Denver carb tune - Alfa Romeo Bulletin Board & Forums
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post #1 of 5 (permalink) Old 06-06-2019, 11:23 AM Thread Starter
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Denver carb tune

Does anyone here have a recommendation for a good Weber tuning shop in the Denver CO metro area? I moved to Denver about 18 months ago from NH (at roughly sea level), and I probably ought to get the Weber 40 DCOEs on my '74 GTV rejetted for the 5300 ft altitude here. Car runs OK now but is rich I think, so could probably be better set up. If nobody has shop recommendations, I could probably tackle this myself if needed. I've never been inside the Webers before but I'm handy and as a bicycle mechanic am used to small and fragile parts. Thanks for any tips!
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post #2 of 5 (permalink) Old 06-06-2019, 07:03 PM
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There is about a 10% decrease in power due to the decrease in air pressure. So try reducing your main jet by 10 %. So if you have a 120 main jet try a 110 or maybe a 105 main jet
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post #3 of 5 (permalink) Old 06-06-2019, 07:44 PM
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Originally Posted by JeffM View Post
Does anyone here have a recommendation for a good Weber tuning shop in the Denver CO metro area? I moved to Denver about 18 months ago from NH (at roughly sea level), and I probably ought to get the Weber 40 DCOEs on my '74 GTV rejetted for the 5300 ft altitude here. Car runs OK now but is rich I think, so could probably be better set up. If nobody has shop recommendations, I could probably tackle this myself if needed. I've never been inside the Webers before but I'm handy and as a bicycle mechanic am used to small and fragile parts. Thanks for any tips!
Go see Greg at Ignite Performance in Arvada. He can give you a good, dyno-based performance tune: Ignite Performance-preserving historic race and street cars.

Years ago, we could tell you EXACTLY what to change with your jetting to transition from sea level to our altitude. However with the newer Ethanol gas blends we find thing tend to burn a lot leaner than they used to and all our carefully prepared advice is no longer accurate - our high altitude jetting would have you running leaner than optimum. So you need to tune with a dyno or a wideband o2 sensor.
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post #4 of 5 (permalink) Old 06-07-2019, 05:16 AM
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I've had nothing but trouble using the new blends of fuel in my vintage cars. Found a source of 90 octane gas without ethanol and use that in my classics. Check and find out if there is a source of non-ethanol gas in your area.
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post #5 of 5 (permalink) Old 06-16-2019, 10:00 AM Thread Starter
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Thanks, Joe - thought I might hear from someone at C’line. I’ll give Ignite a call about scheduling a tune, they’re relatively convenient to me.
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