AMC 360 noisy valves

[Zephrant]

Bought a used 360, rebuilt it, put it in place of a straight six in a 81 Wagoneer.

Hot tanked, decked, line honed block.
Decked heads, new valves and springs, flat top pistons, bearings.
New fuel pump, oil pump, oil pickup, timing set, HEI dist., timing cover, water pump, lifters, alternator, hoses, belts, Edelbrock air gap intake, Holley Street Warrior carb, air filter, fuel filter, fuel pressure regulator, valve covers, sensors, engine mounts.

Reused rockers, exhaust headers, starter, pressure plate.

Same 727A trans, shortened/lengthened drive shafts because I had to bring it forward so the valve covers would clear. New shift linkages.

COMP Cams High Energy Cam and Lifter Kits: K10-202-4
JEGS 20274 AMC Pushrods 7.794 in. Long 5/16 in.

Primed the oil pump, got it running (headers only, no muffler). Did the 20 minute cam breaking at ~2500 rpm. Shut it down, changed the oil. Definitely some metal in the oil.

Got the muffler fixed, then realized the valve train was really loud. Bought the pushrod measure device, spent hours with it and a dial indicator. Figured I needed 7.870”, so switched to: High Energy 7.870" Long, 5/16" Diameter Pushrods. But no change.

Replaced the rockers and bridges with new, re-measured, re-installed the stock 7.794” rods, which should be right in the middle of the lifter range. Still sounds way too loud.

Worried the compression was too high, used premium gas. Added octane boost, should be above 94, no change.

It did take me a long time to get the engine running- several bad fuel pumps, with the one working one turning out to provide 12psi, which made carb adjustment impossible. Not positive I didn’t do some damage with all that cranking, but I did use assembly lube and prime it with Lucas breakin oil.

Adjusted the carb, running 14in vacuum at idle. Runs well, lots of power. Only issue is the valves are way, way louder than anything else I own.

Am at a loss now- over a year of rebuild in to it, and something is still messed up. Thinking I should take it apart again and inspect the cam and lifters, but afraid it will look fine and I won’t know what to check next. ;(

[tgreese]

What's your hot idle oil pressure? If that's too low, the lifters will not pump up enough at idle. However, they should be fine with minimal oil pressure, like 10 psi.

I have not done this, but know about it. You can buy an adjustable pushrod and test each lifter engine off. Measure. Rotate to the bottom of the cam, put the push rod in under each rocker, extend and measure the length. Compare to the length of your pushrods. The lifters will have a spec for how much they can pump up and still be effective.

You could even buy 16 adjustable pushrods, measure to find the ideal length, and set them to the length you need. Sometimes done for custom builds.

Welcome to the forum.

[Stuka]

Welcome to the forum.

It sounds like you did everything corect. I assume when you primed the oil pump, you used the drill method in place of the distributer? And the oil pump was packed with petroleum jelly or similar so it would prime?

My fear is that the cam got wiped during break in. Sadly this is some what common these days with flat tappet cams. Be it materials used or oil without enough zinc in it.

I think you need to pull the valve covers after running the engine for just a minute or so to pump up the lifters, and see if one of the rockers is loose, and hopefully not all of them. It could easily be one of the lifters is bad out of the box and didn't pump up. Which you should be able to notice.

EDIT: Something else that just came to mind, if this engine was an unknown quantity prior to rebuild, the timing cover may be bad. The oil pump is inside that cover, and if the oil pump gears have grooved the aluminum, it will result in really low oil pressure. This is very common on high mileage covers.

[will e]

I looked at the kit on line. A pretty aggressive cam but not crazy. I can't tell if the lifters that come with the kit are 'bleed down' lifters similar to my Rhodes that I have in my Cleveland. It's very noisy, sounds almost like a solid lifter engine.

Does the sound go away as you rev the engine?
Does the noise get worse after the engine warms up a bit?

[Zephrant]

Thank you for the reply- oil pressure is very good, running the straight 30 Lucas breakin oil again, thought I’d run the cam breakin sequence again just in case.

I did measure cyl 1 and 3 pushrods with the adjustable pushrods and a dial indicator. As far as I can tell, I’m right where it needs to be. Confirmed that the rod slop is gone about a 1/2 turn before the bridge is torqued down properly, indicating that the lifter is being depressed a little.

Slow motion video shows a knock exactly when each rocker starts moving. But I can’t tell for sure where the knocks are coming from. Here is no slop on the rods, and they all rotate when it’s running. Oil comes out the top of each of them.

Yes, petroleum jelly in the oil pump, primed with a drill, until oil came out every pushrod.
I did replace the timing cover and oil pump. Oil pressures is strong.

Sound does not go away with RPM or with engine warming up.

I’ve had the rocker covers off several times, all rockers look good, nothing loose.

I’m worried about a wiped cam too, just looking for anything else to check before I take it apart again.

[Yeller]

I will ask a question that I hope isn’t offensive, it is not meant to be.

Your getting oil to the valve train? I’ve seen incorrect lifters or push rods prevent oiling of the valve train.

[Stuka]

I will ask a question that I hope isn’t offensive, it is not meant to be.

Your getting oil to the valve train? I’ve seen incorrect lifters or push rods prevent oiling of the valve train.

He noted in the post above that he had oil coming out each pushrod when priming using a drill.

It really sounds like everything was done correctly.

[Stuka]

Thank you for the reply- oil pressure is very good, running the straight 30 Lucas breakin oil again, thought I’d run the cam breakin sequence again just in case.

I did measure cyl 1 and 3 pushrods with the adjustable pushrods and a dial indicator. As far as I can tell, I’m right where it needs to be. Confirmed that the rod slop is gone about a 1/2 turn before the bridge is torqued down properly, indicating that the lifter is being depressed a little.

Slow motion video shows a knock exactly when each rocker starts moving. But I can’t tell for sure where the knocks are coming from. Here is no slop on the rods, and they all rotate when it’s running. Oil comes out the top of each of them.

Yes, petroleum jelly in the oil pump, primed with a drill, until oil came out every pushrod.
I did replace the timing cover and oil pump. Oil pressures is strong.

Sound does not go away with RPM or with engine warming up.

I’ve had the rocker covers off several times, all rockers look good, nothing loose.

I’m worried about a wiped cam too, just looking for anything else to check before I take it apart again.

Going to throw this out there. I once had a bad water pump, that was hitting inside, (Ford engine in this case), that sounded like it was coming from inside the engine. We finally removed all the belts and started it up and the sound was gone. Its maybe worth a short test if you are running out of ideas. And with the AMC timing cover as it is, its probably not the issue.

You could find a second set of valve covers, cuts the tops off, and then while the engine is running, loosing rockers one by one until you find the one that doesn't change the noise (meaning its generating it). So you can localize which valve/rocker/lifter is causing it (Assuming it is valve train).

[Srdayflyer]

take an oil sample and send it to blackstone labs in indy and have them analyze the metal content runs about 20 bucks they have been in the oil sample for 30 yrs i know of, i use them all the time just my opinion , if the cam is trashed your looking at a tear down to flush the contamination from the motor as any hard face materials cam lobes ,lifters will have gotten everywhere internally , again JMO

[Zephrant]

Water pump is new, but a good idea.

I took a slow motion video, and there was a clear knock every time a valve started moving. Like there was slop in the rods, but they are all snug.

I’ll order an oil test, thank you.

[Stuka]

I have used Blackstone Labs several times. About to send out another sample. Is really great info to have and can tell you a lot about the health of the engine.

[Srdayflyer]

another test i'd do would be to remove 1 spark plug wire at a time when the motor is running and see if the noise goes away when a wire is unplugged , that allows a dead cylinder not to have combustion pressure in that cyl, and will eliminate a possible rod knock and not a tappet noise , initial rod bearing failure starts out as a tick and progresses into a rod knock as failure progresses. if the noise still exsists double check the lifter/pushrod valve a tappet check valve may have failed and it would have initial pressure but upon lifting the rocker arm it immediately bleeds down another possible part of the problem

[Zephrant]

Son got home from college today, will be working on it over the break.
Going to take the intake manifold off and inspect the lifters and cam.

[Scotty54]

I am following this thread with interest. My son is having a similar issue with a rebuilt 258.