Engine rattle on fresh start up

[Kern Dog]

I think that I know what is the problem but I want to quiz you guys to see if we come up with the same thing...
The engine is a '78 or '79 360 from a van that I parted out in 2007. I slipped a 340 cam in it, a Weiand intake and 340 manifolds and stuffed it into a 72 Duster after replacing the rod bearings. The engine had been gone through sometime before I got this van but who knows when....There were a couple of bearings that had some wear. I had some standard size bearings here so I used them.
Here we go....It starts and runs fantastic but after sitting awhile or a cold start, it has what may be a valvetrain rattle/tapping/knocking sound for less than 2 seconds before going completely silent as the engine is running, even at idle. I have no oil pressure gauge in the car but I can rig one up to test, maybe after Christmas.
The car was a project between my Brother in law and myself. I got the car in 2007 and after awhile, he lost interest and I bought him out. The oil level is full but has not been changed in quite awhile. The last oil change could easily have been more than 10 years ago. There is no slop in the rocker arms or pushrods though it does have an exhaust leak.
I suspect the oil filter isn't maintaining any pressure in it, I'm going to change the oil and filter and report back.

 

[Gator]

It sounds like your lifters have bled down and are dry. First thing I would do is definitely change the oil and filter and then before starting remove the coil wire and turn the engine over for about 5-10 seconds allowing the oil pump to supply the engine with fresh oil then reinstall the coil wire and start up the engine. You should not hear your lifters chattering. I hope that when you installed your new cam you included new lifters so that the two can marry themselves together.

 

[Darter6]

your lifters have bled down and are dry.

Quality of todays parts. Had a woman bring in a 73 Cadillac 500 ci with lifter tap. She couldn't stand the constant noise.
We replaced all the lifters. You guessed it. Lifter tap for a few seconds after every cold start. Only driving it on occasions, She was ok with that.
Yes we checked the cam and also put a new timing chain. Still I wish it was cured

 

[Newbomb Turk]

Depending on the lifter, the oil you are using and how much preload you have on the lifters it can be normal.

 

[dano]

Manual or Auto? I've had throw out bearings make funky noises.

 

[drodg58]

Correct if I am wrong but didn't a lot of the small blocks have some lifter clatter at first start up. My 340 in my 72 Demon doesn't but I have had a few 318's that did or I should say between my dad and I we have.

 

[RustyRatRod]

Without hearing it, it will be difficult to tell. Sometimes, valve train can sound like bottom end and bottom end can sound like valve train, so anything said here is only a "guess".

 

[PRH]

Here we go....It starts and runs fantastic but after sitting awhile or a cold start, it has what may be a valvetrain rattle/tapping/knocking sound for less than 2 seconds before going completely silent as the engine is running, even at idle.

While I wouldn’t enjoy a little lifter clatter on a cold start…….. if that was the only complaint…….. I’m not going to devote a bunch of time trying to rectify it.

 

[Hellrats]

New cam and lifters? Hope you broke it in correctly. If so it should be fine. They will rattle a bit after sitting. The lifter bleed off and it takes time to get the oil up there.