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Discussion Starter · #1 ·
OK guys,

Been playing with my '74 BB Truck and cannot for the life of me get it running right. It has a "bluh bluh bluh" type idle, not much better on fast though it will kind of pick up, BUT, it shakes a bit too. Its better after new plugs, but still not quite right, read on.

I took a Compression test and the readings were pretty consistant, not one significantly higher or lower than the others, here are the readings by their proper number (not 1234 down drivers):

drivers side:

1: 130
3: 125
5: 135
7: 140

Pass. bank:

2: 140
4: 130
6: 130
8: 135

This was on a cold engine, throttle and choke wide open. How much difference does warming it up make?

Anyhow, thats not the whole story, not by a long shot. Cylinders number 1, 4, 7, and 8 had their plug gaps CLOSED! Yes, I said that right, CLOSED! :eek: #8 wasnt as bad as the others, but it definitly was closed. The others look like the electrode (the part hanging down, L-shaped) was smashed right up into the plug, two were off to the side a bit.

What do ya think caused that?

Anyhow, got the plugs changed and it still runs like dog crap. Has much more power, but still, isnt right at all.

Setting the dist at 5 degrees BTDC causes it to kick back on starting. I replaced the coil and box, still same deal, except now it pops back through the carb on acelleration unless you do it GENTLY!

Vacuum still reads 15, and the needle fluxuates. Setting the carb manually on fast idle will bring the vacuum up to 18. The choke will stay open and if you close it, it will try to die so I dont think there is a vacuum leak present.

So, whats up here???
 

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what is oyur piston to valve clearnce, only thing i can think of to explain the smashed electrodes is a piston hitting them.

has this engine been worked over at all?

eric
 

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Discussion Starter · #3 ·
As far as I knbow and can tell its all stock. I'm wondering if it might have had a nest in the intake or soemthing got through and made it to those cyls. The new plug in #1 came out after running, it was fine, but blackened from it not running right. I'm going to pull the other plugs and have a looksee.

Discount the timing chain idea, it wouldnt run very well or have any compression if that skipped.
 

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did they have the right size plugs in?
did the balancer outside ring happen to slip and have your timing marks off maybe? maybe double check that timing

other than that i would try a complete tuneup and possibly a carb rebuild.

eric
 

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Discussion Starter · #5 ·
I'm betting on the balancer ring being slipped now that I think about it. Plugs were the right ones. Carb is also good, it came off another car I drove daily, its been rebuilt as well.

So now it has new plugs, known-good coil (it ran another car well), known-good ignition box (again, ran the same car and well, that one lit the tires up nicely), and for sure good wires.
 

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Another member of this site's engine kinda did the same thing when i set his timing to specs. I thought the damper slipped but he went ahead and changed the timing chain and now it runs alot better and the timing can be set to spec and idles great. So there is the possibility that your timing chain could be bad. Its possible you had mud dauber nest in your engine while it sat causing the electrodes to get bent.
 

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if the electrodes get bent again, the problem would have to be clearance. could be buildup on top of the pistons caused by dirty air/fuel mixture, bad valve guides letting oil in and then not getting burnt 'cause the plugs weren't firing. This debris will have to be cleaned out somehow before the bb will run.
 

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Discussion Starter · #8 ·
I checked the electrodes again, they were fine. It runs marginally better now that the tank was ran out and good gas was added (It even had its own dedicated fuel supply for good measure). Still dont sound right though, unless they all have a "Blub Blub Blub Blub" sound from a single glasspack exiting in front of the axle. Power seems to have improved and they are right, the trans is really slipping in Drive. I think with a good trans and some driving it should clear up!
 

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Sticky/burnt valve?
Is the guage fluctuating or fluttering?
-Steve C.
 
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