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MGB questions, comments (long)

To: british-cars@autox.team.net
Subject: MGB questions, comments (long)
From: "W. Ray Gibbons" <gibbons@northpole.med.uvm.edu>
Date: Thu, 29 Jun 1995 11:37:49 -0400 (EDT)
I have had little time to poke around on the BGT I'm evaluating, but I
have a bit more info.  If you recall, the timing seemed way odd.  The car
starts easily, runs very well above 2000 rpm, but the idle is rough.  With
a strobe, the timing mark on the pulley can be seen from the top, whereas
the fixed marks are on the bottom. 

I have determined that the distributor body is in approximately the
factory stock location (69 engine).  The #1 spark plug contact is at about
the 4 oclock position as one stands on the right side of the engine,
staring fixedly at the distributor, just below the point where the low
tension lead enters the distributor.  I believe this to be the stock
location.  If I grasp the rotor and try to twist it in the direction of
distributor rotation (ccwise), it does not move.  I assume the centrifugal
advance is frozen.  If it were my car, I'd take the distributor out and
check, but it isn't mine.  I am reluctant to fiddle with it at this 
point, because the timing might be difficult to get right afterwards 
given the screwiness described below.

The timing marks are on the bottom front of the timing chain cover, with
the fixed prong denoting TDC at 6 oclock as I stand in front of the car
and face the rear.  With the engine running (idling about 1100 rpm), the
strobe illuminates the pulley timing mark at approximately the 9:30
position.  So if one believes the marks, the engine is either running
about 100 degrees retarded or 260 degrees advanced (yeah, riiiight). 
Revving the engine does not perceptibly change the position of the pulley
timing mark.  Clamping the vacuum hose to the distributor slightly retards
the timing--the strobed mark moves to perhaps the 10:30 position (moves in
the direction of engine rotation) and the engine slows perceptably. 

B distributor drive dogs are handed, so the distributor shaft can only go 
in one way, but I gather it is possible to install the cam 180 degrees 
backwards.  However, given how well the engine runs, I'm very doubtful it 
is running 180 degrees out of time.  I once reversed a chevy V8 
distributor, and the imperfection was readily apparent (blew great 
gobbets of fire through the carb, in fact).   Given that the #1 spark 
plug wire seems to be in the proper hole, I don't think the plug wire 
location has been moved to compensate for misplacement of the cam in the 
distr.  Anyway, if the cam location was wrong and the wires were moved to 
compensate, I should think #1 should fire at the right time (is this 
thinking wrong?).

So, to the questions:  apparently, all engines prior to the 18V had the
fixed timing marks on the bottom center.  

Question 1:  Where were they on the 18V engines?  One thought is that a
dpo put an 18V pulley on an earlier engine. 

Question 2:  Are the crankshaft pulleys on Bs made in two parts with a
rubber insert?  My original thought was that they might be, and the two
parts may have slipped.  There is a groove around the front side of the
pulley, but I cannot detect any rubber ring in this groove. 

Question 3:  Is there any way a crankshaft pulley can be put on wrong?

Question 4:  Is there any way this all could be explained by a failure of
a dpo to properly align the marks on the timing chain sprockets?  My gut
instinct is that altering ignition timing can't compensate for bad valve
timing, but I have not thought it through (I get a headache). 

These are niggling questions, however, because one way or 'nother it can 
be diagnosed and fixed.  Given time this weekend, I will try to find 
where the pulley mark is when piston #1 is at TDC.

I have a question about the steering, though, and that relates to the
nature of the beast. 

This car steers like a truck, in comparison with Kermit the frogeye.  I
have determined that the nearside inner tie rod is worn, and there is
about 1/16 play in the lower bushing of the king pins.  Also, the top
bushing of the steering column is worn, giving about 1/8 play.  The car
has worn 185/70 14 tires on original rostyle wheels.  If I jack up the
front end, I can spin the steering wheel from lock to lock with one
finger, so there isn't any severe binding in the unloaded system. 

Question 5:  Clearly, new tires, possibly with a narrower section, would
lighten it some.  But is the steering of B's normally pretty heavy? 

   Ray Gibbons  Dept. of Molecular Physiology & Biophysics
                Univ. of Vermont College of Medicine, Burlington, VT
                gibbons@northpole.med.uvm.edu  (802) 656-8910


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