Computer Controlled HEI Base Timing

[CAChevy]

The CA emissions sticker (XFF) on my '84 w/original 305 says to set base timing @ 6 deg. That seems a bit low to me. I was thinking more along the lines of 10 deg.

I've swapped in a 350 keeping all the smog/computer controlled items. The cam I'm running is a Comp 12-235-2.

I'm curious what base timing you guys with the electronic HEI, CCC Quadrajet and ECM with O2 sensor are running?

[Malo83]

I'm running 8 deg. on my 83 with the stock 305, runs fine, did you disconnect the 4 pin wire off the distributor when you timed it?, you'll be surprised how many don't when they time the motor

[Just call me Sean]

Originally Posted by Malo83

I'm running 8 deg. on my 83 with the stock 305, runs fine, did you disconnect the 4 pin wire off the distributor when you timed it?, you'll be surprised how many don't when they time the motor

You don't disconnect the four pin plug to time it. You unplug the single wire plug which is tan with a black stripe, I don't remember the location offhand but I think it's by the main firewall plug.

[beamn7]

You do disconnect the 4 wire plug on a computer controlled, CA emissioned HEI distributor. The plug is a weatherpack connector, has approx a 6-8 inch lead from the distributor and is on the pass. side of the engine.
The Tan wire with the black tracer is a distributor on a TBI equipped truck with a non-integrated coil.

I run 8 deg also. Remember, here in CA you can go plus or minus 3 deg on the timing and still be legal for your smog inspection.

[CAChevy]

I found out pretty quick that I needed to unplug the distributor from the ECM when I first went to time it. You guys are correct, it is a 4 pin molex plug. I was seriously frustrated trying to adjust it with the computer trying to readjust it.

If I can get away with +/- 3 deg with the smog nazis I think I'll try 9 and see what happens.

Did you guys notice any difference changing it a few degrees BTDC?

[beamn7]

Hard for me to say if I noticed any difference as I up'd mine after building the 350 for it and yanking the tired 305 out. Malo might have better input as he has the 305 still too... One thing to keep in mind is the timing effects HC and NOX also. If your truck is border line out the tailpipe, upping it too much may fail it... Make sure your idle is set also to plus or minus 300 rpm from factory specs after adjusting the timing. I run about 650-700 vs stock of 550.
Seems like they keep tightening our limits out here... think they want our 'ol trucks off the road!

[Just call me Sean]

Them California cars get me every time.

[beamn7]

Originally Posted by Just call me Sean

Them California cars get me every time.

LOL, Tell me about it!

[Malo83]

Originally Posted by CAChevy

I found out pretty quick that I needed to unplug the distributor from the ECM when I first went to time it. You guys are correct, it is a 4 pin molex plug. I was seriously frustrated trying to adjust it with the computer trying to readjust it.

If I can get away with +/- 3 deg with the smog nazis I think I'll try 9 and see what happens.

Did you guys notice any difference changing it a few degrees BTDC?

No difference to me, truck ran the same, but like beamn7 said, changing the timing could affect the outcome of the smog test, I leave mine at 8 deg and the truck runs fine plus she hasn't failed a smog test yet