HELP V6 Tuning (timing, vacuum)

brrian

Apprentice
Jul 7, 2022
87
18
Pittsburgh, PA
After doing work on the top of my 3.8L V6 (all this), I'm attempting to tune my motor. I checked timing & it was at about 10 degrees; factory is 15 degrees, and I now have it at about that, probably within a degree (& I'll fine tune it if I need to).

I checked vacuum next, at the brake booster line (without the check valve). It's a little low, as seen below & as shown in this video: Vacuum

The gauge suggests late timing. Should I go back & adjust timing further using vacuum as an indicator, or look elsewhere first?





1663867484052.jpeg
 

blk7gxn

Royal Smart Person
Feb 7, 2019
1,369
113
I personally would not "compensate" timing to make up for the loss of vacuum....QUESTION?? Did you time the engine with the vacuum advance off the distributor? Depending on year you may have the electronic one, and I believe you need to unplug the connector to the distributor when setting the base timing as well. If you did all this and still have low vacuum, I always checked for vacuum leaks by LIGHTLY spraying ether around the intake gasket and vacuum lines to pinpoint the location of any leaks, if any. Good luck and keep us posted!!!

William
 

brrian

Apprentice
Thread starter
Jul 7, 2022
87
18
Pittsburgh, PA
Vacuum advance: if non-electronic, would there be a vacuum line to the distributor, usually to the little acorn-shaped thing on the side? There isn't any of that. The timing instructions in the service manual don't specify to disconnect anything so I didn't.

I have a smoke tester & plan to use that to check for leaks. I'll do that tonight then recheck vacuum.
 

blk7gxn

Royal Smart Person
Feb 7, 2019
1,369
113
Vacuum advance: if non-electronic, would there be a vacuum line to the distributor, usually to the little acorn-shaped thing on the side? There isn't any of that. The timing instructions in the service manual don't specify to disconnect anything so I didn't.

I have a smoke tester & plan to use that to check for leaks. I'll do that tonight then recheck vacuum.
Yes there should be a vacuum line to that advance unit for sure, and when timing, you unplug the vacuum line from it, time it, and then reinstall the vacuum line to it.

So at this point in time, find out where the line is and where it should come from, reinstall it, and then do the procedure I have stated. Sounds to me like perhaps the source for this vacuum line has been caped off? And in order to get a proper timing, this line has to be functional and THEN removed from that advance, so its "sucking air" when you time your engine, then once you get your proper timing, reinstall the line and it advances to where it should be on its own, nothing else needed to be done.
 
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brrian

Apprentice
Thread starter
Jul 7, 2022
87
18
Pittsburgh, PA
Yes there should be a vacuum line to that advance unit for sure, and when timing, you unplug the vacuum line from it, time it, and then reinstall the vacuum line to it.

So at this point in time, find out where the line is and where it should come from, reinstall it, and then do the procedure I have stated. Sounds to me like perhaps the source for this vacuum line has been caped off? And in order to get a proper timing, this line has to be functional and THEN removed from that advance, so its "sucking air" when you time your engine, then once you get your proper timing, reinstall the line and it advances to where it should be on its own, nothing else needed to be done.
I probably didn't word that well... I meant that I don't have any place to hook vacuum into the distributor.. I don't have that little acorn shaped thing, so I don't think I have vacuum advance.

And I just tried smoke testing & it's useless because I can't get a good seal on the carb & all the smoke is coming out of there.
 

blk7gxn

Royal Smart Person
Feb 7, 2019
1,369
113
I probably didn't word that well... I meant that I don't have any place to hook vacuum into the distributor.. I don't have that little acorn shaped thing, so I don't think I have vacuum advance.

And I just tried smoke testing & it's useless because I can't get a good seal on the carb & all the smoke is coming out of there.
no problem, so you have the electronic distributor then? if so, you unplug the large black plug on the side of it, its behind the one wire plug, and do your timing procedure, and then reinstall the plug..........and are you talking about the base seal to the carb?
 

brrian

Apprentice
Thread starter
Jul 7, 2022
87
18
Pittsburgh, PA
no problem, so you have the electronic distributor then? if so, you unplug the large black plug on the side of it, its behind the one wire plug, and do your timing procedure, and then reinstall the plug..........and are you talking about the base seal to the carb?

The one circled below, right?

& not the base of the carb - the top. (2nd image below).

1663875664927.png


1663875804091.png
 
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brrian

Apprentice
Thread starter
Jul 7, 2022
87
18
Pittsburgh, PA
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.
 
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