Hi out there,
I want to Check/adjust my base timing for my 305 Tpi Iroc with Auto Trans. My problem is that my Throttle Body Shaft is worn (so I've been told and has been adjusted to compensate for any slack in the shaft?). I have a brand new IAC valve fitted. I have checked the TPS switch for correct operation and it appears to be okay. I cannot seem to set the minimum idle as per the tech area article because when I ground A & B terminals and then start the engine (fully warmed up) it will not fire up at all. Before the new IAC valve was fitted the engine idled at 1750rpm. Now with the new IAC valve fitted and when fully warmed up the engine idles at 850rpm in park. So my question is - Will I be able to get an accurate timing check using my strobe light with the engine idling at 850rpm because I checked it and it was way off the pointer scale at maybe 20/22 BTDC. I did not disconnect the EST so maybe this is the cause? But I also couldn't figure which connector to take off (I can see a single brown wire on at the rear of the right valve cover (No 1 Spark Plug Side) connected to a round metal fitting when you look under the hood from the front of the car, is this the EST connector? Also how do I slacken the distributor bolt (Is it 9/16 or 14mm) because I cannot get a socket or spanner on it because of all the pipes and wires etc?
Sorry for the long message but any help gratefully received.

 

FInd the connectors to your distributor (the ones plugged into it) There should be a harness(3-4wires) running from the distributor along the firewall towards the pass side fender. Along that is the connector you want to unplug for checking timing. I believe it's a tan/black wire (w/o going out to look) & the connector is in fairly plain sight. I think (been awile since I've had the original hood) the stock timing should be around the 4-8° area. My bird (standard shift) seems most happy at 6°

My TB used to stick slightly open due to slack from being worn. I installed an extra pull spring to help it snap back shut instead of tapping the throttle to settle back down at every stop. If your car won't idle with the IAC fully closed & disconnected to set minimum air, your throttle blades are shut too much.

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Thanks for the info Deadbird - Will check all that out asap but is there a way of getting at the distributor adjustment bolt without a special tool, it seems very difficult to get a socket or key onto?

 

Autozone has the dist. wrench you need.

I have on that I used on a 72 Buick when I was a tenny bopper. THAT was 17 years ago!

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86 T/A 5.0 A4 & 2.77 gear
15.62 @ 86 mph
93 Civic 1.6L
13.5 @ 100 mph

 

Yeah that bolt is a PITA to get too but with patience you will get to it. Unplug the leads from distributor andmaybe a couple of vacum lines and you should be able to wiggle your way onto it. I just used a normal key.