The results of clean living
Smog Test Results Los Angeles (1 Viewer)
- Thread starter Spike Strip
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- los angeles smog
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cps432
SILVER Star
I personally opted for the elimination diet…
garfieldthecat
SILVER Star
Cant wait to live clean like that. And hopefully the smell of fuel from my truck dissipates as well at some point as a bonus.
@Spike Strip that is clean. Like really clean.
- Thread starter
- #6
Timing at 5* BTDC and an approx 3:1 ratio of 91 Octane summer blend to E-85 (perfectly legal, even in Los Angeles) fresh oil change, fresh air filter, all smog components functional and hooked up correctly. CAT is a magnaflow that's about 12 years old, now, and I've been using high zinc engine oil.
The only thing different is the HIC valve which was non-functional and unobtanium so I added an aftermarket Isuzu valve. That valve is surprisingly important as it bleeds air into the PCV system to lean out A/F when engine or ambient temps are hot (like now).
The slight retard on the timing (in Kalif allowable to be +/- 2* from stock) makes a big difference.
My man with the intel here.... I got a couple questions though.
What's the Isuzu valve replacement for the HIC?
And what's the purpose of the HIC leaning out the mixture via the PCV valve? I assume the porting into the PCV system is out of convenience - Toyota could have picked any opening to the carb or intake manifold. I'm moreso asking what the intention is behind leaning out the mixture. I installed an A:F gauge in my current and former 60, both fully smogged, and they both run very very lean between 20% and 90% throttle, so most of the time you spend cruising at a steady speed. Granted I'm at 5200' where there's less oxygen in the air. My understanding is that mixtures leaner than stoich will be hotter, at least in a localized sense, so I'm confused why this leans the mixture out when ambient temps are hot. The 2F system also has other circuits that lean the mixture out at different times and under different conditions: the AI and secondary slow cut for example. I can't figure out why the engineers wanted the mixture SO lean - or if it's simply altitude and the HIC spark advance isn't enough to make a difference. At highway cruise I run around 16.5-18 on the A:F, and sometimes it pegs lean at 18.5. That's two trucks, both with rebuilt carbs (from different people), all smog gear verified working good manifold and other gaskets, etc, both running exactly the same way.
You mentioning this seems like another piece of the puzzle for me, hence my interest. I will say running so lean on the highway gets me 17-19mpg on flat open terrain, so that's nice!
- Thread starter
- #8
The valve info was posted in your other thread: HAI, HIC, and drawing hot air all the time ... just the way it is? - https://forum.ih8mud.com/threads/hai-hic-and-drawing-hot-air-all-the-time-just-the-way-it-is.1264019/page-2
The valve bleeds filtered air thru the 'T' that's just above the PCV valve. All Carb'd engines have some form of HIC valve. Some Aisan carbs have that valve built into the carb. Most common are the old GM versions you can find on ebay, that are in the Air Cleaner housing. I chose the Isuzu one for no particular reason other than it seemed it would fit in the stock air cleaner without too much modification, and it seemed to function same as stock one.
Hot air is thinner than cold dense air, ergo, hot air richens the mix, so you have two A/F systems: One for elevation, one for relative temp.
At highway speeds, up around 17:1 mix is normal. Will spike to leaner when you let off the gas because of the deceleration circuit which closes the ICS momentarily to prevent backfire. That's that switch on the ABV/ASV cluster.
Heading out to work. Will respond more, later.
Cheers.
The valve bleeds filtered air thru the 'T' that's just above the PCV valve. All Carb'd engines have some form of HIC valve. Some Aisan carbs have that valve built into the carb. Most common are the old GM versions you can find on ebay, that are in the Air Cleaner housing. I chose the Isuzu one for no particular reason other than it seemed it would fit in the stock air cleaner without too much modification, and it seemed to function same as stock one.
Hot air is thinner than cold dense air, ergo, hot air richens the mix, so you have two A/F systems: One for elevation, one for relative temp.
At highway speeds, up around 17:1 mix is normal. Will spike to leaner when you let off the gas because of the deceleration circuit which closes the ICS momentarily to prevent backfire. That's that switch on the ABV/ASV cluster.
Heading out to work. Will respond more, later.
Cheers.
Hell that's probably cleaner than the ambient air in LA!
- Thread starter
- #10
Well, it's certainly cleaner than my conscience
