Small block ticking noise

[smallblocksrock]

I just completed the build and break-in on a 340 and cannot find the source of a ticking noise.  The sound is similar to lifter noise.   It is coming from the #7  cylinder area.  Using a stethoscope on the valve train, I hear the tick, but it is not loud.  The ticking rate matches rpm.  So far I have changed/swapped lifters, rocker, rocker shaft and pushrods.  I also used a valve cover with the top cut off and can see that oil is flowing freely.  When I push a screwdriver down hard on top of a rocker while the engine is running, the sound is still there.   I cannot isolate the cause.

The noise stops when I pull the #7 plug wire.

Specs: new flat top pistons, stock rods,  new rings and bearings,  new cam with .480 lift, rebuilt X heads with a high spring rate, standard 7.5" pushrods, and 6 pack intake.  I am a cruiser, not a racer.

Thanks!

[Bullitt-]

  Just guessing it could be an exhaust manifold leak, they sound much like a lifter tick.

[smallblocksrock]

I already checked for the exhaust leak and replaced the gasket anyway.

[70 Challenger Lover]

Odd that the tick disappears when you remove that plug wire. So maybe it is not something rotating or moving but rather making a tick sound when that particular cylinder fires. I am also thinking gasket. Are you using headers? If so, perhaps a tiny crack in the tube near the head but on the backside where it isn't noticeable. A guy I know had a hairline crack in a header tube and he spent a lot of time chasing it down.

[JonH]

Bad plug wire or not on all the way? Ticking (snapping) is spark jumping somewhere

[340Challman]

Possibly you're hearing spark arcing. Check the insulation on the plug for cracks. Move the wire around to see if that has any affect on it. You should be able to swap #7 for a different wire and move the plug also. Hopefully the sound will move.

[Chryco Psycho]

I would put my $$ on exhaust leak , don't use gaskets they will cause leaks every time , I just use a thin layer of Ultra copper sealant & bolt directly to the head , the factory never used gaskets

[smallblocksrock]

Thanks for the suggestions.  I will work through the list today and report back.

[smallblocksrock]

So today I swapped plugs and wires with no change to the ticking noise.  I removed the exhaust manifold gasket (again) and took a closer look.
It appears there is exhaust soot on the manifold side of the gasket.  I was surprised how thin the #7 exhaust port wall is on the block side.  It does not leave a lot of room for a good seal.   I use Doug's Headers and they have a thick flange which I doubt allows much flex for a bad seal.
I have applied the Ultra-Copper, torqued the header bolts, and now waiting for it to cure.  We will see how it works tomorrow.

[70 Challenger Lover]

You may find a never ending problem with exhaust leaks from headers. I know some guys swear it's possible to seal them perfectly and permanently but I don't believe it. I have found they all develop leaks eventually. I used TTI at one point which are probably the best and I could never get the leaks to stop for more than a few months at a time.

[jimynick]

Well, here's the other side of that coin. My headers have been on for just shy of 5 years and don't leak, and I drive my car regularly. They're cheapies, too. What may have been my saving grace was that I took a large flat machinists file and by hand gave the weld beads on the manifold face a decent flat filing until I got a complete pattern on the whole circumference before mounting and also re-tightened them once they'd run a few hours. If you had access to a vertical mill, you could do a NASA quality job. Good luck! 

[smallblocksrock]

I have used Doug's headers using cheapo gaskets on two other cars with zero leaks. 

[smallblocksrock]

The winners of the online diagnostic testing quiz are those who responded with......   Exhaust leak

I sealed it up with Ultra Copper and it is now "tick free".

Thanks to all who participated.  Much appreciated.

[Scooter]

Glad to hear you got it sorted... did you use a gasket or just the Ultra Copper? 

[smallblocksrock]

No gasket. UltraCopper only.