On Mon, 13 Apr 1998 01:14:52 -0400 Trevor Boicey <tboicey@brit.ca>
writes:
>Bob MGT wrote:
>>
>> I had been having some pinging lately on my '71 MGB. A quick check
>of the
>> static timing showed 7 deg BTDC which is retarded compared to the
>book spec of
>> 10 deg (for the 18GK engine). I tried several different brands of
>premium gas,
>> but the pinging persisted. I finally broke down and bought a timing
>gun
>> (strobe light) and measured 20 deg BTDC @ 1500 rpm. The book says 15
>deg. I
>> adjusted the dizzy for 15 deg and took it for a test drive. Happy
>days, no
>> more pinging! I now believe that static timing is only for
>ballparking from
>> scratch just to get the engine started.
>
> Well, if you have the same dynamic timing but a different static
>timing
>then something is "different" in your set up.
Not the least of which is a different distributor from the original
> Obviously the dynamic setting is what matters, but it all should be
>the same.
Not neccesarily so. The special tuning manual for the B engine from BL
indicates a couple of distributors that will function correctly in the B,
but the static timing has to be changed to correct for the different
advance curves, maximum dist. advance etc.
> For example, if your mechanical advance springs were weak, you'd get
>too much advance at too low of RPMs. That could explain your
>situation, and changing the static timing is only hiding the real
>problem.
Static timing is not some magic number that is "correct" for the B. As
Bob correctly surmised, static timing is a starting point. nothing more.
> If you can find data, plot a full advance curve and see.
A good advance curve is printed in the BL Special Tuning handbook.
Rick Morrison
72 MGBGT
74 Midget
>Trevor Boicey, Ottawa, Canada.
>tboicey@brit.ca, http://www.brit.ca/~tboicey/
>[ Seeking some miscellaneous MG parts, see the list on the web page...
>]
>
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