RandyS

Dude, are you even reading his instructions???

robgarner

Actually I did, three times. I never claimed to b a mechanic, I'm actually an electrical engineer and this is the first time I've ever doing this so bare with me. I'm trying to envision what he's actually suggesting that I do as if I were doing it myself bc obviously I'm not doing something correctly. Ask me about flying an airplane, making beer, or anything mathematical and I can run u down a list of stuff. So instead of insulting me or kicking me why I'm down try to help me to understand his concept.

MDchanic

Oh, you're an engineer. That means that there is a specific way of giving you instructions.
I wish I had known that earlier.

Above, you said you would adjust the idle to 500 RPM in Drive - it's 550 RPM, not 500 (600 RPM if you have a problem with 550). It should run at 500 RPM in Park, but might stall when driving if you hit the brakes hard.

So, to recap:

• Set the initial timing to about 20° BTDC (the exact value is not important, this is just to get you close) at about 600 - 800 RPM, with vacuum advance disconnected and hose plugged with a pencil.
• Rev to about 3,500 RPM and make sure timing advances to about 34°-35° (again, the exact value is not important, and will have to be reduced IF you find that it pings under hard acceleration - every engine is slightly different).
• Reconnect vacuum advance, place in Drive, and adjust idle to 550 RPM, first using idle speed screw, then adjusting idle mixture screws for highest speed and vacuum, then readjusting speed with speed screw, then back to mixture screws, etc.
• You will need to drive the car in order to decide whether to connect the vacuum advance to "ported vacuum" on the side of the carburetor, like the factory did, or directly to manifold vacuum - one will work better for you than the other, but each will give you different idle settings (ported vacuum will give no vacuum until the throttle plates just begin to open, while direct manifold vacuum will give you full vacuum all the time - I personally recommend direct manifold vacuum, but you can try either one, just remember that if you switch, you will have to readjust your idle, because idle will be higher on direct manifold vacuum than it will be on ported vacuum, because timing at idle on direct manifold vacuum will be more advanced).

If any of that wasn't clear, please let me know, and I will explain it further.

You'll get this.

- Eric

robgarner

Yeah ironically i write instruction manuals Ok i understand exaclty now. I have done the first part in setting the timing as close to 20* BTDC. I have not done the next 2 steps.

Step 3 you say "highest speed and highest vacuum". I have my vacuum advance on the distributor connected to manifold vacuum. ( the answer to step 4) When checking vacuum i just hook my vacuum guage to the hose the used to be connected to my vacuum advance on the distributor since its disconnected and plugged.

I understand every step and have envisioned it in my head. Its actually pretty simple but i do need another person for step 3 and i have one. I'm going to print these steps out and re-read them 2-3 more times and do this tonight. It'll be cold but i'm anxious to see the results.

As i re-read this again. i realize that my problem in step 1, setting the initial to 20*, is that i was setting my my rpm to 1100 when doiung this not "about 600-800 RPM". If it were at about 600-800 RPM when setting the initial to 20*, when i place the car in drive the RPM would be around 550 RPM because it drops.

Ohh i see. This is definetly doable! Ok i think im set. I know exactly what to do and exactly what i haven't been doing!

I'll update late tonight! Thanks again!

MDchanic

The thing about engineers is that they hate anything that is uncertain or inexact, unless it has been defined to be within an established tolerance band.

If I tell you that a resistor in a circuit has to be about 20MΩ, you will know that 19MΩ is probably fine, and if you can stand a slight variation in performance somewhere down the line, 16MΩ may be perfectly okay, too. It all depends.

In this case, every aspect of this engine was designed by engineers, who had a very specific set of parameters that they had to work within, many of which do not apply to you.
For instance, they had to retard timing to reduce oxides of nitrogen emissions, which are caused by high combustion chamber pressures ad temperatures, but you don't care about that, and can advance timing to the area where the engine provides the most power and fuel economy, and runs the coolest. in 1973, they specifically did NOT care about fuel economy, so that was ignored.
Also, in your case, you have changed the mechanical advance characteristics of the engine by substituting a different distributor (one that was designed for an even more retarded timing setup), so the established settings no longer apply, and you need to find your own through trial and error, which is within the philosophy of engineering design, so long as you think of it that way.

Once you get the right perspective, it all makes sense. See what I mean?

- Eric

MDchanic

Just use your parking brake, and DON'T rev the engine .

- Eric

robgarner

Yeah i could do that too! I have learned more than i imagined over the course of this. It may seem simple to you but it was initally intimidating but now i'm confident that i can do this. I know i'm so close to burning up the hwy again.

frankr442

[QUOTE=robgarner;473487]Ok so I think I left out a critical aspect. When I measure the timing to set it the timing jumps all around.

Is it possible the pole piece is too loose and moving around too much? It's been years since I looked at an HEI dist, isn't there a bushing at the advance lever? Maybe something's getting sloppy.

robgarner

Ok I did everything according to instructions now I kinda get a hard start and a little knocking noise. Should I turn distributor advanced or what is the next course of action.

robgarner

Set the initial timing to about 20° BTDC (the exact value is not important, this is just to get you close) at about 600 - 800 RPM, with vacuum advance disconnected and hose plugged with a pencil.

DID THIS AT 700 rpm AND NO ISSUES.

Rev to about 3,500 RPM and make sure timing advances to about 34°-35° (again, the exact value is not important, and will have to be reduced IF you find that it pings under hard acceleration - every engine is slightly different).

HAD SOMEONE REV IT UP TO AROUND 3500 AND HAD THE TIMING GUN SET AT 35* AND IT WAS HITTIN IT AT/ABOUT 0*. No knocking or pinging or nothing that i could tell.

Reconnect vacuum advance, place in Drive, and adjust idle to 550 RPM, first using idle speed screw, then adjusting idle mixture screws for highest speed and vacuum, then readjusting speed with speed screw, then back to mixture screws, etc.

SEEMED TO LIKE 600rpm BETTER THAN 550. HOOKED UP VACUUM GAUGE TO MANIFOLD AND WAS GETTING LIKE 15HG. ADJUST SCREWS AND GOT MAYBE 15.5HG.

Now just sitting at idle in drive i hear a knocking. But every step went smoothly. What should i do now? adjust the carb or what. im park it seems to have no knock but i think the RPM is like 700 in park.

MDchanic

That all sounds good.

It sounds like you may be a bit advanced at the low RPM end, but if the engine still starts, that's okay. If it's hard to start, you can install a set of re-curve springs and weights (Moroso and others have them, for less than $20), which will extend your advance a bit and allow you to have the low-RPM end a bit farther from the high-RPM end than it is now (idle at, let's say, 16°, 3,500 RPM at 36°).
You could also back it off (retard it) a couple of degrees.

Idle speed sounds good, but it should be able to idle happily at 550 RPM in Drive, and idle vacuum should be more than 15½"Hg. I would check for a vacuum leak, cracked hose, unoccupied vacuum teat, etc. A vacuum leak will also give you that "rapping" rough idle.
You can use any flammable fluid to test for a leak, within the bounds of reason: Car-startin' æther, propane (not lighted), butane, carb. cleaner, etc. Just move around slowly and carefully and spray the fluid all around the carb. the base gasket, the manifold gaskets, and the vacuum lines (all the way to the brake booster and charcoal canister, etc.) and if the idle picks up, there's a leak there that's pulling in your flammable substance instead of air.
Another technique is to remove one hose at a time and put your finger over the fitting - if the leak is from that hose, the idle will pick up. This will not find gasket leaks, and may not work if you have a number of tiny leaks from different hoses.
DO disconnect the line to the vacuum modulator and cap the fitting, as the transmission-end hose is out of sight and VERY often badly deteriorated (also, the vacuum modulator diaphragm could be shot).
Once you find the leak, it should be no problem to correct it.

Once you've tested for leaks, and either found and corrected them, or proven there aren't any, you can consider readjusting.

You're making progress!

- Eric

robgarner

Ok'll i'll slightly retard the distributor. Now as far as the vacuum goes i did take the vacuum reading from a different spot than i normally was. I normally disconnect the line going to the distributor vacuum advance and hook my gauge up there but your step said to reconnect the vacuum advance. I'll have to look for another spot from the manifold and recheck it becuse i was geting like 18-18.5hg before. sounds like i'm almost there. I have nothing schedule all weekend so hopefully i'll get going.

MDchanic

That's more like what I would expect.

Just get a plastic "T" fitting and a few inches of vacuum line and tee into any line that goes right to the manifold.

- Eric

robgarner

Ok..another question or not sure if I should address it. My vacuum switch is broken off and not hooked up. It's been this way since I started driving it again. Shoukd I replace it and try to hook it up or just leave as is? Just wondering if I should open that bag of worms? But if it helps me in the long run I def will.

MDchanic

What vacuum switch?

robgarner

On the top front of the manifold. Im not sure it the original intake is on the car. But the intake that is on the car has a broken vacuum switch in the front. Just want to make sure I don't need it. Sounds like I don't.

I also have a plastic t fitting..I'll T into the line that goes to the vacuum advance. I think I need to plug a hole in the intake bc that's where I just stuck my gauge into to get the 15hg and it's a threaded screw hole with no screw.

MDchanic

Oh. One of those.
I'm not familiar, off the top of my head, with exactly what that one is, whether transmission-controlled spark, or temperature-controlled vacuum advance, or an EGR controller, or some combination, but, no, you don't need it.
The ones that advance the timing are just workarounds to allow the timing to be set too retarded and still have the car run. Since your timing will be set correctly, you don't need them.
If you were running the car with an original carb., you would actually want to have the EGR operational, as it will run just a bit lean without it, but with the aftermarket carb., that shouldn't be the case, and you should just make sure the EGR is completely closed.

There ya go.

Use Teflon tape (or something similar).

- Eric

robgarner

Ok great! I'm going to address that today when I get off today so we'll see! I'm excited though I can tell you that! Appreciate all your help!!!!!

robgarner

Ok so here's what i did. I plugged the hole on the manifold with a screw. Hooked the vacuum to the manifold and still 15/16hg.

I turned distributor retarted a bit and it got rid of the knock.

I decided to drive it. I can tell it has pep but still hesitates, but drives well and i drove it farther down the street this time. It acts like its ready to get up and go minus the hesitation.

Now i can tell you my manifold gasket it shot. I mean the front side rubber piece is hanging all out. I'm figuring that this will cure my vacuum issue but you think it could be associated with the hesitation?

I'll post a pic of how it looks.

robgarner

Here is the manifold gasket.

robgarner

Sorry late in the say thinking.

MDchanic

Unfortunately, that gasket seals the crankcase and not the intake manifold, so it cannot be the source of a vacuum leak.

How's your PCV valve?

- Eric

robgarner

Wheww bc that would be a pain to change. The pcv valve looks good. I sprayed starting fluid around pall vacuum lines, intake gasket bolts, carb, pvc valve and not increase in rpm. I also took the vacuuum reading with the car in park. I disconnected the vacuum advance line from the distributor and hooked up the vacuum gauge and i adjust the mix screws on carb and i got 17hg. I also hooked it to the the previous spot and got about 16hg. Puzzling but doesn't look like i have any leaks. What should the normal reading be?


My drivers side pcv valve goes to the center spot on my carb and the passenger side goes no where.

MDchanic

... But looks will not tell you whether it works.
The traditional test of a PCV is whether it rattles easily when you shake it.
You can also suck hard on the vacuum side and it should close up.
If it's been around a while, it's never a bad idea to spend the $3 to replace it, "just to be sure."

Good. You probably don't have any vacuum leaks.
Did you check to be sure the line to the modulator isn't leaking?

17" is not bad. In my gut, I feel like an original car should be more like 18", but it's not worth quibbling over. The important thing is whether it acts like it has a vacuum leak (shakes at idle, hesitates).

You should have only one PCV valve. If you have two, that may be a problem.

- Eric

robgarner

Ok. I changed the PVC valve and also all the hoses that i could tell had any signs of a crack. Now in park or drive i got a vacuum of 18hg.

At idle it doesn't shake or anything and i drove it and it still hesitates. you think it could be the spark plugs. I was thinking of checking them and making sure the gap was .035. I used to have a gap of .060. not sure if this is the difference or not. Not sure what else i could check or try.

MDchanic

Now yer talkin'!

0.035" should be fine, and shouldn't cause this.

It sounds like you've slain your vacuum problems and got your timing set right.
Your idle settings seem good, but with an off-idle hesitation, it would be reasonable to try opening your mixture screws ½-turn each and seeing whether it improves.

If it is running well under all other conditions, the hesitation definitely sounds fuel-related, and the most common causes would be mixture screws too lean, bad or misadjusted accelerator pump, or float level set too low.

Anybody else out there have anything else to add to this list?

You're getting there, and at least now you've got a car that runs and drives!

By the way, in this process, you replaced the original QuadraJet with an Edelbrock, didn't you?
Getting a $20 rebuild kit and $8 float and rebuilding and reinstalling the QJ would be a minimal investment, and could conceivably fix it at this point - it would at least eliminate a lot of carb-related possibilities.

- Eric

robgarner

Ok i'll adjust the screws and drive it.

Yes i bought a brand new edelbrock 750.

robgarner

Ok so i went and adjusted spark gap to .035 and screws out 1/2 turn at a time and no difference. Made sure plug wires were not resting against the exhaust manifold. Well I'm at a loss for right now. No other ideas. the only thing i haven't changed is the distributor but it seems to be working correctly. Any more ideas?

oldcutlass

It could be the accelerator pump set to the wrong notch. Move it up 1 on the front right of the carb facing it from the front.

robgarner

Ok i drove to the gas station bc was running out of gas. I drove there with the pump link notch on the bottom hole. it drove better but still hesitated.

I drove home with the pump link in the middle hole and it seemed to drive worse.

Now to make sure i didnt miss anything i tried to go back over the timing steps again. setting BTDC at 20* at 550 rpm. Well it knocks in this spot now. idk y but its knocking towards the front. I adjust the distributor advanced and retard and advanced seems to improve it but it was at like 23*.

I'm all confused now. Don't know where the knocking came from all of a sudden.

MDchanic

23° at idle is fine with HEI, as long as it doesn't ping on hard acceleration.

I'm afraid that though I've owned one car with an Edelbrock carb. (installed by the previous owner on a 9.5:1 390 FE motor), I have never messed with one, so I can't give you any tuning advice for it.

If the knock in your engine at idle sounds anything like the one you had before, then it's probably due to the idle being a bit too low, and I'd wonder whether you accidentally dislodged a vacuum hose somewhere.

It might not hurt at some point for you to post a bunch of pictures of the engine, vacuum hoses, carb., etc., so we can try to spot something wrong.

Botom line: This doesn't sound like ignition, timing seems to be good, mixture is definitely not rich, so that leaves a lean mixture as a high-level possibility.
Does anybody know whether those Edelbrock 750 carbs are jetted lean or rich?
If the carb came lean, and you're not using your EGR, the leanness from two different causes might be enough to cause your hesitation.

- Eric

robgarner

Ok gotcha. I'll adjust the timing and go from there. Gonna start back up tomorrow morning.

Kolby66

I had this same thing happening with my 455, with standard ignition. I actually had 2 cracks in my cap, that were internal. The cracks were 180 deg apart and went from one lead in a u shape to the next one. This caused me to have popping in the carb and the exhaust at the same time. Usually under accelleration in my case

Delmont 88 PA

I don't know what it cost to get your car hooked up to an oscilloscope at a local garage but it might be worth it. In a half hour or less the garage would be able to tell you if your distributor cap is cracked, if your spark plugs are firing at the right voltage and evenly, if you have a defective spark plug wire and (if the scope is able) a dynamic cylinder test (kill each cylinder one at a time and check to see if each cylinder slows the engine the same amount). This would put a lot of ignition questions to bed.

MDchanic

+1. Oscilloscopes can really help with these sorts of mystery problems.
The tough part is finding a mechanic who still remembers what they were.

- Eric

Rickman48

Or finding one that's still useable!
Many left them go, as it's expensive to repair, and hard to find parts at all.

Delmont 88 PA

When my brother sold his repair shop in the 80's the guy didn't know how to use the perfectly good (and expensive) SnapOn scope and junked it.

MDchanic

Which is why you can still find working oscilloscopes, R-12 recovery units, and similar "outmoded" devices dirt cheap if you keep your eyes open.

I bought a Snap-On MT-460 clamshell cylinder-grounding Dwell / Tach at a flea market a few months ago for $15 (this pic is from eBay),



got a full oscilloscope, with cables and manual, a couple of years ago for $20, and got an R-12 recovery unit, in good condition, for $35.

It's all out there, if you're watching.

- Eric

Marc A Levy

I'm new to this whole thing but I just rebuilt my 455 and replaced gears and chain. And I'm no expert and if I'm wrong then my car won't start when I'm done but isn't one of the gears suppose to be set at 6 o'clock and the other at twelve? Lining the corresponding dots up together?

gregvm

Crankshaft sprocket MUST be at 12 o'clock to set timing(top dead center). Cam sprocket doesn't matter if it's at 6 or 12, although 6 is easier to line up the mark with the crank. If you install with the crank at 6, the cam will be 90 degrees out of phase.