I have heard that advancing the base timing from 0* to 6* will increase perfomance on a TBI 305 with a better flowing air intake system and exhaust work. How is this so? I would think that retarding the base timing would help performance while advancing it would adversely affect it. Am I right or am I just an idiot?

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Never trust anything that bleeds extensively for about one week out of the month, every month, and doesn't die...

91 Camaro RS
305 TBI w/700R4
14X3 Open element w/ K&N, all Ultimate TBI mods, Accel cap and rotor and coil, Taylor Spiro Pro wires, Accel Plugs,Hypertech Thermomaster Chip, 160* stat, 170* fanswitch, Edelbrock Elite Series Air Cleaner and valve covers, Dynomax Cat-Back, gutted cat, Centerline polished rims with 255/50 BFG Comp TA's all around.
On the way... Hooker Super Comp Shorty Headers and FRESH PAINT!

 

a slow burning air/fuel ratio (rich) with gasoline, or an inefficient combustion will require more timing advance to produce maximum power output.

yes you can sometimes make more power by advancing your timing higher than the stock setting.

 

Yes, it does work.

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Looking For:

87 IROC-Z28 350 TPI: The car I want.

84 TRANS AM 305 H.O.: Another car that would be OK to own while I look for the IROC-Z!!

 

What your car's set for from the factory isn't always for the most power, but rather, usually for the best mix of power, fuel efficiency, and lowest emmisions.

Retarding your timing means that you're putting your timing after top dead center, or.. You're having the spark plugs fire afterthe piston is at the top of it's travel, already on it's way down. This may make the car really easy to start, but it wastes gas, because by the time the gas is done burning the piston is ready to come back up again.

Advancing it means you're putting it more towards the before top dead center area, or you're firing the sparkplugs while the piston is traveling up. This makes it harder to start, as it's almost trying to force the piston back down.

However... If you can find just the right amount of timing, usually before topdead center, you can get the most power from the gas. This is because if you get it just right, the fuel will have fully combusted at just the right moment, right as the piston's near the top of it's travel.. That way it can "push" the hardest and give you the most power.

Every engine is different though, so you just have to play around with your timing to find the right settings. There won't be a huge different in performance, unless your timing is wayyyyyyyyyyyyyyy off, like mine was when I first got my car.

Anyways, I hoped this helped, although I must admit I'm a bit intoxicated right now so if I didn't make any sense I'm sorry.

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

Twigg,

Advancing the timing can increase power output, efficiency, and reduce emissions. But like anything, too much of a good thing can be a bad thing. Advancing the base timing too far can cause the ESC and ECM to detect detonation and retard the timing father than it normally would, possibly resulting in a net LOSS in performance.

The factory timing marks should only be used as a reference, since they can actually be way off the true crankshaft positions.

My TA runs very well at 11-12° BTDC, while the factory setting is supposed to be 6°BTDC. I always use higher octane fuel with slower-burning alcohol additives, so your numbers may be different. The key is to advance the timing a little at a couple of degrees and drive it for a while, then increment again if there are no problems. I would advocate advancing the timing in these small increments until you notice a decrease in fuel mileage and/or performance, then back it off to the last point of good performance.

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Later,
Vader
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"I'm'a do Things My Way - It's My way or the Highway."
Adobe Acrobat Reader

 

Yeah I agree with Vader. I did the same thing and I'm not putting it to the stock setting again. It is faster, but I have to use higher octane gas.

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Looking For:

87 IROC-Z28 350 TPI: The car I want.

84 TRANS AM 305 H.O.: Another car that would be OK to own while I look for the IROC-Z!!

[This message has been edited by IROCZTWENTYGR8 (edited March 23, 2001).]

 

you can always unplug the knock sensor.

 

I noticed when i was playing with time, there was a point (too far adv.) i hit where the 1-2 shift bogged. I got a scan tool and saw the knock counts so backed it off until it stopped. Runs great now, but the sh** still happens when I run cheap gas.

I never looked at those timing marks and never will. Knock counts is true (unless something else......)