>snip<
>When I replaced the distributor I stuck in a stock Toro one. The one
>put in the motorhome was made to compensate for the use of off the
>shelf parts. I am not there now---------whole new ball game. From where
>I sit it looks like with what I have done and will do the advance should
>be near the same as the Toro. I am not asking you to tell me what to do.
>snip<
Arch, had a email discussion w/Dick Paterson (who sells "Springfield
Ignition" HEIs and wires) re distributors, timing, advance, etc. last
winter. Here are some unedited tidbits from Dick that might help ya:
===============
....i wuold verify would be true top dead center on no 1 cyl. to be sure
tha t the timing mark on the harmonic balancer is dead on ,with the age
of these coaches the rubber ring in the balancer has deteriorated to the
point where the outer ring has rotated around the hub and throws off the
timing mark.. this usually happens if the motor sneezes or backfires..
You must have true T.D.C. to accuratelly sey the initial timing. Usually
even a bone stock motor likes more initial adv. .....its speeds the idle
up runs smoother and will show an increase in vac. at idle
next I would go thro the distributor to see if the weights were free to
advanc and return fully to rest at idle also check with the rotor
fastened down tight to see if you can twist it and feel or hear the weights
move .. some times the rotor does not clear the wieghts making them stiff
to advance or even holding them stationary (no advance) TO
ANSWER YOUR QUESTION ON WEIFGTS AND SPRINGS ,,,,IS DIFFICULT AS IT ALSO
INVOLVES THE CENTER pole piece as a base you wolld have to take the
dist. to a shop that has a dist. machine to set it up... you want to
have a steady curve that will gieve you 20 to22 degrees as seen on the
damper (10 to12) at the dist. this advance should be all in at 2400 to
2600 rpm... then with your initial timing of 10 to 12 degrees you arrive at
a total of 32 to 34 degrees total allowing the vacuum adv. to pull in
an additional 10 degrees when cruising (to help GAS MILEAGE) if thats
possible to notice on a GMC.
Often the distributor on coaches i see are not originals mostly scalped
from toronados and the curve is way off .....
....there should not be any vac at idle acting on the vac can at the dist.
....The other way you could approach the problem requires the use of a dial
back timing light then you can run the motor up to say 25 2700 rpm turn
the dial back to bring the timing mark back to zero on the balancer and
that reading on the light will tell you how much adv. in total there is.
You want the total to be 34 degrees. by setting the timing to give 34
at 2700 rpm you then tighten down the dist and resd the timing again at
idle to see what it now shows hopefully abouit 8 to 10 degrees.
....Rich looks like you are trouble shooting the right way 20 inches
of vac is super high.. and steady i hope .The initial timing is always
set with the vac adv. can disconnected stick a golf tee into the vac hose
to retain idle speed. The reason you disconnect it is that at idle where
you set this initial or (static) timing is always where you have the
highest vacuum i: e: your 20 inches .... thie vacuum can uses the vacuum
to pull in additional timing So if you are looking at the timing mark
with vac hooked up you are retarding the dist.by rotating it to line up
your marks for say 10 degrees for example the vac can has already pulled
in whatever it is calibrated for (on stock gmc dist. it was23 degrees
your new can is 10 degrees) with the new can if you are seeing say 12
degrees on the timing tab and the vac is hooked up you will really have 12
plus 10 equals 22 degrees initial.
======================
FWIW, my HEI had a 23 deg vac can on it when I got it so obviously it was a
Toro unit. The numbers are stamped on the arm. I installed a correct 10
deg vac can from Dick at the Marion rally - the springs & counterweights
(mech advance) still isn't right - feels like the advance is all in way too
early - but I'll fool with them later - don't wanna spend $$$ on a new dist.
HTH
As always, best regards.
~ Ritch & Betty Hwang ~ Clarkston, MI ~ mailto:rhwang
Visit our home page ~ http://www.concentric.net/~rhwang/
~ =^..^= Trinket ~ the shy Persian kitty ~
~ 76 GMC Birchaven ~ FMCA F249339 ~ RVClub 00930 ~ ICQ# 6408591~
(B}>
>When I replaced the distributor I stuck in a stock Toro one. The one
>put in the motorhome was made to compensate for the use of off the
>shelf parts. I am not there now---------whole new ball game. From where
>I sit it looks like with what I have done and will do the advance should
>be near the same as the Toro. I am not asking you to tell me what to do.
>snip<
Arch, had a email discussion w/Dick Paterson (who sells "Springfield
Ignition" HEIs and wires) re distributors, timing, advance, etc. last
winter. Here are some unedited tidbits from Dick that might help ya:
===============
....i wuold verify would be true top dead center on no 1 cyl. to be sure
tha t the timing mark on the harmonic balancer is dead on ,with the age
of these coaches the rubber ring in the balancer has deteriorated to the
point where the outer ring has rotated around the hub and throws off the
timing mark.. this usually happens if the motor sneezes or backfires..
You must have true T.D.C. to accuratelly sey the initial timing. Usually
even a bone stock motor likes more initial adv. .....its speeds the idle
up runs smoother and will show an increase in vac. at idle
next I would go thro the distributor to see if the weights were free to
advanc and return fully to rest at idle also check with the rotor
fastened down tight to see if you can twist it and feel or hear the weights
move .. some times the rotor does not clear the wieghts making them stiff
to advance or even holding them stationary (no advance) TO
ANSWER YOUR QUESTION ON WEIFGTS AND SPRINGS ,,,,IS DIFFICULT AS IT ALSO
INVOLVES THE CENTER pole piece as a base you wolld have to take the
dist. to a shop that has a dist. machine to set it up... you want to
have a steady curve that will gieve you 20 to22 degrees as seen on the
damper (10 to12) at the dist. this advance should be all in at 2400 to
2600 rpm... then with your initial timing of 10 to 12 degrees you arrive at
a total of 32 to 34 degrees total allowing the vacuum adv. to pull in
an additional 10 degrees when cruising (to help GAS MILEAGE) if thats
possible to notice on a GMC.
Often the distributor on coaches i see are not originals mostly scalped
from toronados and the curve is way off .....
....there should not be any vac at idle acting on the vac can at the dist.
....The other way you could approach the problem requires the use of a dial
back timing light then you can run the motor up to say 25 2700 rpm turn
the dial back to bring the timing mark back to zero on the balancer and
that reading on the light will tell you how much adv. in total there is.
You want the total to be 34 degrees. by setting the timing to give 34
at 2700 rpm you then tighten down the dist and resd the timing again at
idle to see what it now shows hopefully abouit 8 to 10 degrees.
....Rich looks like you are trouble shooting the right way 20 inches
of vac is super high.. and steady i hope .The initial timing is always
set with the vac adv. can disconnected stick a golf tee into the vac hose
to retain idle speed. The reason you disconnect it is that at idle where
you set this initial or (static) timing is always where you have the
highest vacuum i: e: your 20 inches .... thie vacuum can uses the vacuum
to pull in additional timing So if you are looking at the timing mark
with vac hooked up you are retarding the dist.by rotating it to line up
your marks for say 10 degrees for example the vac can has already pulled
in whatever it is calibrated for (on stock gmc dist. it was23 degrees
your new can is 10 degrees) with the new can if you are seeing say 12
degrees on the timing tab and the vac is hooked up you will really have 12
plus 10 equals 22 degrees initial.
======================
FWIW, my HEI had a 23 deg vac can on it when I got it so obviously it was a
Toro unit. The numbers are stamped on the arm. I installed a correct 10
deg vac can from Dick at the Marion rally - the springs & counterweights
(mech advance) still isn't right - feels like the advance is all in way too
early - but I'll fool with them later - don't wanna spend $$$ on a new dist.
HTH
As always, best regards.
~ Ritch & Betty Hwang ~ Clarkston, MI ~ mailto:rhwang
Visit our home page ~ http://www.concentric.net/~rhwang/
~ =^..^= Trinket ~ the shy Persian kitty ~
~ 76 GMC Birchaven ~ FMCA F249339 ~ RVClub 00930 ~ ICQ# 6408591~
(B}>
