Ever notice how clarity can come a microsecond after you've hit the "send"
button?
The first number is the onset of advance, the second number is the point at
which maximum advance takes place, and the third number is the total advance
provided by the vacuum unit.
Lonn Howard
rocket scientist
"We are but temporary custodians with an obligation of preservation."
----- Original Message -----
From: HolePuncher <hoops@owt.com>
To: MGs <mgs@autox.team.net>
Sent: Tuesday, December 08, 1998 10:37 PM
Subject: Re: 25d4 advancer distributer on a 68 B
>Something seems to be missing in this equation. I may be wrong, but it
>seems very unlikely that the vacuum advance is designed to produce such a
>linearly progressive advance, such that 1inch of mercury equals 1 degree of
>advance.
>
>I'm going to put a vacuum pump on my distributor so that I can plot the
>advance. It's got me curious...
>
>Lonn Howard
>'70 TR6 -mine
>'71 TR6 -in my garage, therefore it's mine (dad might disagree)
>'70 MGB GT -mine, mine... all mine
>
>"We are but temporary custodians with an obligation of preservation."
>----- Original Message -----
>From: Unger, Larry G <larry.g.unger@lmco.com>
>To: 'Rene van Maanen' <renevm@support.neth.hp.com>; <mgs@autox.team.net>
>Sent: Wednesday, December 09, 1998 6:45 AM
>Subject: RE: 25d4 advancer distributer on a 68 B
>
>
>>Rene van Maanen wrote:
>>
>>> Does someone know what the number of degrees is that the
>>> vacuum advancer creates for the ignition?
>>>
>>> It's a 25d4 advancer distributer on a 68 B.
>>
>>Rene,
>>
>>Here is info that Kelvin posted awhile back ...
>>
>>
>>> MGB Dist# Vac.# Vac.Adv. Type
>>>
>>> 18GF 40897 54411230 5.13.10 ported
>>> 65-67 41288 54411985 5.13.10
>>> 67 41290 54412170 5.11.7
>>> 68 41288 54411985 5.13.10
>>> 69 41264 54415625
>>> 70 41288 54411985 5.13.10
>>>
>>> 71 18GK 41339 54414868 7.13.5 manifold
>>> 72 18V 41370 54423989 7.13.3
>>> 73-74 41491 54425359 10.15.5
>>> 75 41599 54425516 10.15.5
>>>
>>> Note the change in advance characteristics in 1971.
>>> The later units come in at a higher vacuum and gives
>>> less advance.
>>>
>>> 10.15.5 = Movement starts at 10 ins of Mercury
>>> Movement stops at 15 ins of Mercury
>>> 5 distributor degrees advance at maximum movement
>>>
>>
>>Hope this helps ...
>>
>>**********************************************************
>>Safety Fast! ... larry.g.unger@lmco.com
>>'61 MGA 1600 MkII
>>
>
>
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