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Old 11-21-2006, 01:04 AM
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Tuning SBC?

Hey guys. What is the order in wich you tune your car? I have a 350 engine, 350 trans (auto), and a holley 600 Vac. Sec. carb.(1850) in a 63 Nova.
Now, should all the tuning be done while the car is in drive? I am experiancing a little trouble. When the engine is in park it revs fine, but when I put it in drive the engine stalls and dies.
In wich order should I go about tuning the car?
1) Timing with the advance plugged. Then, timed. Then, connect the advance back to the carb.
2) Set idle speed
3) adjust mixture screws
4) re-adjust idle speed
Is this correct? And should this be done in Park or Drive? Thanks in advance, SS.

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Old 11-21-2006, 03:13 AM
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Quote:
Originally Posted by SuperSport
Hey guys. What is the order in wich you tune your car? I have a 350 engine, 350 trans (auto), and a holley 600 Vac. Sec. carb.(1850) in a 63 Nova.
Now, should all the tuning be done while the car is in drive? I am experiancing a little trouble. When the engine is in park it revs fine, but when I put it in drive the engine stalls and dies.
In wich order should I go about tuning the car?
1) Timing with the advance plugged. Then, timed. Then, connect the advance back to the carb.
2) Set idle speed
3) adjust mixture screws
4) re-adjust idle speed
Is this correct? And should this be done in Park or Drive? Thanks in advance, SS.

Doc here,

Never attempt any adjustments in DRIVE.

Generically speaking, Start the engine, let it warm, FULL open Choke, Set your CURB IDLE for 650 RPM for automatic, 950 RPM for manual, set the timing static, at about 12 BTDC, (whatever is recommended for your application) with the advance line disconnected and plugged.

Recheck the RPM, adjust if required..then apply your advance and set your total timing..Stock good is 36-38 degrees..Recheck the IDLE..and adjust if required.

Next , adjust the mixture screws, SLOWLY , turn them in small increments until you have the highest idle, THEN small movements, adjust them going forth and back, after EACH turn, let the engine normalize, (burn off excess Fuel) , may take up to 30 seconds, This is KEY to a good mixture. You are going for the highest idle, with no random "Pops" or stumble ..when you think your done, go to the back, What do you smell? It should be NOTHING if you did it right. TAKE your time to do this right! if you don't allow "burn time" between adjustments, you'll tune right through the "sweet spot".

Check the Idle,If it changed, It won't be by much, readjust as needed.

NEXT check the idle in drive, it should fall from 950 to 650 and hold.

IF your still experiencing stalling, get out a vacuum gauge , hook to any manifold source, and monitor, 17 to 21 In Hg is good, low vacuum could be leaks , or hoses that have fallen off, to valve train issues..Check the Vacuum modulator hose at the transmission for a broken line and all other vacuum sources.

That should fix or lead you to the problem.

Doc
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Old 11-25-2006, 02:02 AM
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Umm.. yeah, not too fond of the highest RPM method as its almost impossible to do by yourself. Best way to adjust your mixture is with a wide-band air/fuel gauge...Next best, hook up a vacuum gauge to your carb, back the mixture screws just about all the way out and then turn them back in until they are barely touching the springs...then turn them both a half turn at a time to try and keep them even. Watch your vaccum gauge and shoot for the setting with the highest vacuum reading and adjust your idle accordingly. I have used both methods and the vacuum gauge works pretty good, its not perfect, but darn close when taking a reading from a wide-band. I adjust my carb mixture screws with it fully warm and in drive to get it as close to 14.7afr as possible since it idles in gear most of the time... If your going to do this, be smart about it and use some common sense.

Hope this helps.
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Old 11-26-2006, 10:29 AM
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Thanks guys.
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