the strangest thing, i have had this happen about 2 or 3 times in the past 3years, i bought a 1973 440 from a buddy of mine, he sd the heads were rebuilt with harden seals for unleaded gas, he sd the bottom end looked great, he checked out everything and it was fine, this is an old motor home motor with low original miles, all the bottom end is original, the cam, lifters, intake carb and headers been added, sometimes when i crank the motor, it sounds like a rod knocking or a spun bearing, the more i rev up the motor the sound gets better, however at idle it really sounds like the motor is junk, it last for about 5mins then goes away, and i may not hear it again for 6mths, i have been restoring the car and have not had the car on the road for 3years, i have made several trips around and around the block, i usually crank the car at least 1 every 2weeks and let run to normal temp, great oil pressure, running at idle has over 70 at cranking and about 60when idling hot, during the sound, the oil pressure is at high reading, has anybody ever heard of this?

bad lifter or preload (pushrod cup) on them on the ragged edge of not deep enough down into the lifter body. EDIT next time it happens STOP the eng/pull the valve covers and start it & push on each rocker arm on the pushrod end w a hammer handle & the offender will quiet down some. R&R the bad lifter(s) & repeat the cam break in procedure

Automatic or manual transmission? If automatic, check for a broken flexplate. A broken flexplate can cause this sound.

it is auto, i can i check the flex plate while in the car?

if it was the flex plate, why is it only doing this a couple of times in a 3years?

hey Robert, i have replace the cam and lifters about 3mths ago, it did this same noise before i changed the cam and lifters, i had a bigger cam 280 492 i put back a 268 454, it is a comp cam and lifters, so what do you suggest?

i changed the cam due to the duration of the extreme engery cam, the motor is 8/1 motor and the cam that was in it needed 10/1

that would make it way less likely to be a lifter internal prob. I would check preload

i am a banker by day and a mopar junkie by night, how do i check preload and how do i fix it?

i went out and checked the old lifters and cam, i found some very interesting things, some of the lifters, have chips in them on the side at the top of the lifter and 2 or 3 of the cam lobes have some chips, what does this mean, maybe i had a problem with the old cam and now i have the same problem with the new cam and lifters?

i am getting a bad feeling here, the heads have been milled and my buddy sd he used shims to get the right height, do you think the push rods are wrong and it is causing damage?

put the timing marks on TDC w the rotor on the #1 plug wire and take off the dr rocker arm. (Undo the center bolt a quarter turn then the one to the left (front) a quarter turn then the bolt on the other (rear) side of the center bolt a quarter turn then the front bolt a quarter turn then the rear bolt a quarter turn then back to the center bolt & repeat so the shaft is not cocked but come straight up). Make a mark on the 2 pushrods in relation to the valve cover rail so you can easily refer to it then retorque everything back down a quarter turn at a time starting at the center bolt then near right then near left then far right then far left then center. A piece of welding rod works good to hold the pushrods in line. When down all the way/torqued to spec make a new mark on the p rods & see how far they have traveled down into the lifter. If the preload is making the cup on occaision contacting the lifter body that'll make a racket. Not sure offhand how much is OK but I think at least..020-.030"? is enough but post what you get. Not sure on the chipped cam/lifters & you'd think that blatant damage would make a full time noise but w lifters rotating I am not sure but I'm concerned at that (amt of) destruction. I had a 80's hyd cam slant 6 & it had a horrendous lifter noise that would come and go (good psi) just like your descrip. I continued to run it & no probs (you cant kill a slant 6 even if you tried) and I saw one at the Nebraska state fair run wo oil & no blow (after the snake oil salesman put his panther pi$$ into it)

thanks for the help Robert, it will probaly take me awhile to do this, i am trying to finish up the restoration and i guess i will get back to this motor problem, will it hurt to continue to crank the motor every 2 weeks till i finish the restoration?

Had a racket like that in one of my 440s, and it turned out to be the rockers hitting the stock valve cover baffles, and the rocker shaft hold-downs transferring noise (and small dents) into the valve covers after I'd re-tightened them. Quick check is to let the thing idle and tighten/loosen the valve cover bolts, assuming you have a similar setup.
When you pull the covers, look for little gouges or dents in the baffles. The hold-downs on mine were square and I ended up filing chamfers at the outside corners of the front & rear ones. A few whacks to the baffles with a punch (protecting the outside of the covers), and no more contact or noise.

I'd be patient & let the eng be until you can get back to it & get some ans. Like me you have plenty of other stuff to deal w. Holler when you can w what you find out & we'll continue onward

yep,gotta love hack-job,uninformed mechanics. i had a 318 a while back,when i got it,guy said it was nice and quiet running around town,but,after 30-45 minutes on the highway (55-60mph) it developed a belt squeak. said he replaced the belts,and altenator twice. after buying the car,and a few more conversations with the PO,he said that he and his son replaced the valve stem seals due to some early morning smoke on start-up. after i pulled the valve covers,found the goofballs spun the rockershafts around during reassembly,and had the oil holes in the shafts pointing up!!!!! that belt squeak was the front 2 rocker arms chirping on the shaft. i spun them back around,and she was quiet from then on. goober asked if i ever fixed the "belt squeak".....

Ever hear a rod bolt tapping on the windage tray? It will only do it at idle or low rpm's.Sounds just like a rod knock.

i put my hands on the vc when the noise was happening and i could not feel any vibrations on the vc, sound i be able to feel this on the vc?

hey Bill , you may be on to something, my motor does have a windage tray, and i did drop the oil pan to fix a rear main seal leak, and to come to think of it, this noise did not start till after i fixed the rear main seal, do you think that i may not have put the windage try back on correctly?

i know what you mean about this, alot of people do things to their cars no knowing what the end result is going to be, what is so bad, i really do not know alot and i have to research and hunt down what the problem is, i am glad we have moparts.com and have alot of good people helping us to hunt down the problems,
thanks for the input