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emissions where I am for a '87 ?  I could do anything . Where are you ? it matters .

headders will not give you much if anything besides a headache maintaining them .  smaller tires or lower gears ?
 

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what equipment does your '87 have on it now a 4 barrel or 2 ? air pump ? computer behind battery ? ( sbec )
'87 was a change over year , there were a few different systems used depending on the optioned equipment and where it was sold ....  the underhood sticker can help ... if its there still ... is it a feed back carb with many electric wires to it ? ... check with your emissions inspector FIRST , find out if they must SEE all factory installed things OR it must simply have low enough sniff numbers to pass , because making it run better / stronger does NOT automatically raise those numbers , BUT does not include all the 1987 factory installed equipment ... then discuss it more here  ;)  ignition , ing timing control , compression , fuel delivery . all can help , BUT can you change those visible parts ? and still pass if it sniffs ok?
 

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up the compression , replace the dizzy with a new one,  a single pick up WITH a vacume advance  ( me ? I'd use the same little silver box and the dodge type dizzy that goes with it ) install a coil from a dodge magnum . take a photo of your carb , post it ? 
 

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'79 Macho 360 Magnum, Comp 480 cam, Hughes springs, 650 Thunder AVS, Pertronix Flamethrower ignition
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KurtfromLaQuinta said:
If they just sniff the exhaust, you can do lots of things.
In fact, you can make it run cleaner than stock.
Of course, all you need is some money.
I was going to say the same thing - it depends on how much money you want to spend. You could go from mild to wild to pass the sniff test. But you can't go wrong if you start with your ignition system and induction system (carb or EFI) and the exhaust system but I just spoke $2000.00 minimum. So how much do you want to spend because you can go further like cylinder heads, cam, intake and so on but I just spoke another $3000.00+ or so.
 

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all the extra air in and out don't help much , unless that fuel and air are burnt well , up the compression , improve the spark and its timing control .  low compression and lots of carb = high emissions .. 
 

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dodge82273 said:
all the extra air in and out don't help much , unless that fuel and air are burnt well , up the compression , improve the spark and its timing control . low compression and lots of carb = high emissions ..
Totally agree.
And with more compression you'll increase the torque.
But you'll need to run premium gas. Worth the trade off.
 

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I understand that.  Point is that higher firing pressure, however one arrives at it, causes higher NOX.  Advanced timing, or high static CR, or very early closing intake cam timing...
 

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87 360 should have a rochester quadrajet carb- Finicky critter- theres tricks to rebuilding them and making them run right.  I would start by having a pro go thru that carb.

Sniffer test should do hydrocarbons and Nox.  Gotta keep the EGR in your case and probably the air injection too as they keep the Nox and HC down. 

You're in Colorado so you're at altitude.  You have a low compression engine that effectively is really really low up there.  Very tough to do anything to that engine to overcome that

Consider a head swap to the 88-91 "308" heads.  That will slightly adjust compression and can be decked slightly too.  Would do a custom cam if you gotta pass the sniffer test.  Q-jet and stock intake are good enough to leave alone, though edelbrock 3776 is a bolt on and lighter. 

Or just swap in a 98-03 5.9 magnum, put the edelbrock 4 barrel intake on it and be done and mostly legal. May need to swap to LA valve covers if they do a visual. 
 

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Knox is caused by burning lean. Leaner means less fuel byproducts but more Knox.
Leaner mixtures take longer to burn properly. Hence, leaner mixtures require more ignition advance than their richer counterparts.
Keep your vac can on your dizzy. Set your idle lean. If you have no egr valve, or emissions systems, you should be running full manifold vacuum to your dizzy. If you are running emissions systems like cats, run ported.

Ported vacuum advance: makes your idle mixtures richer and hotter, increasing idle engine temps to promote the “after burn” effect, activating cars sooner.
Manifold vacuum advance: allows for a leaner mix to burn more cleanly, but produces more Knox. Idle temps will reduce dramatically which is why when ford was introduced to emissions systems, they have a valve that switches  from porter to manifold in the even the engine runs too warm at idle, and switches back when the engine cools off.

In your case, stick with porter. Install an egr valve, as it’s job is to introduce already burned air into the combustion chambers to “re”burn it, install a high flow car, and have an a/f ratio gauge. Dial it in as close to 14:5-15 as you can, which with a carb will never be perfect but idk how strict your state is. Your aiming for a lean idle, and a 13:5-14:5 pulling a/f ratio, but it’s hard to be that specific because wideband O2 sensors aren’t very accurate. They give you a ballpark idea.
 

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Discussion Starter · #15 ·
thanks for the info.  The engine was recently rebuilt about 1500 miles ago.  I haven't cranked it yet, previous owner hasn't cranked for several years.  Gas was bad so we removed the tank and cleaned it.  I have the engine out and on a stand so we can paint the engine bay.  Its got all the emissions stuff and they do a visual inspection here as well, unfortunately, although i don't know if they know what they are looking for besides a cat converter.  The emissions system is intact.  Don't know how much i want to tear into it since its a fairly new rebuild.  Keep the ideas coming though, i might change my mind.  Thanks
 

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mkalinow said:
, although i don't know if they know what they are looking for besides a cat converter.
Thermostatic air cleaner if originally equipped with heat riser from exhaust manifold, EGR valve and amplifier, charcoal canister, correct gas cap, O2 sensor, cat, and original number of exhaust pipes (don't add dual if it was certified for single). If they follow similar rules to CARB, it'll mean OEM catalytic with factory stamp on it and original intake manifold or CARB-exempt one.
 

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'79 Macho 360 Magnum, Comp 480 cam, Hughes springs, 650 Thunder AVS, Pertronix Flamethrower ignition
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dodge82273 said:
all the extra air in and out don't help much , unless that fuel and air are burnt well , up the compression , improve the spark and its timing control . low compression and lots of carb = high emissions ..
You can't up the compression too much though as 91 octane (which I believe is the highest octane in the USA) can only support up to 10.5:1 (approx) w/aluminum heads or (approx) 9.8:1 with iron heads (dynamic CR) without detonation. Good cam timing and a strong ignition system and a clean fuel system (including chambers, piston tops, valves) is good for low emissions.
 

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Canadian country boy said:
You can't up the compression too much though as 91 octane (which I believe is the highest octane in the USA) can only support up to 10.5:1 (approx) w/aluminum heads or (approx) 9.8:1 with iron heads (dynamic CR) without detonation. Good cam timing and a strong ignition system and a clean fuel system (including chambers, piston tops, valves) is good for low emissions.
Those ratio's you suggested are plenty for the street.
Compared to 8.5- 8.8 to 1... they're plenty healthy.
 

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Agreed. Those numbers I posted are just the extreme numbers for that octane level. Plenty of power and low emissions can be achieved at lower compression ratios. My last car had a CR of 10.28:1 that made over 500hp and ran on 94 octane pump gas (94 is the highest we got in my neck of the woods) with undetectable detonation. The closer you can get your A/F ratio to stoich (14.7:1) the better your emissions.
 
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