vacuum advance idle issue?

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InItSwingIt

InItSwingIt

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66 /6 basicallydart stock...I thouht id set the timing before i drove over to the shop to do the breaks. Noticed niether the chocke vaccume or the vaccime advance where MIA...thought it might explain my mysterie rattle if myim tinings retarted. What coulda whover dithed the advance and reset the timing to work without havethe possibly done towrong a slanrt to runthe like this? Soooo, in theory i set #1top dead senter alighn the dizzy do everything as the book says and it just wont idle right when you hook up the hose for the advance off the dizzy. i dont have any special tools wanted to do this befori drove it anywhere else. But it makes me think the carb is not working right or the distributer is bad/wrong. Im sure the answe is very simple... who knows how to find the bad part ir what might be going on...iv got good spark and get get it to run real good all hooked up, but it just wont idle without pings' pops and carb backfires. I end up setting the idle WaY to high, even for an auto cus when i put it in gear it sounds like hell runs like shate till you punch it and it wakes right up. Whats goin on...
 
Your post is not clear.
- Does it idle OK at a low idle when the vacuum advance hose from the carb is removed from the distributor AND that hose is plugged?
 
Your post is extremely unclear.
-Sounds like a faulty low-speed circuit in addition to any timing issues.Or possibly a fairly large vacuum leak.If you put a vacuum gauge on the manifold and it gives you a nice steady number like 16 or better, you could probably skip the next tests,for now.However, if the number is drifting around,or bouncing, or low, like 14 or less; I would do a serious search for a vacuum leak, including a valve adjustment.Tight valves will destroy low speed vacuum, which the low speed circuit depends on for proper operation.
-You will need some tools or a good friend with the tools.
A basic tune-up is a good place to start including a compression/cylinder leakage test, and a search for the possible intake leak.
You cant really start at the carb, until the timing is close. You may, I say MAY, be hooking the advance up to the wrong port. From here its hard to tell because you mention the very high idle speed. So, for now, disconnect it and plug the line to the carb, just as poster nm9 says. This is important for us to help you at all from way over here.
-Is your distributor complete? Is it still point triggered? Its unclear.The vacuum can locates/indexes the point plate relative to the housing. If its MIA, the plate can move around and of course the timing with it.
-Did I mention that you will need tools?
-Here is a starter list; Vacuum gauge, Timing lite, basic tool kit with your specific sparkplug socket.
-Additionally, you might need; TDC locator, Feeler gauge set, Screw-in Compression tester
-And later, you might need; Dwell meter, Leak-down tester
 
Sorry... i do this all on my phone...to the point....with the timing completely off i can get it to idle OK, but it rattles and soundsit like the timing is too retarded and isthe barely drivable. When you set the timing correctely and set the idle rpm drops to where it should be but begins to sing a similar retarded sounding 3 cylender song untill you get the rpm farly high, where all horible sounds cease completely untill droped back to idle. With the baccume hose from the distributer to the carb UN-hooked it idles ok untill you rev it and it rattles and misses. Is it my carb? My distributer? Or vaccume plumbing issues? How can i eliminate as many culprits as possible. What it isint might be more revealing than guessing what it might be...someone ditched the stock points as well, dunno if they used the right distributor when they did...
 
OK, it would help to answer some simple questions. You're giving too much info in a confused fashion; not trying to be mean at all, it is just not clear enough to make heads or tails of.
1. When you remove the vacumm advance hose from the distributor, do you plug it? You need to do so.
2. Are you using a timing light to set timing? If so, then have you identifed the timing marks on the cover and on the pulley? The mark on the pulley is a smal vee-shaped notch. If you are not using a timing light, then you can't set timing properly.
3. Do you have a factory service manual? Many can be found on-line. That wil lshow you where to connect the vacuum line to the distrobutor and to the choke pull-off. By the way, the early Holley carbs did not have an external choke pull-off but a choke piston in the top of the throat so that can be confusing.
4. Can you take and post pictures? If so can you post a few pix of the carb?
5. So your distributor is not stock with points? Is it a Mopar distributor with a Mopar ignition control unit? Pix?

We really need a more complete baseline of info to work from.

4.
 
Maybe the fuel is contaminated, or just plain wrong.
Maybe water or diesel or really stale fuel. Diesel will do that, but my nose has always been able to detect that, at the tailpipe, even in small amounts.
 
The only other port on the carb (which is later model) is a totally different size and on the opposite side of where my manual shows it going.
 
Dont worry about sounding "mean" nothing said online will ever really "hurt my feelings" ...im not that insecure. Rather get to the truth of the matter than pussyfoot around making life hard on other people....but anyhow... It runs too good all hooked up once its above idle speed..unhooked and yes plugged the idel is allright, not perfect. anything above that goes to hell unless i set the timming way off..if i hook it all up and set the idle really high i can get in in gear and running ok, but i can feel it sressing the tork converter, it dosent want to fully stop and feels like it pulls way to hard when you put it in gear. Almost like a neutral drop because its idleing so high, and wants to idle foward too fast.
 
Timing light revealed both factory tdc 0 marks as well as the previus owner painted on marks which it was ruunning at vaccume unhooked ALL to be off true TDC of cylander #1. with timing set according to the book and actual TDC all is standard procedure untill the advance is hooked up...ill post a pic tommorow when there is light...looks like a later model stock electronic distributer...could one of the weights/springs in the distributer cause this low end issue and not present itself at speed? Tganks for evrybodys problem solving insight and genius on this one..
 
Is there a way to post a video?..ill fire her up n walk eryone through how i been setting the timing and where im hooking erything up.
 
nm9stheham said:
Your post is not clear.
- Does it idle OK at a low idle when the vacuum advance hose from the carb is removed from the distributor AND that hose is plugged?
Click to expand...
yes unhook+plug = idle ok crap top end. Hooked it purrs too sweet untill you let off the gas then idles like its too retarded and misses half the cylanders.
 
Well if the vacuum line is on the correct carb port, that is 'ported vacuum', which is taken out of the carb throat above the throttle plate. It is low at normal idle, and rises when you open the throttle. So the distributor advances with throttle opening from idle to mid-throttle.

If it idles OK with the hose plugged, then goes to heck with the hose connected, I would check for a leak in the diaphragm of the vacuum advance cannister. With the car idling and the port from the carb plugged, have a vacuum hose connected to the advance cannister and suck on it. If OK, you will hear a change in engine operation AND you won't be able to keep sucking air through the diaphragm.

Now, if the diaphragm is punctured, then I would not expect as much effect at idle, since the vacuum leak is above the throttle plate. But, if the carb is adjusted for some reason with the throttle plate a bit open, then a leak in the diaphragm would effect idle. And such a leak would certainly effect mild throttle openings. So, it might no be a leak, but that is a first check on the vacuum advance diaphragm.

Do you have a vacuum gauge? It would be good to have for this. OK, good deal on the timing marks and timing light. Just was not clear how you were doing this.

And the notes above on the valve lash is good. Can't help you on the video posting!
 
We are assuming that you are checking the timing with the vacuum can NOT connected, and that the timing is advancing with increasing rpm, and in a somewhat linear fashion, and that the mechanical advance stops at about 30 to 35* at some higher rpm,usually between 3000 and 4000 rpm.
 
If the engine rattles, the timing is too far advanced. Make sure your vacuum advance is attached to ported vacuum. That means at idle, there is no vacuum applied. As the engine RPM increases, vacuum is applied. There should be a vacuum port ABOVE the throttle plate that is ported.

To set the timing, disconnect the vacuum advance from the distributor and plug the line. Get a timing light and set the timing to 10* before top dead center. Reconnect the line and drive it. Readjust as needed. What I would do is advance it until it rattles on a slight incline going slow lugging in high gear, then retard the timing until it stops and lock it down right there. Recheck it with the timing light and record where it is so at the next tune up you will know where it likes to be set.
 
AJ/FormS said:
Maybe the fuel is contaminated, or just plain wrong.
Click to expand...
Along those lines, if the car has been sitting for a while, the fuel will be broken down and crappy and will tend to knock badly. Did you get all of the old gas out? If not, time to do that before you go ANY further. It will not just knock, but will varnish up the intake guides badly and cause the valves to stick/sieze (intakes in particular). That will cause bent pushrods.

Just dumping fresh fuel in with the old bad fuel will not fix this.
 
RustyRatRod said:
If the engine rattles, the timing is too far advanced. Make sure your vacuum advance is attached to ported vacuum. That means at idle, there is no vacuum applied. As the engine RPM increases, vacuum is applied. There should be a vacuum port ABOVE the throttle plate that is ported.

To set the timing, disconnect the vacuum advance from the distributor and plug the line. Get a timing light and set the timing to 10* before top dead center. Reconnect the line and drive it. Readjust as needed. What I would do is advance it until it rattles on a slight incline going slow lugging in high gear, then retard the timing until it stops and lock it down right there. Recheck it with the timing light and record where it is so at the next tune up you will know where it likes to be set.
Click to expand...

I found the port its supposed to go to on the carb. Thanks for the idiot check, unfourtunately routinely neccesary for me. idiot savant souds better than idiot alone...

But it ran far worse when I advanced it, clean up to the stop...took out the distributor and advanced a tooth sounded like gremlins hammering inside my bottem end. Did this two more times in either direction of origonal position but put it back how it was origonally. Pulled #1 plug and set the timing with actual TDC. Warms up and idles good, pull the stop off the port, no change-then connect vac hose and even in park it drops and sputters and jumps around like its not fireing on all 6 and will die every time unless you IMMEDEATELY pull the rpm up 3000 4000(but runs smooth dosent miss and sounds like a 10,000mi engine. The only way iv got it to stay alive is by setting the fast idle screw undrivably fast. Like a 35hundred neutral drop comming out of park. Even then it has to idle way to high to be good for the 904 sloshbox? Id expext it to get HOT if you rode the break all around town or had to stop at a light spinning 3k.
 
nm9stheham said:
Along those lines, if the car has been sitting for a while, the fuel will be broken down and crappy and will tend to knock badly. Did you get all of the old gas out? If not, time to do that before you go ANY further. It will not just knock, but will varnish up the intake guides badly and cause the valves to stick/sieze (intakes in particular). That will cause bent pushrods.

Just dumping fresh fuel in with the old bad fuel will not fix this.
Click to expand...

You never REALLY know till you put your own two eyes but, the guy i got it from pullepd the tank cheched and cleaned it. Dosent SMELL like it either andthe iv used more than 1 tank. It runs too good in the high end, dosent smoke. Tho ongly funky smell it makes is the lame-O fake spray on chrome finish on the tailpipe burning off.
I can get it to run really really good...way to good for something like that or valve issue...just wont idle all hooked up. Theres no obvious sign of rust/corrosion on the filler neck...im suspecting the distributor itself...or thethe guy who swithed it over from points in thee first place.
 
I don't see how anyone could come up with anything other than a guess or an oppinion with the information we have.

I didn't see any mention of a possible jumped timing chain (which could do exactly this)
or mention of TDC checking with the piston stop method to verify the balancer/timing mark position.

I'd start with those on an engine described by the OP.
 
It sounds to me like he is confusing ported with manifold vacuum. That would certainly cause what he is experiencing.
 
Stuupid question...would vaccume leaks bad ebough to cause this present itself all the time, getting worse with increasing rpm?
 
After rebuilding the engine the cam sprocket locating pin snapped off. As a quick fix had the sprocket spot welded to the center bolt and also where the pin should be. Long story short having almost the same issues. Distributer is reman plugs,wires ect...all new. I suspect the weld job isn't quite right and will investigate tomorrow.
 
InItSwingIt said:
Stuupid question...would vaccume leaks bad ebough to cause this present itself all the time, getting worse with increasing rpm?
Click to expand...
Vacuum leaks under the manifold that effect fuel/air mixture gets worse with higher vacuum conditions. With the throttle wide open, the effects are minimum, since the vacumm is close to zero.

Having said that, for a non-wide-open throttle, the vacuum WILL rise with RPM, and such leakage problems effects could get worse for small to modest throttle openings.

But you can quit guessing: just spray WD40 around any sealing point to the manifold (under carb or at manifold to head gasket) and see if it effects the idle speed and smoothness at a particular location.

If I can make a suggestion: This troubleshooting over the internet works best if you follow a procedure of steps to investigate A, then B, then C, etc., and let folks know exactly the result of each step. In clear language..... for example, the report of "idle OK crap top end" is hard to understand plus vague....what is 'crap top end' exactly? 1500 rpm sitting still in neutral, or 5000 rpm pulling up a mountain at 100 mph?
 
Back to flogging a dead horse, found my leak, carb gasket had halfway disintegrated. Probablu been leaking a long time, bozo thoroughly futsed the timing and idle mixture so as to "work" with a massive leak and no advance. Scares me ito drove it homeround that way. Everything is being set right. BTW will a huge crack in the exaust manifold cause any real harm other than sounding lame?
 
InItSwingIt said:
Back to flogging a dead horse, found my leak, carb gasket had halfway disintegrated. Probablu been leaking a long time, bozo thoroughly futsed the timing and idle mixture so as to "work" with a massive leak and no advance. Scares me ito drove it homeround that way. Everything is being set right. BTW will a huge crack in the exaust manifold cause any real harm other than sounding lame?
Click to expand...

It could. If it's big enough, it can cause bent exhaust valves. Cool air can enter through the crack after the car is cut off and hit the hot exhaust valves and cause them to warp and bend. Much like hosing off a piece of red hot metal with water.
 
^^^ Yep, or just provide enough oxygen to burn the edge and then you have a burned valve to replace. I have a very small exhaust leak at the manifold gasket that I will fix just to avoid these possible issues.

BTW, glad you found the core issue with the carb gasket.
 
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