Hi Mike,

I drove it in this morning. There may have been a subtile difference, but
not much. One thing I forgot to mention last night was that MAN. is labeled
above the nipple on the vac. advance. Is this to signify that the vacuum
line needs to be connected to manifold vacuum?

I did connect it to the manifold port and the timing jump up significantly.
I have not driven it this way though.

The other thing I failed to mention was I don't have the CTO valve
connected. The CTO I believe changes the distributor's vacuum line from
manifold to carb depending on engine temperature. Is a CTO valve a crutial
component or does it just enable the engine to run better at a cold start
up?

Thanks
Paul

 

Some engines were tuned for a manifold vacuum that goes full advance at
idle, some are tuned for a ported vacuum.

Some have both and the CTO in there to change it as you are thinking.
They were getting 'creative' with the emissions junk there for a while.

What are you doing about the EGR valve? That really needs the CTO and
the thermostat inside the air filter to work properly, but at least the
CTO.

It will run like a pig cold if the EGR is kicking in and it will not
have the same top power with the EGR disconnected. They made a
different cam for the engine without the EGR.

When I killed the computer in mine I went to a ported vacuum. I get the
best performance like that and the emissions sniffer likes it that way.

I can get 15-17 ppm HC's at idle tuned that way, If I tune it for
manifold vacuum at idle my HC's jump up to 1585 ppm or so and it fails
miserably.

There is no difference at 2500 rpm on the dyno though, the timing is at
full advance there no matter which vacuum I use. The weights pull it to
full advance around 2300 rpm I believe.

The difference is in the acceleration power. I get a smooth pull all
the way up to 4500 rpm with ported, it has big dead spots in the pull
with manifold vacuum.

I am running the Carter BBD 2 bbl on my 78 engine though and just have a
straight pipe with a Dynomax high flow muffler. I don't need a Cat for
emissions on my 'utility' vehicle.

So I just went out and sucked on my vacuum line to the advance and I can
easily suck it to full advance. Didn't need to put the light on it,
when I have it sucked, my fingers cannot move the advance lever any
more. I guess you could remove your distributor cap and watch the rotor
while sucking. Then when it is sucked hard, see if you can twist the
rotor more.

Mike

Paul Brogren wrote:
>
> Hi Mike,
>
> I drove it in this morning. There may have been a subtile difference, but
> not much. One thing I forgot to mention last night was that MAN. is labeled
> above the nipple on the vac. advance. Is this to signify that the vacuum
> line needs to be connected to manifold vacuum?
>
> I did connect it to the manifold port and the timing jump up significantly.
> I have not driven it this way though.
>
> The other thing I failed to mention was I don't have the CTO valve
> connected. The CTO I believe changes the distributor's vacuum line from
> manifold to carb depending on engine temperature. Is a CTO valve a crutial
> component or does it just enable the engine to run better at a cold start
> up?
>
> Thanks
> Paul

 

Some engines were tuned for a manifold vacuum that goes full advance at
idle, some are tuned for a ported vacuum.

Some have both and the CTO in there to change it as you are thinking.
They were getting 'creative' with the emissions junk there for a while.

What are you doing about the EGR valve? That really needs the CTO and
the thermostat inside the air filter to work properly, but at least the
CTO.

It will run like a pig cold if the EGR is kicking in and it will not
have the same top power with the EGR disconnected. They made a
different cam for the engine without the EGR.

When I killed the computer in mine I went to a ported vacuum. I get the
best performance like that and the emissions sniffer likes it that way.

I can get 15-17 ppm HC's at idle tuned that way, If I tune it for
manifold vacuum at idle my HC's jump up to 1585 ppm or so and it fails
miserably.

There is no difference at 2500 rpm on the dyno though, the timing is at
full advance there no matter which vacuum I use. The weights pull it to
full advance around 2300 rpm I believe.

The difference is in the acceleration power. I get a smooth pull all
the way up to 4500 rpm with ported, it has big dead spots in the pull
with manifold vacuum.

I am running the Carter BBD 2 bbl on my 78 engine though and just have a
straight pipe with a Dynomax high flow muffler. I don't need a Cat for
emissions on my 'utility' vehicle.

So I just went out and sucked on my vacuum line to the advance and I can
easily suck it to full advance. Didn't need to put the light on it,
when I have it sucked, my fingers cannot move the advance lever any
more. I guess you could remove your distributor cap and watch the rotor
while sucking. Then when it is sucked hard, see if you can twist the
rotor more.

Mike

Paul Brogren wrote:
>
> Hi Mike,
>
> I drove it in this morning. There may have been a subtile difference, but
> not much. One thing I forgot to mention last night was that MAN. is labeled
> above the nipple on the vac. advance. Is this to signify that the vacuum
> line needs to be connected to manifold vacuum?
>
> I did connect it to the manifold port and the timing jump up significantly.
> I have not driven it this way though.
>
> The other thing I failed to mention was I don't have the CTO valve
> connected. The CTO I believe changes the distributor's vacuum line from
> manifold to carb depending on engine temperature. Is a CTO valve a crutial
> component or does it just enable the engine to run better at a cold start
> up?
>
> Thanks
> Paul

 

Some engines were tuned for a manifold vacuum that goes full advance at
idle, some are tuned for a ported vacuum.

Some have both and the CTO in there to change it as you are thinking.
They were getting 'creative' with the emissions junk there for a while.

What are you doing about the EGR valve? That really needs the CTO and
the thermostat inside the air filter to work properly, but at least the
CTO.

It will run like a pig cold if the EGR is kicking in and it will not
have the same top power with the EGR disconnected. They made a
different cam for the engine without the EGR.

When I killed the computer in mine I went to a ported vacuum. I get the
best performance like that and the emissions sniffer likes it that way.

I can get 15-17 ppm HC's at idle tuned that way, If I tune it for
manifold vacuum at idle my HC's jump up to 1585 ppm or so and it fails
miserably.

There is no difference at 2500 rpm on the dyno though, the timing is at
full advance there no matter which vacuum I use. The weights pull it to
full advance around 2300 rpm I believe.

The difference is in the acceleration power. I get a smooth pull all
the way up to 4500 rpm with ported, it has big dead spots in the pull
with manifold vacuum.

I am running the Carter BBD 2 bbl on my 78 engine though and just have a
straight pipe with a Dynomax high flow muffler. I don't need a Cat for
emissions on my 'utility' vehicle.

So I just went out and sucked on my vacuum line to the advance and I can
easily suck it to full advance. Didn't need to put the light on it,
when I have it sucked, my fingers cannot move the advance lever any
more. I guess you could remove your distributor cap and watch the rotor
while sucking. Then when it is sucked hard, see if you can twist the
rotor more.

Mike

Paul Brogren wrote:
>
> Hi Mike,
>
> I drove it in this morning. There may have been a subtile difference, but
> not much. One thing I forgot to mention last night was that MAN. is labeled
> above the nipple on the vac. advance. Is this to signify that the vacuum
> line needs to be connected to manifold vacuum?
>
> I did connect it to the manifold port and the timing jump up significantly.
> I have not driven it this way though.
>
> The other thing I failed to mention was I don't have the CTO valve
> connected. The CTO I believe changes the distributor's vacuum line from
> manifold to carb depending on engine temperature. Is a CTO valve a crutial
> component or does it just enable the engine to run better at a cold start
> up?
>
> Thanks
> Paul

 

Hi Paul,
the "suction thing" should have rotated the plate holding the points
and condenser. Capping that hose with your tongue should have held it
there, if the diaphragm is good. The springs on the centrifugal advance
weights should be strong enough to spring back when released. wiggle the
shaft to make sure it's not worn out so much that you can open and close
points. maybe, put a little oil on that felt pad to keep that way.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

Paul Brogren wrote:
>
> Mike,
> I did the suction thing to see if the rotor moved. It does not. I can
> physically move it, but it stays where I put it. With or without suction.
> Does this sound like the distributor weights / springs are about worn out.
>
> Thanks,
> Paul
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:3F859210.563965F1@sympatico.ca...
> > Some engines were tuned for a manifold vacuum that goes full advance at
> > idle, some are tuned for a ported vacuum.
> >
> > Some have both and the CTO in there to change it as you are thinking.
> > They were getting 'creative' with the emissions junk there for a while.
> >
> > What are you doing about the EGR valve? That really needs the CTO and
> > the thermostat inside the air filter to work properly, but at least the
> > CTO.
> >
> > It will run like a pig cold if the EGR is kicking in and it will not
> > have the same top power with the EGR disconnected. They made a
> > different cam for the engine without the EGR.
> >
> > When I killed the computer in mine I went to a ported vacuum. I get the
> > best performance like that and the emissions sniffer likes it that way.
> >
> > I can get 15-17 ppm HC's at idle tuned that way, If I tune it for
> > manifold vacuum at idle my HC's jump up to 1585 ppm or so and it fails
> > miserably.
> >
> > There is no difference at 2500 rpm on the dyno though, the timing is at
> > full advance there no matter which vacuum I use. The weights pull it to
> > full advance around 2300 rpm I believe.
> >
> > The difference is in the acceleration power. I get a smooth pull all
> > the way up to 4500 rpm with ported, it has big dead spots in the pull
> > with manifold vacuum.
> >
> > I am running the Carter BBD 2 bbl on my 78 engine though and just have a
> > straight pipe with a Dynomax high flow muffler. I don't need a Cat for
> > emissions on my 'utility' vehicle.
> >
> > So I just went out and sucked on my vacuum line to the advance and I can
> > easily suck it to full advance. Didn't need to put the light on it,
> > when I have it sucked, my fingers cannot move the advance lever any
> > more. I guess you could remove your distributor cap and watch the rotor
> > while sucking. Then when it is sucked hard, see if you can twist the
> > rotor more.
> >
> > Mike
> >
> > Paul Brogren wrote:
> > >
> > > Hi Mike,
> > >
> > > I drove it in this morning. There may have been a subtile difference,
> but
> > > not much. One thing I forgot to mention last night was that MAN. is
> labeled
> > > above the nipple on the vac. advance. Is this to signify that the
> vacuum
> > > line needs to be connected to manifold vacuum?
> > >
> > > I did connect it to the manifold port and the timing jump up
> significantly.
> > > I have not driven it this way though.
> > >
> > > The other thing I failed to mention was I don't have the CTO valve
> > > connected. The CTO I believe changes the distributor's vacuum line from
> > > manifold to carb depending on engine temperature. Is a CTO valve a
> crutial
> > > component or does it just enable the engine to run better at a cold
> start
> > > up?
> > >
> > > Thanks
> > > Paul

 

Hi Paul,
the "suction thing" should have rotated the plate holding the points
and condenser. Capping that hose with your tongue should have held it
there, if the diaphragm is good. The springs on the centrifugal advance
weights should be strong enough to spring back when released. wiggle the
shaft to make sure it's not worn out so much that you can open and close
points. maybe, put a little oil on that felt pad to keep that way.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

Paul Brogren wrote:
>
> Mike,
> I did the suction thing to see if the rotor moved. It does not. I can
> physically move it, but it stays where I put it. With or without suction.
> Does this sound like the distributor weights / springs are about worn out.
>
> Thanks,
> Paul
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:3F859210.563965F1@sympatico.ca...
> > Some engines were tuned for a manifold vacuum that goes full advance at
> > idle, some are tuned for a ported vacuum.
> >
> > Some have both and the CTO in there to change it as you are thinking.
> > They were getting 'creative' with the emissions junk there for a while.
> >
> > What are you doing about the EGR valve? That really needs the CTO and
> > the thermostat inside the air filter to work properly, but at least the
> > CTO.
> >
> > It will run like a pig cold if the EGR is kicking in and it will not
> > have the same top power with the EGR disconnected. They made a
> > different cam for the engine without the EGR.
> >
> > When I killed the computer in mine I went to a ported vacuum. I get the
> > best performance like that and the emissions sniffer likes it that way.
> >
> > I can get 15-17 ppm HC's at idle tuned that way, If I tune it for
> > manifold vacuum at idle my HC's jump up to 1585 ppm or so and it fails
> > miserably.
> >
> > There is no difference at 2500 rpm on the dyno though, the timing is at
> > full advance there no matter which vacuum I use. The weights pull it to
> > full advance around 2300 rpm I believe.
> >
> > The difference is in the acceleration power. I get a smooth pull all
> > the way up to 4500 rpm with ported, it has big dead spots in the pull
> > with manifold vacuum.
> >
> > I am running the Carter BBD 2 bbl on my 78 engine though and just have a
> > straight pipe with a Dynomax high flow muffler. I don't need a Cat for
> > emissions on my 'utility' vehicle.
> >
> > So I just went out and sucked on my vacuum line to the advance and I can
> > easily suck it to full advance. Didn't need to put the light on it,
> > when I have it sucked, my fingers cannot move the advance lever any
> > more. I guess you could remove your distributor cap and watch the rotor
> > while sucking. Then when it is sucked hard, see if you can twist the
> > rotor more.
> >
> > Mike
> >
> > Paul Brogren wrote:
> > >
> > > Hi Mike,
> > >
> > > I drove it in this morning. There may have been a subtile difference,
> but
> > > not much. One thing I forgot to mention last night was that MAN. is
> labeled
> > > above the nipple on the vac. advance. Is this to signify that the
> vacuum
> > > line needs to be connected to manifold vacuum?
> > >
> > > I did connect it to the manifold port and the timing jump up
> significantly.
> > > I have not driven it this way though.
> > >
> > > The other thing I failed to mention was I don't have the CTO valve
> > > connected. The CTO I believe changes the distributor's vacuum line from
> > > manifold to carb depending on engine temperature. Is a CTO valve a
> crutial
> > > component or does it just enable the engine to run better at a cold
> start
> > > up?
> > >
> > > Thanks
> > > Paul

 

Hi Paul,
the "suction thing" should have rotated the plate holding the points
and condenser. Capping that hose with your tongue should have held it
there, if the diaphragm is good. The springs on the centrifugal advance
weights should be strong enough to spring back when released. wiggle the
shaft to make sure it's not worn out so much that you can open and close
points. maybe, put a little oil on that felt pad to keep that way.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

Paul Brogren wrote:
>
> Mike,
> I did the suction thing to see if the rotor moved. It does not. I can
> physically move it, but it stays where I put it. With or without suction.
> Does this sound like the distributor weights / springs are about worn out.
>
> Thanks,
> Paul
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:3F859210.563965F1@sympatico.ca...
> > Some engines were tuned for a manifold vacuum that goes full advance at
> > idle, some are tuned for a ported vacuum.
> >
> > Some have both and the CTO in there to change it as you are thinking.
> > They were getting 'creative' with the emissions junk there for a while.
> >
> > What are you doing about the EGR valve? That really needs the CTO and
> > the thermostat inside the air filter to work properly, but at least the
> > CTO.
> >
> > It will run like a pig cold if the EGR is kicking in and it will not
> > have the same top power with the EGR disconnected. They made a
> > different cam for the engine without the EGR.
> >
> > When I killed the computer in mine I went to a ported vacuum. I get the
> > best performance like that and the emissions sniffer likes it that way.
> >
> > I can get 15-17 ppm HC's at idle tuned that way, If I tune it for
> > manifold vacuum at idle my HC's jump up to 1585 ppm or so and it fails
> > miserably.
> >
> > There is no difference at 2500 rpm on the dyno though, the timing is at
> > full advance there no matter which vacuum I use. The weights pull it to
> > full advance around 2300 rpm I believe.
> >
> > The difference is in the acceleration power. I get a smooth pull all
> > the way up to 4500 rpm with ported, it has big dead spots in the pull
> > with manifold vacuum.
> >
> > I am running the Carter BBD 2 bbl on my 78 engine though and just have a
> > straight pipe with a Dynomax high flow muffler. I don't need a Cat for
> > emissions on my 'utility' vehicle.
> >
> > So I just went out and sucked on my vacuum line to the advance and I can
> > easily suck it to full advance. Didn't need to put the light on it,
> > when I have it sucked, my fingers cannot move the advance lever any
> > more. I guess you could remove your distributor cap and watch the rotor
> > while sucking. Then when it is sucked hard, see if you can twist the
> > rotor more.
> >
> > Mike
> >
> > Paul Brogren wrote:
> > >
> > > Hi Mike,
> > >
> > > I drove it in this morning. There may have been a subtile difference,
> but
> > > not much. One thing I forgot to mention last night was that MAN. is
> labeled
> > > above the nipple on the vac. advance. Is this to signify that the
> vacuum
> > > line needs to be connected to manifold vacuum?
> > >
> > > I did connect it to the manifold port and the timing jump up
> significantly.
> > > I have not driven it this way though.
> > >
> > > The other thing I failed to mention was I don't have the CTO valve
> > > connected. The CTO I believe changes the distributor's vacuum line from
> > > manifold to carb depending on engine temperature. Is a CTO valve a
> crutial
> > > component or does it just enable the engine to run better at a cold
> start
> > > up?
> > >
> > > Thanks
> > > Paul

 

Hi Mike,

I don't have an EGR. It's port on the carb is capped. What I have on the
carb is a capped EGR (port that points straight at the valve cover), vacuum
line on the diagonal port that (points toward water pump/front of engine)
goes to distributor nipple, and a capped spark port that points toward
drivers side headlight. I don't have an emissions diagram for my year 1975,
but I believe that the '74 did not have an EGR.

Sounds crazy, but all this power lack came after I replaced the header
w/stock manifold and re-built the carb. 65-70 mph is definitely top speed
now. Where as before the changes I had much more.

I do the suction thing on the distributor and see if the rotor can be moved
more.

Thanks Again,
Paul
"Mike Romain" <romainm@sympatico.ca> wrote in message
news:3F859210.563965F1@sympatico.ca...
> Some engines were tuned for a manifold vacuum that goes full advance at
> idle, some are tuned for a ported vacuum.
>
> Some have both and the CTO in there to change it as you are thinking.
> They were getting 'creative' with the emissions junk there for a while.
>
> What are you doing about the EGR valve? That really needs the CTO and
> the thermostat inside the air filter to work properly, but at least the
> CTO.
>
> It will run like a pig cold if the EGR is kicking in and it will not
> have the same top power with the EGR disconnected. They made a
> different cam for the engine without the EGR.
>
> When I killed the computer in mine I went to a ported vacuum. I get the
> best performance like that and the emissions sniffer likes it that way.
>
> I can get 15-17 ppm HC's at idle tuned that way, If I tune it for
> manifold vacuum at idle my HC's jump up to 1585 ppm or so and it fails
> miserably.
>
> There is no difference at 2500 rpm on the dyno though, the timing is at
> full advance there no matter which vacuum I use. The weights pull it to
> full advance around 2300 rpm I believe.
>
> The difference is in the acceleration power. I get a smooth pull all
> the way up to 4500 rpm with ported, it has big dead spots in the pull
> with manifold vacuum.
>
> I am running the Carter BBD 2 bbl on my 78 engine though and just have a
> straight pipe with a Dynomax high flow muffler. I don't need a Cat for
> emissions on my 'utility' vehicle.
>
> So I just went out and sucked on my vacuum line to the advance and I can
> easily suck it to full advance. Didn't need to put the light on it,
> when I have it sucked, my fingers cannot move the advance lever any
> more. I guess you could remove your distributor cap and watch the rotor
> while sucking. Then when it is sucked hard, see if you can twist the
> rotor more.
>
> Mike
>
> Paul Brogren wrote:
> >
> > Hi Mike,
> >
> > I drove it in this morning. There may have been a subtile difference,
but
> > not much. One thing I forgot to mention last night was that MAN. is
labeled
> > above the nipple on the vac. advance. Is this to signify that the
vacuum
> > line needs to be connected to manifold vacuum?
> >
> > I did connect it to the manifold port and the timing jump up
significantly.
> > I have not driven it this way though.
> >
> > The other thing I failed to mention was I don't have the CTO valve
> > connected. The CTO I believe changes the distributor's vacuum line from
> > manifold to carb depending on engine temperature. Is a CTO valve a
crutial
> > component or does it just enable the engine to run better at a cold
start
> > up?
> >
> > Thanks
> > Paul

 

Hi Mike,

I don't have an EGR. It's port on the carb is capped. What I have on the
carb is a capped EGR (port that points straight at the valve cover), vacuum
line on the diagonal port that (points toward water pump/front of engine)
goes to distributor nipple, and a capped spark port that points toward
drivers side headlight. I don't have an emissions diagram for my year 1975,
but I believe that the '74 did not have an EGR.

Sounds crazy, but all this power lack came after I replaced the header
w/stock manifold and re-built the carb. 65-70 mph is definitely top speed
now. Where as before the changes I had much more.

I do the suction thing on the distributor and see if the rotor can be moved
more.

Thanks Again,
Paul
"Mike Romain" <romainm@sympatico.ca> wrote in message
news:3F859210.563965F1@sympatico.ca...
> Some engines were tuned for a manifold vacuum that goes full advance at
> idle, some are tuned for a ported vacuum.
>
> Some have both and the CTO in there to change it as you are thinking.
> They were getting 'creative' with the emissions junk there for a while.
>
> What are you doing about the EGR valve? That really needs the CTO and
> the thermostat inside the air filter to work properly, but at least the
> CTO.
>
> It will run like a pig cold if the EGR is kicking in and it will not
> have the same top power with the EGR disconnected. They made a
> different cam for the engine without the EGR.
>
> When I killed the computer in mine I went to a ported vacuum. I get the
> best performance like that and the emissions sniffer likes it that way.
>
> I can get 15-17 ppm HC's at idle tuned that way, If I tune it for
> manifold vacuum at idle my HC's jump up to 1585 ppm or so and it fails
> miserably.
>
> There is no difference at 2500 rpm on the dyno though, the timing is at
> full advance there no matter which vacuum I use. The weights pull it to
> full advance around 2300 rpm I believe.
>
> The difference is in the acceleration power. I get a smooth pull all
> the way up to 4500 rpm with ported, it has big dead spots in the pull
> with manifold vacuum.
>
> I am running the Carter BBD 2 bbl on my 78 engine though and just have a
> straight pipe with a Dynomax high flow muffler. I don't need a Cat for
> emissions on my 'utility' vehicle.
>
> So I just went out and sucked on my vacuum line to the advance and I can
> easily suck it to full advance. Didn't need to put the light on it,
> when I have it sucked, my fingers cannot move the advance lever any
> more. I guess you could remove your distributor cap and watch the rotor
> while sucking. Then when it is sucked hard, see if you can twist the
> rotor more.
>
> Mike
>
> Paul Brogren wrote:
> >
> > Hi Mike,
> >
> > I drove it in this morning. There may have been a subtile difference,
but
> > not much. One thing I forgot to mention last night was that MAN. is
labeled
> > above the nipple on the vac. advance. Is this to signify that the
vacuum
> > line needs to be connected to manifold vacuum?
> >
> > I did connect it to the manifold port and the timing jump up
significantly.
> > I have not driven it this way though.
> >
> > The other thing I failed to mention was I don't have the CTO valve
> > connected. The CTO I believe changes the distributor's vacuum line from
> > manifold to carb depending on engine temperature. Is a CTO valve a
crutial
> > component or does it just enable the engine to run better at a cold
start
> > up?
> >
> > Thanks
> > Paul

 

Hi Mike,

I don't have an EGR. It's port on the carb is capped. What I have on the
carb is a capped EGR (port that points straight at the valve cover), vacuum
line on the diagonal port that (points toward water pump/front of engine)
goes to distributor nipple, and a capped spark port that points toward
drivers side headlight. I don't have an emissions diagram for my year 1975,
but I believe that the '74 did not have an EGR.

Sounds crazy, but all this power lack came after I replaced the header
w/stock manifold and re-built the carb. 65-70 mph is definitely top speed
now. Where as before the changes I had much more.

I do the suction thing on the distributor and see if the rotor can be moved
more.

Thanks Again,
Paul
"Mike Romain" <romainm@sympatico.ca> wrote in message
news:3F859210.563965F1@sympatico.ca...
> Some engines were tuned for a manifold vacuum that goes full advance at
> idle, some are tuned for a ported vacuum.
>
> Some have both and the CTO in there to change it as you are thinking.
> They were getting 'creative' with the emissions junk there for a while.
>
> What are you doing about the EGR valve? That really needs the CTO and
> the thermostat inside the air filter to work properly, but at least the
> CTO.
>
> It will run like a pig cold if the EGR is kicking in and it will not
> have the same top power with the EGR disconnected. They made a
> different cam for the engine without the EGR.
>
> When I killed the computer in mine I went to a ported vacuum. I get the
> best performance like that and the emissions sniffer likes it that way.
>
> I can get 15-17 ppm HC's at idle tuned that way, If I tune it for
> manifold vacuum at idle my HC's jump up to 1585 ppm or so and it fails
> miserably.
>
> There is no difference at 2500 rpm on the dyno though, the timing is at
> full advance there no matter which vacuum I use. The weights pull it to
> full advance around 2300 rpm I believe.
>
> The difference is in the acceleration power. I get a smooth pull all
> the way up to 4500 rpm with ported, it has big dead spots in the pull
> with manifold vacuum.
>
> I am running the Carter BBD 2 bbl on my 78 engine though and just have a
> straight pipe with a Dynomax high flow muffler. I don't need a Cat for
> emissions on my 'utility' vehicle.
>
> So I just went out and sucked on my vacuum line to the advance and I can
> easily suck it to full advance. Didn't need to put the light on it,
> when I have it sucked, my fingers cannot move the advance lever any
> more. I guess you could remove your distributor cap and watch the rotor
> while sucking. Then when it is sucked hard, see if you can twist the
> rotor more.
>
> Mike
>
> Paul Brogren wrote:
> >
> > Hi Mike,
> >
> > I drove it in this morning. There may have been a subtile difference,
but
> > not much. One thing I forgot to mention last night was that MAN. is
labeled
> > above the nipple on the vac. advance. Is this to signify that the
vacuum
> > line needs to be connected to manifold vacuum?
> >
> > I did connect it to the manifold port and the timing jump up
significantly.
> > I have not driven it this way though.
> >
> > The other thing I failed to mention was I don't have the CTO valve
> > connected. The CTO I believe changes the distributor's vacuum line from
> > manifold to carb depending on engine temperature. Is a CTO valve a
crutial
> > component or does it just enable the engine to run better at a cold
start
> > up?
> >
> > Thanks
> > Paul