V6 Tuning (timing, vacuum)

blk7gxn

Royal Smart Person
Feb 7, 2019
1,378
113
No problem! Short story: I didn't plan on doing much engine work myself - I have no garage & limited tools. For work that needed done, my plan A fell through (an acquaintance that could do anything I needed, then sketched out when I asked him to) and my plan B fell through (a local hot rod garage that sat on my car for 2 weeks & BS'ed me about it until I went & picked it up). Plan C was a local, highly recommended old car mechanic but he's booked for a year. So I ended up just doing everything myself. It took lots of help & research but I'm pretty happy with how things have turned out so far. With enough time, research & help I could probably get this thing 'finish' tuned & daily drivable but I'd rather have it done by somebody who knows what they're doing. Last night I happened across a mechanic with a small garage only a mile away from me, and I feel good about having him finish this. So fingers crossed, that'll happen next week.

Thanks for the help - much appreciated & even if I don't do this myself, it's good to know what's what.
Your very welcome!! My pleasure, and glad you found a garage close that's willing to help, its always a nice backup. Please keep me posted, id love to know how it turns out, have a great day!

Will
 

brrian

Greasemonkey
Thread starter
Jul 7, 2022
103
28
Pittsburgh, PA
Not there yet... met the new mechanic; good guy & I think I'll use him for my other cars but he's not familiar enough with this old of a car to help. He was honest & cool about it & knows somebody that he thinks can help, & he's going to hook me up with him. But while we checked stuff out, I found a set of disconnected vacuum lines tucked down in the back of the motor. See the pic below. There's a 4-way tee... one line goes to the reservoir ball, one to the cruse control transducer, and the other two are short & disconnected. Does anybody know where these go?

*edit*: there was a hose incorrectly routed directly from a port on the back of the carb to the thermac sensor. I removed that, and one end of this went to the thermac sensor & the other end to the carb port.

1664321598162.jpeg
 
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blk7gxn

Royal Smart Person
Feb 7, 2019
1,378
113
I know your grand Prix is an 81, all I could find quickly was an 1983 GP diagram, Ill post this up in case it may turn out useful until I can dig in my manuals to find your exact 81

1664334153285.png
 

brrian

Greasemonkey
Thread starter
Jul 7, 2022
103
28
Pittsburgh, PA
My diagram is below. See the top image... the line I highlighted green is what I installed when I put everything back together. I put a new line there because I thought it was missing. In reality it should've been as in the second image below... that line is teed with additional runs to the reservoir ball and cruise transducer. I'm not sure why those aren't shown on this diagram, except that cruise is an option?

Also: with the EST connector disconnected from the distributor, the car won't start. I didn't put much thought into it when we were diagnosing, but after reading tonight I think that's a problem... it should run? So, something else to troubleshoot?

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1664331101002.png
 

blk7gxn

Royal Smart Person
Feb 7, 2019
1,378
113
My diagram is below. See the top image... the line I highlighted green is what I installed when I put everything back together. I put a new line there because I thought it was missing. In reality it should've been as in the second image below... that line is teed with additional runs to the reservoir ball and cruise transducer. I'm not sure why those aren't shown on this diagram, except that cruise is an option?

Also: with the EST connector disconnected from the distributor, the car won't start. I didn't put much thought into it when we were diagnosing, but after reading tonight I think that's a problem... it should run? So, something else to troubleshoot?

View attachment 207808

View attachment 207809
That would be correct! Cruise was an option, not sure why GM wouldn't have had a label containing this option, must have been another cost saving move from corporate at the time.
 

brrian

Greasemonkey
Thread starter
Jul 7, 2022
103
28
Pittsburgh, PA
With EST disconnected, the car won't start. I replaced the ignition module and coil and it still won't start. I thought it might be because it's too far out of base timing, or that it's not getting spark. If I turn the engine over with EST disconnected, the timing light won't flash, so It's not getting spark (right?). Where to go from here? Getting frustrated...
 

blk7gxn

Royal Smart Person
Feb 7, 2019
1,378
113
With EST disconnected, the car won't start. I replaced the ignition module and coil and it still won't start. I thought it might be because it's too far out of base timing, or that it's not getting spark. If I turn the engine over with EST disconnected, the timing light won't flash, so It's not getting spark (right?). Where to go from here? Getting frustrated...
Question, did you put an aftermarket ignition control module on your car? Why I ask is this, sometimes aftermarkets will do exactly what your describing. Its always best to go with ac/Delco parts with anything to do with ignition.
 

blk7gxn

Royal Smart Person
Feb 7, 2019
1,378
113
.....But if not, it sounds like to me, your timing is TOO far retarded, try advancing it 1/4 " at a time until it starts, then time in correctly from there using the procedure we talked about in previous conversations, good luck!!
 

brrian

Greasemonkey
Thread starter
Jul 7, 2022
103
28
Pittsburgh, PA
It's not ACDelco - it's "Standard Ignition" brand. The one I took out was the same brand. I'll try an ACDelco module.
& even if timing is too far retarded, I should still have spark, right? Timing being way off wouldn't affect spark?
By the way, I'm on my 5th attempt to find an old school mechanic. I have a lead on another local place & if I can get them to take me I'll turn this all over to them.
 

blk7gxn

Royal Smart Person
Feb 7, 2019
1,378
113
It's not ACDelco - it's "Standard Ignition" brand. The one I took out was the same brand. I'll try an ACDelco module.
& even if timing is too far retarded, I should still have spark, right? Timing being way off wouldn't affect spark?
By the way, I'm on my 5th attempt to find an old school mechanic. I have a lead on another local place & if I can get them to take me I'll turn this all over to them.
I wish I lived close to you, id help you! i'm going to send you a PM
 

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