psquare75
03-16-2007, 10:04 PM
I took my 75 Olds to be tested for emmisions today and it failed..
What can I do to bring down the CO%? The limit is 5.00 i'm at 6.97.. Limit
for HC are 500 i'm at 311.
I have a 455 with a 800cfm holley on it. thanks.
KEith
Tue Oct 19, 1999 4:18 pm
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Keith455@xxx.xxx
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Re: help me pass emissions.
Keith,
The first thing to do is verify that the EGR is
opening under load.
Since the diaphram gets hot use something hook or "J"
shaped to feel up under the diaphram. With the motor
hot, rev it up to 2K or so RPM. The valve should open.
If it doesn't put straight vacuum to it and see if it
opens. If it opens, (it will stall the motor) then the
vacuum heat valve that should be inline with the EGR
is bad. If the EGR still doesn't open, then the EGR is
bad. Replace it.
Even if the EGR is working and good the EGR passages
in the intake are probabaly plugged. Under the
secondaries in the intake should be the EGR tubes. I'm
not if you have a stock manifold under that Holley.
Use a strong phillips screw driver. Probably a #3 to
ream through the carbon. Then run a strong steel wire
through the EGR passages from the valve towards the
tubes in the intake floor. When done, use compressed
air in both directions to blow out the passages.
Also, with the engine cold and idling, if you manually
squeeze the EGR valve open, it should stall the motor.
Next, to burn all carbon out which will make the
Oxides of Nitrogen and Hc's higher, pour some
transmission fluid down the carb with the engine
running. You'll need to rev it for a few seconds to
keep it running. It will push some wierd white smoke
out that will hang low to the ground, so just keep
track of which way the car is pointed an where any
open windows or doors to houses are.
If you're sporting your original Cat Conv (I think
'75's had them) for $80.00 you should probably replace
that too. By now it's so plugged and inefficient that
the platnum isn't doing anything. Go to your best
in-town old established parts house for this. They'll
be able to get one with the pipes already bent and
sized to fit right in place of the original. Dwon't go
to Autozone or any of these discount places that have
sprung up all over the place.
If a '75 requires an air pump make sure it's pumping
air. My 74 doesn't use an air pump or cat converter.
This was the last year of a factory leaded gas car. I
only had an EGR. I put an older manifold on that
doesn't have an EGR valve. EGR's are actually good in
that they keep the center pistons cooler.
You probably get one free re-test, so the cat
converter is a judgment call. On my truck and wife's
Olds powered Riviera, I've changed the catalytic
converter along with doing all the other things and my
cars have been the poster children for perfect
emmissions. My truck is approaching 300,000 miles and
the Riviera has 150k miles. Many times cleaning out
the motor w/ trans fluid, and fixing the EGR system is
enough.
Make sure the baffle in your LH Valve cover is clear,
and that you have a good (get and AC Delco) PCV valve.
Replace your air filter, and definitely make sure you
have good clean oil.
You could also probably lean out the mixture and set
the timing back, but wait to see what the other stuff
does.
Mike
--- Keith455@... wrote:
> I took my 75 Olds to be tested for emmisions today
> and it failed..
> What can I do to bring down the CO%? The limit is
> 5.00 i'm at 6.97.. Limit
> for HC are 500 i'm at 311.
> I have a 455 with a 800cfm holley on it. thanks.
> KEith
>
>
Tue Oct 19, 1999 6:48 pm
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mike dziadik <dziadik@xxxxx.xxxx
dziadik@xxxxx.xxxx
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What can I do to bring down the CO%? The limit is 5.00 i'm at 6.97.. Limit
for HC are 500 i'm at 311.
I have a 455 with a 800cfm holley on it. thanks.
KEith
Tue Oct 19, 1999 4:18 pm
Show Message Option
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Keith455@xxx.xxx
Keith455@xxx.xxx
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Re: help me pass emissions.
Keith,
The first thing to do is verify that the EGR is
opening under load.
Since the diaphram gets hot use something hook or "J"
shaped to feel up under the diaphram. With the motor
hot, rev it up to 2K or so RPM. The valve should open.
If it doesn't put straight vacuum to it and see if it
opens. If it opens, (it will stall the motor) then the
vacuum heat valve that should be inline with the EGR
is bad. If the EGR still doesn't open, then the EGR is
bad. Replace it.
Even if the EGR is working and good the EGR passages
in the intake are probabaly plugged. Under the
secondaries in the intake should be the EGR tubes. I'm
not if you have a stock manifold under that Holley.
Use a strong phillips screw driver. Probably a #3 to
ream through the carbon. Then run a strong steel wire
through the EGR passages from the valve towards the
tubes in the intake floor. When done, use compressed
air in both directions to blow out the passages.
Also, with the engine cold and idling, if you manually
squeeze the EGR valve open, it should stall the motor.
Next, to burn all carbon out which will make the
Oxides of Nitrogen and Hc's higher, pour some
transmission fluid down the carb with the engine
running. You'll need to rev it for a few seconds to
keep it running. It will push some wierd white smoke
out that will hang low to the ground, so just keep
track of which way the car is pointed an where any
open windows or doors to houses are.
If you're sporting your original Cat Conv (I think
'75's had them) for $80.00 you should probably replace
that too. By now it's so plugged and inefficient that
the platnum isn't doing anything. Go to your best
in-town old established parts house for this. They'll
be able to get one with the pipes already bent and
sized to fit right in place of the original. Dwon't go
to Autozone or any of these discount places that have
sprung up all over the place.
If a '75 requires an air pump make sure it's pumping
air. My 74 doesn't use an air pump or cat converter.
This was the last year of a factory leaded gas car. I
only had an EGR. I put an older manifold on that
doesn't have an EGR valve. EGR's are actually good in
that they keep the center pistons cooler.
You probably get one free re-test, so the cat
converter is a judgment call. On my truck and wife's
Olds powered Riviera, I've changed the catalytic
converter along with doing all the other things and my
cars have been the poster children for perfect
emmissions. My truck is approaching 300,000 miles and
the Riviera has 150k miles. Many times cleaning out
the motor w/ trans fluid, and fixing the EGR system is
enough.
Make sure the baffle in your LH Valve cover is clear,
and that you have a good (get and AC Delco) PCV valve.
Replace your air filter, and definitely make sure you
have good clean oil.
You could also probably lean out the mixture and set
the timing back, but wait to see what the other stuff
does.
Mike
--- Keith455@... wrote:
> I took my 75 Olds to be tested for emmisions today
> and it failed..
> What can I do to bring down the CO%? The limit is
> 5.00 i'm at 6.97.. Limit
> for HC are 500 i'm at 311.
> I have a 455 with a 800cfm holley on it. thanks.
> KEith
>
>
Tue Oct 19, 1999 6:48 pm
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mike dziadik <dziadik@xxxxx.xxxx
dziadik@xxxxx.xxxx
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