I HAVE A 92 CAMARO WITH A 305 TBI. CAN I ADVANCE THE TIMING A FEW DEGREES OR DOES THE PROM CONTROL THAT?

 

BF,

Yes, and yes.

The ECM and EST work together within the parameters set by the PROM to control ignition timing under varying conditions. However, the ECM only advances or retards the ignition timing from a "base" point determined by the installed position of the distributor. This is called the base timing setting.

To adjust base timing, loosen the distributor clamp bolt then just snug it into place. Start the engine and allow it to warm to operating temperature. Shut off the engine, connect your timing equipment, and disconnect the EST bypass connector located at the right rear side of the engine compartment along a tan/white wire.



Restart the engine and note the timing marks on the harmonic damper outer ring. Loosen the distributor clamp bolt and adjust the distributor to the desired timing. Snug the clamp bolt and recheck the setting. Once satisfied, shut off the engine, tighten the clamp bolt, and reconnect the EST bypass wire.

Your base timing is now whatever you set it at, and the EST and ECM are free to adjust timing around that set point.

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Later,
Vader
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"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

Yes you can advance the timing. Get a timing light, loosen the distributer hold down and turn until desired advance is achieved

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My 1986 Z28
GM350, T-5, 3.23's, lots of go fast goodies, 4th gen Firebird interior etc...
85 IROC w/ 1364 miles!

You'll always find what you've lost in the last place you look

R.I.P Dale Earnhardt

 

No no no Zup! That's NOT the way to set timing on a computer controlled car.

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

 

I just want to add on that pretty picture of Vaders that wiring loom looks new and possibly in the wrong location. My connector would be on the lower left corner of that pic in front of the blower fan. Of course my car is old and the harnes probably just fell off the firewall

 

Vader, what do you recommend for a base timing mark? I would like to bump it up maybe 4-8 degrees just to crisp up the throttle response. Is that enough? It was on my 70 1/2 Z-28 but that was 30 years ago.

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'92 firebird t-tops
305tbi,670cfm tbi, 2 1/2" Dynomax catback, 9x3 K&N open element

 

6 degrees is stock on TPI systems, so 8 wouldn't do much damage. Play around with it until you get the best results.

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

 

if his base timing is 8 degrees, and he bumped it 4-8 more, that would bring him to 12-16 degrees of advance. And by the way, that would be perfectly fine. You will know when you go alittle to far when your engine starts knockin....

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thanks for the help. I'm doing it tomorrow.

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'92 firebird t-tops
305tbi,670cfm tbi, 2 1/2" Dynomax catback, 9x3 K&N open element

 

Quote:

<font face="Verdana, Arial" size="2">No no no Zup! That's NOT the way to set timing on a computer controlled car.</font>

ahh yes computer control, I remember when I had that..... and im glad its gone....

------------------
My 1986 Z28
GM350, T-5, 3.23's, lots of go fast goodies, 4th gen Firebird interior etc...
85 IROC w/ 1364 miles!

You'll always find what you've lost in the last place you look

R.I.P Dale Earnhardt

[This message has been edited by zupmanZ28 (edited June 09, 2001).]