Chinese distributor dead, under 5,000 miles

[mcintyrederek]

This is a follow-up on a previous post about the 350 running rough and I blamed the carb (which could still need attention).

I bought a no-name distributor off Ebay a year ago, for $39 or somewhere around there, and it was called a 65K HEI distributor.  It looked nice, so I bought it.

It seemed to work fine for a while and then I got hard starts, and now the bad idle problem.  I finally took it out and the attached pics is what happened.  The button is burned to a nub and it's obvious it has been arcing for a while.  What would have caused this problem?

I have since rebuilt my old original Delco Remy distributor and will probably get it back in this weekend. 

I do know the ignition wire going to the Delco has the voltage drop resistive wire in line with it which drops the B+ down to about 8 or 9 volts.  The Chinese thing probably calls for a fill 13.8 volts, and hind-sight says this could be what damaged it.  Your thoughts please.

[timthescarrd]

I've been running a Chinese dizzy similar to that one for 3 years now with no issue.  Under-voltage could certainly cause that, the point of the coil on top is to increase the 13V your truck is giving it up to around 50000V (They claim 65K but few get there) so that may be it.  Is the Delco an HEI?

[zieg85]

Before scrapping the distributor try a Delco cap and rotor and go back to a regular HEI coil.  My $.02.  Worth a try?

[mcintyrederek]

I am not really sure if the Delco is an HEI or not.  The coil is built into the cap and there is a small electronic module mounted inside with two prongs on one side and two on the other..  It looks the same as my '85 Monte Carlo but it does NOT have the external connections for the ECM.  It only has a BATT, GND and TACH terminals.

It was working fine before I changed it, but the vacuum advance was not working (I got that fixed now).  That was the only reason I changed it to begin with a $40 for a whole new unit seemed too good to pass up.

Other hot-rod forums turn up some negative reports on bargain distributors.  My timing mark was all over the place and several others have said the same thing.  My original Delco would be so steady you couldn't even tell the crank was moving.

[bd]

I've encountered that same scenario even with factory HEI, several times - lol.  It probably isn't "Chinese manufacturing" so much, as an unnoticed "gap" between the distributor cap's carbon button and the rotor center wiper contact, a 'gap' between the carbon button and the coil terminal due to a 'sprung' or missing contact spring, a bad coil (as in perforated insulation), or a poor dielectric seal between the coil and cap from a missing or uncompressed gasket.  I tuned up an engine with HEI one time that had the carbon button and cap burned similar to yours - that is, similar except for the 1-1/2" diameter cavern where the button was supposed to be.  It ran great and had a textbook perfect scope pattern!  Haha.  Couldn't believe it!

I agree with Zieg.  Replace the cap and rotor.  When you remove the coil to transfer it to the new cap, look closely at the underside of the coil and inspect it for evidence of heat stress and arcing.  Don't reuse the coil if the insulation appears compromised.  When you install the cap and rotor, smear some dielectric grease on the carbon button and lock the cap down onto the distributor housing.  Then, remove the cap and make sure the carbon button is making contact with the rotor's wiper contact by inspecting for a witness mark.  You may need to arch the wiper contact upward a little to ensure there is no gap.  You should also smear a little dielectric grease on the eight high tension terminals that protrude inside the cap.

--------------------------

You posted a comment that caught my attention: "... the Delco has the voltage drop resistive wire in line with it which drops the B+ down to about 8 or 9 volts."  Rest assured you do have HEI, yet HEI uses no such resistance wire.  Explain what you mean in greater detail or post a pic.

[mcintyrederek]

Maybe this was for points style systems only. 

Copied and pasted from a Wiki article.

...the ballast resistor unit (early vehicles)or ballast resistor wire feeding the points-type coil needs to be bypassed with regular copper wire. This is because the points system used this resistor to reduce the voltage to the coil to around 9 volts while the ignition switch is in the "run" position to prevent overheating the points. The points system has a "bypass" wire from the ignition switch or the starter solenoid to deliver full battery voltage to the coil during cranking. The HEI system needs the full battery voltage at all times to work its best. One common hookup method is to replace the ballast resistor or wire with a normal copper wire and attach both wires to the HEI's power input terminal. This ensures the HEI receives full power while running.

[bd]

Yeah... your 86 came with factory HEI and no resistance wire.  The distributor receives full primary system voltage.

[mcintyrederek]

Just to keep beating the subject to death, here's another pic.  The red one obviously from the "new" discount distributor.  The beige, my stock Delco piece that was pulled from an engine with over 200K miles on it.  Notice the 1/16" or better difference. 

The discount distributor looks great otherwise.  The mechanical parts anyway..  Like someone mentioned above, you could probably change the cap, carbon button and rotor and it might work fine.  The metals used in China to build this must be something to the consistency of melted down coat hangers.

A $39 lesson learned.  Glad it didn't just kill over on the highway.

[csdineley]

I had the same thing happen to my cheap 65k distributor. For me it was right after rebuilding my carb and I was testing and tuning when it went out. I replaced the cap and rotor with AC delco parts and it's been running great ever since.

[mcintyrederek]

Thanks for the reassurance that I'm not the only one who has had the problem.  The rest of the unit looks GREAT.  The button and rotor contacts, not so great, as we have seen.

I started noticing hard starting as first.  That's when the coil was getting the least amount of power obviously, with the starter running, the B+ voltage down into the 10 or 11 volt area with a halfway decent battery.  Later on the idle was getting crappy.  I blamed it on a bad Quadrajet idle problem which wasn't the case.

I have since freshened up the old original Delco with a new button and rotor.  I have yet to put it on but I'll be very surprised if that doesn't fix pretty much all that was wrong with the whole thing.

[Irish_Alley]

like others i wouldnt put the blame on the Chinese parts 100% yet, if more people have this problem then yeah. but from working at autozone ac delco parts can be bad right out of the box.

[blazer74]

Lot of AC delco parts are made on China.


Sent from my iPhone using Tapatalk

[mcintyrederek]

Yes but the ones I am using personally on this project are made in the U.S.  or... at least, that's what is stamped on the items.   

[mcintyrederek]

The rebuilt Delco is working great but I have run out of room to advance.  Just to be sure I'm not thinking backwards here...

Turning the unit CCW will advance the timing.  I am running at about 4 degrees advance now, and have run out of room.  The vacuum canister is hitting the air cleaner.

To correct this, I need to mark the distributor and rotate clockwise exactly 45 degrees, then move plug 1 where 2 is, plug 2 where 7 is, plug 7 where 5 is, and so on.  Then I'll be right back where I started, except now I'll have more room to turn the unit CCW to further advance the timing without hitting the air cleaner.

I don't know how my #1 got where it is now.  Seemed like when I pulled it out several years ago, #1 was facing the intake.  Now it's facing the passenger fender.  I don't guess that matters, though, does it.

See pic.

Thanks.

[timthescarrd]

All the GM HEI's I've worked with, #1 is where your #5 is, not sure how you'd move that so hopefully someone else will chime in