# 66 Gto



## POOF (Jan 16, 2007)

I know you guys can help. I need the timing on A 66 with the 389 tripower auto engine code YS. thanks Herb.:seeya:


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## Rukee (Feb 8, 2007)

You basicly want as much timing as possable without pinging (up to 36*). Old school would be to tach the motor up to about 2500rpm, and with an adjustable timing light set to 36* adjust the distributer to zero out the timing mark on the crank. Then just let the timing at an idle be were ever it wants. Test drive and if you have any pinging, back the timing off till it just stops, then an additional 3* or so to give you a safe zone. If it starts hard, or rolls over hard, you may have to back it off a few more degrees.


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## geeteeohguy (Feb 2, 2008)

The specs are 6 degrees BTDC with the vacuum hose disconnected and plugged while setting the timing. That is for base timing, and it is set at idle speed. The hose gets re-connected when you're done. Now, this will work fine if you're running 98-100 octane fuel. Not se well with 92 octane. What Rukee says above is a better way to set timing on today's poor fuels. Or, you could set base at 6, see if it pings, and if it does, retard it about 2 degrees at a time. My guess is that you'll probably be at 2 degrees BTDC or 0 TDC with a little less "oomph", but remember, you DO NOT want to run a piniging engine..you will damage it!


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## POOF (Jan 16, 2007)

Ok, thanks. geeteeohguy, I did the way you said plugg hose at the distributor and with A timing light. it wasnt hitting the marker. Actually its way left of it thats why I was asking. Timing was this way when I got it. No pins though, At first engine runs fast seems because of the cold weather. Then sounds normal. I just want to make sure it was timed correctly. So Rukee is that what you meant let the timing set where it wants? Its not even hitting the marker? Im working on get the tach right on it it flutters a little bit, any help on that? A bad connection? Thanks for taking the time to help me.


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## Too Many Projects (Nov 15, 2008)

Which side of the marker is it off; advance or retard ??
You don't want your car to be retarded....


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## Rukee (Feb 8, 2007)

Yes, that's what I meant. As long as your not over 36* total when revving, and it starts good, I would leave it alone. And if it's retarded, it sounds retarded, no throttle response, low power, sounds like it's lagging at an idle.


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## POOF (Jan 16, 2007)

Its advanced, just seems to be running fast. Does anyone have A idea about the Tach? it flutters a little ... is that a bad connection? Im A little retarded on this.


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## Rukee (Feb 8, 2007)

The original tach is 44 yrs old, it may need to be rebuilt.
If you have a working aftermarket tach you could try to hook it up at the hood tach and see if it still fluctuates so you know if it's the original tach or the wiring to the tach.


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## Too Many Projects (Nov 15, 2008)

If it's still running points, it's probably the tach. If it has an electronic conversion ignition, it may need a filter.
Does the timing drop down to 6-8 with the hose off the vacuum advance ?


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## POOF (Jan 16, 2007)

Im using A Sunpro3 tach. Im not even sure if the timing is dropping after I plugged the hose because timing mark is advanced of the marker. I do have the MSD 5 electronic system in it. Any idea?


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## geeteeohguy (Feb 2, 2008)

At idle speed, vacuum line disconnected, the timing mark on the pulley should be lined up with the pointer on the timing cover. The 6 degree mark on the pulley is the left one, facing the engine. If you have an adjustable timing light, you should be able to turn the knob 6 degrees, and have the mark now line up on the first line (TDC). If it's "too fast" your timing could be too far advanced, or your idle speed could be too high. Proper base timing will give you 18-20 inches of vacuum at about 700rpm.


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## likethat (Oct 5, 2007)

I know this is old but if it is way out on the timing marks. It could be off 1 tooth on the distributor. I have had to pull a couple and re-clock them for friends that got in over there heads. Well even I have missed it before when reinstalling one.


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