
timing while the engine is running now. And all four plugs are
connected and firing right before I zap myself.)
120 is indeed the nominal compression for an 8.0:1 engine... at least
according to my math 118 or so).
> when I was removing them while running on #2. I could have carburetor
> problems, but since 1&2 seem to run on one carb and 3&4 seem to run on the
> other, I would expect #1 to be working at least somewhat if #2 is working.
>
That's why I think it isn't a fuel problem, as well.
Well, OK. "Static timing ritual" you say. I'm not sure what you mean by
all that, except for the voodoo animal sacrifice you do right before
inserting the distributor drive dog. Notice that this ritual is listed
as different for different year engines in the Haynes manual. If you are
absolutely sure you have done this right, then your valve timing should
be close enough to make it run. That is, given that the valves are
actually opening!
Check your valve lash adjustment. Make sure the rockers are going up and
down in a reasonable fashion during >this< ritual. That is, they
actually seem to open the valves in the expected order. When you are
done, go through the static timing ritual again to check that the rotor
is indeed pointing at spark wire #1.
You mentioned the "distributor cap key" as your reference. The key locks
the cap down to the housing, which is not really keyed to the camshaft.
It's just there so you put the cap on the same way each time >once the
static timing is right<. The real reference would be vs. the block...
on my car, the #1 spark plug wire is on the side of the cap nearest the
block, a bit to the front. Then #3, #4, and #1 going around
anticlockwise. I know this because #2 and #1 wires cross, and the others
don't.
Anyway, here is my theory. The PO oriented the distributor with the
rotor OFF. It is extremely easy to set the drive dog in 180 degrees out
this way, because the rotor key is on the opposite side of the shaft from
the rotor contact. (Ask me how I know... g'haid, ask... <g>). You've
been doing your best to plug up the wires according to the book value,
which assumes everything else is proper.
It may not be 180 degrees, since circumstances have conspired to make #2
actually fire.. it just >happens< to have the right combination of valve
and spark timing.
The other option I see is that your camshaft is now perfectly round
except for the #2 cylinder lobes (or that you have no pushrods or lifters
except on those valves)... yeech! But going through the lash adjustment
should clue you in on those items.
John M. Trindle | jtrindle@tsquare.com | Tidewater Sports Car Club
'73 MGB DSP | '69 Spitfire E Stock | '88 RX-7 C Stock
Home Page: http://www.widomaker.com/~trindle
"Men always want to be a woman's first love - women like to be a man's last
romance. -- Ocsar Wilde"
|