Thread: Did my 305 sbc bite the dust?

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I'm copying this from another forum:

I hope that's not the case but it didn't sound good. So, yesterday I went for a nice 44 mile round trip drive and the car was running great. Today I did some minor work on the electrical system (Installed a new alternator wire) and removed and rearranged some spark plug wires while I was at it... I went to start the engine and it cranked right up but it was knocking pretty loud and shaking...Almost sounded like it was backfiring or a piston hitting metal at the top of its stroke. I immediately shut it off and assumed that maybe I had installed the spark plug wires incorrectly, but the wires were fine

Troubleshooting:


#1 What changed.

#2. Look at the simple stuff first

#3. Change one thing at a time.

Hand crank the engine to compression stroke cylinder #1

Verify the direction of distributor rotation

Verify the rotor points to #1 wire

Verify firing order.

How did you rearrange the wires? Might have some crossfire somewhere in the ignition. The spark may be jumping from the wires to ground or to each other if the insulation is bad enough. Could also be crossfiring in the cap.

Originally Posted by Hotrod46

How did you rearrange the wires? Might have some crossfire somewhere in the ignition. The spark may be jumping from the wires to ground or to each other if the insulation is bad enough. Could also be crossfiring in the cap.

I just removed 3 spark plug wires from the distributor to organize them better and put them back on... I also moved the electrical junction point where the alternator/ignition/starter wires connect. However, I don't think messing with those electrical wires would cause the engine to misfire and knock loudly. At this point I am suspecting a broken timing chain as I think I might have heard some rattling the 2nd time I restarted the engine. I will confirm tomorrow.

OK, it's tomorrow. What did you find?

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Originally Posted by techinspector1

OK, it's tomorrow. What did you find?

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Just what I was afraid of... pushrods and valves that came apart (cylinder 7) I was able to pull out one of the push rods by hand, it was totally lose but not bent, the other one seems to be stuck but I can't tell if it's bent. I'm currently trying to figure out how to upload pictures here.

How can I attach some pictures?

This is what was causing all the clunking...that second from the left pushrod was totally lose and i was able to pull it out by hand

Conventional rockers used on L31 head. OUCH. Needs rail rockers or mill pedestals, drill and tap for screw-in studs and guideplates.
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