Honda Car Forum

Out of curiosity today I disconnected the EGR valve on my '86 Prelude 1.8
dual carb w/ 5 speed. My good ness what a difference it made. Drivability
when the engine is cold is great, I don't have to rev it out the wazoo to
keep it from shuddering and bucking anymore. Also, I immediately noticed a
huge increase in power. The thing loves to rev now, I step on the gas and it
really winds up, and throttle response is so crisp and quick. Before it
would accelerate and rev nicely (though not as good as it does now) until a
certain point of throttle opening when presumably the EGR valve would really
start to open up. The car would then fall flat on it's face and bog down, if
I backed off the throttle it would perk back up. Now I can slam the throttle
down and the thing winds up and keep going.

I guess what I'm getting at is that it feels like a whole new car. I would
prefer to have the EGR valve connected to reduce emissions, but not unless
the car will run right with it connected. I think I'm going to try taking it
off and cleaning it out to see if that helps at all. If not then I'll leave
it as it is now. So does it sound like the EGR is working properly? It
definitely is 'working' as I can tell a huge difference when it's connected.
The car will now push you back into the seat if you get on it, I love the
performance. Also I expect mileage to increase, as I've heard others say
that when their EGR valve broke or they disabled it their mileage increased
a good bit. I would think the increase in mileage from a better running
engine would help offset the increased pollution. Anyway, let me know what
you guys think about keeping the EGR disabled, and if there is any way to
get the engine running well with it connected.

Cory

In article <1GXrb.21128$y95.14191@nwrdny01.gnilink.net>, "Cory Dunkle"
<cadnews@verizon.net> wrote:

> Out of curiosity today I disconnected the EGR valve on my '86 Prelude 1.8
> dual carb w/ 5 speed. My good ness what a difference it made. Drivability
> when the engine is cold is great, I don't have to rev it out the wazoo to
> keep it from shuddering and bucking anymore. Also, I immediately noticed a
> huge increase in power. The thing loves to rev now, I step on the gas and it
> really winds up, and throttle response is so crisp and quick. Before it
> would accelerate and rev nicely (though not as good as it does now) until a
> certain point of throttle opening when presumably the EGR valve would really
> start to open up. The car would then fall flat on it's face and bog down, if
> I backed off the throttle it would perk back up. Now I can slam the throttle
> down and the thing winds up and keep going.
>
> I guess what I'm getting at is that it feels like a whole new car. I would
> prefer to have the EGR valve connected to reduce emissions, but not unless
> the car will run right with it connected. I think I'm going to try taking it
> off and cleaning it out to see if that helps at all. If not then I'll leave
> it as it is now. So does it sound like the EGR is working properly? It
> definitely is 'working' as I can tell a huge difference when it's connected.
> The car will now push you back into the seat if you get on it, I love the
> performance. Also I expect mileage to increase, as I've heard others say
> that when their EGR valve broke or they disabled it their mileage increased
> a good bit. I would think the increase in mileage from a better running
> engine would help offset the increased pollution. Anyway, let me know what
> you guys think about keeping the EGR disabled, and if there is any way to
> get the engine running well with it connected.
>
> Cory

Cory,
I suggest that you buy a NEW EGR valve and try it for a week. It's
possible that your old EGR valve was clogged up. If you have a state
inspection of any type--make sure you reinstall the EGR valve prior to the
inspection. I once had a 1969 Chevy Nova. It ran much better after I
removed all of the anti pollution equipment. I would never do it on my
1999 Honda Accord since it runs just great even with all of the
anti-pollution equipment. We all should care about our environment.

EGR valve is closed when doing the things such as idle. If
disconnecting EGR valve changes engine (such as accelerate
from idle), then EGR valve remains closed always - which can,
worst case, result in burned cylinder valves.

Dual carb Honda would be a CVCC engine. Many previous
owners or mechanics thought they were smarter than the shop
manual and changed some screw settings on that CVCC carb (its
more than just a two barrel carburetor). Those settings
required factory adjustment. IOW those who first did not read
then made a mess of things. EGR valve would not fix their
messups.

EGR valve might be opening prematurely or might not be
leaking down to permit valve to close - causing your symptoms.
Best and simple is to buy a plastic tee, some rubber hose, and
a vacuum gauge. Very little money and very educational. Run
the car with that hose 'teed' to EGR vacuum line. Watch how
vacuum changes as car does various actions. No vacuum means
EGR valve is closed. What EGR valve does under various
conditions is nicely explained in 1980's Honda shop manuals -
that also shows how those vacuum lines are controlled.

A problem with those older Hondas was grease used inside
distributor. It would get sticky with age. Then the vacuum
advance and vacuum retard would not always adjust engine
timing properly. With extreme care and shop manual, removed,
disassembled, and greased those points with a special high
temperature wheel bearing grease (not oil or WD-40). Made
that Honda into a brand new engine. Worst problem was when
timing should have relaxed back to idle position, but remained
advanced as if in high speed operation due to sticky grease.
Then the engine would knock and buck.

Just some ideas on how to find the problem rather than
curing the symptoms - ie. disconnecting EGR valve to burn
cylinder valves.

EGR valve should not even be opening when engine is cold.
Furthermore, all those hoses, even on the Chevy Nova, were not
really anti-pollution equipment. Go back to the 60s before
pollution control was required. All those same hoses, etc
were on the 1960 engines that were sold as higher mileage
engines. Those hoses were required so that engine adapted
better to changing loads. But since MBAs were now top
management, they wants to call more expensive engines evil -
and called it anti-pollution equipment.

Get the vacuum gauge, monitor what those vacuum lines are
doing when cold, when accelerating, etc. They replace the
part that would be causing erratic operation. Easy to do with
a shop manual.

"Bill B. Johnson" wrote:
> In article <1GXrb.21128$y95.14191@nwrdny01.gnilink.net>, "Cory Dunkle"
> <cadnews@verizon.net> wrote:
>> Out of curiosity today I disconnected the EGR valve on my '86
>> Prelude 1.8 dual carb w/ 5 speed. My good ness what a difference
>> it made. Drivability when the engine is cold is great, I don't
>> have to rev it out the wazoo to keep it from shuddering and
>> bucking anymore. Also, I immediately noticed a huge increase in
>> power. The thing loves to rev now, I step on the gas and it
>> really winds up, and throttle response is so crisp and quick.
>> Before it would accelerate and rev nicely (though not as good
>> as it does now) until a certain point of throttle opening when
>> presumably the EGR valve would really start to open up. The car
>> would then fall flat on it's face and bog down, if I backed off
>> the throttle it would perk back up. Now I can slam the throttle
>> down and the thing winds up and keep going.
>>
> Cory,
> I suggest that you buy a NEW EGR valve and try it for a week. It's
> possible that your old EGR valve was clogged up. If you have a state
> inspection of any type--make sure you reinstall the EGR valve prior
> to the inspection. I once had a 1969 Chevy Nova. It ran much better
> after I removed all of the anti pollution equipment. I would never
> do it on my 1999 Honda Accord since it runs just great even with all
> of the anti-pollution equipment. We all should care about our
> environment.

"w_tom" <w_tom1@hotmail.com> wrote in message
news:3FB13D47.AAE3F84C@hotmail.com...
> EGR valve is closed when doing the things such as idle. If
> disconnecting EGR valve changes engine (such as accelerate
> from idle), then EGR valve remains closed always - which can,
> worst case, result in burned cylinder valves.

Perhaps larger jets would be the cure then.

> Dual carb Honda would be a CVCC engine. Many previous
> owners or mechanics thought they were smarter than the shop
> manual and changed some screw settings on that CVCC carb (its
> more than just a two barrel carburetor). Those settings
> required factory adjustment. IOW those who first did not read
> then made a mess of things. EGR valve would not fix their
> messups.

What is CVCC? Factory settings are not always optimal for max performance or
even necessarily mileage... In fact more often than not you can get better
performance and mileage with some tweaks... The cost is a little more
pollution. I haven't touched the carbs other than to spray them with some
good carb cleaner, which seemed to help the idle a bit.

> EGR valve might be opening prematurely or might not be
> leaking down to permit valve to close - causing your symptoms.
> Best and simple is to buy a plastic tee, some rubber hose, and
> a vacuum gauge. Very little money and very educational. Run
> the car with that hose 'teed' to EGR vacuum line. Watch how
> vacuum changes as car does various actions. No vacuum means
> EGR valve is closed. What EGR valve does under various
> conditions is nicely explained in 1980's Honda shop manuals -
> that also shows how those vacuum lines are controlled.

It would be interesting to see when the EGR valve opens and how much at
under what loads. I'll probably end up getting a sho manual for the car as I
plan to keep it as long as it isn't prohibitively expensive to fix anything.
I would assume it's ported vacuum that goes to the EGR valve, as manifold
vacuum would open it at idle and close at higher throttle. Unless Honda made
some other screwy vacuum source that is waht it would ahve to be, which
gives me a good idea of when the EGR valve is open.

> A problem with those older Hondas was grease used inside
> distributor. It would get sticky with age. Then the vacuum
> advance and vacuum retard would not always adjust engine
> timing properly. With extreme care and shop manual, removed,
> disassembled, and greased those points with a special high
> temperature wheel bearing grease (not oil or WD-40). Made
> that Honda into a brand new engine. Worst problem was when
> timing should have relaxed back to idle position, but remained
> advanced as if in high speed operation due to sticky grease.
> Then the engine would knock and buck.

I'm planning on advancing the timing as much as it will take to increase
mileage and perforamnce. While I'm at it I will check that the mechanical
advance is working properly. I'm not sure that I remember there being a
vacuum advance on the distributor though. I will check, and ensure they are
working smoothly.

> Just some ideas on how to find the problem rather than
> curing the symptoms - ie. disconnecting EGR valve to burn
> cylinder valves.
>
> EGR valve should not even be opening when engine is cold.

Well it must have been as it made a difference.. Also, the car no longer
stalls at the first stop in the morning.

> Furthermore, all those hoses, even on the Chevy Nova, were not
> really anti-pollution equipment. Go back to the 60s before
> pollution control was required. All those same hoses, etc
> were on the 1960 engines that were sold as higher mileage
> engines. Those hoses were required so that engine adapted
> better to changing loads. But since MBAs were now top
> management, they wants to call more expensive engines evil -
> and called it anti-pollution equipment.

I don't believe a '69 Nova would have had anything involing a significant
amount of vacuum hoses. It would have had a PCV valve, with most likely a
closed crankcase ventilation system (fill cap vented to the air cleaner); a
vacuum _retard_ in addition to advance; and perhaps a smog pump if it was a
California car.

> Get the vacuum gauge, monitor what those vacuum lines are
> doing when cold, when accelerating, etc. They replace the
> part that would be causing erratic operation. Easy to do with
> a shop manual.

Where do I get a shop manual for an '86 Prelude 1.8? I'd rather get the real
thing than a Haynes or Chiltons.

Cory

> "Bill B. Johnson" wrote:
> > In article <1GXrb.21128$y95.14191@nwrdny01.gnilink.net>, "Cory Dunkle"
> > <cadnews@verizon.net> wrote:
> >> Out of curiosity today I disconnected the EGR valve on my '86
> >> Prelude 1.8 dual carb w/ 5 speed. My good ness what a difference
> >> it made. Drivability when the engine is cold is great, I don't
> >> have to rev it out the wazoo to keep it from shuddering and
> >> bucking anymore. Also, I immediately noticed a huge increase in
> >> power. The thing loves to rev now, I step on the gas and it
> >> really winds up, and throttle response is so crisp and quick.
> >> Before it would accelerate and rev nicely (though not as good
> >> as it does now) until a certain point of throttle opening when
> >> presumably the EGR valve would really start to open up. The car
> >> would then fall flat on it's face and bog down, if I backed off
> >> the throttle it would perk back up. Now I can slam the throttle
> >> down and the thing winds up and keep going.
> >>
> > Cory,
> > I suggest that you buy a NEW EGR valve and try it for a week. It's
> > possible that your old EGR valve was clogged up. If you have a state
> > inspection of any type--make sure you reinstall the EGR valve prior
> > to the inspection. I once had a 1969 Chevy Nova. It ran much better
> > after I removed all of the anti pollution equipment. I would never
> > do it on my 1999 Honda Accord since it runs just great even with all
> > of the anti-pollution equipment. We all should care about our
> > environment.

"Bill B. Johnson" <billbjohnson555@nospamhotmail.com> wrote in message
news:billbjohnson555-1111030937280001@pm5-broad-123.snlo.dialup.fix.net...
> In article <1GXrb.21128$y95.14191@nwrdny01.gnilink.net>, "Cory Dunkle"
> <cadnews@verizon.net> wrote:
>
> > Out of curiosity today I disconnected the EGR valve on my '86 Prelude
1.8
> > dual carb w/ 5 speed. My good ness what a difference it made.
Drivability
> > when the engine is cold is great, I don't have to rev it out the wazoo
to
> > keep it from shuddering and bucking anymore. Also, I immediately noticed
a
> > huge increase in power. The thing loves to rev now, I step on the gas
and it
> > really winds up, and throttle response is so crisp and quick. Before it
> > would accelerate and rev nicely (though not as good as it does now)
until a
> > certain point of throttle opening when presumably the EGR valve would
really
> > start to open up. The car would then fall flat on it's face and bog
down, if
> > I backed off the throttle it would perk back up. Now I can slam the
throttle
> > down and the thing winds up and keep going.
> >
> > I guess what I'm getting at is that it feels like a whole new car. I
would
> > prefer to have the EGR valve connected to reduce emissions, but not
unless
> > the car will run right with it connected. I think I'm going to try
taking it
> > off and cleaning it out to see if that helps at all. If not then I'll
leave
> > it as it is now. So does it sound like the EGR is working properly? It
> > definitely is 'working' as I can tell a huge difference when it's
connected.
> > The car will now push you back into the seat if you get on it, I love
the
> > performance. Also I expect mileage to increase, as I've heard others say
> > that when their EGR valve broke or they disabled it their mileage
increased
> > a good bit. I would think the increase in mileage from a better running
> > engine would help offset the increased pollution. Anyway, let me know
what
> > you guys think about keeping the EGR disabled, and if there is any way
to
> > get the engine running well with it connected.
> >
> > Cory
>
> Cory,
> I suggest that you buy a NEW EGR valve and try it for a week. It's
> possible that your old EGR valve was clogged up. If you have a state
> inspection of any type--make sure you reinstall the EGR valve prior to the
> inspection. I once had a 1969 Chevy Nova. It ran much better after I
> removed all of the anti pollution equipment. I would never do it on my
> 1999 Honda Accord since it runs just great even with all of the
> anti-pollution equipment. We all should care about our environment.

I care about the environment, but my wallet comes first. I'm already doing
the environment a huge favor by switching to a sub-subcompact Honda 4 banger
with overdrive from the '67 and '68 Galaxie 500s I used to drive every day
400 miles/week getting 14-17 MPG, ~15 MPG average. I want the car to run
optimally, get great mileage, and have enough power to be safe to drive. Now
that I removed the EGR valve it meets the first and third of those, and the
mileage is good enough at nearly 30 MPG. Maybe more since disabling the EGR
valve.

I got the car for $300... It is an sub-subcompact econo-box I bought purely
for utility getting from point A to point B safely with good mileage. The
plan is to put no more money into it than it needs to pass inspection and
keep running, unless perhaps it is something that will increase mileage. I
don't mind putting labor into it, but no money unless I absolutely have to.
I am planning on removing and cleaning the EGR valve. I want to see if I can
get it working properly, as I would like to be as 'green' as is practical.
As I said though, I'm leaps and bounds above my '67 and '68 Fords are as far
as pollution per mile. The Fords have over two and a half times the
displacement of the Honda, and virtually no pollutions controls (yeh, PCV.
LOL), not to mention weigh twice as much and have automatic transmissions
with no overdrive. I'm helping the environment plenty even if this Honda had
no pollution controls. Anyway, I would like to keep the pollution controls
enabled, but not at any cost to my wallet or to the car running properly and
safely. Hopefully cleaning it out will help.

Cory

Shop manuals are sold (for all automakers I suspect) from a
publishing company in MI. Often that company is listed in an
order blank at the back of owners manual. I found the company
for my latest vehicle by doing an internet search. Also
dealer will often have an order card or the address.

Larger jets would not cure your problems. The car as
designed was optimized for best mileage and performance (a
word often misrepresented in North America where low
performance GM vehicle use large, low performance engines -
and people foolishly called that high performance). Do not
change the timing. That was already optimized by the original
design. The only way you could improve engine by timing is
make the timing more accurate - vary better to adapt the
changing conditions. The shop manual will provide some
limits. Notice that with mechanical timing, the actual engine
timing can vary widely from optimum only because it is
obsolete mechanical controls.

But you don't appear to have enough knowledge yet to even
consider timing changes. Keep asking those questions though.
Advancing timing too much could actually be destructive.

Again, many screws on that CVCC engine's carb are not field
adjustable. Shop manual will explain why but in not great
detail. Changing some screws can cause irreparable problems.

Reread what I said about pollution equipment. Not all (in
fact I think none) 1969 Novas came with the high mileage
package. Therefore it did not have all those hoses found in
post 1970 vehicles. Those hoses are traditionally mileage
enhances and performance adjusters - not anti pollution
devices. Early 1970 cars typically had but a few anti
pollution devices - called retarding the cam shaft in relation
to the crank. That's right. Notice what the pollution
control system was - a change on the gear at the end of one
shaft.

Also known as performance destroyers. That was almost the
pollution control system in 1970 to 1975 cars because bean
counters (not engineers) were designing all American engines
back then. Don't get fooled into thinking all those hoses
were anti pollution devices. And reread what I posted in that
earlier thread. You did not read it carefully enough and
jumped to a different conclusion.

As for that smog pump - again a classic distortion by those
who never bothered to learn facts. What did that pump do?
Pump air into the exhaust pipe. That was it. To get gasoline
to burn in the exhaust pipe that was not burned by the engine
- because engine was designed by 'bean counters'. The classic
example is explained in DeLorean's book "On a Clear Day You
Can See GM". Superior carburetor was Holley 5210 - designed
by Weber of Italy. But Rochester was a GM company. Holley
got the carburetor for the Vega because they were American
patriots - they did the innovations. But when the last GM
engineer left GM corporate, then Holley was removed and
Rochester installed. That meant the car polluted more because
Rochester made crap carburetors. So bad that engines with
Rochester carburetors required air pumps. So bad that much
gas was not burned in the engine and had to be burned in the
exhaust pipe.

Notice what good car designer did to decrease pollution.
Increased engine performance, horsepower, and gas mileage - by
making engine smaller. IOW they burned the gasoline in the
engine. Many pollutants are actually energy not burned in the
engine. 'Bean counter' engine designers preferred you did not
know this. Again, we thank god that he gave us Japanese and
European car manufacturers who let their engineers innovate.

Its not called a smog pump by those who first learn the
reasons why. It is better called a $60 trophy to anti
Americans who did not bother to use better technology. Anti
Americans distinguished first and foremost by cost controls
and lessons from the business schools.

EGR is controlled by more than just ported vacuum. That was
the 70s when EGR valve was controlled by 'bean counter'
designs. Honda EGR valve is controlled by a chain of vacuum
and electronic controls. Just another in long list of reasons
why Hondas were so superior to domestic products. One of my
early suspects would be the EGR control device that also
monitors engine coolant temperature.

Learn about CVCC technology in the shop manual. It would be
the paragraphs that Chilton, etc eliminated when they copied
selected parts of that shop manual. CVCC was pioneered by
early 1960 Ford (Stratified Charge engine) and kept out of
America by another anti-American 'bean counter' called Henry
Ford.

Honda engineers were on the Ford development team. Old man
Honda had designed pistons and piston rings. Therefore,
unlike at Ford, the top man was the classic example of an
American patriot. He innovated. He had dirt under his
fingernails. Therefore he could understand an innovation
while it was still innovative - and yet could not be
quantified by any spread sheet. That Honda CVCC engine is but
another long list of American innovations only found in
foreign products because domestic top management was
anti-American; also known as graduates of the business
schools.

Cory Dunkle wrote:
> ...
> Perhaps larger jets would be the cure then.
> ...
> What is CVCC? Factory settings are not always optimal for max
> performance or even necessarily mileage... In fact more often
> than not you can get better performance and mileage with some
> tweaks... The cost is a little more pollution. I haven't touched
> the carbs other than to spray them with some good carb cleaner,
> which seemed to help the idle a bit.
> ...
> It would be interesting to see when the EGR valve opens and how
> much at under what loads. I'll probably end up getting a sho
> manual for the car as I plan to keep it as long as it isn't
> prohibitively expensive to fix anything. I would assume it's
> ported vacuum that goes to the EGR valve, as manifold vacuum
> would open it at idle and close at higher throttle. Unless Honda
> made some other screwy vacuum source that is waht it would ahve
> to be, which gives me a good idea of when the EGR valve is open.
> ...
> I'm planning on advancing the timing as much as it will take to
> increase mileage and perforamnce. While I'm at it I will check
> that the mechanical advance is working properly. I'm not sure
> that I remember there being a vacuum advance on the distributor
> though. I will check, and ensure they are working smoothly.
>
> Well it must have been as it made a difference.. Also, the car no
> longer stalls at the first stop in the morning.
>
>> Furthermore, all those hoses, even on the Chevy Nova, were not
>> really anti-pollution equipment. Go back to the 60s before
>> pollution control was required. All those same hoses, etc
>> were on the 1960 engines that were sold as higher mileage
>> engines. Those hoses were required so that engine adapted
>> better to changing loads. But since MBAs were now top
>> management, they wants to call more expensive engines evil -
>> and called it anti-pollution equipment.
>
> I don't believe a '69 Nova would have had anything involing a
> significant amount of vacuum hoses. It would have had a PCV
> valve, with most likely a closed crankcase ventilation system
> (fill cap vented to the air cleaner); a vacuum _retard_ in
> addition to advance; and perhaps a smog pump if it was a
> California car.
>
> > Get the vacuum gauge, monitor what those vacuum lines are
> > doing when cold, when accelerating, etc. They replace the
> > part that would be causing erratic operation. Easy to do with
> > a shop manual.
>
> Where do I get a shop manual for an '86 Prelude 1.8? I'd rather
> get the real thing than a Haynes or Chiltons.

"Cory Dunkle" <cadnews@verizon.net>
news:fkisb.14093$hB5.563@nwrdny02.gnilink.net...
<SNIP>
> I don't believe a '69 Nova would have had anything involing a significant
> amount of vacuum hoses. It would have had a PCV valve, with most likely a
> closed crankcase ventilation system (fill cap vented to the air cleaner);
a
> vacuum _retard_ in addition to advance; and perhaps a smog pump if it was
a
> California car.
>

1. PCV stands for positive crankcase ventilation so the fill cap is NOT
vented to the air cleaner.

2. What EGR does is to reduce the oxygen content of the intake charge (less
than the 21% atmospheric) thus lowering the flame temperature hopefully
reducing NOx emissions. If you disable the EGR you may experience pinging
because EGR cars usually have a more aggressive timing advance curve in the
lower rev range.

Bye,
Leon

"Leon" <leonp_nospam@bigfoot.com> wrote in message
news:newscache$4v89oh$wxn$1@ithaca.tee.gr...
> "Cory Dunkle" <cadnews@verizon.net>
> news:fkisb.14093$hB5.563@nwrdny02.gnilink.net...
> <SNIP>
> > I don't believe a '69 Nova would have had anything involing a
significant
> > amount of vacuum hoses. It would have had a PCV valve, with most likely
a
> > closed crankcase ventilation system (fill cap vented to the air
cleaner);
> a
> > vacuum _retard_ in addition to advance; and perhaps a smog pump if it
was
> a
> > California car.
> >
>
> 1. PCV stands for positive crankcase ventilation so the fill cap is NOT
> vented to the air cleaner.

Perhaps you don't understand how a normal PCV system works. On one valve
cover there is a PCV valve connected to manifold vacuum. The valve opens
more as manifold vacuum drops, the idea is that the valve is always pulling
air from the crankcase into the intake to be burned. On the other valve
cover you have the oil fill cap, which pre-'68 was just a normal cap vented
to atmosphere. In '68 the PCV system evolved some more and the oil fill cap
had a tube connected to the air cleaner. The idea being that whenever the
PCV valve couldn't keep up with any pressure in the crankcase instead of
venting out the fill cap to atmosphere it would be pushed out the cap,
through the tube, and then sucked through the carburetor to be burned.

Have you ever seen an old car with 200,000+ miles on the original engine
that is equipped with a road-draft tube? Yeh, they smoke a lot don't they?
Now put later model valve covers and a PCV vale on it and the smoke is
significantly reduced if not gone altogether. Then vent the oil fill cap to
the air cleaner and unless you've got _really_ bad blowby problems (rings
can't hold much/any pressure or cracked rings) there shouldn't be any smoke
visible under any engine load as it's all getting burned in the engine.

> 2. What EGR does is to reduce the oxygen content of the intake charge
(less
> than the 21% atmospheric) thus lowering the flame temperature hopefully
> reducing NOx emissions. If you disable the EGR you may experience pinging
> because EGR cars usually have a more aggressive timing advance curve in
the
> lower rev range.

Interesting.

Cory

"w_tom" <w_tom1@hotmail.com> wrote in message
news:3FB277C4.D0F3886E@hotmail.com...
> Shop manuals are sold (for all automakers I suspect) from a
> publishing company in MI. Often that company is listed in an
> order blank at the back of owners manual. I found the company
> for my latest vehicle by doing an internet search. Also
> dealer will often have an order card or the address.
>
> Larger jets would not cure your problems. The car as
> designed was optimized for best mileage and performance (a
> word often misrepresented in North America where low
> performance GM vehicle use large, low performance engines -
> and people foolishly called that high performance). Do not
> change the timing. That was already optimized by the original
> design. The only way you could improve engine by timing is
> make the timing more accurate - vary better to adapt the
> changing conditions. The shop manual will provide some
> limits. Notice that with mechanical timing, the actual engine
> timing can vary widely from optimum only because it is
> obsolete mechanical controls.
>
> But you don't appear to have enough knowledge yet to even
> consider timing changes. Keep asking those questions though.
> Advancing timing too much could actually be destructive.

An engine will perform optimally with as much spark advance as it will take
without pre-detonation. The fuel burns more completely and more of its
energy is used to power the engine. My '68 Galaxie with 302 got about 12 MPG
set at factory timing with the factory vacuum advance/retard unit. I
advanced my initial timing as far as I could get it, then swapped on the
adjustable advance only vacuum unit from my old '67 289 car. I adjusted the
new vacuum advance unit to give me as much advance as possible without
pinging, which was more than the original unit gave.

Right away I noticed the car was significantly faster. It would now toss you
back in the seat and even chirp the tires with a little encouragement (quite
a feat for a 3,600+ lb car with only a little 302, low compression in one
cylinder and 2.80:1 'highway' gears out back. My mileage increased from ~12
MPG to 15-16 MPG with normal driving, and I even saw as high as 17 MPG once
cruising the two lane blacktop at 75-85 MPH all day. Go ahead and tell me
factory specs are optimal on all cars, I ahve proof otherwise. Also, if you
know anything about how engines work you will know more advance gets you
more power and mileage.

> Again, many screws on that CVCC engine's carb are not field
> adjustable. Shop manual will explain why but in not great
> detail. Changing some screws can cause irreparable problems.
>
> Reread what I said about pollution equipment. Not all (in
> fact I think none) 1969 Novas came with the high mileage
> package. Therefore it did not have all those hoses found in
> post 1970 vehicles. Those hoses are traditionally mileage
> enhances and performance adjusters - not anti pollution
> devices. Early 1970 cars typically had but a few anti
> pollution devices - called retarding the cam shaft in relation
> to the crank. That's right. Notice what the pollution
> control system was - a change on the gear at the end of one
> shaft.

Why don't you actually tell me what "those hoses" were? Hoses don't dso
anything to an engine. Tell me what they were connected to and the purpose
of those devices.

> Also known as performance destroyers. That was almost the
> pollution control system in 1970 to 1975 cars because bean
> counters (not engineers) were designing all American engines
> back then. Don't get fooled into thinking all those hoses
> were anti pollution devices. And reread what I posted in that
> earlier thread. You did not read it carefully enough and
> jumped to a different conclusion.
>
> As for that smog pump - again a classic distortion by those
> who never bothered to learn facts. What did that pump do?
> Pump air into the exhaust pipe. That was it. To get gasoline
> to burn in the exhaust pipe that was not burned by the engine
> - because engine was designed by 'bean counters'. The classic
> example is explained in DeLorean's book "On a Clear Day You
> Can See GM". Superior carburetor was Holley 5210 - designed
> by Weber of Italy. But Rochester was a GM company. Holley
> got the carburetor for the Vega because they were American
> patriots - they did the innovations. But when the last GM
> engineer left GM corporate, then Holley was removed and
> Rochester installed. That meant the car polluted more because
> Rochester made crap carburetors. So bad that engines with
> Rochester carburetors required air pumps. So bad that much
> gas was not burned in the engine and had to be burned in the
> exhaust pipe.

Yep, smog pumps are only there to water down the exhaust and encourage
'controlled backfire' to compensate for an engine that runs poorly. Timing
too far retarded will result in combustion in the exhaust pipes, as so much
of the air/fuel mixture is wasted and unburned, or still burning as it
enters the exhaust. Ever watch a new engine's cam being broken in when
the owner 'eyeballed' the timing? Sometimes it's too far advanced and
sometimes it's too far retarded. When it's too far retarded the headers will
start to glow red from the combustion taking place inside of them.

Cory



> Cory Dunkle wrote:
> > ...
> > Perhaps larger jets would be the cure then.
> > ...
> > What is CVCC? Factory settings are not always optimal for max
> > performance or even necessarily mileage... In fact more often
> > than not you can get better performance and mileage with some
> > tweaks... The cost is a little more pollution. I haven't touched
> > the carbs other than to spray them with some good carb cleaner,
> > which seemed to help the idle a bit.
> > ...
> > It would be interesting to see when the EGR valve opens and how
> > much at under what loads. I'll probably end up getting a sho
> > manual for the car as I plan to keep it as long as it isn't
> > prohibitively expensive to fix anything. I would assume it's
> > ported vacuum that goes to the EGR valve, as manifold vacuum
> > would open it at idle and close at higher throttle. Unless Honda
> > made some other screwy vacuum source that is waht it would ahve
> > to be, which gives me a good idea of when the EGR valve is open.
> > ...
> > I'm planning on advancing the timing as much as it will take to
> > increase mileage and perforamnce. While I'm at it I will check
> > that the mechanical advance is working properly. I'm not sure
> > that I remember there being a vacuum advance on the distributor
> > though. I will check, and ensure they are working smoothly.
> >
> > Well it must have been as it made a difference.. Also, the car no
> > longer stalls at the first stop in the morning.
> >
> >> Furthermore, all those hoses, even on the Chevy Nova, were not
> >> really anti-pollution equipment. Go back to the 60s before
> >> pollution control was required. All those same hoses, etc
> >> were on the 1960 engines that were sold as higher mileage
> >> engines. Those hoses were required so that engine adapted
> >> better to changing loads. But since MBAs were now top
> >> management, they wants to call more expensive engines evil -
> >> and called it anti-pollution equipment.
> >
> > I don't believe a '69 Nova would have had anything involing a
> > significant amount of vacuum hoses. It would have had a PCV
> > valve, with most likely a closed crankcase ventilation system
> > (fill cap vented to the air cleaner); a vacuum _retard_ in
> > addition to advance; and perhaps a smog pump if it was a
> > California car.
> >
> > > Get the vacuum gauge, monitor what those vacuum lines are
> > > doing when cold, when accelerating, etc. They replace the
> > > part that would be causing erratic operation. Easy to do with
> > > a shop manual.
> >
> > Where do I get a shop manual for an '86 Prelude 1.8? I'd rather
> > get the real thing than a Haynes or Chiltons.

You are describing a 1960 automobile where crude designs
were used for engine timing. Therefore the timing advance had
to be set so that even a more defective distributor would
work.

In fact, most every 1960 carburetor was not even adjusted to
factory specs. It was easier to just slap parts together and
forget about the adjustments. Car still sold no matter how
poorly it ran. It was the late sixties when the concept of
'quality be damned' became the new philosophy.

But you now have a Honda. It had finer adjustments which
means you have minimal variance in timing 'tweaking'.
Electronic controlled cars have even less variance.

Those mileage figures for a 1960s engine are really quite
unacceptable. For example, a 1964 Ford 390 in a large car
would routinely get 17 MPG highway in repeated tanks.
Sometimes even 18. Local driving numbers were not much
lower. IOW I suspect you were really only restoring
distributor timing advance curves to where it should have been
originally. But again, one way routinely used to cut costs in
the later 1960s was to eliminate adjustments to those springs
inside distributors and other adjustments in carburetors.
Gas mileage was that irrelevant back then. Cost controls
began replacing good designs starting with Ford's Wiz Kids.

Cory Dunkle wrote:
> An engine will perform optimally with as much spark advance as it will take
> without pre-detonation. The fuel burns more completely and more of its
> energy is used to power the engine. My '68 Galaxie with 302 got about 12 MPG
> set at factory timing with the factory vacuum advance/retard unit. I
> advanced my initial timing as far as I could get it, then swapped on the
> adjustable advance only vacuum unit from my old '67 289 car. I adjusted the
> new vacuum advance unit to give me as much advance as possible without
> pinging, which was more than the original unit gave.
>
> Right away I noticed the car was significantly faster. It would now toss you
> back in the seat and even chirp the tires with a little encouragement (quite
> a feat for a 3,600+ lb car with only a little 302, low compression in one
> cylinder and 2.80:1 'highway' gears out back. My mileage increased from ~12
> MPG to 15-16 MPG with normal driving, and I even saw as high as 17 MPG once
> cruising the two lane blacktop at 75-85 MPH all day. Go ahead and tell me
> factory specs are optimal on all cars, I ahve proof otherwise. Also, if you
> know anything about how engines work you will know more advance gets you
> more power and mileage.
> ...