Tuning new setup
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Senior Member
Joined: Jul 2001
Posts: 616
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From: Langley, BC, Canada
Tuning new setup
I just installed my new engine and broke in the cam with no major problems. Trouble is now im not sure where to start to or how to tune it. Everything seems to be working properly no vaccum leaks, a get a pretty steady 15"s very tiny rapid fluctuation, maybe 1/4" up and down, carbs been rebuilt all new ignition
350 20 over
summit 1103 cam 214/224 duration
ported 76cc 1.94/1.5 heads
shorty headers
performer intake
non cc qjet
vaccum advane hei
Im familar with the vacuum gauge method of adjusting the idle mixture. I played with different timing the car seems to like 12-14+ initial, is this too high? if i set it lower i have to turn the idle screw in farther to maintain 800-900 rpms idle, but then the timing increases, mechanical advance im guessing?
I also tried adjusting the idle mixture to get the highest vacuum reading but it didnt seem to do anything, unless they were right closed, then the vaccum dropped to 9-10 and become unstable.
I havent driven it yet, the header melted my clutch line now i have no clutch.
Ive read many many posts, tech articles, how to's and i have 3 qjet books. someone point me in the right direction
btw
before and after pics
http://sneakweasel.freeservers.com/
i havent cleaned up any wiring yet, ran out of time.
350 20 over
summit 1103 cam 214/224 duration
ported 76cc 1.94/1.5 heads
shorty headers
performer intake
non cc qjet
vaccum advane hei
Im familar with the vacuum gauge method of adjusting the idle mixture. I played with different timing the car seems to like 12-14+ initial, is this too high? if i set it lower i have to turn the idle screw in farther to maintain 800-900 rpms idle, but then the timing increases, mechanical advance im guessing?
I also tried adjusting the idle mixture to get the highest vacuum reading but it didnt seem to do anything, unless they were right closed, then the vaccum dropped to 9-10 and become unstable.
I havent driven it yet, the header melted my clutch line now i have no clutch.
Ive read many many posts, tech articles, how to's and i have 3 qjet books. someone point me in the right direction
btw
before and after pics
http://sneakweasel.freeservers.com/
i havent cleaned up any wiring yet, ran out of time.
Joined: Mar 2000
Posts: 43,187
Likes: 43
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
That much initial timing isn't out of line. It would be nice to know the total timing (mechanical only, at the RPMs where it's all in), but not critical. You should set the initial timing with the vacuum line off the vacuum advance, even though there shouldn't be any vacuum on it at idle.
The idle mixture not having an effect could be from too much throttle blade opening. Might also explain your timing pick-up when you adjust the idle speed up. What you can do is adjust the idle speed down, adjust the idle mixture screws, then set the idle speed back up where it runs better.
Both the Doug Roe and Haynes "Rochester Carburetor" books are pretty good discussing the operating theory and adjustment procedures. Are they amoung the 3 you have?
The idle mixture not having an effect could be from too much throttle blade opening. Might also explain your timing pick-up when you adjust the idle speed up. What you can do is adjust the idle speed down, adjust the idle mixture screws, then set the idle speed back up where it runs better.
Both the Doug Roe and Haynes "Rochester Carburetor" books are pretty good discussing the operating theory and adjustment procedures. Are they amoung the 3 you have?
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