Mystery knocking sound after rebuilding the top end

[Guanfy]

Got my truck running again but now there is a very obvious knocking sound that was not there before. I suspect I didn't get the valvetrain rocker bolts quite right. Don't think it's piston rod knock. Looking for some advice though. I had to replace heads after overheating due to rust clogging the cooling channels in the heads but I don't remember hearing this sound when I started the truck after it cooled down at the side of the road. Please see the attached audio file for a listen.

 

[Uncle Gump]

Definitely sounds like some valve train noise.... kinda also sounds like it's popping back into the intake.

You sure you have the plug wires connected right?

 

[Guanfy]

Reasonably sure. When I took it apart last time I marked the wire that went to cylinder 1 so I had a point of reference when it came time to install the wires again. Could have that wrong I suppose...

 

[alwaysFlOoReD]

I'm going to say its very easy to install the wires in the wrong order because that makes me feel better....
I didn't listen to the vid because I'm low on data right now.

 

[Guanfy]

Figured out the pop issue I think. I looked over the engine and found a loose spark wire on the plug side and a few wires that were not seating on the cap side. Still need to address the knock from the valvetrain though. I'll dig into that next weekend and report back.

 

[Guanfy]

Did some checking last night. I thought the timing was a bit off so I started working on that with a timing light and indeed saw it was off. Wasn't able to finish before I had to wrap up for the day. Question for everyone. When I line the 0 mark on the balancer up with the small blade to the left of 12 o'clock on the crankcase cover, that should be TDC right? And at that point the dizzy should be pointing at the number 1 cylinder post on the hat? When spinning the crank by hand I saw there are two times in the rotation of the dizzy that you get TDC. My plan is to have an inspection mirror so I can see when the piston is coming up to TDC on cylinder 1 so I can set it to the right TDC during the cycle of the dizzy. Just want to make sure that I am lining up the timing marks right.

 

[Guanfy]

So it turns out why I couldn't get the timing sorted was that the outer ring of the harmonic balancer has slipped, so the timing marks on it are no good. The backfire and clacking noise was a rocker that was loose enough that the pushrod it was supposed to be attached to was just sitting there, not doing anything. After reseating and retightening the pushrod and rocker, finally getting the timing right the engine runs great. The coolant system flush I'm doing is making all sorts of things leak but that is another story... Thanks to anyone who chimed in.

 

[alwaysFlOoReD]

Thanks for the update.