Chinese distributor dead, under 5,000 miles

[bd]

Well, the way you have the distributor wired in the image, #1 actual is directly over the vacuum advance can already - where you have indicated #2.  The firing order in your image is off of actual by one position CW.  So, moving all of the wires as you intend will in fact place #1 actual where #7 is in your image.  That's only one position off from the original factory position pointed out by timthescarrd.

Instead, why not properly locate TDCC #1 and restab the distributor, so #1 and the vacuum advance are where they belong?  And while you're at it, verify that the harmonic balancer hasn't slipped and the timing marks are correct.  Then you will have a known base for your tuning efforts.

[mcintyrederek]

I'm not sure how that happened either.  You're right, it seems like when I got the truck, #1 and #8 were facing the intake.  Now they're 90 degrees clockwise.  The oil pump drive slot is just that, a slot, like a screwdriver blade.  So how the heck the rotor got 90 degrees out is beyond me.

At this point I really don't care where the numbers are.  The rebuilt Delco runs excellent and it fires up & runs just with a bump of the starter; something it hasn't done in a while, so I'm not messing with it.  I'll just live with the numbers being rotated.

[mcintyrederek]

Does it make a difference where the numbers are at?  As long as rotor is pointing to the #1 plug wire when piston #1 is at TDC compression stroke, does it matter? 

Harmonic balancer came on the engine from the factory, has never been changed.  Timing mark shows up where it's supposed to and engine is set for about 6 degrees advance, initial timing.

[bd]

Does it make a difference where the numbers are at?  As long as rotor is pointing to the #1 plug wire when piston #1 is at TDC compression stroke, does it matter? 

It doesn't matter where #1 is as long as the individual wire lengths allow a proper fit and routing.

Harmonic balancer came on the engine from the factory, has never been changed.  Timing mark shows up where it's supposed to and engine is set for about 6 degrees advance, initial timing.

Here's the reason behind my earlier post:
The outer ring of the balancer that bears the timing mark attaches to its hub through an elastomer (flexible) band.  Although your balancer maybe in perfect condition, with age and use the bonds between the outer ring, elastomer, and hub often weaken to the point that the outer ring migrates around its hub, throwing the timing marks off.  The process is gradual, but occurs frequently enough that it is worth checking as a precaution once a balancer has accumulated +20 years (±200,000 miles) of use.  When timing is set based on a mark that has shifted, performance suffers.  This isn't to imply that your balancer isn't serviceable.  It is just an added precaution.

[mcintyrederek]

I will certainly check the balancer.  I am now questioning if the timing mark is actually in the right spot.  I am going to pull the plugs out again and verify that #1 is at TDC when the timing mark says so.

[mcintyrederek]

With the Q-jet carb, stock cam, stock-build 350 engine and the Delco dizzy, would it be best to run vacuum advance on full manifold vacuum or just use "ported" vacuum like it's on now?

Looks like most people are recommending setting the initial timing to 10 degrees advance.  If I plug the vacuum advance canister into full manifold vacuum, the engine runs crappy. 

Your thoughts please.

[mcintyrederek]

I am beginning to wonder if I am seeing the symptoms of a bad distributor CAP.  The timing light is flashing all over the place like a disco party and it's flashing at multiple times on the harmonic balancer like a disco party.  I have cylinders that are misfiring, I can tell by the way it sounds out the exhaust. 

If a cap goes bad or gets a hair-line crack in it, could it cause firing at multiple places and cause the timing light to go a little crazy?

[bd]

Although a cracked and/or carbon tracked distributor cap can cause misfires and spark scattering, you just put a new Delco cap on it.  Check the spark plug wires.  When you 'rebuilt' your HEI distributor, did you reinstall the coil frame ground strap?  Did you install the carbon button above or below the silicone gasket?

Some timing lights are hypersensitive when used with HEI and similar electronic ignitions.  Try moving the inductive pickup to a different spot on the wire.  How did you route the plug wires?  You may be arcing to ground or getting a little crossfire.

[timthescarrd]

check where your spark plug wires are routed, the drivers side bank is odd 1,3,5,7 from front of engine to back, passenger side is 2,4,6,8

[mcintyrederek]

Plugs are going to the right place, just checked again. 

I did NOT put a new cap on the distributor when I rebuilt it.  I did put a new bushing, pinion, HV coil, carbon button, silicone gasket, switching module with heat sink compound, rotor, and AM radio interference capacitor thing.

I just cleaned up the old cap and dremel tool'ed the contacts with a wire brush attachment.  This cap is probably an original from the mid-80's.  I have a neon sign transformer I could test the cap with but at $15, I should just buy a new one.

Yes I am positive I installed the coil/frame ground strap as well.  I'm going to take the cap off once more and just check to be sure I didn't miss something.  I'm usually pretty detailed and meticulous when it comes to rebuilding or repairing things but I could have missed something.

[mcintyrederek]

It looks like I found an answer to "when should you replace the cap.."  I guess treating it like all other ignition parts, plugs, wires, etc.  I never thought about it, so I'll get a new cap from NAPA tomorrow and give it a try, for $16..

Copied & pasted from a Yahoo conversation.

Best Answer:   Yes, they should all be replaced at the same time. The life expectancy for the cap, rotor, plugs and wires is all about the same - 50K miles. Of course, that assumes you have a car or truck old enough to have a distributor.

The rotor is actually pretty reliable until the spring and contact on the top give out, but it can arc through to the shaft. When that happens the engine dies like you turned off the key. The caps are more vulnerable. They tend to "track" - contamination builds up on them until high voltage finds a way from one of the towers to the base where it fastens to the distributor. At that point the track burns into the plastic and creates a carbonized path so cleaning the cap won't help... the engine develops a steady misfire on that cylinder. Besides ruining the power and fuel economy it will kill the catalytic converter rapidly (as little as 12 seconds) at freeway power. Spark plug wires fail either as the resistance increases or the insulation fails. High resistance wires are a common cause of igniter failure in Honda vehicles.

[bd]

When you replace the cap, make sure to install the carbon button below the silicone gasket, so the button's flange is caged between the gasket and cap.  Inspect inside the old cap before removing the coil to make sure the coil retaining screws didn't penetrate far enough to perforate the cap, or you could wind up in the same soup.

[mcintyrederek]

I will certainly check the gasket and button placement.

Thanks for the advice, everyone.

[mcintyrederek]

Got time enough to pull the cap off today and the broken button is what I found.  The bottom half just dropped out and the top half with the spring still hooked to the coil.

This would explain why it worked just fine several days ago.  It must have been weak and broke on the road. 

Do you think a new cap at NAPA will come with a new gasket and button as well?  Would this broken button cause timing light errors/scattering and obviously misfiring?

Going to replace the cap anyway just as a precaution and because I know it's old.

[bd]

That broken button could be the cause of the misfire.  Better take a look at the rotor wiper contact too and make sure it isn't twisted or bent.  Replacement caps typically are packaged with four new coil retaining screws, the carbon button and a silicone gasket.