NEW PROBLEM(S):

[Stewart G Griffin]

i have determined--------through a "strong hunch" (NOTE:i know absolutely zilch about distributors and ignition systems in general) that the distributor body, cam gear, shaft and bearings are ok.  Despite my non-knowledge of distributors, i can still visually see and sense that the above mentioned items are ok;  Thus, this strongly must mean that they probably are?

So, i've decided to swap parts from the not-being-used ESC distributor to the present distributor in the truck----because it's probably wiser and more efficient this way, but also because i don't want to get into having to take the distributor out and put a different one in. i think i can swap everything except for the module?   First, i plan on swapping out the vacuum advance thing---because, i believe, that symtoms suggest that this is the problem.

Anyways, upon starting to take apart the not-being-used right now ESC distributor, i can see that the vaccuum advance thing pulls on the larger "star wheel" thing making it go counter-clockwise.  Since the rotor and shaft and smaller "star wheel" turn clockwise, this means that when the larger "star wheel" thing  gets turned counter-clockwise, the electrical contact will happen sooner---thus advanced timing?

When both sharp points of both star wheels line up, this produces a magnetic signal which is then sent to the module which then sends the signal "upstairs" to the coil which then sends this to the rotor, and depending on which post on the dist cap the rotor is pointing to will send the electrical signal to the corresponding spark plug thru the plug wire?

Assuming the above is true, (more or less) what i can't visualize is how the centrifical advance works.  i know what is for----as the engine rpm increases, so does the distributor rotor's rpm and these weights are supposed to swing outwards somehow advancing timing which the engine really needs at higher rpms.   
But i can't visualize it like i can with vacuum advance because it seems like these weights are above where the "star wheels" are.

Could you explain to me how centrifugal advance physically works to advance timing?

i know it may be hard to do without pictures, but i have a distributor sitting right in front of me.

[Irish_Alley]

sounds like to me you just might need a tune up, also if your going to do the distributor thing then just switch it. might as well instead of just leaving the pick up coil that lil star thing you keep on talking bout and changing everything else. i really don't know if it will help but its easer in my opinion to change the who thing instead of working with the icm, va and Pu coil. I'm trying to think about when my 86 was acting up think it was the timing but want the only prob think the carb need adjustment also. pull the vacuum line off the advance and see if anything changes.

[VileZambonie]

Just spend $50 bucks and get a new loaded distributor Click here

The HEI system utilizes an all electronic module, pickup coil and timer core in place of the conventional breaker points, condenser and distributor cam. In addition, a specially designed ignition coil, distributor cap, rotor and high tension leads are used to provide and distribute high intensity secondary system voltages to the spark plugs. 
The magnetic pickup consists of a rotating timer core attached to the distributor shaft, a stationary pole piece, permanent magnet and pickup coil. When the distributor shaft rotates, the teeth of the timer core line up and pass the teeth of the pole piece inducing voltage in the pickup coil which signals the electronic module to open the ignition coil primary circuit. Since this is a full 12 volt system that does not use a resistance wire, high current saturation occurs in the coil primary windings. Maximum inductance occurs at the moment the timer core teeth are lined up with the teeth on the pole piece. At the instant the timer core teeth start to pass the pole teeth, the module opens the primary circuit, and the current decay causes a high voltage to be induced in the ignition coil secondary winding. The high secondary voltage is directed through a specially designed cap, rotor and high voltage leads to fire the spark plugs.
HEI systems use conventional vacuum and centrifugal advance mechanisms. The vacuum diaphragm is connected by linkage to the pole piece. When the diaphragm moves against spring pressure it rotates the pole piece allowing the poles to advance relative to the timer core. The timer core is rotated about the shaft by conventional advance weights, thus providing centrifugal advance.
Some models are equipped with and Electronic Spark Control (ESC) system that controls spark timing in order to provide maximum engine performance while preventing detonation. The ESC system consists of an engine mounted knock sensor and an electronic controller. ESC is a closed loop system that monitors engine detonation through a sensor and constantly adjusts ignition timing to provide the maximum usable spark advance while preventing prolonged detonation.
The ESC knock sensor monitors the presence and intensity of engine detonation by sensing the resultant vibrations. The sensor produces a voltage signal which is proportional to the intensity of the detonation and this voltage signal is transmitted to the controller. The ESC controller is a hard wired signal processor/amplifier that operates in the 6-16 volt range, and has no memory storage provisions. The controller monitors knock sensor voltage output, processes these signals and controls the amount of spark advance through a special circuit in the HEI ignition module.
In addition, models with automatic transmissions include an ESC vacuum switch. The vacuum switch provides a signal to the ESC controller during throttle tip-in which causes the module to momentarily retard spark timing to prevent detonation on acceleration.

[Stewart G Griffin]

thanks for the link, but what brand are these distributors and where are they made?   In china perhaps?

Because in order to sell it that cheap and for the seller to make a profit..........etc. etc. etc.......

[VileZambonie]

I'm sure like everything that is manufactured for sale for our "American" vehicles it was made overseas. Nevertheless I know several people that have used them. I am putting one in a 68 firebird next week that the guy wants to convert to HEI. He bought it from the same seller. I'll let you know how it goes if you want.

[Lt.Del]

the seller has terrific feedback.  That's what I look at when buy from that site.

[Stewart G Griffin]

Yes, please let us know how it goes.  To be honest, i'm very skeptical at a $49 brand new distributor no matter how shiny.

2) i just grabbed the bottom of the distributor at the cam gear and found out that the part where the centrifugal weights are actually can turn independent of the shaft clockwise---which advances timing.  So now i basically, as far as the physical part of it, understand how a distributor works which considering just two days ago, i basically had no idea, is pretty amazing.

[JJSZABO]

I installed one in my sons truck and it works GREAT.  It has WAY too much advance so I installed one of these  Crane advance kits from Summitt Racing:



http://store.summitracing.com/partdetail.asp?part=CRN-99600-1&autoview=sku

and installed it in accordance with this article:

http://www.73-87.com/7387garage/drivetrain/hei.htm

Hope this helps - good luck.

[Stewart G Griffin]

Alright what just happened is i swapped vacuum advance canisters---and no improvment.

So, what else could be causing the following symptoms:
The engine will stall out unless i rev it to at least 1000rpmish.  If i release the accelerator it engine goes to 700-600-500  and then stalls out---this is in neutral.  And this condition just started 4 days ago.  Before this it ran just fine.

Let's assume:
1)it has nothing to do with the carburetor and/or fuel system.

2) The distributor body never moved (counterclockwise or clockwise) thus the intial timing could not have changed from 4 days ago.  So this is a very strong assumtion with good supporting evidence---i couldn't rotate it.

3) All vaccum lines are good ( i checked)

4) All plugs and plug wires are good (i also checked)



So what else could be causing the above problem?  Remember that the engine runs ok, more or less, above 1200 rpm.
 

[VileZambonie]

cup your hand over the airhorn on the carburetor and see what it does.

[Stewart G Griffin]

i was hoping we could just assume it's not the carb or fuel system for now.

Alright let's say i do put my hand over the the horn;  What is this supposed to or not supposed to do?



2) P.S.
when examining the inside of the distributor today, it looked all crusty.  The weights had an orange/brownish appearance as opposed the normal silver color.  Also, i could not move the vacuum advance by hand although that has turned out not to be the problem.  The person i bought the distributor from said, i believe, from a 76 chevelle.  So, the distributor may very well be 33 years old.

3) So what "brand" are these razzle-dazzle distributors everyone has taken a shine(pun intended) to?

[VileZambonie]

Does your truck have EGR?

Restricting the air flow will help us determine if it is a lean condition or not

You probably saw insulation crumbling from the pick up coil or rust from around the pole piece

What are you looking for in a replacement distributor? Performance? Oem?

[eventhorizon66]

I think the biggest "razzle dazzle" brand would be MSD.  That's what mine is - an HEI Pro Billet.  But if I had it to do all over again, I would have just freshened up my stock HEI with this kit from Petronix.  Probably would result in about the same performance for about $250 less than the Pro Billet.

If you want a 100% new distributor, this one looks nice, but I have no experience with it.  Looks like my distrubutor but with the lower grade module (still better than factory) and cast aluminum housing (as opposed to billet).

[Stewart G Griffin]

By "razzle-dazzle" i mean the $49.95 ebay unit that everyone is holding in high esteem.

1) yes, i have egr

2) as far as replacement(s), i would prefer oem---i'm thinking ac delco, anything known name brand and good quality.  The GM performance parts one, i originally, thought was too hi-po, but after doing more reading on distributors, i'm thinking it might, with it's curve, be really good with the 350 crate engine i have.

More info on the situation:
the engine starts fairly easy.
the idle speed screw is not the problem because i just tell it isn't

Actually, let's just rephrase the whole question:
The engine will not keep running unless i gas it up to 1000rpm or so.

[VileZambonie]

Make sure the egr isn't hung open.