Rebuilt 360 4-speed in a 73 dart sport. Motor had a good break-in with brad penn break-in oil left in for first 500 miles per builders suggestion.Switched to shell rotella after first change of oil. After about 800 total miles motor started ticking on cold startup after sitting for a few days. Lasts for say 3-5 minutes, exhaust note sounds odd and runs a little rough. sound goes away and motor smooths out.Runs fine after that, yet always has the same symptoms after sitting for say 5-6 hours.no overheating missing or other symptoms
Could it be a lifter gone bad and bleeding down? I pulled the valve covers and did not notice anything obvious a miss, no bent pushrods or rocker adjustments let go. Has comp cams pro magnum adjustable rockers. Thinking of pulling the intake and inspecting lifter and cam to eliminate fear of wiped cam lobe.

Find the noisy lifter and check the adjustment. One rocker may have gotten a bit loose.

get of the rotella

mine did the same thing,high milage engine

I use a good straight 30 weight oil from napa

with a good wix filter

like said check lash if adjustable or replace lifter/push rod/rocker on offending valve,if non adjustable

good luck and hope it did not wipe a lobe

I do have an old set of valve covers.Thinking of cutting the tops off so i can run it without oil running out all over the exhaust mainfolds. I did spin push rods and could not feel any of them being loose ones that were on base of cam lobe at least. I need to hook up my remote starter and tap motor over to check the ones that valves were open. Suppose you could be right just a little loose could do it.

And he's right lose the Rotella oil. I'm old school 20 50 Castrol. In almost 40 years of beating the hell out of Big Block mopars i've never had an oil related problem.

sounds like an oil change is on the list of things to do also. I do use a wix filter.

i agree with changing the oil to castrol 20/50 and also run some lucas oil treatment, i have the same noise with a 440 with xe 274 comp cam

this oil combo helps

With any flat tappet cam you need to use a Zinc additive. Since rollor cams became factory spec oil companies have reduced the zinc levels in oil. Did so as to lower emissions. But flat tappet cams need the zinc. Ever oil change i add a bottle of ZDDPlus from Kirban Performence. High Zinc forular. There web site is kirbanperformence.com

Oil change is definitely easier than pulling intake to inspect lifters and cam.Dont think it is a wiped lobe as it goes away after a few minutes.Did start a few hundred miles after draining brad penn breakin oil. Thanks for the tips i'll try it tomorrow if I can get the kids to bed early enough, Heck I'll have my 6 year old do the oil change for me, he loves wrenchin on the dart and feelin chirpin of the gears from the back seat. How about the high zinc oil additive I've read about here?

The high zinc additives are good for us flat tappet guys. No need in roller motors

try some thicker oil. EDIT Your cam/lifters are fine

Thanks for all the info, I will Run it to warm it up then do an oil change with a zinc additive. What zinc additive can i get locally? Did someone here mention one available from the GM Dealer?
I'm in metro detroit area

Talked with my engine builder and he suggested using brad penn 10w-30. I used the brad penn breakin oil yet had switched to rotella after first 500 miles. He also suggested increasing the preload of the lifters, 1/4 turn of adjusters. I have the comp cams pro magnum rockers which are adjustable. Going to adjust the rocker 1/4 turn, button it up, warm it up and do the oil change

I'd leave the rocker adjustment alone for now and do the oil change. I'm not big on 10 30 in a performence motor. Maybe i'm old school but i'll stick with 35 years of good luck with 20 50.

oil and filter change first

I use some of the STP oil tratment for extra ZDDP,said it right on the bottle,the 4 cyl "red" bottle is supposed to have more ZDDP in it too..

the GM ESO is good addative also

running a good diesel fleet oil is good,I use the napa fleet brand in the 15/40 grade also

I read the roller lifters need a little lighter/thiner oil to make sure the needles in the roller get lube good...they only get "splash oiled"..

some edm oiling on flat tappets and pressure lubed roller bearings on the lifter is the new cats meow..so I have read anyways

had no probs with the straight 30 or the 15/40 deisel oils so far on mine

and I to have run the 20/50 for yrs

Builder suggests 10w-30 for my 360. My motor was built as a "steet strip package". He said my motor should run @ 25 pressure hot at idle and 50 psi when off idle. I'm going to warm it up do the oil change with the brad penn 10w-30 and a WIX filter as he recommends (I use WIX anyways). Then I will Check the pressure to verify where it is at. I had looked at the gauge I have under the hood and verified it had pressure not specifically what it is at, my bad I guess. Only had under hood small screw in gauges for break in monitoring as I'm going for the stock interior look. Thanks for all the input, hope to get to it tonite.