Help Me Diagnose This Tap/knock.

[Blown2vDonnie]

Hey guys, this is my first post, I spend a lot of time on corral. Well to keep this short, I recently built my 98 GT with this:

4.6 Romeo block bored .020 over torque plate honed
Stock heads
Modular headshop Real Street Blower cams(Huge duration cams)
Forged H beams, Stock Crank polished, Forged D.S.S. -18cc dish pistons with valve releifs. Moly Rings
King Si Rod and Main Bearings
The car runs very good, does not miss or anything.

Well for about the 1500 miles it has on it now, it always has had a very, very annoying knock/tap that I just cannot figure out what it is. I have taken the engine out twice now, once to fix a bad throwout bearing and rear main seal leak, and to fix some broken header studs. All the header studs are in now and nice and tight so no leaks. I have swapped a set of lash adjusters for another used set that previosuly worked, and still the noise is there. I took the oil pan off and looked inside, and saw nothing out of the ordinary. I have swapped from crap ported heads back to stock, re timed engine, noise still there. PTV clearance was .097 at its smallest on # 5 cylinder.

The noise is very tough to hear with the hood open, but its loudest in the car. It's only loudest under load. Does not change with operating temperatures. Gets faster with revs and is loudest when accelerating, but when crusing in 5th gear its hardly noticable at all.

My buddy who is a mechanic says he thought for sure the noise was coming from in the bellhousing when we listened to it.

So anyone, please help! It drives me nuts! Heres a vid of my car btw since im new.

 

[joshjwc9]

Have to change my underwear now very nice car man!


Is the timing stuff new? Could be some rubbing or something to do with the pullies. I had a knocking that got progressively worse. Did timing since the stock shortblock had 150k miles, no luck, replaced noisy OEM water pump, no improvement, then finally last week had an idler pulley just go and catch fire since the bearings took a dump..Car now sounds eerily quiet and even more stealthy with the SQ trim, before it sounded like I had an exhaust leak and a T Trim, now, its whisper quiet at idle...

 

[Blown2vDonnie]

The timing stuff is used. Tensioners, chains, gears, guides all came out of my old 2000 engine with 60k, and it had no noises.
Oh and sorry forgot to say I ran the car without a belt to check for pulley noise, but noise was still there.

 

[joshjwc9]

Hard to diagnose over the internet, but it sounds internal or is something to do with the timing components. It also could just be the fact the engine was just built and the tolerances are still breaking in. You'll need some other know-it-alls in here to give you some tips or ways to narrow it down..