David,
The Lucas 45/DE4 electronic distrubutor (US SPEC) has vacuum retard not
advance (10 to 14 degrees). I seem to remember that the one I had had more
vaccum at idle but dropped off completely as the revs went up. Also the
timing set (2 to 10 degrees) is _After_ TDC not BTDC. Centrifugal advance
is varies by year, but it ranges from 1 to 19 degrees depending on RPM and
model year. The Bentley MG 1500 manual has all the specs.
Gerard
At 10:13 PM -0800 2/2/02, David Riker wrote:
>I'll take a stab at this, someone jump in and correct me if I'm wrong. My
>experience on 1500's has been 1979's in California Emissions trim.
>
>Basically speaking, the distributors on the 1500's have very little
>mechanical advance available because advance = higher NOX emissions. I
>think it is in the neighborhood of 12-14 degrees mechanical advance by
>2500-3000 RPM. For optimum performance without regard to emissions, total
>advance should be around 32-34 degrees. (I'll assume you are not running
>vacuum advance or retard) Therefore, a static timing of 22 degrees, plus
>the mechanical advance of 12 more would yield the ideal 32 degrees. The
>draw backs of this much static advance is the possibility for dieseling, and
>hard starting. I have found these two problems to crop up before pinging.
>If they do, back up the timing one degree at a time, until the symptoms
>stop.
>
>A nice solution is to fit a distributor from an A or B series MG that has
>more mechanical advance available. You can then run less initial advance
>with the same combined advance available at higher Rpm's. Adapting vacuum
>advance helps as well. The 48 state MGB distributor is a good choice. it
>has 22 degrees (again from memory, could be off a pinch) of mechanical
>advance available, and 6 degrees of vacuum advance available. I have this
>distributor on my 1275 and have added a vacuum port to the DCOE 40 just
>infront of the throttle plate. At idle, no vacuum, at part throttle, high
>vacuum, wide open low vacuum. I have the initial timing set at 6 degrees,
>which makes for easy starting, but total advance while cruising at 3000 RPM
>and above is 34 degrees.
>
>Hope this helps.
>
>David Riker
>74 Midget
>63 Falcon
>70 Torino
>http://home.pacbell.net/davriker
>----- Original Message -----
>From: "Brent Wolf" <wolfbj@prodigy.net>
>To: "Spridgets" <spridgets@autox.team.net>
>Sent: Saturday, February 02, 2002 9:39 PM
>Subject: 1500 Weber and Timing
>
>> Under fine tuning, it says to reset the timing to match the additional
>power
>> output. It says to reset the ignition timing to 22-25 BTDC at 900-1000
>> rpm.. I am a little leery here. This entire instruction is titled for an
>> MGB. I don't know what the original ign. timing was. My 1500s original
>> timing was either 2 ATDC or 10 BTDC (depending on where you read).
>>
>> I have adjusted my timing to 16 BTDC and I am impressed with the
>> performance, etc. My question - Is anyone running around with a1500 set at
>> 22-25 BTDC? What kind of indications should I expect if I advance my
>timing
>> to far? Overheating??? Ping or knock?? (none yet) Run on (None Yet)
--
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