I got it started up today and ran it for a few minutes to burn the paint off the headers. I was tinkering around with it and noticed when I lean on the valve cover when the engine is running I can feel it slightly knocking, not a spun bearing knock but a knock none-the-less. I confirmed it with a flex radiator hose on the valve cover its a knockin. So out it comes this week and I'll be praying every night that some idiot installed a wrong size bearing on one of the rods. I don't get it the inside is really clean, I doubt any kind of debris got into the bearings. At least I got a taste of the Dark Side.

are you sure it's rod knock?

I'm pretty sure. When I go out monday I'm going to unbolt the torque converter to eliminate the possibility of the transmission making noise. It has nice oil pressure when cold (75 psi) but when it's hot it's like 20 but I didn't have it real hot yet, I didn't want ot hurt it any worse than it is. The timing chain was stretched but not real bad and the back and forth on the thrust bearing is very little so the mains should be fine. The sound is worse on the rear of the passenger side. It's kind of hard to notice but I would bet it is slightly knocking, I'm running open headers.

Sure it isn't detonation ?

Timing all set and whatnots ??

Steel or aluminum valve covers? If aluminnum, do you have cast-in drippers on the inside of the top?

just like batman said make sure you don't have interference issues with the rocker arms and the valve covers . also a slow thud/knocking noise can also come from the fuel pump arm/pushrod

I turned the distributor both ways while listening and the knock doesn't get any lesser, so I guess detonation can be ruled out. Can I pull the fuel pump out and fire it up for a minute or so while listening to it? oil leaks are the least of my worries. I can tell that the knock is with the rotating assy. because the knock is every revolution and not every now and then, you know like how a rocker taps every other revolution, this is every turn.

Does the exhaust "sound" sound different ? Like it could be a loose or tight rocker or bad lifter ??

It's actually uniform in sound, no popping or irregular rythm.

Rocker arm hitting something. Uniform in sound coming from the valvecover area. Take the valvecover off and duct tape some card board all around the head so oil doesn't go every where and run the engine. Oil won't go flying at idle anyway. Mine was hitting the valvecover and made a uniform knocking sound. I could actually feel the knocking with my hand on the outside of the valcecover.

I'll keep all of you guys suggestions in mind when I go out there tomorrow.
I'd s**t my pants if it was something stupid causing the knock.
I'm staying home today my nerves are wrecked after last week. I worked 12 hrs a day on this thing starting on tuesday and thats getting everything done, one person. My hands are hurting as well as the rest of me, I should be on antibiotics from all the cuts and scrapes I have!
I'm going to kill me a few beers and burn some steaks up today. Just going to enjoy the nice weather:)

One other thing I'd recommend is to pull the plugs and then rotate the engine by hand. If it's hitting somewhere you should feel it.

one other item to consider that makes noise for every crankshaft rotation is a loose torque converter bolt

Them converter bolts are pretty tight so I would count them out. I'll know tomorrow for sure.

Well I pulled it out today and the bottom end is perfect, no loose anything.
Can a worn water pump bearing make this kind of knock? As I was bolting the engine stand onto it I bumped the fan and it made a knock, I was thinking on the way home that the pulleys for the fan and crank are just about the same diameter so that would give the impression that it could be a rod because it knocks with the rotation of the engine. I'll have it bolted back in tomorrow morning so I'll run it till it's hot and making the thud and then I'll remove the fan belt.

Good luck, good news its not a bearing. Take your time, you will get it figured out

Take all of the belts off and run the engine. No powersteering, alternator, waterpump or fan. that will eliminate alot. Its not a ticking sound right? Header leak? try the engine with the valve cover off too...

Keep us updated, I'm curious.

I had a big block one time that knocked for a long time and I could never figure it out. That is, until I replaced the water pump. It never failed or leaked but it was knocking as it turned out.

I put it back in today and the little knock is still there. Maybe I jumped to conclusions about it? I dunno, it's not as bad as I thought. I ran it with no belts or torque converter and it's still there. I guess I can live with it. I probably won't hear it when the exhaust gets put on as I basically use a stethoscope to hear it and it doesn't get worse with rpm. I went down the driveway and back to make sure everything was good to go and MAN does this thing have a pair, I can't wait to take it out for a good cruise!

It doesn't get worse with RPM but it gets faster with it right? Do you hear it without a stethoscope?

I goes away with rpm. I heard it with a straight piece of 2" rubber hose on the valve cover. Every bearing in the bottom is perfect, maybe the cam is wobbling slightly? You can't hear it over open headers.

One thing I dont think anyone has mention is it could maybe have a little piston ratle/slap in one cylender if it has a scuffed piston or a little more clearence in one cylinder than the rest. I have a engine right now (IH 345 engine) that has been doing this since I built it 50k ago i just honed it and put rings and bearings on it the pistons looked a bit rough but I didnt care I had another to build fresh if it failed so I floged the hell out of it. Never missed beat and it still has that little nooook noook noook kinda deep in the engine sound when ever you start it and even when it hot some times you can hear it if your right on top of it with the hood open.

But when I built it run me crazy I even changed the oil pump and pulled caps just to see. So happend I build another engine a ford 460 for one of our work trucks bores were great but one piston had some scuff to it and I talked to my machinist about it and he said that it would cause it to make noise. Then I put two and two together and asked him if he thought it may be what the other engines mystery noise was and he seemed to think it was a very very good chance. But that it would prob never cause much trouble in a mild build.

I know alot of people runing Hyper pistons complain of this alot too do to the diffrent expansion rates.

Just my 2 cents but even if it is I would run it.....

I'm getting it towed down to the exhaust shop this morning. I'll be running it all weekend long. First I'm going to go down to the garage and run it for about a half hour and maybe even a trip up the road and back to burn off the rest of the header paint. One thing I did notice is that it is a little quieter since I changed the plugs around it may have been detonation, I try and put some of that octane boost in it this morning, maybe that will clear it up? that and a bottle of that Street Legal Oil Boost stuff.

Well I figured it out, it was the open headers making the knocking sound. If I go behind the car I can hear the same exact knocking sound as I do if I listen to the engine up close. I wish I would have known this a few days ago:(

Awesome, glad you got it figured out!

What about the headers was knocking? Header leak? Header vibrating?

It was the sound that was coming out of them.

Well I figured it out, it was the open headers making the knocking sound. (

thud, thud = pulse, pulse

LOL. Glad it was a 'cheap' fix for ya ;)

i got that problem now, it's got it pulsing noise, not metalic and we can't hear it on the motor but you can hear it from the exhaust making it sound like a knocking lol