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So, I recently detected some valvetrain noise from my 455. I reomved the driver's side valve cover and found out the valves on the #7 cylinder are chirping/tapping. I confirmed it was the #7 cylinder by pouring oil on the rockers as the engine ran. The noise went away.
There's actually small wear marks on the pushrods where they've been contacting the guide plates. I have the Comp Cams roller tip rockers.
Do I just need to disassemble the rocker arms on the #7 cylinder and look for more wear? Or should I buy two new rockers and reinstall them and set the lash?
Yes. All of the rocker arms on the driver's side have oil flow from the pushrod.
I started the engine this morning and ran it until hot. At first I squirted oil on the back rockers with an oil can and it didn't do anything to suppress the noise. Last night I doused them with about 1/4 quart from a bottle of oil. I stopped the engine and cleaned the rockers on #5 and #7 thoroughly with engine degreaser and rags. I started the engine again and let it idle for awhile (off fast idle). I could clearly see oil flowing into all of the rocker arms. Here's an attempt at a pic (the best of 5 or 6).
Correct. The Comp Cams roller tip rocker kit is adjustable. Should I move #7 to TDC and adjust the valve lash, or do I need to disassemble the rockers on #7 and adjust the guide plate before setting valve lash?
So, I rotated the engine by hand to put #7 at TDC. I disassembled the #7 rocker arms and removed the pushrods. I didn't find any abnormal wear. I removed the valve guides then reassembled everything and set the valve lash.
The #7 rocker arms still make noise.
Interestingly, I removed the spark plugs when I rotated the engine by hand and found that the #7 plug was completely fouled. I cleaned and gapped it before install and found that #7 is a dead hole. I swapped the #7 and #3 spark plug wires and #7 was still a dead hole while #3 operated normally. I can remove the #7 spark plug wire and it doesn't change the idle. If I remove the #3 spark plug wire it kills the engine unless I hook it back up promptly.
During all this I killed an HEI module. Luckily I had a spare and didn't kill the battery cranking the engine.
What's up with #7? The rockers move. Might I have a damaged cam? Tell me what to do so I don't sell this Olds. Very frustrated right now!
I did not but I swapped the distributor cap. #7 is still dead. I can ground the #7 spark plug wire to the frame and see arcing. Next thing I will do is swap or replace the #7 spark plug. For now I think I'm done though.
Could be a defective spark plug. Try removing #7 plug, hook up to #7 spark plug wire (which you said sparks without the plug) and ground the side of the plug. Have someone crank and look for a spark across the spark plug gap. If there is no spark the plug is defective. Replace it. Although this doesn't fix the valve noise, I always fix the obvious simple problems first.
As I feared, a new spark plug didn't cure the problem. While idling I can remove the #1, #3 and #5 spark plug wires and it significantly effects the idle. When I remove the #7 spark plug wire the idle doesn't change.
I did a compression test on #7 and it's 145 psi (with all of the spark plugs installed). A year ago I did a compression test and I had 150 psi in each cylinder +/- 10%.
I am going to change all the spark plugs and finish the compression test.
Here are the official compression test numbers (all of the spark plugs removed).
So, I put the original spark plugs back in and swapped #7 to cylinder #3. The spark plug is good. I set the valve lash a 2nd time on #7 and it still seems to chatter. I feel like I am chasing my tail...
How are you lashing the valve lash? I'm assuming its a hydraulic cam & not solid...
You could try adjusting lash while the engine is running by tightening unil it stops tapping, then an additional 1/4-1/2 turn to see if it helps.
If the noise doesn't go away rapidly, do not keep turning it in excessively as you can eventually cause valve to piston interference.
Also look to see if the pushrod/lifter is rotating while running... assuming again it is a flat tappet cam & not a roller grind, it should rotate. If not your cam could be losing a lobe.
The first sign of a cam going bad is often a valve tap at first, then a misfire/fouled plug as it gets worse.
A cam usually has to get pretty bad before it effects cranking compression, but it will not run properly way before that.
May not be a bad idea to look for any metallic in the oil.
If you can borrow a dial indicator, you can check for max valve lift at the rocker or valve & compare to an adjacent cylinder.
Last edited by Lonnies Performance; March 26th, 2019 at 06:29 AM.
You could try adjusting lash while the engine is running by tightening until it stops tapping, then an additional 1/4-1/2 turn to see if it helps.
I set the lash statically per the instructions in the Comp Cams roller tip rocker kit. I will try to set it with the engine running as well.
Originally Posted by Lonnies Performance
Also look to see if the pushrod/lifter is rotating while running...
The intake/exhaust valve pushrods both rotate while running on #7 as well as #1, #3 and #5.
Originally Posted by Lonnies Performance
May not be a bad idea to look for any metallic in the oil.
If you can borrow a dial indicator, you can check for max valve lift at the rocker or valve & compare to an adjacent cylinder.
I actually just spoke to a friend at work that said the same. He suggested I drain the oil and use an old magnet to see if there are any iron filings in the oil. He also suggested I use a dial indicator to measure the lift of each intake/exhaust valve at the rocker arm. I do have a cam card that indicates the lift and duration of my cam.
Truthfully, this all started last weekend when I was trying to dial in my timing and vacuum advance. I could occasionally hear the #7 rocker arms ticking when driving my car. My friend suggested we remove the driver's side valve cover. I was never happy with any of the timing settings I tried. I suppose regardless of the timing, rocker arms should NOT chatter.
I set the lash statically per the instructions in the Comp Cams roller tip rocker kit. I will try to set it with the engine running as well. I actually just spoke to a friend at work that said the same. He suggested I drain the oil and use an old magnet to see if there are any iron filings in the oil. He also suggested I use a dial indicator to measure the lift of each intake/exhaust valve at the rocker arm. I do have a cam card that indicates the lift and duration of my cam.
Truthfully, this all started last weekend when I was trying to dial in my timing and vacuum advance. I could occasionally hear the #7 rocker arms ticking when driving my car. My friend suggested we remove the driver's side valve cover. I was never happy with any of the timing settings I tried. I suppose regardless of the timing, rocker arms should NOT chatter. Thanks for the tips.
"Fish" around in the oil pan for hydraulic lifter parts.........the wire retainer on top of the lifter. I am sorta wondering if the retaining clip has come loose and the disk is lifting partially out of the bore and sticking and making the noise because.......... Statically setting lash on hydraulic lifters isn't what I would do. I am with Lonnie, set lifters when running.......
"Fish" around in the oil pan for hydraulic lifter parts...
That would be horrible!
I will though. I suppose a failed lifter is better than a failed cam. FWIW, I inspected the pushrods on #7 and found no abnormal wear, aside from some marks from contact with the guide.
You can set your valves using the EOIC method statically or with the engine running the way Lonnie said. The easiest way to see if your cam is eaten up is to see if all the rockers are moving the same distance opening and closing. Another tell tale sign would be a lot more rocker arm stud threads sticking up out of the nut than the rest of them.
Flat tappet cams always worry me with the new oils in use today.
About 10 years ago, I had a mishap on my 68 Camaro. I thought I would do a fluid change since it's not driven often, even though there were not many miles on the oil.
Without thinking, I put in some Mobil 1 Synthetic oil & took it out for a ride.
I came back home & heard a lifter tapping. I was disappointed, as the car has solid lifters & a stud girdle that requires removing the wiper motor to get the valve cover off.
Pulled it apart & set all valves & thought it was good.
Went for another ride & came back to the same thing all over again.
I quickly realized the cam was self destructing from the oil I put in it.
Really it was the oil from the open valve cover and some oil I poured on the #7 exhaust valve that ignited. Luckily I had a fire extinguisher nearby and promptly put it out before it did any damage.
Before the oil caught fire I killed the engine twice by tightening the exhaust valve. It died at +3/4 and +7/8 turns. I'm reluctant to tighten it much more. I only tightened the #7 intake valve 1/2 a turn, but I think it's the exhaust that is chattering. Unfortunately, even after tightening the valves it still chatters. So...
I will get to the oil change tomorrow. Maybe fate is trying to tell me something?
I usually make a dam out of a card board boxtop to keep most of the oil off the exhaust. I think its time to pull the manifold and physically check the lifters and the cam.
You backed it off until it tapped loudly & then went to zero lash, plus 7/8 turn?
Please remember what I said about over-tightening... Be careful. I never go beyond 1/2.
If you do it too fast (lifter has to bleed down) or too much, you hold the valve open & it may stall the engine or make piston to valve interference.
Sounds like you may have a lobe going out or a bad lifter.
You backed it off until it tapped loudly & then went to zero lash, plus 7/8 turn?
I never backed it off, I tightened it from 0 lash. I tightened the exhaust valve +3/4 turns and it died. I started the car and tightened it to +7/8 turns and it died. I started the car again and tightened the intake valve to +1/2 turns and the exhaust valve was still chattering. When I poured 1/8 quart of oil on the exhaust valve to silence the chatter the oil ignited.
I suppose I will remove the intake to inspect the lifters and cam.
I disassembled the intake and lifter valley cover. Suprisingly the intake valve lifter and lobe has more wear than the exhaust valve lifter and lobe. Also, there is nothing that strikes me as catastrophic damage.
There is pitting or scoring on the body of the intake valve lifter.
There is also a small amount of pitting on the intake valve lobe.
This pitting is small enough that I can't catch my finger nail on it, but it is definitely a flaw. It doesn't wipe off. Otherwise the wear seems pretty normal on the camshaft.
I guess I should get a dial indicator and measure the lift of the cam. I am using cam # 402194 it's 308*/308* duration and .474"/.474" lift. Is any wear acceptable on the cam? How much wear would cause valve train chatter? I suppose it could be in the pushrods or rocker arms but they all have what appears to be normal wear.
Have you checked the pushrods to see if they are straight ? Are the lifter disks in the lifter sticking ? Do the lifters seem to rotate freely in the lifter bores ? How do the rocker arms look ? Checking the cam lobes for wear and lift is next.
I like the 308/308 cam ! How does that cam work in big car ?
I have my fingers crossed for you.
I actually forgot to mention. The intake valve lifter has scoring and pitting on the foot of the lifter. The lifter is actually worse than the intake valve cam lobe...
I checked the rocker arms on #7 for excessive wear and couldn't find any. I need to check the pushrods and see if they're true.
To answer your question Ralph I like the cam... when the car is running right. It's the "factory muscle" cam. Bob Gerometta says in his "Wild About Cars Engine Modification and Tuning Guide" that this cam is iffy for power brakes and gives poor vacuum. However I have never had a problem with it until now. Let's hope it is a lifter or pushrod though.
I always liked the 308/308 cam. I first used it in my '65 4-4-2 (with 1966 block), way back when. With W-30 valve springs shimmed to specs, it would " real good. Later they used it in the W-45 '68 H/O. They used the Pontiac OHC 6 torque converter for a little extra stall. I had a Lunati "blueprinted" 308/308 cam in my '68 H/O.
Its a little weak on vacuum, but now they have these cute "vacuum pumps" to solve that problem.
I picked up a couple new 308/308 cams that were for sale on here last year. I have thought about using one in the 455 in my '64 Starfire, but I figured it was to much cam. I may rethink that before the engine is installed. What valve springs are you using ?
And finally....I hope a couple new lifters solves the problem.
Didn't tinker with the Olds this evening because I had to mow for the first time this season. Luckily it started with a bit of ether.
I did find out that the exhaust valve pushrod is slightly bent. It definitely doesn't roll straight. If I can get away with a set of pushrods and lifters to repair the Olds then that's great. I will do the lift check with a dial indicator though.
Bent push rod was the one that was rubbing ? I am hoping for you that only a couple thousanths wear on the lobe and some new push rods and a couple lifters solves the problem. Good thing you caught the problem early.
Do you remember specs or spring part numbers ? I am getting antsy about changing the cam.
Thanks for the info. Those are the springs I'll be getting.
In recent years, there seem to be a lot of cam failures. I remember the old days, pour on some EOS and you were good to go. The lubricants have improved a lot. More cars are running roller cams. Spring pressures have increased some, but I am wondering if the cams are a hard as they used to be.
I want to see if someone will nitride the cam lobes. I have seen that some cams are made from 8620 steel. 8620 is not a full hardening steel, and the hardness isn't terribly deep maybe .020-.030".
Maybe when you shop for a cam ask how hard the lobes are. I am not a fan of CompCams, and I thought Lunati had a bad (soft) batch of cams a while back.
......Just my two cents worth
I tried to start my Olds today. I replaced the pushrods and lifters after using a dial indicator to verify that each of the intake lobes on the cam is .304" while the exhaust lobes are .298".
Unfortunately, I couldn't get the Olds started to see if my valve lash was set correctly. I can crank it and it will try to start. Sometimes I can coax it to run with the accelerator but it always dies before I can get out of the car. It's definitely timing related. I keep adjusting the distributor and I can't find the sweet spot. Sometimes it wil start and race to WOT. Of course I shut it off promptly.
I'm done for the day. Not only because I am exhausted but because the battery is dead... again.
March 23rd, 2019, 06:19 PM
