Serious misfire issues after tune up on '86 (305c.i.d.) Silverado with HEI

[Greg!]

Figured this is getting crazy enough that it needs it's own thread...

I am having a multitude of issues with a newly purchased (Thursday last week) '86 long bed Silverado.

Vehicle specs:
1986
Chevy Silverado
305 c.i.d.
Firing order 1-8-4-3-6-5-7-2
HEI
Timing 4 degrees
Quadrajet
A/C (134a retrofit)
3 speed automatic
Longbed
Mechanical Fuel Pump
Dual Tanks

Now the low down:

Supposedly this truck had been sitting for some time after "a little old lady, who only drove it to church and the grocery store", sold it to a man who gave it to his son. The son "allegedly" wrecked it (and it does have a crunched passenger fender)...so the man took it back from his son, and so it sat.

The truck idled crazy high when I drove it home (so crazy high that the brakes felt like there was a brick wedged under the pedal at speed).

When I got home the timing was set at 45 degrees (wowsa)...so I reset it to 4 degrees (as per the label under the hood).

It ran so-so, with some sputtering on the low end...but ok at speeds...and the brakes worked fine.

I drove it to get new tires and tune up supplies, then I parked it on Friday, so that I could do the tune up this weekend.

Before the tune up Saturday I decided to fix the wobbly tilt steering column, put in new door lock cylinders (only had an ignition key), and fix a couple of dents in both doors (using the basketball/football trick).

Started the tune up on Saturday:

New plugs (went with a little colder plug 43 as opposed to a standard 45)
Plug wires
MSD Cap & Rotor
Fuel filter (internal Quadrajet)
Fuel pump
Belts
Thermostat (195 degree)
Air filter element
PCV
Fuel Lines (next to the pump)

I installed the fuel pump (with an ample amount of thick grease to keep the rod from falling down...tell me again why Chevy could not put a keeper or even access hole in the block to help with that's...never in my life have I had a mechanical fuel pump "just slip right in").

Pulled the distributor to install the cap, rotor, and inspect the weights. I noticed the inside of the distributor looked really bad and the weights seemed rusted in place. So, I took it apart and cleaned the weights, then put a small dab of lithium grease under each weight (yeah I know I didn't use dielectric grease).

Re-stabbed the distributor at 5:30...but it kept wanting to walk to 6:30 (and fall onto the oil pump rod)...got the oil pump rod turned correctly with my oil pump primer rod, and it dropped in at 5:30.

Changed the fuel filter (which looked like it had never been replaced).

Flushed the block & radiator. Changed the hoses & all four belts.

Changed plugs (gapped at 45) & plug wires...making sure that I ran the timing order of 1-8-4-3-6-5-7-2 (which has been imprinted into my subconscious since I was 16...so it has been there fe over 22 years)...I noticed that there were only seven wires in the box...so I had to use another known good wire.

Changed the oil and filter (Valvoline 10-30).

Filled the radiator with a gallon of the funky green stuff and the rest with water.

Went to fire it up...and that is when all Hades was unleashed...it was like I was opening a portal to the underworld it's self.

The truck was rocking like an off balance washing machine (you know the kind that overweight prom queens from years gone by sit on while their husbands are at work nailing their secretaries?)...the tailpipe started blowing soot and black smoke out of it...and I noticed something hitting the grass in the yard, by the tailpipe, which sounded like the kids across the street were laying a SEAL Team 6 reinactment of Zero Dark Thirty and I was UBL...remembering my training, I exited the vehicle, with it still running, so that I could charge my adversaries, with a thunderous war cry I ran past the tailpipe..."I'M HIT!", I cried. "Man Down! Medic!"...but my cries were not answered...instead I continued to get pelted by what felt like a bazillion BBs.

It was then that I noticed that the assault was not coming from some future special forces soldiers at all...but it was coming from my own truck (Dot "Dirty Old Truck")...she was attacking me! That Bi*#h!

Somehow during the tune up Dot's catalytic converter had decided to decentagrate and start barfing her insides across my driveway into my lawn...it literally looked like I had ran a drop spreader full of fertilizer across my driveway a couple times.

So at that point I called it a night.

Long story short...

I have since cut the cat out of the exhaust system, replaced it with a pipe (still have a muffler, although it is probably fully of BBs).

Replaced the HEI with a known good one.

Replaced vacuum lines.

And it is still running like it is missing, shaking like crazy, and blowing black smoke.

My thoughts now are either:

1. Drop tanks and check them for debris (from sitting with possibly old gas).

2. Carb decided to go bad at same time as Cat-Converter went bad.

3. Bad plug wires from my FLAPS.

4. Bad plug/plugs (or too cold of a plug.

5. Belts over tightened (addressing the washing machine effect only).

6. No clue?

Also when I set the timing I do block off the vacuum advance...but I cannot find any wire to unhook for timing adjustment...are '86s equipped with that? Or is that just a general "catch all" statement for adjusting timing?

Any and all help is appreciated...thanks in advance,
Greg!

[bake74]

     Sounds like you did everything as far as tuneup goes.  I am curious if you thought about doing a compression and leak down test to see exactly what is going on with the engine.
     Also curious about the 45 degree timing set you found.  How long did PO run it that way ?  Your cat exploding that way, how bad is the exhaust system been filled with carbon/unburnt fuel ?  Your probably right, the muffler is more than likely plugged.
     Wondering if by chance since you had such a hard time getting the dist. Back in properly if something inside the engine has jumped or slipped out of sync.

[Fairlane514]

Sounds like a timing issue. I would reinstall the distributor, starting over with the balancer set at 10 degrees before TDC.  After start up use a timing light and set it at 12-14 before TDC.

 Im not sure what wire you are talking about to unhook while setting the timing, you are only unhooking a vacuum line to the distributor and plugging the source.

I would lean towards a timing issue, since you removed the distributor and had problems clocking it upon reinstall.

When you say the truck was set at 45 degrees before you started working on it, was that total timing? 

[Boone83K10]

sounds like you have it stabbed at TDC on the exhaust stroke instead of the compression stroke. That means that it is firing 180* off. Find TDC on compression stroke by either using a piston stop or a straw in the #1 plug and watch it come up and then ever so slightly down. Pull motor back to TDC. Stab the distributor again.

Also, why would you go "colder" with a plug. Then it won't burn as hot and allows unburnt fuel down the exhaust.

Black smoke is almost certainly running too rich/unburnt fuel. Tune the mixture screws after you time it to 12-14 degrees BTDC.

[454Man]

To me it seems if you have
1.Installed the distributor wrong.
2. Bad plug wires.....
3. Plus gapped at 35. Would be better for a stock app.
Hope this helps

What's under the hood??? If you have to ask maybe we shouldn't race...

[454Man]

And one more....
4. Crossed plug wires...

What's under the hood??? If you have to ask maybe we shouldn't race...

[Greg!]

I appreciate all the responses

After reading all of the responses I am really hoping that I have the distributor 180 out, I have never done that before but it is a possibility (I have been reduced in life four years ago to selling my '68 shortbed and getting into aircooled VWs...so when my finger was over the plug hole getting it up to TDC then I thought the compression was a little weak...but it was still stronger than most VWs I have been dealing with

If I did that then I will fess up to it, and assume all razzing as you can throw at me.

Another dumb question...but I forget, can I just reverse the wires on the distributor to test it?

The timing was set at 45 degrees at idle before and I do not know how long it was set at that setting...but I believe that it was because the weights in the distributor were stuck possibly open.

If it is not 180 out then I am really thinking the FLAPS wires are bad...

[Greg!]

Well it was not 180 out (or at least by swapping the plugs in the cap it did not show to be 180 out)...when I tried it was actually backfiring thru the pipe and carb...and would not run.

Put the wires back to the normal spot on the cap and now it will not run at all, unless I pour gas down the carb.

So, now I am thinking that the tank is dirty (from sitting) and possibly clogging the fuel filter.

Next step is to pull the fuel line and measure the fuel flow...and try to inspect the fuel for debris.

One thing I can say is that it ran really good for the brief seconds it would run with just the gas poured down the carb.


Please tell me if I am way off base on my thinking.

[Greg!]

Ran a compression tester on the engine today.

Cylinder #5 showed 45 psi...all the rest showed 110-120.

My only guess at this point is that when the catalitic converter collapsed that is created enough detonation and back pressure in the cylinder to blow the rings on that cylinder.

I pulled the valve cover and the valves appear to be moving properly for that cylinder.

Any thoughts?

[VileZambonie]

Perhaps a stuck float, give the carb a few good slaps and see if you can get it to stop flooding. Sounds like your ignition timing is off as well. Ensure the firing order is correct.

[Irish_Alley]

put a cap full of oil into number 5 and see if it helps.

[Greg!]

put a cap full of oil into number 5 and see if it helps.

By "helps" do you mean that it will help with a compression test...or you mean that it will help quasi repair the poor compression?

I have heard of that before, and just don't understand the theory or longevity of the increased compression.

[rich weyand]

put a cap full of oil into number 5 and see if it helps.

By "helps" do you mean that it will help with a compression test...or you mean that it will help quasi repair the poor compression?

I have heard of that before, and just don't understand the theory or longevity of the increased compression.

If that helps on a compression test, that'll tell you that its rings.  It's not a fix, it's a diagnostic tool.  If it doesn't help, you can start looking at things like bent valves.

[Greg!]

Sounds good, thanks.

[Greg!]

And now there is gas actually dripping out of the spark plug holes.

This is getting awesomer by the day.

I took the carb off to start a rebuild on it this week.

Anyone have any advice on whom sells the best rebuild kits?