fulo

Folks, I hope you can help me here. I have a GM ZZ3 engine that modified with:
Flat Pistion (10.5:1 CR),
CAM GM ZZ3: 208, 221, LB112,
Trickflow Twisted Wedge ALuminun Heads,
1.6 Crane Gold Roller Rocker Arm
Edelbrok Performer Aluminun Intake,
TES Jet HOt coated Edelbrock Headers
Q-Jet Carb


My question deals with timing. Given this configuration, how many degrees should I advance the timing? At this moment I have the timig set a ZERO. NO problem there, but I have a rich condition that I cannot adjust with the Carb. The spark read the typical retard ignition condition.

Hope you can help me out.

Thanks!

sofakingdom

iTrader: (1)

It should be around 34-36° at 3000 RPM or higher with the vacuum advance disconnected.

Ideally, it should probably be at around 15° at idle; with, obviously, around 20° of centrifugal advance, to get to that 34-36° neighborhood. It should probably start advancing at around 1100-1200 RPM, and the advance should be all in by 2600-2800.

It should have 12-15° of vac advance on top of that; for something in the 48-50° kind of range when cruising.

Ignition systems do not feed fuel. If you have a rich condition, it's the fault of the fuel system. Not the ignition system. Believe that.

I'd suggest you go buy a book on tuning car engines; sounds like it would do you more good, to know what you're doing, and to understand how it actually works, than for us to it here and type stuff at you.

Sonix

iTrader: (1)

Yea, I have a hard time believing you have a rich condition that you cannot adjust with the carb. How else would you fix a rich condition?
I'm assuming this is a NON-computer controlled q-jet right? I doubt that's enough cam to need holes in the throttle blades.

fulo

Thanks!... I have some books, and some are really good, but I feel there are to many variable... this is part my fault.. when I built the engine, I was a not too knowledgeable, so I bough part I did not truly comprehend ... like this mallory comp 9000 Unilte Vacuum Advance with the Ignition box Hyfire VIA. Then I put 1.6 ratio roller rocker arm lifter, wich change the geometry...

However, May be the wording I choose is not appropriate.. May be is not a totally rich condition (even thouhg I have that mechanical Q-jet lean to the max, and a 2nd Oxygen{for the gauge} sensor is already bad), but some strong emission odors.. You start the car and you feel it. No black smoke at the pipes, though.

I have 3 Q-jets, they all have the same problem... one in particular that was prep by JET, I cannot use it beaucause the sympton is worst (emission odors). THe emission are strong.

The spark plug have the typical light black coating (NOT OILY), that can be read as retarder ignition... and here is the thing: I have hard time adjusting the timing beacue my timing gun cannot lock with the Multi-spark ignitnio box. I adjusted the timing by making sure that I have TDC and the distributor is on synch. ( i know, very embarrasing).

So to sum, My plan are the disable to Ignition box in order to adjust the timing, at idle, with the vacum advance disconnected, I will adjut the timing to 12degree in advance. Then I will enable the ignitio box.

(p.S. thei CD ignition boxes should have a by pass function that allows to adjust the timing!!!!)

Thanks for your comments!

rgarcia63

what spark plugs are you using and gap. Can you post some closeups of the plugs.

fulo

Tomorrow I will take some picts fo the sparkplugs and post them. Thanks! I do believe they are the standard GM spark (for my car) with a a bit wider gap.

fulo

First, my camaro in computer stripped. And have an indepedent Mallroy Ignition system and a normal Mechanical Q-jet.

My current problem was with the emission odor, For me a a bit strong. The car does not have a CAT. The card does not consume oil, I do not have any black or blue smoke at the tail pypes

I took all the spark plugs out (a job in it self with the edelbrock headers!!!). and they all had close to the same apppearance. I took pictures. Please note that there is no oily residue on any of the plugs, only a thing black poewder coat.

http://img167.imageshack.us/img167/3894/mvc820fld9.jpg
http://img396.imageshack.us/img396/9044/mvc818fjz5.jpg

After conversing with a Mallory Tech Rep, I decided to temporarly bypass the Mallory CD Ignition box and run the car. FINALLY I COULD ADJUST THE TIMING WITH MY OLD TIMING GUN.

I have a vacuum advance Mallory Unilite Distributor. Withou adjusting the timing and reading witht he gun, I had 10 Advance.

I disconnected the vacuum fromt he distributor advance and plug the line, and i ran rougth, but had a timing set at zero (0)

WItht he vacuum advance disconnected, I adjusted the timing to 15 degree. Engine ran good.

Connected back the vacuum line to the Vacuum advance distributor, read the timing and had 30 degree advance. The engine ran smoothly.

I even think it ran a bit cooler. But that will have to be confirmed. I will now connect back the Ignition box a take it to a test drive.!

Please let me know if I follow proper procedure in the tunning?

Thanks

F-BIRD'88

You'll want to set the total timing. get a balancer timing tape to allow you read the total mechanical tiiming when all maxed out. Should be 32 to 36deg. Usually 34 is good enough. Then reconnect the vac advance. Usually ported vacuum gives and better overall vacuum signal to modulate the distributor relative to load. You only need to run as much advance as is needed and no more. This is more important than the intial timing as long as the initial falls in the 10 to 16 range at idle.
The "emissions odor" you were smelling when the timing was set to 0 deg at idle was unburned fuel passing right thru the motor and out the exhaust. (Late burn) The fuel needs to be all burned before the exhaust valve opens. This "rich condition" should disappear once the timing is corrected and the carb is readjusted. 0deg at idle is not enough.

fulo

Thanks for your post... Anad pardon my ignorance, but I am not clear on "get a balancer timing tape to allow you read the total mechanical tiiming when all maxed out. Should be 32 to 36deg"

Did the last procedure (on previous post in this thread) was not proper?

I have a regular timing ligth...and how to adjust the timing on a regular conventional engine. I say this because I will like for you to elaborate more on this? THANKS!

Sonix

iTrader: (1)

No, sofakingdom and F-bird'88 both gave virtually the same advice, just worded differently.

Your timing light should light up, but not have the dialback feature right? Ok, so rather than using the single line on the balancer, and measuring up to 8* or so with a timing tab, you buy "timing tape", and wrap it over your balancer. It's a strip of tape with numbers on it. Then you can measure 34* on the balancer, and line it up with 0 on the timing pointer. It's about $4 for the tape, or you can make your own using some high school trigonometry. I pay $4, it's more accurate.

rgarcia63

The most I can read on my Edelbrock timing tab with an analog Timing Light is 11°, to read 30° I'd need to put Timing tape on the balancer, or use a digital Timing Light, which, if I'm not mistaken is what you're are using.

fulo

I have a FLuidDamper Harmonic on my car. Ibelieve it has all the information that will be on a timing ligth tape? Rigth?

My timing light gun is the MOST basic one. No dail back feature.

To reinforce, this is what I did:

1) I bypassed the Mallory CD ignitino box
2) Disconnected the vacuum line at the vacuum advance on the Distributor.
3) Started the engine. Adjusted (Advance)the timming form zero* to 15*.
4) reconnected the vaccum advance vacuum light
5) Read the timing and have about 30*.
6) Activate/engange the Mallory CD ignition box.

I notice that the car runs cooler. THe emission odors are still present.

Thanks the all your post. I apprecite all the feed back. Can anyone tell me is the steps above are correct? I want to make sure I am adjusting the timming correctly.

rgarcia63

Yes, that's the correct prpcedure, I beleive the reason for bypassing the Igintion box is because the basic analog timing light won't work with it.
What model CD box to you have?

fulo

Hyfire VI A

Thanks!

fulo

Ok, WItht he system Ignition box Bypass and the vacumm, the engine at idle and the vacuum advance connected, I read 30*

I have driven the car for a a couple of days and I feel I have less power that before. It runs a bit cooler (temp wise), nonetheless. The emission odor are strong (I will play the card as soon as the timing is correct).

Before I had the timing (vacuum advance disconnected) set a Zero.

I have a GM ZZ3 engine that I modify with Flat pistos (10.5:1 CR), Trickflow twisted wedge aluminun heads, and 1.6 Roller rockers. The cam is 208/221, LB112.

Given this set up and this results (less power), should I reduce the advance to say 7*???

THanks for you continuing feedback!!!!

F-BIRD'88

The GM "ZZ3" did not come with the 208-221-.474-.510 112LSA cam ... the ZZ4 motor did.
The "ZZ3" version cam was bigger 235/235@.050 .480" lift on 112 or 114LSA. Are you sure on the camshaft?
they are differnt cams and makes a difference.

GM revised the ZZ3 cam in the newer revised ZZ4 motor casue it was too big for most peoples driving habits and the new milder ZZ4 cam idled nicer, made more low end torque and gave up nothing in top end power.

I can see you having a smelly idle with the bigger ZZ3 cam but not with the revised ZZ4 cam.

You are missing the point on setting the timing. Disconeect the vacuum advance. read the timng at idle. Should be 12 to 16deg at idle. Rev the motor up while watching the timing marks with the timing light. Should advance to around 34-36deg. make sure you are reving the motor high enough to max out the timing. (vacuum advance is disconnected)
if the timing does not reach 34-36deg adjust the timing as nessessary. Then after its all adjusted right, reconnect the vacuum advance to "ported vacuum" source. if you do not know which one this is look at the instructions for the carb.
the advance (at idle) should not change from the base timing (12-16deg at idle),by reconnecting the vacuum advance. If it does you have the wrong vacuum source. Plug the hose on the other one.

If you infact your motor has the larger, earlier "ZZ3" camshaft, you will need to modify the distributor advance curve for proper idle
It's long duration and overlap requires a lot more base timing at idle.
like 24deg at idle or more. You would have to remove the distributor and modify it. How much manifold vacuum do you have when the motor is idling? You may also need to change the power step up spring in the carb. is this a factory GM QJet or a Edelbrock Qjet?
Need to know how much manifold vacuum at idle with the timing set correctly.

fulo

Thanks for the feed back. I the can that I have is a 208, 221, lb 112. Nothing radical.

I have a vacuum/boost gauge on my card. It reads about 18 of vaccumm. I even have a A/F ratio gauge, but the O2 sensor is bad, and I am tired of allways replacing this. At the time, the gauge was working, it mostly read rich.

The vacuum for the distributor is connected at the back of the throtle base plate of the stock q-jet. I have several book on this carb, I will search for the "ported source" for the vacuum.

As if, witht he vacumm advance disconnected, engine idle (800 RPM), the timing is about 16*. with the vaccum advance connected and at idle, it read 32*

I do feel the engine has left power, specially as i floor it. If the the power rannge decreases sharply as I rev it.

I really want to know for sure how to adjust the timing on my car so I can move to the carburetor and fine tune it.

I will follow your recomendations tomorrow and will post the results.

thanks!

fulo

Tell me if I am getting this correctly... The vacuum souce for the advanve on the distributor should come from the carburetor and should not have any vacuum at idle, only when I accelerate it????

I say this because following the suggestions, the timing at idle witn no vacuum at the distribuor advance shoult be about 12* to 16*. (since the ported vacuum source should not change the base timming of 12 to 16* at idle).


If this is correct, then I have a continuous vacuum source at the advance, that will have the timing always at 32* at idle.

Comments please! THANKS ALLOT

rgarcia63

Yes, a ported vacuum source will have no vacuum at idle.
This TGO article "Non-Computer Controlled HEI Setup For Performance" by Damon has all the info you need https://www.thirdgen.org/hei
Your Unilite should have come with 24° of mechanical advance between 3k to 3.2k rpm (if you ordered it with mechanical advance, a must without computer control.)

fulo

Thank for the link. Very intructing.

I have located the ported vacumm source at the carb and connected the vaccum advance house to it.

fulo

Folks,

Thanks for all your insigths and advice. This is what I have done some far.

1). I have by passed the Mallory Hyfire VI CD box.

2). I have disconnected the vacuum for the vaccum advacne ont he Mallory COmp 9000 UNitle Distributor.

3) WIth a regular/simple timing ligth I adjusted the timing to 12* (no vacuum at the advance.

4) I them rev the engine to about 4000 to 5000 RPM and the timing advance to about 36*

5) Then I reconnected the ported vacuum source to the distributor and comfirmed no change in timing (from step 3).

6) Rev the engine to about ~5500 rpm with the ported vacuum connecte to the vacuum advance on the distributor. Timing read about 50*

Are this steps and results correct?

THanks

F-BIRD'88

yes

rgarcia63

How does it run under load?

fulo

The problem has been alivates allot... but to answer just question when the problem was at is worst.. it ran pretty good.. meanin.. always had *****!

fulo

Thanks folks.. I have been driving the car for about 3 week know, and the issue with the strong emission (rich condition), has been MUCH improved...

The problems were:
1)Base Timing set at zero (instead of 14-16 Advance).
2) Vacuum advance connected to wrong Vacuum Port. It was conneccted to a port that had allways vacuum.. so at idel the timming was about 32 in advance...
3) Not being able to get timing gun (standar) to work with Iginition box.

The solution were:
1) By pass the Ignition box.
2) Connect Vacuum ADvance to correct Vacuum ports.
3) set the base timing at 15 advance.

Results:
The car runs better, sounds better, and there is less emission.. I can wait to check the spark plugs!


Next to do:

Adjust caburetor!, replace damange O2 (for in dash A/F gauge).


Thanks allot for all your help!