70 Challenger stock 318 I am changing the lifters due to some noisy ones. The question is do I need to use a break-in oil to prevent damage to the cam or once a cam is broke in is it good to go? I don't want to ruin something for the price of an oil change. Thanks, Lou

Yes i would use break in oil and run engine on startup like if it whas a new cam so dont let it idel !

Fully agree................

i bought a 73 plymouth 4dr one time with a 318 that had a bad misfire.
turned out to be two push rods went through the rockers, allowing the lifters to jump around and come apart.
it was run quite a while by the previous owner, and by the time i got it, the lifter parts were MIA.
i just got a couple lifters off the shelf, plus a couple of rockers, and stuffed everything together.
ran it for several years after that with no problems.

but in the OP's case, use new lifters with a dab of cam paste on the bottoms, break in oil, and treat it like a cam change.
as said, NO idle time.

You could just disassemble and clean the lifters and see if they quiet down.

The most important thing if you are replacing them is to coat the lobes and bottom of the lifters liberally with cam assembly lube and then assemble and rotate the engine a couple of times to verify that all the lifters spin. They should all turn like they are gear driven together at the same speed. I believe at least 95% all of cam failures happen because a lifter or lifters don't rotate consistently on the cam.

As for oil, you can pay the $$$ for the flavor of the month boutique oil if you want but if the lifters all spin as they should, any 15w40 diesel oil be it Rotella, Delvac or Walmart brand will be more than sufficient IMHO.

Kevin

that's what I'd do. In the same hole(s) of course. No (related) changes preceding this? I would check preload. they got noisy all of a sudden for a reason.

Thanks for all the replies guys. I actually forgot about using cam lube. I'm not sure why they started to get noisy but they have been in the engine 20 years but only about 10,000 miles on them I figured maybe sitting in one spot over the winters may have taken a toll on them . I figure if i'm going through the trouble of taking it apart I might as well change them.

You may have better hydrauilc lifters in your motor now than you can buy now

Have you checked oil pressure? Maybe your pump is going south and causing the lifter noise. Just a thought.

If it's the original 318 and never been apart or hasn't had a timing chain in decades, the pump pickup could be plugged up with assorted nylon timing gear teeth too.

Kevin

The engine was rebuilt in the mid 90's with new pump and timing chain. I only have the rallye dash oil gauge but it still shows good pressure. The lifters do quiet down after a few minutes but it tells me some of them are leaking down. I currently have the motor out of the car because my power steering box was leaking which I sent out for rebuild so I figured I would pull the the motor for easier access and while it was out detail it and perform some maintenance.

What grade of oil are you running in it?

Kevin

For the last 4 or 5 oil changes I have used Mobil one 10w30

Mobil one with a ZDDP addative hopefully?? If not, I would highly recommend a ZDDP addative, or an oil with a high ZDDP content to prevent issues with a flat tappet cam. I hope it's not too late.

Mobil 1 15W-50 has plenty of ZDDP, but he may want to run a lighter oil.

https://mobiloil.com/~/media/amer/us/pvl/files/pdfs/mobil-1-oil-product-specs-guide.pdf

Mobil 1 15w-50 sounds like a diesel blend that may have enough ZDDP, but the 10w-30 is a modern synthetic oil that is engineered for modern roller cams, ... not flat tappets. Hopefully it's just an issue with lifter bleed down, but for future reference when choosing a flat tappet cam oil, make the Zinc/ZDDP level your first priority.

I thought he was running a flat tappet cam.

From the Mobil chart I linked (15W-50):

"Boosted, higher viscosity, advanced full synthetic formula designed for performance vehicles. For high HT/HS applications. Racing and flat tappet applications."

Yes I have been putting a ZDDP additive in it

Ok, cool.. that ZDDP content is the key to making these flat tappets live a long healthy life, aside from proper break in if course. And yes, to your original question, definitely use a "break-in" oil with a new set of lifters. No idling, bring it up to at least 2k and vary the rpm between 2k and 2,500 rpm over a 20 min heat cycle. This method has worked for me several times over the years. Joe Gibbs break in oil is great stuff.