Cannot pass Hoston,TX emissions.
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New User
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I am not real familar with the intake and carb combo but as long as you tune and jet the carb right I think you should be okay. Not sure though I mean as far as I know none f the pollution stuff would be removed jut a bigger carb I am wondering if I can run a edelbrock 500cf carb though and jet it down.
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I guess that would depend on what year truck you have
and what connections there are from the carb to other
equipment. My '84 has a throttle position sensor that
has to work correctly for the engine to idle properly. I'm
not sure where the TPS is but if it is connected to the carb,
replacing the carb with a different one that did not have a
TPS would be an emissions problem.
As to using a 500 cfm carb and jetting it down, I don't see
why that would not work for you. The 390 cfm Holly 4-bbl.
carb seems a popular item on the older Fords with the I6
engine. The Offenhauser intake manifold is the usual
companion for it.
I saw a message online that showed the optimal air flow for
gasoline engines based upon a selected rpm and engine
displacement. For a 300 CID engine at 4000 rpm , this
was just under 400 cfm. I'm not sure what the highest
operating range for the 300 I6 is, so just used 4000 rpm
as a guess. Actual highway operating rpm is probably
more like 2500-3000 rpm.
Ed
and what connections there are from the carb to other
equipment. My '84 has a throttle position sensor that
has to work correctly for the engine to idle properly. I'm
not sure where the TPS is but if it is connected to the carb,
replacing the carb with a different one that did not have a
TPS would be an emissions problem.
As to using a 500 cfm carb and jetting it down, I don't see
why that would not work for you. The 390 cfm Holly 4-bbl.
carb seems a popular item on the older Fords with the I6
engine. The Offenhauser intake manifold is the usual
companion for it.
I saw a message online that showed the optimal air flow for
gasoline engines based upon a selected rpm and engine
displacement. For a 300 CID engine at 4000 rpm , this
was just under 400 cfm. I'm not sure what the highest
operating range for the 300 I6 is, so just used 4000 rpm
as a guess. Actual highway operating rpm is probably
more like 2500-3000 rpm.
Ed
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New User
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I have an 84 but don't recall seeing a tps on the carb. As far as the edelbrock goes Im just not a holley fan and I think the polished edelbrock would compliment the polished hooker headers. Since the 84 is carberated does it have 02 sensors? Im guessing not, that would be the only thing keeping me away from the headers.
Senior User
Joined: Nov 2005
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My truck was originally purchased in California, so it may have a TPS where non-Cal. trucks do not. I'm sure that whichever carb you end up getting will do a good job for you. If you're more comfortable with one brand vs. another,
then go with the one with which you're most familiar. That will make tuning and rebuilding somewhat easier.
The presence of an O2 sensor was also a likely California emissions requirement, so trucks from other states may
not have needed them.
My truck also has a cat. converter which may not have been required in the other 49 states on vehicles with GVWs
above 6000 lbs. at the time. I'm not sure when all these anti-pollution devices became required but there was a
period of several years there where things were added.
Ed
then go with the one with which you're most familiar. That will make tuning and rebuilding somewhat easier.
The presence of an O2 sensor was also a likely California emissions requirement, so trucks from other states may
not have needed them.
My truck also has a cat. converter which may not have been required in the other 49 states on vehicles with GVWs
above 6000 lbs. at the time. I'm not sure when all these anti-pollution devices became required but there was a
period of several years there where things were added.
Ed
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Joined: May 2002
Posts: 336
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Just an idea for ya!
Cannot pass Hoston,TX emissions.
I live in Delaware where we have to go thru emissins testin' every 2 years. {misspelled on porpose!}
Not that I am advocating any kind of nefarious actions,
but in the past I have had great luck with: less than a 1/4 tank of gas, and 4 or 5 bottles of HEET {in the yellow bottles} gas additive. It is pure methanol, and seems to bring all of the #'s into an area that makes the inspectors happy. Just one word of advice, put it just before going, and fuel ALL the way up when done. 
Good luck
Senior User
Joined: Jun 2002
Posts: 330
Likes: 1
From: Chandler,Arizona - USA
I was considering putting an Offy intake and a 4 bbl carb in my '85 w/ 300 I6. I decided against it because unless some major fabrication is done, the emissions equipment will not hook up to the Offy/Holly setup. You stated that in two years your truck will be exempt from emissions testing. If I was in your shoes, I would wait the two years before switching to the 4 bbl.
On you failing emissions - Your cat is probably clogged. Also, you most likely have the electronic feedback/TFI IV ignition(no vacuum advance). Your carb is controlled by a computer under the dash by the ash tray. Get the computer tested to make sure that it is functioning properly. You will not be able to pass emissions if the computer is not working properly. I removed the computer crap and put in the older
Duraspark-2 ignition, as well as replacing my catalytic converter, because it was clogged, the truck now works like a charm, and passes emissions with no problem.
P.S. Keep the 300. Great motor. Good luck.
On you failing emissions - Your cat is probably clogged. Also, you most likely have the electronic feedback/TFI IV ignition(no vacuum advance). Your carb is controlled by a computer under the dash by the ash tray. Get the computer tested to make sure that it is functioning properly. You will not be able to pass emissions if the computer is not working properly. I removed the computer crap and put in the older
Duraspark-2 ignition, as well as replacing my catalytic converter, because it was clogged, the truck now works like a charm, and passes emissions with no problem.
P.S. Keep the 300. Great motor. Good luck.
Senior User
Joined: Nov 2005
Posts: 364
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Originally Posted by ridgerider3
I live in Delaware where we have to go thru emissins testin' every 2 years. {misspelled on porpose!}
Not that I am advocating any kind of nefarious actions, but in the past I have had great luck with: less than a 1/4 tank of gas, and 4 or 5 bottles of HEET {in the yellow bottles} gas additive. It is pure methanol, and seems to bring all of the #'s into an area that makes the inspectors happy. Just one word of advice, put it just before going, and fuel ALL the way up when done.
Good luck
Not that I am advocating any kind of nefarious actions,
but in the past I have had great luck with: less than a 1/4 tank of gas, and 4 or 5 bottles of HEET {in the yellow bottles} gas additive. It is pure methanol, and seems to bring all of the #'s into an area that makes the inspectors happy. Just one word of advice, put it just before going, and fuel ALL the way up when done. Good luck
Interesting idea. In WA state, they put a "sniffer" into the
gas filler tube and test the atmosphere in the tank for a
couple of minutes before they do the actual tail-pipe test.
Don't know what they are looking for by doing this but gas
additives could be high up on the list.
On the other hand, not all gas contains alcohols. We have
a local Arco station that sells regular gas + 10% ethanol or
"gasohol". Maybe running a tank or two of that through the
old girl would help those hydrocarbon emission readings?
Ed
New User
Joined: Jan 2008
Posts: 0
Likes: 24
Is the engine IDentification decal still on the engine valve cover.
There are some hypenated characters on that label under the word calibration.
Post that info.
There are some hypenated characters on that label under the word calibration.
Post that info.
Last edited by Mil1ion; Jan 26, 2007 at 08:44 PM.
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Senior User
Joined: May 2002
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In WA state, they put a "sniffer" into the
gas filler tube and test the atmosphere in the tank for a
couple of minutes before they do the actual tail-pipe test.
gas filler tube and test the atmosphere in the tank for a
couple of minutes before they do the actual tail-pipe test.
Had a brand new cap fail once.
The first time I watched them do this test, they pumped the pressure up to 25 psi, and I came UNGLUED on them.
Since then, they test the older vehicles at approx. 5 to 10 psi. Before they start the test, they also put a pair of vise grips on the fuel line under the hood.
Full size vans don't get that part because of not being able to even see the hose, let alone clamp it!
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From: Virginia
Originally Posted by j.whitten
I have an 84 but don't recall seeing a tps on the carb. As far as the edelbrock goes Im just not a holley fan and I think the polished edelbrock would compliment the polished hooker headers. Since the 84 is carberated does it have 02 sensors? Im guessing not, that would be the only thing keeping me away from the headers.
1. Do they lift the hood? If so, you are sunk.
2. Tuning. Yes, you can bolt all that stuff on, and it may run good, and it may not. But that's only the first part. The 2nd part is; Will it pass emissions? I can bet no. Can you tune it to pass? Possibly. But it's very very tricky, and takes a lot of time and know how.
Ever wonder why Ford put all that junk on the engine in the first place? Believe me if they could save $1.00 on every truck and leave something off, (and they make thousands of trucks), they would do it.
Most of the stuff on the engine is to make it run when it's cold, because they calibrate the carb so lean. And then when it's warmed up, you have the EGR system to deal with, which your aftermarket system does not address.
It's a big can of worms, and I am glad we do not have very strict inspectors in my area. But I have had my vehicles fail more than once for something not looking right under the hood.
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