[corellian corvette]

Those are all fair points PontGuy - but since we don't know, and he doesn't know, the possibility of an over-advanced condition is much greater using stock GM parts.

Many/most non-performance GM motors were set with lower mechanical total advance, and more vacuum advance to prevent detonation at WOT, but should still give plenty of advance at mid-to-part throttle where there is good manifold vacuum.

Since Darth isn't a tuner per-se, and he did describe that his Freeway experience has the car "shaking" could be indicative of detonation or over-advanced condition.

So again I'll suggest putting the car back to 6 deg, with the stock springs and the stock vac advance canister. Tune the car from there. Part throttle should be fine, cruising should be fine. You should have 15-17 HG if vaccum at idle, smoothly. Car should not surge or stall.

If it does - the problem is not timing. Adding timing without understanding what's happening with the baseline motor or fuel situation could make it worse.

My guess however is that it has something to do with the timing gears as suggested previously, in which case you need to get to a professional. If the cam is out of phase you're gonna have a bad time. I'm not sure if you can re-establish the correct cam timing from outside the engine.

Put simply - if my engine isn't running smoothly with good vacuum at 6deg initial, then something is wrong. Adding timing just masks the problem.

Alternatively - just remove the vacuum advance for now. It's NOT necessary, and removing unnecessary parts will help narrow down the problem vs. compounding it. Plug the vacuum advance and take the car for a drive and see what happens.

[ra96]

OK i think im missing something here-I mean this in all due respect to Darth -what im missing is i know he doesnt have much experience with old pontiac's or any old 60's- or 70's engine set up and is not familiar with setting timing -carb adjustments- so how did he (you darth) ( i dont mean to be talking in 3rd person) install the petronix module- the gap has to be set and it wires up a bit differently than the dist did before-again in all due respect it might be or have been over zealous with his knowlage base to remove and re-intall the dist -or did he have someone else do it ? and if socould it possibly be set back in a bit off?
also sounds like there are a lot more gremlins than just the dist and timing-i couldnt find the lack of fuel thread so not sure if the whole fuel problem has been solved -and to agree somewhat with Corellian in a simpler way as i said in an ealier post if the car doesnt feel right from the seat of your pants do adjust timing adv -i didnt mention retart i should have this method while time consuming will work
again untill all the other problems are solved it wont run 100%

[PontGuy]

Glad you posted back CC, and you too make some fair points. So some good debate.

Remember that the title of this thread is "Lack of Power". From everything I have read it sounds like it is hitting on all 8, just not pulling. If that is correct, and all the vacuum lines have been sorted so there is no major vacuum leak, and the carb is OK, then it ought to go. Here is the lack of gas thread: http://forums.maxperformanceinc.com/...d.php?t=745946

Key one for me is your reference to "most non-performance Pontiac motors". I admit it has been a very long time since I've owned one of those, and you would not expect that an engine in a GTO would fall into that category, but got to admit that it is possible.

On the other hand we are assuming that he has 061 heads which are big valve, small chamber. And 4bbl manifold and carb. So the only piece that would make it low-performance is the cam. And my assumption has been that it has some sort of performance cam in it. I've run 061 heads with a few performance cams from mild to pretty wild and the best all-in was always around 34-36.

Assuming that it has some sort of good cam (even just a factory 068) it will need timing to develop good power when the throttle is opened fully, and setting the all-in timing back to 24 deg will make it lethargic. If the vacuum can gives it too much advance at part throttle that should be pretty obvious when road testing and then it just needs to be replaced. No problem testing with it disconnected. I would only do that if it showed up as a problem, but for someone not familiar with tuning maybe not a bad idea.

ra96, no doubt this would be a lot easier if one of us could spend a few hours in the garage with Darth to make sure the simple things are right. Unfortunately best we can do is internet advice.

[ra96]

Darth Im still wondering about who put the petronix in your distributor did you yourself or is that the way you bought the car? -
I ask because they wire up a little different than the stock dist -also plug gap should be a bit wider
and if the car came with it-- petronix make- many- modules perhaps its not the right one for a pontiac
Perhaps i missed it but what were your last results trying run the car?

[Darth Menace]

Yah, I think my lack of knowledge has started a debate. To make it worse I typed a reply and it didn't work because my cookies didn't match up. Go figure.

Anyway, to answer your question yes when I unplugged the vacuum advance the idle did slow down. I didn't check the timing before and after i unplugged it though.

Ya, I think it was decided in another thread that my carb is likely gummed up and needs an adjustment. I wont be able to do a highway drive for a while, but can take a cruise around. It won't take much for me to know if the car has improved since I first drove it. When it was a shakey slug

Originally Posted by PontGuy

I found your "lack of gas" thread.

One more thing before moving on. When you pull the vacuum hose from the vacuum advance (when checking timing) does timing jump back and the engine slow down? If so that's good. Just want to make sure that the vacuum diaphragm on the distributor is OK.

The vacuum gauge should be hooked up to any manifold vacuum source. Since you have the vacuum advance connected to the manifold you can tee it into this hose.

Regarding the engine quitting when you put the car in gear- if you have the PVC hooked up properly and there are no major vacuum leaks, timing is set properly, and it is firing on all cylinders then it sounds like a carb problem. Assuming that the Edelbrock has a big enough idle circuit for your cam (I have no experience with Edelbrock) then the idle speed and mixture screws probably just need some adjusting. Having the vacuum gage connected will help with this.

Yes the engine needs to be warmed up and the choke disengaged to get good vacuum readings and to make carb adjustments.

[Darth Menace]

Originally Posted by corellian corvette

Also what's your vacuum readings at idle? A vacuum tester will tell you a lot about how your engine is running.

I will be testing this the same time I adjust the carb. Sorry it looks like I don't have much time for the car, but work/family take up a lot of time. I work in front of a computer so it makes it an easy reply when I am free to. I do have a vacuum gauge and will get this done. Getting info on the internals of the motor is kind of fun in a sick and demented sort of way

[kyle_blake]

Hi

Just caught up on read:

Another quick test is to take the timing light wire connector piece[part that attaches to plug wire], remove it from #1 cylinder wire and try it on another wire(yes not to time engine) but to see if (when you press the timing gun button) that THE WIRE INDEED is getting a spark. (flashes)

So no need to point it at timing marks but as you go through doing that you may see a pulse of light change indicating something not firing right on a cylinder. Very quick way to see if you're firing on all 8. you can also test resistance of each wire to using a multimeter.

I would agree with other posters - disconnect vacuum advance !!! It offers very little gas mileage savings and is a fine tune item AFTER THE ENGINE RUNS GOOD.- plug the ports that were used by vac advance until we sort out what the heck is up with engine.

Lastly imo I would try and work around the 850 rpm mark until py helps sort it out.

- so hook up rpm gauge - raise idle to 850
- disconnect vac advance
- hook up vacuum gauge to a manifold vacuum port(not sure on what port that is on edelbrock) they are the base of lower part of the carb.
- Write down the value and let us know.
- Get timing light out and test each plug wire, press the timing gun button and check and see that it pulses on each wire.
- Put it back on #1 cylinder plug wire, check initial timing. you said 14 degrees ?
- you mentioned you have 32 total, did you put the dial to 32 on your dial gun and rev engine to 3000-3500 and see if it lines up with "ZERO" on the timing mark?

I know this isn't 100% accurate on my statements being absolute. meaning the distributor could add more past 3500 but who the heck wants to rev their engine in the driveway way the hell up in that rpm?

If it were me, I would put it at 36 degree total timing, meaning dial on 36, rev it up to 3000 and move distributor until white line is perfect on "0" on timing mark.

From there check initial which should be 18.

Turn down RPM to 850ish.

Then double check petronix install.

I think that's a good approach?

[Darth Menace]

Originally Posted by ra96

OK i think im missing something here-I mean this in all due respect to Darth -what im missing is i know he doesnt have much experience with old pontiac's or any old 60's- or 70's engine set up and is not familiar with setting timing -carb adjustments- so how did he (you darth) ( i dont mean to be talking in 3rd person) install the petronix module- the gap has to be set and it wires up a bit differently than the dist did before-again in all due respect it might be or have been over zealous with his knowlage base to remove and re-intall the dist -or did he have someone else do it ? and if socould it possibly be set back in a bit off?
also sounds like there are a lot more gremlins than just the dist and timing-i couldnt find the lack of fuel thread so not sure if the whole fuel problem has been solved -and to agree somewhat with Corellian in a simpler way as i said in an ealier post if the car doesnt feel right from the seat of your pants do adjust timing adv -i didnt mention retart i should have this method while time consuming will work
again untill all the other problems are solved it wont run 100%

The Pertronix was just installed about a month ago (there is a thread about that too haha) I did gap it as per the instructions, and it worked fine right off the hop (minus the first time when I had a wrong spark plug wire in the wrong place. Prior to taking the distributor off, I marked where everything was on the distributor and placed it back accordingly. I am thinking I did this correctly, but who knows...I guess everything is a gamble.

What makes me know this isn't a pertronix issue is the crap driving took place last September when I bought it. At that time there were the points in there, which I took out in February of this year.

[Darth Menace]

I will check all the wires with the timing light and get back to you. Hope it checks out well. I don't think the wires should be an issue as they are brand new. Spark plugs, wires, ignition, and coil are all brand new. Obviously parts can be crappy right out of the box, but all these have been replaced prior to the drivability issue from when I first did the 1.5 hour hideous drive with it.

As far as the 850 RPM, is this significantly too high for idle, or just right for a motor with kinks to be worked out? All I am doing is going by the write-up posted earlier that 625RPM is ideal, and 650+ is getting a touch high. By no means do I have a problem with it idling at 850, but just don't want to go around sounding like a helicopter is ready to take off.

Also, you had asked about the 32 total degrees and how I did it. I did the same process for the idle timing as well as the total timing. With both of them I set the dial to the appropriate number (14 while at idle and 32 while at all out), and when the dial was on those numbers, they showed at 0 on the timing mark.

I will take the car for a quick jaunt and see how it goes. Like I said it won't take long to see if there are vast improvements in the drive-ability of this thing or not. I will get these little things out of the way, try to get the carb adjusted as good as I can, and then take it out..now that the roads are clear.

In all honesty I know that there will be big improvements in the car from driving it in September to now. Having to rev the snot out of it and throw it into drive to get it from stalling, dieing at the lights,....In the little amount I have driving it since fiddling with it, I know for a fact those issues are gone. I doubt the car is as good as it can get, and will take some more testing/tuning, but I can tell you it has been night and day even with the changes that have been done so far.

Originally Posted by kyle_blake

Hi

Just caught up on read:

Another quick test is to take the timing light wire connector piece[part that attaches to plug wire], remove it from #1 cylinder wire and try it on another wire(yes not to time engine) but to see if (when you press the timing gun button) that THE WIRE INDEED is getting a spark. (flashes)

So no need to point it at timing marks but as you go through doing that you may see a pulse of light change indicating something not firing right on a cylinder. Very quick way to see if you're firing on all 8. you can also test resistance of each wire to using a multimeter.

I would agree with other posters - disconnect vacuum advance !!! It offers very little gas mileage savings and is a fine tune item AFTER THE ENGINE RUNS GOOD.- plug the ports that were used by vac advance until we sort out what the heck is up with engine.

Lastly imo I would try and work around the 850 rpm mark until py helps sort it out.

- so hook up rpm gauge - raise idle to 850
- disconnect vac advance
- hook up vacuum gauge to a manifold vacuum port(not sure on what port that is on edelbrock) they are the base of lower part of the carb.
- Write down the value and let us know.
- Get timing light out and test each plug wire, press the timing gun button and check and see that it pulses on each wire.
- Put it back on #1 cylinder plug wire, check initial timing. you said 14 degrees ?
- you mentioned you have 32 total, did you put the dial to 32 on your dial gun and rev engine to 3000-3500 and see if it lines up with "ZERO" on the timing mark?

I know this isn't 100% accurate on my statements being absolute. meaning the distributor could add more past 3500 but who the heck wants to rev their engine in the driveway way the hell up in that rpm?

If it were me, I would put it at 36 degree total timing, meaning dial on 36, rev it up to 3000 and move distributor until white line is perfect on "0" on timing mark.

From there check initial which should be 18.

Turn down RPM to 850ish.

Then double check petronix install.

I think that's a good approach?

[kyle_blake]

yah for sure the 850 thing was just to get things up into the "damnit" just run for me range. Obviously after driving it for a while you'll get a feeling and say , crap this is way to high for me when going in and out of park to drive or something to that affect so you turn it down to 750, recheck all the timing etc, idle screw etc. then try it out.

Sounds like you got the timing bang on! A good start or you can always try the 6 degree method as well like the other poster recommended.

No one wants to tranny drop from the lights when the car stalls out, lol.

Lastly the springs and weights should move outward and back inward really easy in distributor, I totally agree with all the comments others have said.

Well keep us posted. Remember you can upload vidoes into youtube and make your own channel.

[corellian corvette]

If you have very heavy original springs, revving the motor up to 3K and dialing into 36 may not work. It's possible your springs don't allow full advance at that low RPM.

Also, revving the motor that high with no load isn't that great for the engine, not to mention it's hard to get exactly 3K while playing with a timing light.

There is a DEAD simple way to get 36deg if you have a POINTS distributor (which, based on your installation of pertronix, you do) and it will take less than 5 min.

Pull the cap, and remove the springs. Plug the vacuum advance. Set you dial-back light to 36 deg.

Start the car. It may buck (hard start) because of the over-advance. You are now running with FULL mechanical advance. Set your balancer to 0 with your dial-back at 36.

You now know, with 100% certainty, that your distributor will not go past 36 deg.

Re-install the springs, re-start the motor. Set your idle speed as you would, and take note of your initial number.

This is your new initial advance. You should never have to mess with your timing again. From here, you can tune. Play with advance spring-rates to dial in your curve, play with different vacuum advance cans to play with your curve.

Your timing it idle is somewhat irrelevant - it's simply a function of your total advance. This is the proper and accurate way to set your total advance without putting a strain on your motor.

Regarding idle - 850 seems fine with an automatic. Again, the proper way to set idle speed, idle mixture, etc. would be to put your car in D or R, chuck the wheels, put on the emergency brake, and set that way.

Set your load-idle at the proper settings (between 550-650 RPM if your motor can do it). Check your timing at this speed, and set your idle mixture screws at this speed. THIS is where your car will spend most of it's idle time when you're driving the car, and I've never understood why people set these things in Neutral since the car spends no time in neutral.

Again, setting to 550-650 in D or R, take note of what your idle speed is when you go into Neutral. Now you know what your correct settings are, and can determine if you have too much or too little stall on your torque convertor.

Good luck, keep us posted!

[kyle_blake]

c corvette - > Hey thanks for teaching me something new! I had no idea, a much better way then revving!!! Thanks!!!

Great reply and totally agree tuning it while in drive which is where people sit at the lights and notice how well an engine runs, I figured that step was stage two for darth after "N" adjustment!

Hopefully Darth has time to take it out.

[corellian corvette]

No problem! This is so much faster and more accurate, but it only works on points distributors. It won't work on HEI since that mechanism uses the spring's centrifugal force to pull the cam mechanism. HEI is best to put SUPER light springs and still rev..

[kyle_blake]

Awesome! Thanks!

[Darth Menace]

well here is a crap update...I did the timing light on all spark plug wires as instructed, and there was no light on #8. Super crappy if you ask me. Does this make sense when the compression test on #8 was good?

Know what I did after that? Shut off the car, drove the Viper and then went in and had some drinks to calm the soul

[gto4evr]

Originally Posted by Darth Menace

well here is a crap update...I did the timing light on all spark plug wires as instructed, and there was no light on #8. Super crappy if you ask me. Does this make sense when the compression test on #8 was good?

Know what I did after that? Shut off the car, drove the Viper and then went in and had some drinks to calm the soul

Darth,

pull a plug wire off of another cylinder and swap them. see if the problem moves with it to prove it's the wire. (swap the entire wire, not just switch which plug it goes to) and that's not a crap update, that's a GOOD thing to find something that easy!

[Darth Menace]

Originally Posted by gto4evr

Darth,

pull a plug wire off of another cylinder and swap them. see if the problem moves with it to prove it's the wire. (swap the entire wire, not just switch which plug it goes to) and that's not a crap update, that's a GOOD thing to find something that easy!

Alright, I have two sets of new NGL wires (kind of a cool story about them. Great customer service). Hopefully its just a wire.

Pardon my ignorance though, but how is finding out a piston isn't firing a good thing? Can't it be a possibility that the internals are F'd?

[Greg Reid]

Since you verified compression, unlikely there's anything bad wrong in the cylinder...Plus, the mechanics of the piston and valves have nothing to do with the electrical pulse that fires the plug. The timing light just looks at the electrical part of the equation....and generally speaking, finding a problem is always a step forward since you have to find it to fix it...right?

[paint guy]

If your compression checked out on #8, you have a problem with a plug or wire, or maybe a distributor cap, etc. Nothing wrong with your piston/rings, etc. Take the wire off and put an ohm meter to it, there will be a resistance spec it should meet. Or compare the resistance to a known good wire of about equal length (same brand, of course as resistance can vary between brands).

[corellian corvette]

You may just want to get an old spark plug, connect it to #8 wire, set it on the intake manifold, and start the car. You can physically see if its sparking.