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Registered
Join Date: Nov 2001
Location: Birmingham, MI
Posts: 55
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Weber tuning - Can a relative novice do it right?
I am wondering what the best manual for tuning weber 40 IDA 3Cs.
I have an Intermeccanica Speedster with a 2.7 RS - trimmed as a Carrera. It's a blast. It will be featured in the October Excellence. The idle circuit is not right. Running rich at idle and the idle is too slow. The car has driveability issues when driven at 2000-3000 for an extended period. Seems like it loads up. I have Haynes Carb manual. Are there others that are good? Is this something that I will never get right and need a pro? Or can I do it well assuming that I have the right tools and follow the manual? Baseline - I am not an idiot (however I am an EE not ME), can do valve adjustment and other minor work. 
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05-29-2003, 12:58 PM
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Registered
Join Date: Nov 2001
Location: Birmingham, MI
Posts: 55
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Thanks
Thanks for your help. I will buy the tools and give it a go.
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05-31-2003, 05:37 AM
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Senior Member
Join Date: Jun 2000
Location: N. Phoenix AZ USA
Posts: 28,943
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Experience sure helps! I still remember how sore my knees were after hours trying to get mine right. Start at the beginning and work through them. Keep clean gas going in and they should stay in tune!
Joe
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2013 Jag XF, 2002 Dodge Ram 2500 Cummins (the workhorse), 1992 Jaguar XJ S-3 V-12 VDP (one of only 100 examples made), 1969 Jaguar XJ (been in the family since new), 1985 911 Targa backdated to 1973 RS specs with a 3.6 shoehorned in the back, 1959 Austin Healey Sprite (former SCCA H-Prod), 1995 BMW R1100RSL, 1971 & '72 BMW R75/5 "Toaster," Ural Tourist w/sidecar, 1949 Aeronca Sedan / QB |
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05-31-2003, 05:43 AM
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Registered
Join Date: May 2001
Location: Peoples Republic of Long Beach, NY
Posts: 21,140
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Re: Weber tuning - Can a relative novice do it right?
Quote:
Bob Tomlinson's "Weber Tech Manual" Pat Braden "Weber Carburetors" by H.P. Books
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Ronin LB '77 911s 2.7 PMO E 8.5 SSI Monty MSD JPI w x6 |
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05-31-2003, 07:24 AM
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Registered
Join Date: Mar 2001
Location: Marysville Wa.
Posts: 22,431
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each carb bore is basically just a one barrel carb. they all need to flow the same amount of air and fuel. get a syncrometer for the air flow check, and the fuel mix is just a good ear when turning the mixture screws. the idle speed needs to be at least 1000 rpm to get a decent adjustment response. go to a quiet place, close your eyes, tune in on the sound of the engine, start any one screw turning clockwise, and when you hear the idle just starting to drop, or falter a bit, start turning it the other way until it gets to the point where it idles the fastest and smoothest without unscrewing it any more than necessary. then go on to the next screw. a few times around, readjusting all the screws is usually necessary, to bring it to the point where the slightest movement in or out will make it drop off a bit. the idle speed needs to be corrected back to 1000 as needed, while you are doing the adjustments. a 2.7RS will probably need .60 idle jets, so check them with a jet gauge to be sure, because any jet could have been resized, and still have it's original number on it. there's a real fine line between fouling plugs and not fouling them, and still having all the power you can get out of the engine. i assume that the compression is 8.5:1, and if you have performance cams, the engine demands more fuel to perform well. cold plugs will soot up on low compression engines like this, so hotter plugs help a lot to prevent fouling. NGK Iridiums in a 5 heat range should survive.
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https://www.instagram.com/johnwalker8704 8009 103rd pl ne Marysville Wa 98270 206 637 4071 Last edited by john walker's workshop; 05-31-2003 at 07:33 AM.. |
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05-31-2003, 07:26 AM
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