I suppose I knew that academically at least -- I did read that so much fuel condenses onto the manifold at -40 degrees that the computer commands for enough fuel for a 2:1 (yes *2* to 1!) mixture at the throttle body.Perhaps what caddyman was meaning is that if you stick the sniffer of the two gas infrared machine that we used in 1980 into the tailpipe of a 2010 you will be hard pressed to see the needles move. Now if you sniff a modern car with a 5 gas analyzer you could get (I say could as all my sniffing was done in the early 2 gas years) readings that are of value. This 5 gas machine would go beserk if stuck in the tailpipe of a 1980 vehicle, unless the correct scale was selected.
The two gas machines had a gross and a fine scale and I bet the fine scale could not detect a car of today.
My parents moved here in 1966, Costa Mesa, CAā¦30km from Saddleback mountain. It was 8 months before they even knew there were mountains visible 18 miles away! Im trying to get a 83 Mazda B2000 to pass cali smog here and it is tough as all the emissions parts are N/A to replace and the referee refuses to issue a waiver for parts not available. He told me look on Ebay! After 6 years of collectiing NOS and good used smog parts and finding a NOS carb still in the box, my little truck passed with flying colors, even with the original cat! Granted it was a FED registered truck and was tested to a lower emissions standard, it still surpassed the Cali specs. 84 model had 2x the vacuum hoses and vacuum solenoids, yikes! EFI came right on its heels.
I moved to Pasadena in 1971. We couldnāt see the San Gabriel mountains, 10 miles away, a mile higher, many days. I remember my eyes watering and noticing the drop in visibility down the street. Motorcycle messengers in the '50s wore gas masks.
The 28 Chevy probably had a 4:1 compression ratio. That easily explains the low emissions. But it probably topped at 60 if that. No one would buy a truck with that performance today.
The 390 59 Ford truck probably was 7:1 maybe 8. Harder to explain but using ppm (parts per million) like your shop class did is not particularly reliable. It was not under load. Thatās where the bad stuff happens.
All emissions regs are measured in grams per mile under varying loads and acceleration and deceleration which is when emissions actually occur but that requires a sophisticated lab and dyno rollers to test. A simple tailpipe sniffer will āoutā a really bad car but any reasonably tuned car will likely pass.
Iāve had cars pass a sniffer without a catalyst but it would never pass an EPA lab.
Why are you repliing to someone who has not posted here in 15 years ?
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Why not? Interesting conversation.