Questions about timing for 305 LG4
02-25-2006, 07:56 PM
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Car: 1983 Trans Am t-top
Engine: 305 4bbl carb (vin code H)
Transmission: 4 speed automatic
Questions about timing for 305 LG4
I have been reading a lot of posts about timing and have a few questions.
1, the VECI label says 6* @ 500 RPM, how do i get 500 RPM, my car idles at about 700 - 800 RPM when warm? or do i ignore the RPM. or does the RPM go down when i disconnect the 4 wire EST.
2, my car is a 83 T/A 305 LG4. only mods are good plugs/leads etc, new ignition control module in the dist. and a hypertech thermomaster chip i will install after the tune-up. how much advance could i use, is 10* ok? i use 95 octane.
3, is it true that i can keep advanceing it until it pings, the retard it 2* inorder to get maximum performance?
oh and how much HP/torque will this give me and how will it affect fuel economy?
Thank You very much.
1, the VECI label says 6* @ 500 RPM, how do i get 500 RPM, my car idles at about 700 - 800 RPM when warm? or do i ignore the RPM. or does the RPM go down when i disconnect the 4 wire EST.
2, my car is a 83 T/A 305 LG4. only mods are good plugs/leads etc, new ignition control module in the dist. and a hypertech thermomaster chip i will install after the tune-up. how much advance could i use, is 10* ok? i use 95 octane.
3, is it true that i can keep advanceing it until it pings, the retard it 2* inorder to get maximum performance?
oh and how much HP/torque will this give me and how will it affect fuel economy?
Thank You very much.
02-25-2006, 08:27 PM
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1) RPM should drop a little with EST unplugged. You can time your car slighly above and below this RPM with relative accuracy.
2) Advancing timing past 6* can help in power down low, but often at a sacrifice of power up top. You could probably get away with advancing it up to 10* without your Knock Sensor pulling timing and slowing you down, but unless testing on a dyno, the results would be hard to quantify. I suppose track testing could give you some idea if there was a gain etc...
From what I've seen, advancing timing will usually have a negative, but not drastic effect on MPG.
2) Advancing timing past 6* can help in power down low, but often at a sacrifice of power up top. You could probably get away with advancing it up to 10* without your Knock Sensor pulling timing and slowing you down, but unless testing on a dyno, the results would be hard to quantify. I suppose track testing could give you some idea if there was a gain etc...
From what I've seen, advancing timing will usually have a negative, but not drastic effect on MPG.
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