Tonight's Mystery of "How The Berk Was This Still Running?"

I was driving home Saturday night, minding my own business on a freeway, when suddenly POPOPOPPPOPPPPP *studder* POPOPPPOP clunkclunk pop pop pop. So I steer my trusty El Camino onto the shoulder to investigate. I can't find anything wrong. I barely get it started again, limp it to a gas station, and still can't find a damn thing wrong. It was a like a "run like E36 M3" switch was flipped and there was nothing I could do about it. Bad gas? Dropped a valve? About to blow apart the engine? No idea.

So I just start revving it out, figuring I have nothing left to lose, and that actually seems to help. Eventually it settles into a predictable state of runs pretty bad, but really likes WOT. Whatever, it got me home another 20 miles. 

Tonight I finally got a chance to look at it. With the engine running and dicking around near the distributor, I shocked the crap outta myself. I figured a cracked plug wire, so I turned out the lights and witnessed an intense electrical storm jumping between the dizzy cap and the firewall. Huh, that's not good.

So I popped the cap off and found this mess.

And a giant hole in the cap, leaking out them electrons all up in the 'bay.

Here's everything I could recover from under the cap. From left to right: mechanical advance spring (now stretched), buncha plastic chunks from rotor I assume, mech advance washers, pin, and broken circlip, mech advance weight (just one, the other is still on and happy with its spring), and one pissed off rotor with a bent contactor.

My working theory is the following:

1. Circlip gets tired and fatigue snaps.
2. Mech advance pin says F U I'm finally free and wiggles away.
3. Mech advance weight gets yeeted against the inside of the cap, probably run over a few times by the rotor, bending the rotor contact.
4. During this tornado of mechanical mayhem, plastic is getting chunked off everywhere in its path.
5. The parts eventually settle into the base of the distributor body, allowing the engine to run crappily.

I'm open to alternative theories. The Truth is out there.

The annoying part is I just replaced the cap, rotor, HEI, adv springs, and vacuum diaphragm last winter after 12 years and 40k miles of flawless performance. Guess I have new rebuild kit to buy, with pins and clips this time. 

Wow.  What a mess.  Be glad you made it home!

I'm now finding it impossible to source just the pins with e-clips. You can find weights, but no pins and clips. I don't want to replace the whole distributor, but that might be the safe bet. Might be damage I can't see.

+1 for new distributor. Even the good ones are less than most towing services. 

When I read the title, I thought: "SBC."

Oh look: SBC.

Grins.

A whole new distributor is pretty cheap...

SkinnyG said:

When I read the title, I thought: "SBC."

Oh look: SBC.

 

Yeah, same here. 

Floating Doc said:

SkinnyG said:

When I read the title, I thought: "SBC."

Oh look: SBC.

 

Yeah, same here. 

Well, yeah.

Every TV car show has cars that refuse to start, let alone run, because of some minor distributor issue and yours ran LIKE THAT?

I guess I need some HEI distributor recommendations for SBC? I don't know what brands are good anymore. This Summit store brand one lasted about 12 years.

In reply to maschinenbau :

Rock Auto sells good stock re-man ones. Better than the JEGS or SUmmit store brands. They are just Chinese junk. (Not that I am opposed to buying Chinese junk) I had a lot of issues with one of their GM style HEI distributors made to fit the small block Mopar. Module went ad, coil went bad, shaft seal started leaking, you name it. They refunded my money on it. I bought a reman off rock Auto and have been happy ever since. 

Why buy a blender when you can use an HEI distributor?

I heard they make great margaritas 

Proof positive that a small block Chevy will run like E36 M3 longer than most engines run at all.

Appleseed said:

Proof positive that a small block Chevy will run like E36 M3 longer than most engines run at all.

Came here to say this. 

My 2001 GMC Savana ran ok with 7 out of 8 wires arcing to the body inches away, a bad cap and worn plugs.  That slight low speed under a load stumble went away after a standard tune up.  How did it even run.

I like the old German Capri's and I very often look at YouTube videos featuring them.  There is a series of them posted about a group of Brits in the UK trying to get a first year  1969 Capri up and running.  They got it running in one point but determined that the engine was coming out to fix various things under the hood.  While the engine was out and on an engine stand they went and tore  it down to inspect it.  They found all of the main cap bolts on one side of the engine "LOOSE"!

In fact one of the bolts had come completely out and was laying in the bottom of the pan. How the engine ran that way, or for how long I find hard to believe.  

In response to the question posed in the title- Blind berkeleying luck.

SkinnyG said:

When I read the title, I thought: "SBC."

Oh look: SBC.

Grins.

A whole new distributor is pretty cheap...

+1 . SBC's Run poorly longer than many engines run

Okay I ordered a re-man AC Delco distributor off Rockauto. We'll see how long this one lasts.