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CA smog test
Just went to the BAR referee yesterday with my 1967 427 sideoiler. Non SB-100 and must pass 1967 smog standards for HC emissions. The 2500 rpm test with 218ppm measured, 600ppm allowed. However, the engine failed the idle test miserably with 2686ppm measured, 700ppm allowed. Any ideas how to get the emissions down at idle? Widen plug gaps, backoff initial timing, lean the carb. I need an expert mechanic in this area (Los Angeles/Orange County) to perform this miracle. This is my last hurdle to get a 2year green light to operate, and hopefully obtain a SB-100 number.
Thanks, Bill |
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That idle test is a real killer. I tried it with smaller carb, jetting, and yes known fuel adds, tuning, more tuning, and then some. I passed it with my last 282 cam in my last car - just barely, but anything with a more radical cam seems to put it on tilt for the idle test.
It was amazing to see how much modulation/difference there was at the 900rpm idle test as compared to the 2500 test. Short of swapping out the cam or backing off the rockers to a point where its risky, there were no other options for me to try. :( |
Using a PCV valve will lean you out... not likely 2000 ppm. I'd gap my plugs at .055 if you are using an MSD. Running a 195 thermostat will help and run Autolite 45 or hotter plugs. I'd even run platinums during the testing process.
If that fails I have a pair of 450 holleys ready to put on you can use for the test. They ran well under 350 ppm... What is your intake vacuum at idle??? If it's 5-6 or lower (common on 8V 427's) your power valves are likely open at idle. 600 cfm holley's use 8's for which 11" of vacuum is needed to keep them closed. If you are at or within 3 inches (if you engine idles at 8" of vacuum you want to use a pair of #5 power valves.) Hope this helps, |
I ran 4.0 power valves with 9" of vacuum and still did not pass with the 450 holley on the idle test. Once above 282 on the cam, the numbers are off the chart on the idle test.
I was able to get my last motor, exact same setup, to pass with the 282 cam, and a slightly smaller one before that. Once I tried it with the 295-300 duration cams - no dice! |
There's aways Jan. 2... I suggest getting there early. Another option is to run on alcohol... No Hc's...
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Thanks for the info, keep it coming. Probably will not tackle this problem until after April 15th.
Bill |
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