Valvetrain noise?

[46flattie]

Guys,
Hopefully you can help me out, I have exhausted all my resources on this one.

The engine:

fresh 401, .030 over, balanced, TRW forged pistons, summit 8600 cam/lifters, used summit recommended valve springs (Crane 64308 120 lb seat pressure), Edelbrock performer intake and carb, Carter Hi volume mech fuel pump, Chevy 1.6 ratio roller rockers, comp cam guide plates, studded the heads and running TrickFlow 8.300" length push rods

The problem:

I have valvetrain noise similar to loosely adjusted rocker arms.

I set the valve lash using a dial indicator to .040" and due the the noise I have since set the valve lash twice using the "Chevy" method w/ no change. However, by doing that I have eliminated that the noise is valve lash.

I have verified no interference between push rods and rocker arm bodies, clearance holes in the head, etc.

No header leaks.

The noise is amplified when the valve covers are on as well.

Is it common for roller rockers to make some noise? I've be told yes and no. Seems like they would not. I have about 700 miles on and no change in the noise - worse or better. Oil has looked good at the changes w/no obvious metal, etc.

Any suggestions, The ticking noise is embarassing! and I don't want to tear up my new 401!?

Thanks,
Scott

[tufcj]

The summit 8600 is a hydraulic cam. Valve lash should be 0.

My thought is that it's the Chevy rockers. The length is different between the pivot and tip (shorter I think). Crane does make a AMC specific roller rocker.

Also, how much were the rocker bosses milled for the studs (I'm assuming these were bridged rocker heads)? It generally takes about .250" PLUS the thickness of the guide plate, or about .375" for 1/8" thick guide plates.

I'm thinking the ticking your hearing is from incorrect rocker geometry. I have Crane AMC rollers on my Jeep and AMX, and both are as quiet as stock.

Bob
tufcj

[82Waggy]

I'd be looking at rocker geometery as well. That you had to use an 8.300" pushrod suggests that the Chevy rockers are too short - Might be running close to or off the inside edges of the valve stem at full open. Also check that the pushrod is not bottoming out in the guide throughout the full range of travel.

I recently set up my heads with guideplates and Crower rollers for AMC and only had to go to an 8" pushrod to get them to center up on the valve stem. Also, only milled off .125 for guideplate clearance and used BBC studs. Worked out perfectly.

[46flattie]

Thanks for the responses.

I think you guys might be right. I did not mill the pedestals down at all. I also noticed the Chevy rocker arms were slightly shorter based on the contact point of the roller tip to the valve stem. It contacts basically in the center of the stem and rolls to the inside of center when fully opened vs. rolling thru the center. The roller does not fall off the stem though.

I got this set-up from MC at Bulltear (No offense intended, just trying to get this figured out). He figured I would need something around 8.25" push rods and did not need to mill the pedestals. I found that at 8.25" I had rocker interference on the stud radius trying to get the right lifter preload. Therefore I went just long enough to prevent that and found that anything longer than 8.300" caused interference between the push rod and rocker arm body when the valve was fully open.

MC, Any ideas.....?

82 Waggy: I don't think I'm bottoming out on the guideplates but, I need to double check. Got a part number for what Crower rockers you are running in case I have to ditch the Chevys?

TuffCJ: Sorry, I should have said lifter preload vs. valve lash.

I sure do appreciate the input....

Scott

[82Waggy]

Crower 73646-16, These are kind of expensive.

http://i142.photobucket.com/albums/r107/82Waggy/401/401bld001.jpg


You should also check out Harland Sharps alum RR for AMC.

[jeepsr4ever]

When using Chevy rockers to AMC valvetrain the pushrod length is important otherwise you will either hit the edge of the hole in the head or hit the the bottom of the rocker (depending on type). You say 8.300 is too long and at 8.250 you cant get them adjusted? I would say forget about the .040 lash just get them to stop maing noise.

[46flattie]

When using Chevy rockers to AMC valvetrain the pushrod length is important otherwise you will either hit the edge of the hole in the head or hit the the bottom of the rocker (depending on type). You say 8.300 is too long and at 8.250 you cant get them adjusted? I would say forget about the .040 lash just get them to stop maing noise.


Let me clarify:

Anything longer than 8.300" is too long and causes the push rod to come into contact w/the backside of the rocker just below the push rod cup and the lock nut to come into contact w/the inside of the rocker arm, both cases w/valve 100% open. At 8.300, I will admit that it is very close, but I have verified no contact using "bluing ink" on all assemblies. I also know I have no interference w/the holes in the head. And at 8.25 I could not adjust to .040" preload w/o some rockers contacting the stud radius. I suppose I could have set it up w/less preload as you are suggesting (?), but I figured it was too close. There are 8.275" push rods available, but I hate to waste money if there is something else going on here.

As stated earlier I need to double check any interference at the guide plate inside edge, but I have not seen any unusual wear on the push rods in this area.

82Waggy: Nice set-up fixture!

Thanks everyone for all the help!

[46flattie]

Tonight I have verified that there is no clearance issue at the guide plate throughout the push rod travel. However, I did notice that the push rod "socket" in the rocker arms are starting to get some unusual wear. Almost like the push rod is chattering when it pivots in the socket or the socket insert is not hard enough material. The push rod looks fine and I have lots of oil.

Could this be my noise?

Thanks,
Scott

[AMX69PHATTY]

Any chance the valve spring retainers are hitting the valve guides ?

[tufcj]

Did you check piston/valve clearance during assembly? I saw the pushrod pockets get damaged on a 304 I built once because the valve was just barely tapping the piston (after I was assured by the machinist that there would be no clearance problems).

Bob
tufcj

[46flattie]

Any chance the valve spring retainers are hitting the valve guides ?

I don't think so, but that's another item to check....thanks!

[46flattie]

Did you check piston/valve clearance during assembly? I saw the pushrod pockets get damaged on a 304 I built once because the valve was just barely tapping the piston (after I was assured by the machinist that there would be no clearance problems).

Bob
tufcj

Yes, I did using clay. I can't seem to find where in my build notes I wrote it down, but I know I had well over .100", closer to .200". The block and heads were virgins. I did not deck the block and only had the heads surfaced enough to flatten them out.....took about .010" off them.


Thanks,
Scott

[jeepsr4ever]

Scott I think your using too much lash and your making the valvetrian sloppy. Does the pushrod move around when the rocker is seated?

[82Waggy]

Tonight I have verified that there is no clearance issue at the guide plate throughout the push rod travel. However, I did notice that the push rod "socket" in the rocker arms are starting to get some unusual wear. Almost like the push rod is chattering when it pivots in the socket or the socket insert is not hard enough material. The push rod looks fine and I have lots of oil.

Could this be my noise?

Thanks,
Scott

Sounds like something is bottoming out.

Let's back up a minute.

How much lift are you running, both intake and exhaust?

Are all pushrod cups showing damage or just the intakes or just the exhausts?

Check for spring coil bind & valve seal to spring retainer clearance at full open.

Double check that the rocker is not hitting the stud (underside of rocker) or the adjuster nut at full throw.

[46flattie]

Scott I think your using too much lash and your making the valvetrian sloppy. Does the pushrod move around when the rocker is seated?

I not exactly sure what you mean by "move around", but here's what I can describe:

When the lifter is on the heal of the cam - I can rotate the push rod in the cups by hand, but have no noticeable end play. And I can move or twist the rocker side to side a little bit, but again no end play at the push rod or the valve stem that is noticeable.

What I did to adjust lash in the beginning was using a dial indicator, I set the lifter preload to .035" to .040" when the lifter was on the heal of the cam. (Spec was .020" - .060"). I was careful to let the lifter bleed down as I adjusted the preload and to start the measurement at zero end play.

When that was not successful, I switched to the Chevy method, adjusting while idling at oper. temp: back off the adjuster until it clatters and tighten 1/4 turn at a time to 3/4 to 1 turn once the clatter quiets down.

While adjusting using the Chevy method I did not notice much change in the ticking, once the clatter stopped.....in other words after the first 1/4 turn past the clatter, which would be about .015" preload, no better than at 3/4 turn (.045").

Thanks for all the help! I'm sure we can get this figured out.

[jeepsr4ever]

Hmm hard to say what kind of preload the lifters need but if your comfortable with a different rocker I will gladly take them back and give you your money back if it helps you get on the road faster! Sorry your having troubles bud!

[46flattie]

Sounds like something is bottoming out.

Let's back up a minute.

How much lift are you running, both intake and exhaust?


Are all pushrod cups showing damage or just the intakes or just the exhausts?

Check for spring coil bind & valve stem seal to spring retainer clearance at full open.

Double check that the rocker is not hitting the stud (underside of rocker) or the adjuster nut at full throw.

Intake = .472"
Exhaust = .496"

Yes, both int and exh exhibit this wear.

No coil bind, and it's hard to tell in regards to the valve seal due to the inner spring on the valve spring, but I don't think so. I had the heads set up w/the newer style valve seal vs. using the old "umbrella" style.

Looks good, no indication of contact at the current time. I did have 3 rocker arms out of the 16 that I had to touch on the back side (relief area for the push rod) w/a die grinder to provide more clearance for the push rod when the valve was fully open. I did not have a good way to measure the rockers, but the relief visually did not look as deep as the rest and there was contact occurring based on witness marks. I have since blued all 16 and checked this area, the inside edge near the nut, as well as the bottom side at the stud radius, looking for any signs of contact in the bluing ink or the factory anodizing. I do believe I am at the limit of the rocker arm throw though w/o contact issues.

Thanks for all discussion, it really is helping to eliminate all the variables.