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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: mcintyrederek on July 16, 2015, 07:15:05 pm

Title: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on July 16, 2015, 07:15:05 pm: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: timthescarrd on July 16, 2015, 07:22:10 pm: 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?
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: zieg85 on July 16, 2015, 07:24:00 pm: Before scrapping the distributor try a Delco cap and rotor and go back to a regular HEI coil. My $.02. Worth a try?
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on July 16, 2015, 08:42:08 pm: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: bd on July 16, 2015, 08:48:08 pm: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on July 16, 2015, 09:33:23 pm: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: bd on July 16, 2015, 11:19:40 pm: Yeah... your 86 came with factory HEI and no resistance wire. The distributor receives full primary system voltage.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on July 17, 2015, 06:29:20 am: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: csdineley on July 17, 2015, 07:04:00 pm: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on July 17, 2015, 10:36:17 pm: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: Irish_Alley on July 18, 2015, 07:42:25 am: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: blazer74 on July 18, 2015, 12:22:14 pm: Lot of AC delco parts are made on China.

Sent from my iPhone using Tapatalk
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on July 18, 2015, 04:22:51 pm: 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. :D
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on July 18, 2015, 04:26:34 pm: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: timthescarrd on July 19, 2015, 08:20:44 pm: 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
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: bd on July 19, 2015, 09:43:29 pm: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on July 20, 2015, 06:32:33 am: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on July 20, 2015, 06:39:30 am: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: bd on July 20, 2015, 08:52:10 am: Quote from: mcintyrederek on July 20, 2015, 06:39:30 am
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.

Quote from: mcintyrederek on July 20, 2015, 06:39:30 am
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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on July 20, 2015, 04:14:51 pm: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on July 20, 2015, 04:17:35 pm: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on July 20, 2015, 05:09:32 pm: 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?
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: bd on July 20, 2015, 05:24:56 pm: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: timthescarrd on July 20, 2015, 06:03:57 pm: 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
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on July 20, 2015, 08:11:24 pm: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on July 20, 2015, 08:22:10 pm: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: bd on July 20, 2015, 08:35:13 pm: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on July 20, 2015, 08:41:21 pm: I will certainly check the gasket and button placement.

Thanks for the advice, everyone.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on July 21, 2015, 02:47:23 pm: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: bd on July 21, 2015, 03:27:03 pm: 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.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on July 21, 2015, 03:32:52 pm: OK that sounds good. The rotor blade/wiper is straight and clean, not twisted. On my way now to pick up new cap, dielectric grease, silicone boot and carbon brush.
Title: Re: Chinese distributor dead, under 5,000 miles
Post by: mcintyrederek on August 03, 2015, 06:37:21 pm: Thanks for all the replies and information. It turned out to be a problem with several different things. I believe I also had a problem with the hall effect switch and the coil. I pretty much did a complete tear-down and rebuild of the distributor and it worked great. I am using a good quality cap and rotor, and Belden plug wires and new AC plugs. The ignition system is working correctly now.