I'm stumped...maybe two problems going on

I sanded down the balancer and found the numbers, and clearly marked them. I was running about 12 degrees at idle, backed it off to 10, and with the vacuum line on, was running WAY up around 50 degrees before TDC, way off of the scale, so it could have been 60 for all I know. I took the vacuum line off and it runs just a bit over 30, so I left it off, hoping this would fix my problem.

It did not. It feels like it accelerates a little better, but...

It still spits and sputters, but I have recognized that if I depress the pedal until I feel the pressure of the secondaries, it will be fine, but as soon as I press past there so the secondaries start to open, I lose all power and it all goes to hell with backfires and pops and good ole loss of power.

1st questions is why am I getting 50+ degrees advance with the vacuum line on?

2nd is why the loss of power when the secondaries open, when I should be getting a boost of power?

I am out to get some WD40 right now and start testing for vacuum leaks. Where, specifically, should I start to shoot at, and am I looking for anything more than just a mild rpm increase, or will it rev up really good?

Should I plug my carb off on both vacuum lines and just run it with centrifugal advance until I buy a new electronic system?

 

timing chain could have jumped a cog or 2, how long since you had a new timing set put in

 

Did you have the distributor out? I had a similar problem on a fresh rebuild once. We could only get it to run at a crazy setting on the distributor. I had the distributor off one tooth on the drive. My guess is that or the timing chain mentioned.

 

New cam and timing chain etc last year. And it runs great as long as I don't kick in the secondaries on the carb. I mean...it runs GREAT!!! fishtails when it hits 2nd gear, sometimes third, etc. Just when I press the accellerator past where the secondaries are suppposed to open, it gives out.

As for the distributor, it is about 3 years old, just an Autozone stock replacement.

Could a vacuum issue with the carb/intake cause the excessive pull on the vacuum advance?

 

This thing is really starting to pi$$ me off!

I am back on hold with Edelbrock tech. It HAS to be the damned secondaries not opening up. I have made a greasy mess out of the entire top of the engine by spraying wd40 all over it. Nothing is happening. I doubt it is a vacuum leak. If anything, I am pulling too much vacuum.

What I DO know is that the advance is too far at accelleration, and I doubt the weighted secondary flaps are opening.

I don't know if the advance is too far because of the carb pulling too much, or if it is a bad distributor.

If I use the EGR side vacuum, I can get the car to idle at 30 degrees, and accellerate at something like 70 or 80 degrees. AND it runs good (even though I haven't driven it like that).

If I use the non-EGR side, it will idle at 10 and accellerate at 50-60.

If I use no vacuum, it idles at 10, accellerates at 30.

I just can't seem to figure it out.

I think the secondaries are opening, but not the weighted flap above it, and it is literally flooding itself because it is choking itself with that weighted flap.

I am thinking of rigging that flap open and trying it to see if it runs good with it open.

First, I will talk with Edel tech and see what he has to say...

 

the problem is them junk Edelbrock carbs ..sorry for the bad news i have not seen to many of them last very long velocity sec suck for performnce sort of like a GM Q-junk or carter AFB the more you play with them the more problems you will have i say Ebay it and get a demon or holley

 

I had that problem with my engine awhile back. If I just went 25 or 30 mph it would run kinda fine. If I put my foot to the floor, it would pop & backfire thru the carb. Ran like CaCa...DooDoo...I ended up putting a new vaccum advance in the distributor ($35.00 fix). Haven't had a problem since...I did the same test you did, with the vaccum line off. Ran Okay. That's what told me, it was the vaccum advance that took a dump...Hope this helps.

 

I am almost there MavGrab.

I just spent another 20 minutes on hold, but got someone who apparently had some knowledge, or at least fed me a GOOD line of logical bull...

He initially said that my ported T-289 was too big for my carb, then that my cam was too small, and I was going to have all kinds of problems. I told him it ran great for about 6 months, and just recently crapped out.

Then he said I have a vacuum leak, and to cover the primaries and if it continues to run, there is a leak. It died quickly.

Now, he thinks that the manifold to block has a leak, internally, in the lifter valley. I believe him, since I have seen a very slow leak of antifreeze behind the distributor and have assumed it was coming from the thermostat housing, but if the cork front and rear seal are lifting it too high, then I might leak around there.

He also thinks that after 3 years, I need to disassemble and rebuild the carb. Sounds kinda early to me, but what do you guys think?

I ran some vacuum checks on the high and low vacuum advance ports, and he says the numbers are appropriate, pretty much. A little low on the high side, should be 14-16, i have 12. He said to advance the timing to 14 from 10 and it should go up, but it stayed at 12. So he thinks it is more the vacuum leak in the lifter valley.

I will wait for some input from my trusted forum friends before I take the top end apart, but at least it is an easy and cheap fix, if it is just poor gasket seal.

Besides buying a holley, what do you guys think of these suggestions?

 

Scoop, you know by now i'm not one for B.S. but you and othes need to learn about how a vacuum assisted centrifigal distributor is supposed to work with the engine.
.
There are two seperate functions going on.
One is rpm related to centrifigal force only.
The second one is the vacuum operation.
The centrifigal rate of advance and it's max advance is controlled by the spring tension and the limiter stop within.
The vacuum operation is controlled by a port from the carb.
.
Normally the engine has little additional advance at starting beyond what you set as inital static advance.
After starting, the vacuum source and the calibration may advance the ignition timing a small amount but still not very far or the engine will idle rough from it.
There is a vacuum advance can that is adjustable for tuning purposes just like a trans modulator.
As the engine rpm is raised both the vacuum and centrifigal begin to get in the ACT.
At light loads and road cruise speeds the vacuum can advance the timing as much as 50+ degrees depending on calibration and setup.
This is to assist fuel milage and works the same on FI cars and also normally, EGR gets invokes if present in the system
When you call for some power, the vacuum lowers and retards the timimg from the later hi values because the engine won't take that much timing under power and should be limited to no more than about 38* with most head combinations.
To your problem: It appears that you have the dist vacuum hooked up to full manifold vaccuum all the time keeping the timing adcanced too far and only gets a small amount of retard from it when the throttle is opened a good amount. As the rpm rises the manifold vacuum rises back up again and causes the timing to go back to a higher amount hence all the carryon you are experienceing. To much timing! This may make you think there is a fuel problem when in reality it is not.
You have to be sure the vacuum to the dist is on the correct port first.
To test this out, use a vac gauge on the port to see what you have.
Normally the port you want is "above" the throttle plates for vacuum pickup so it can 'correctly modulate' the dist advance vs load.
Then test the centrifigal advance without any vac assist to see what it is doing and dial in the spring tension for beginning advance rpm, rpm at max advance and the stop for a max of 38*, alone.
The vacuum diaphram is able to make the total timing go beyond the centrifigal limit because it moves the plate changing the physical location of the pickup and advancing the timing more. These two have no connection to each other.

Now I'm not trying to be tough but realistic with overview help that is accurate and useful once you analyze it and see how the operation fits togather to meet all engine operating conditions without problems.
Dialing in a modified engine can take weeks of trial adjustment with record keeping so you can return to settings that tend to work the best.
The last time I did this the engine had very nearly the throttle response of a modern FI engine with a custom tunning a Holley vac sec 600 cfm carb.
You need a vacuum gauge, timing lite and patience to work toward a smooth engine in all aspects.
With a Holley you can change the secondary tip in point that I don't think you can do with your present carb.
Good luck.

 

Make sure you have the advance vacuum line hooked up to the proper port on the Edelbrock ... or did you verify that already. Once you hit around 2000 RPM or so there should be little to no vacuum to the advance.

 

think you have that backward ported vacuum rises with rpm manifold drops...some dizzys had both a retard and a advance ......Manifold vacuum is highest at idle and drops under acceleration

That much I do remember it was on one or both of the ASE tests think it was engine performance or was it engine diagnostics

 

Vacuum Advance: Vacuum advance is controlled by the canister that's on the side of the distributor. Its function is to provide extra advance at high vacuum to increase fuel economy. The amount of advance can be adjusted by swapping on a different vacuum canister or by putting on an aftermarket adjustable canister. Also, where you have the vacuum line hooked up affects the vacuum advance. Ported vacuum (above the throttle blades, usually on the side of the carburetor) gives you no advance at idle and increasing advance (to a point) as the throttle opens. As the throttle approaches wide open, the vacuum goes away and so does the vacuum advance. Full manifold vacuum takes its signal from below the throttle blades and is highest at idle and gradually drops to zero at WOT. Full manifold vacuum generally isn't used except for some factory stock applications, and even then it's often not a good idea.

 

here some more info

http://www.centuryperformance.com/timing.asp

 

K,,, for what it is worth. my opinion and experience. Take off that edelbrock carb, I have seen nothing but disatisfied people who have them. Second, I really dont think you have enough cfm. Now, another can of worms. I ran a 600 holley for a hunert years on mine. Went to a 700 double pumper and just can tell you how happy I am with it. Now, If I would address my traction issues ( like actually putting on my slicks) I would probably run low 13's or high 12's. I really believe you are not getting enough fuel.
Dan

 

From the sound of it, it appears that you have your vacuum advance hose connnected to full manifold vacuum. You should have 12 degrees at idle (6 drgrees is stock) and 36 to 38 total in by 3000RPM...