Chevy Engine Guru help needed.. (ticks under load)

[Tonka]

77 350 w/041 heads, unknown date of last rebuild if ever, holley 4 barrel recently rebuilt and tuned, MSD billet ignition timed by local shop (as well as carb final adjustment), Engine starts right up, idles beautifully and pulls pretty hard. Seems to run great. However...
I thought the ticking sound I heard was an exhaust leak. It is only present when the engine is under load as in, in gear and driving or in gear with brake depressed and slight throttle press.
If you let off gas while driving it stops so it is not something to do with the running gear. The reason I thought it was an exhaust leak is after final assembly it was on open headers (glorious sound I might add) for about a hundred miles while we finished the build. But when I had the dual exhaust hung up that is when I noticed. I cursed the muffler shop and attributed it to their seeming poor fitment of the collectors to the pipes.
Just this weekend I installed an aftermarket oil pressure gauge (knee knocker) and it is getting 30-35 psi at start up and around 15 once warm (at idle).
I climbed under the truck, had my buddy put it in gear, press the brake and give it slight gas. The ticking sound turns out to be coming from the engine. Possibly bottom end at least thats where I was when I diagnosed this (under the truck laying down).
The engine ran great when I bought it and I did not notice the tick then. Truck was immediately torn down and a 4 year restoration took place. After restoration I changed the oil, plugs etc and ran the engine.
Is the knock or tick or ping the result of carbon build up? Would this be the exacerbated by the fact that the engine had not ran in 4 years? Do I have rod knock? Is the engine out of timing and what I'm hearing is pinging?

Thank you for reading this lengthy post but I wanted to help with as much info on this issue as possible.

[rich weyand]

It may be nothing more than header slap.  Exhaust pulses hit the bend in a header, and the thin metal ticks.

What headers are they?

One thing you can do to see, is to have someone rev it in gear as you did, then use a piece of 1/2" hose as a stethoscope and see if you can localize the sound more.  Another is to have them rev it is gear, and then touch and gently push on each header tube about 6" out from the engine (i.e. after the bend) with a 1x2, and see if you can change or muffle the sound.

If it is header slap, then it's not a problem.  That's just how some headers are.

[LTZ C20]

If it's header slap, you can put a new insulation pad on the under side of the hood. It absorbs the sound so you don't hear it. It's not harmful but can be annoying, my buddy did the insulation and now he doesn't hear the tick.

[Engineer]

Here is a free (will not cost you a dime) tip based on the fact that I can't hear your tick over the www.

Check all of your spark plug wires to be sure you don't have one "leaking". Occasionally a spark plug wire that is jumping fire will give a tick that sounds like a lifter.

Under a load your engine demands higher ignition voltage to arc the gap on your spark plug to overcome the higher combustion chamber pressure. This rise in voltage could be just enough to cause one of your plug wires to arc to ground before the spark plug causing an audible tick.

[Tonka]

Thank you so much for your repoes gentleman. I will check these out but my gut tells me I need to just go ahead and do what I should have done prior to final assembly which is in the very least, a bottom end rebuild. I've taken truck off the road until I find out what is up. Thank you again and if anyone else has anything to suggest I appreciate it

[Tonka]

It may be nothing more than header slap.  Exhaust pulses hit the bend in a header, and the thin metal ticks.

What headers are they?

One thing you can do to see, is to have someone rev it in gear as you did, then use a piece of 1/2" hose as a stethoscope and see if you can localize the sound more.  Another is to have them rev it is gear, and then touch and gently push on each header tube about 6" out from the engine (i.e. after the bend) with a 1x2, and see if you can change or muffle the sound.

If it is header slap, then it's not a problem.  That's just how some headers are.

Richard thank you for your reply. They are jet hot coated Hooker long tubes. I will try the stethoscope trick soon and keep you posted. Thank you!!

[Tonka]

Here is a free (will not cost you a dime) tip based on the fact that I can't hear your tick over the www.

Check all of your spark plug wires to be sure you don't have one "leaking". Occasionally a spark plug wire that is jumping fire will give a tick that sounds like a lifter.

Under a load your engine demands higher ignition voltage to arc the gap on your spark plug to overcome the higher combustion chamber pressure. This rise in voltage could be just enough to cause one of your plug wires to arc to ground before the spark plug causing an audible tick.

Engineer- Thank you sir. I am running a full MSD billet distributor and wiring. I don't have the wire routing as "mint" as I see some guys. Having a hard time getting that perfect loom. It is clean however as I have messed with it a couple times trying to route them just perfect. I am using the plastic MSD wire separators but a couple of them do cross over each other. Could that be the cause? Tips on routing these wires perfectly? It puzzled me based on the 'twist' of the distributor after having set timing.

[rich weyand]

I run the Taylor wires, and I just jammed any extra behind and below the distributor, then loomed them perfectly to the plugs.  So all the wires come off the distributor and go down and back, then a perfect loom comes out to the plugs.  Cheating, I guess, but it looks good.  And I have wires crossing each other all over back in there with no problems.

You should know that the Hooker headers for the C and K trucks do exhibit significant header slap.  I thought it was an exhaust leak or a misadjusted rocker when I first heard it, but it's just the Hooker headers.  Mine sounds just like you describe yours.  (Which is why I asked what headers you have....)

[Engineer]

I'd say your ignition is gtg.

When I bought my '94 K2500 it had a brand new set of el-cheapo wires. 7mm.

One rainy day I had a tick, and a miss. Thought I had an intake lobe going south. Turns out it was those new plug wires.

A brand new set of GM Packard 8mm wires and I was back in business. The new plug wires fixed my bad EGR valve at the same time. Well, sort of. There was a bad EGR symptom that wasn't the EGR valve at all. Turns out the surge I was dealing with all along was the 7mm "just as good as OEM" wires. They were at fault all along, it just took a rainy day to push them over the edge.