Engine Knock At Idle
Melting Slicks
Joined: Mar 2002
Posts: 2,164
Likes: 7
From: Beringen
Ok, here is another clip where you can definitely hear it - I refuse to believe this is just my exhaust.
https://vimeo.com/96229784
Password is knock
https://vimeo.com/96229784
Password is knock
An exhaust leak can actually make you wonder if you have a valvetrain issue.
Racer
Joined: Jan 2006
Posts: 313
Likes: 3
From: North of Boston Ma
Pull each plug one at a time of the cap till noise is eliminated that would give you a very good idea of cylinder to focus on IF TAPING SOUND IS ELIMINATED.
Melting Slicks
Joined: Mar 2002
Posts: 2,164
Likes: 7
From: Beringen
Thread Starter
Racer
Joined: May 2013
Posts: 421
Likes: 6
From: Chicago IL
Yeah, I got zapped really good twice last year when using a make-shift timing gun - almost crapped my drawers it was so bad! 
So I decided to go through and unplug plug wires after driving it some more. I noticed that cylinder one made the noise quieter, but not completely eliminate it. When I went to put the plug back on cylinder one, I noticed one of the two exhaust gaskets on that cylinder was off centered. Loosened my manifold and fixed it. Decided to check lash again since I had driven it a little more. Guess who was loose - cylinder 1 exhaust. Stud was tight and it seemed really loose, but only took between 1/4 and 1/2 of a turn to tighten it. Put it all back together, started it up. Much quieter, but still there. Took off the VC on the other side and cylinder 8 exhaust was loose as well - same amount. Makes sense since these are back-to-back on the firing order. Tightened it up, put it all back together and started it up. Knock is gone!!! Took it out for a drive and it drove like a completely different car! Thanks for all the help! 
Now the question becomes, how much rocker adjustment would be considered normal after break-in and how much if the lobes were wiped on the cam? It literally only took 1/4 - 1/2 turn, but they seemed really loose and only those two.
Now the question becomes, how much rocker adjustment would be considered normal after break-in and how much if the lobes were wiped on the cam? It literally only took 1/4 - 1/2 turn, but they seemed really loose and only those two.
Last edited by Jartanyon; May 25, 2014 at 07:27 AM.
Safety Car
Joined: Jan 2009
Posts: 4,000
Likes: 299
From: New York
I like to set the lash on flat tappet cams with the motor running. It is easy and fool proof.
Pull a valve cover , if you have an old set cut the top off it so it stops oil from spraying all over or just set a rag across top of rockers.
Back off rocker nut until you here a clatter , then turn the nut slowly until clatter is gone . that will be zero lash , then add 1/2 turn or what ever your cam and lifter company suggests. do all 16 and done should take 30 minutes tops .
Pull a valve cover , if you have an old set cut the top off it so it stops oil from spraying all over or just set a rag across top of rockers.
Back off rocker nut until you here a clatter , then turn the nut slowly until clatter is gone . that will be zero lash , then add 1/2 turn or what ever your cam and lifter company suggests. do all 16 and done should take 30 minutes tops .
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
Yeah, I got zapped really good twice last year when using a make-shift timing gun - almost crapped my drawers it was so bad!
So I decided to go through and unplug plug wires after driving it some more. I noticed that cylinder one made the noise quieter, but not completely eliminate it. When I went to put the plug back on cylinder one, I noticed one of the two exhaust gaskets on that cylinder was off centered. Loosened my manifold and fixed it. Decided to check lash again since I had driven it a little more. Guess who was loose - cylinder 1 exhaust. Stud was tight and it seemed really loose, but only took between 1/4 and 1/2 of a turn to tighten it. Put it all back together, started it up. Much quieter, but still there. Took off the VC on the other side and cylinder 8 exhaust was loose as well - same amount. Makes sense since these are back-to-back on the firing order. Tightened it up, put it all back together and started it up. Knock is gone!!! Took it out for a drive and it drove like a completely different car! Thanks for all the help!
Now the question becomes, how much rocker adjustment would be considered normal after break-in and how much if the lobes were wiped on the cam? It literally only took 1/4 - 1/2 turn, but they seemed really loose and only those two.
Last edited by bluedawg; May 25, 2014 at 11:18 AM.
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
I like to set the lash on flat tappet cams with the motor running. It is easy and fool proof.
Pull a valve cover , if you have an old set cut the top off it so it stops oil from spraying all over or just set a rag across top of rockers.
Back off rocker nut until you here a clatter , then turn the nut slowly until clatter is gone . that will be zero lash , then add 1/2 turn or what ever your cam and lifter company suggests. do all 16 and done should take 30 minutes tops .
Pull a valve cover , if you have an old set cut the top off it so it stops oil from spraying all over or just set a rag across top of rockers.
Back off rocker nut until you here a clatter , then turn the nut slowly until clatter is gone . that will be zero lash , then add 1/2 turn or what ever your cam and lifter company suggests. do all 16 and done should take 30 minutes tops .
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
U need to adj a hyd lifter with 1 full turn of preload. In your case i would adj all the lifters again with the engine running. I use a vlv cover with the top cut off/open.
Myself i hate to bear the bad news but there is a good possibility both those #1 & #8 lopes are wiped. Adj hyd lifters is critical as too little or to much preload can ruin the entire vlv train or even engine. U have to know the adj order and how to identify zero lash - errors here ruin lobes no margin for error.
Best of luck,
cardo0
Myself i hate to bear the bad news but there is a good possibility both those #1 & #8 lopes are wiped. Adj hyd lifters is critical as too little or to much preload can ruin the entire vlv train or even engine. U have to know the adj order and how to identify zero lash - errors here ruin lobes no margin for error.
Best of luck,
cardo0
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Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
U need to adj a hyd lifter with 1 full turn of preload. In your case i would adj all the lifters again with the engine running. I use a vlv cover with the top cut off/open.
Myself i hate to bear the bad news but there is a good possibility both those #1 & #8 lopes are wiped. Adj hyd lifters is critical as too little or to much preload can ruin the entire vlv train or even engine. U have to know the adj order and how to identify zero lash - errors here ruin lobes no margin for error.
Best of luck,
cardo0
Myself i hate to bear the bad news but there is a good possibility both those #1 & #8 lopes are wiped. Adj hyd lifters is critical as too little or to much preload can ruin the entire vlv train or even engine. U have to know the adj order and how to identify zero lash - errors here ruin lobes no margin for error.
Best of luck,
cardo0
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
Yeah, I got zapped really good twice last year when using a make-shift timing gun - almost crapped my drawers it was so bad!
So I decided to go through and unplug plug wires after driving it some more. I noticed that cylinder one made the noise quieter, but not completely eliminate it. When I went to put the plug back on cylinder one, I noticed one of the two exhaust gaskets on that cylinder was off centered. Loosened my manifold and fixed it. Decided to check lash again since I had driven it a little more. Guess who was loose - cylinder 1 exhaust. Stud was tight and it seemed really loose, but only took between 1/4 and 1/2 of a turn to tighten it. Put it all back together, started it up. Much quieter, but still there. Took off the VC on the other side and cylinder 8 exhaust was loose as well - same amount. Makes sense since these are back-to-back on the firing order. Tightened it up, put it all back together and started it up. Knock is gone!!! Took it out for a drive and it drove like a completely different car! Thanks for all the help!
Now the question becomes, how much rocker adjustment would be considered normal after break-in and how much if the lobes were wiped on the cam? It literally only took 1/4 - 1/2 turn, but they seemed really loose and only those two.
So I decided to go through and unplug plug wires after driving it some more. I noticed that cylinder one made the noise quieter, but not completely eliminate it. When I went to put the plug back on cylinder one, I noticed one of the two exhaust gaskets on that cylinder was off centered. Loosened my manifold and fixed it. Decided to check lash again since I had driven it a little more. Guess who was loose - cylinder 1 exhaust. Stud was tight and it seemed really loose, but only took between 1/4 and 1/2 of a turn to tighten it. Put it all back together, started it up. Much quieter, but still there. Took off the VC on the other side and cylinder 8 exhaust was loose as well - same amount. Makes sense since these are back-to-back on the firing order. Tightened it up, put it all back together and started it up. Knock is gone!!! Took it out for a drive and it drove like a completely different car! Thanks for all the help!
Now the question becomes, how much rocker adjustment would be considered normal after break-in and how much if the lobes were wiped on the cam? It literally only took 1/4 - 1/2 turn, but they seemed really loose and only those two.
I had to adjust my lifters 3 times after break in before everything settled in. I was concerned about premature lobe wear and such things as well. measured rocker lifts never found anything wrong. It just took time for those new components to wear together and get settled in.
I'm at 2500 miles now with no issues.
It's always nerve racking with a new build for me until I get a good 1000 miles under the belt. You always wonder if you got it all together right and all the bolts tightened.
Last edited by REELAV8R; May 25, 2014 at 11:45 PM.
Melting Slicks
Joined: Jul 2010
Posts: 2,503
Likes: 33
From: McGrady NC
St. Jude Donor '15-'16
Good news for sure. I also had to adjust mine a couple of times after initial break-in to get it right. Almost 30K miles later on a CompCams 268H with no problems. Runs great and runs quiet. I drive mine a bunch so problems would have come up before now.
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
No bull s41t there. That's me to the t. Even with 5000 miles every sound (most old like my memory) has guessing and second guessing. Turns out to be nothing. Puts a hole new perspective on paranoid.
Thread Starter
Racer
Joined: May 2013
Posts: 421
Likes: 6
From: Chicago IL
U need to adj a hyd lifter with 1 full turn of preload. In your case i would adj all the lifters again with the engine running. I use a vlv cover with the top cut off/open.
Myself i hate to bear the bad news but there is a good possibility both those #1 & #8 lopes are wiped. Adj hyd lifters is critical as too little or to much preload can ruin the entire vlv train or even engine. U have to know the adj order and how to identify zero lash - errors here ruin lobes no margin for error.
Best of luck,
cardo0
Myself i hate to bear the bad news but there is a good possibility both those #1 & #8 lopes are wiped. Adj hyd lifters is critical as too little or to much preload can ruin the entire vlv train or even engine. U have to know the adj order and how to identify zero lash - errors here ruin lobes no margin for error.
Best of luck,
cardo0
I do like the idea of setting them while the car is running. I heard the little rod plugs are bad to use so I am not sure on those.
Let's just say hypothetically those two lobes are wiped (which being a Comp cam it wouldn't surprise me from what I hear), how long would I have before I would know for sure? Will it wear down fast? If I measure lift on those two lobes, will it show this early? There was "glitter" in the break in oil, but I was told by someone that was normal as long as there are not larger pieces of metal.
Quote:
Originally Posted by REELAV8R View Post
It's always nerve racking with a new build for me until I get a good 1000 miles under the belt. You always wonder if you got it all together right and all the bolts tightened.
No bull s41t there. That's me to the t. Even with 5000 miles every sound (most old like my memory) has guessing and second guessing. Turns out to be nothing. Puts a hole new perspective on paranoid.
Originally Posted by REELAV8R View Post
It's always nerve racking with a new build for me until I get a good 1000 miles under the belt. You always wonder if you got it all together right and all the bolts tightened.
No bull s41t there. That's me to the t. Even with 5000 miles every sound (most old like my memory) has guessing and second guessing. Turns out to be nothing. Puts a hole new perspective on paranoid.
Last edited by Jartanyon; May 26, 2014 at 08:48 PM.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
There was "glitter" in the break in oil, but I was told by someone that was normal as long as there are not larger pieces of metal.
Worrying about what hasn't happened and not knowing if it's ever gonna happen is like paying a bill you don't owe.
A wiped lobe will show itself very plainly. Drive it.
If it develops a miss or obvious loss of power to a cylinder then start looking.
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
Check the heatriser on the exhaust manifold to make sure it's not bouncing to the tune of the exhaust.
To be honest, I can't discern anything going on in the video. Way to much mechanical and exhaust noise for me to pick out anything.
Also, EVERYTHING has the potential to make noise. You need to use a mechanic's stethoscope, a steel rod, a plastic tube or something to narrow down from where the noise is coming. Everyone is just throwing stuff out there for you to check and without some idea where the noise is, everyone is just guessing.
To be honest, I can't discern anything going on in the video. Way to much mechanical and exhaust noise for me to pick out anything.
Also, EVERYTHING has the potential to make noise. You need to use a mechanic's stethoscope, a steel rod, a plastic tube or something to narrow down from where the noise is coming. Everyone is just throwing stuff out there for you to check and without some idea where the noise is, everyone is just guessing.
a leaky manifold or header gasket had me panic on a few occasions! Very common and it sounds just like a knock when it's a small leak.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Let's just say hypothetically those two lobes are wiped (which being a Comp cam it wouldn't surprise me from what I hear), how long would I have before I would know for sure? Will it wear down fast? If I measure lift on those two lobes, will it show this early?
If its making noise the damage is done. U should be able to take a straight edge along the rocker arms and any rocker arms that move less than others (#1 & #8) are suspect. Also the compression in cyls with wiped lobes will increase in compression due to reduced duration and leakdown.
Of course the final say would be remove the intake and pull those lifters.
Hey ive been there - denial. Had to be something else until i finally pulled the intake and lifters. With the new heads and cam the engine was still much stronger - with 3 wiped lopes.
I did have the crank bolt pad smack a bent in corner of the trans inspection cover once - thought for sure it was a rod.
cardo0
If its making noise the damage is done. U should be able to take a straight edge along the rocker arms and any rocker arms that move less than others (#1 & #8) are suspect. Also the compression in cyls with wiped lobes will increase in compression due to reduced duration and leakdown.
Of course the final say would be remove the intake and pull those lifters.
Hey ive been there - denial. Had to be something else until i finally pulled the intake and lifters. With the new heads and cam the engine was still much stronger - with 3 wiped lopes.
I did have the crank bolt pad smack a bent in corner of the trans inspection cover once - thought for sure it was a rod.
cardo0
Thread Starter
Racer
Joined: May 2013
Posts: 421
Likes: 6
From: Chicago IL
I got a chance to pull the valve covers today after putting 500 miles on the rebuild. Sure enough, cyl 1 and cyl 8 exhaust valves were slightly loose as well as a few others this time. Tightened them up again and decided to check them all with the engine running. Bad idea! The way the rockers are shaped causes them to catch the ratchet and shake it so I was unable to tighten them this way. I was, however, able to check the distance and they all look the same so hopefully no wiped lobes.
Now here is where I am confused. On the XE262, it says the cam itself is advanced 4 degrees. If I aligned the circle on the cam and the crank sprocket when installed, does that mean the cam is already advanced 4 degrees if it is at 0? I set the timing with vacuum and get the best vacuum with initial advance at 20 degrees! That means another 20 with my weights. The only thing I can think of is that the distributor is off by a tooth or so. I did not degree the cam
Now here is where I am confused. On the XE262, it says the cam itself is advanced 4 degrees. If I aligned the circle on the cam and the crank sprocket when installed, does that mean the cam is already advanced 4 degrees if it is at 0? I set the timing with vacuum and get the best vacuum with initial advance at 20 degrees! That means another 20 with my weights. The only thing I can think of is that the distributor is off by a tooth or so. I did not degree the cam
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
Now here is where I am confused. On the XE262, it says the cam itself is advanced 4 degrees. If I aligned the circle on the cam and the crank sprocket when installed, does that mean the cam is already advanced 4 degrees if it is at 0? I set the timing with vacuum and get the best vacuum with initial advance at 20 degrees! That means another 20 with my weights. The only thing I can think of is that the distributor is off by a tooth or so. I did not degree the cam
05-27-2014 10:49 PM
05-27-2014 10:49 PM
Ignition timing is for when the spark is initiated, two different systems.
Your best vacuum may be at 20* right now, but you'll probably have to back that down for best drivability.
If the spark is initiated too soon the expanding gasses in the combustion chamber will be working against your rising piston too much and cause very high cylinder pressures before TDC which could reduce power output or lead to detonation.
You may have some carb adjustments to do yet for best vacuum and idle.
I found mine idles and best off idle at 19* of initial advance. I modded my mechanical advance to limit the total advance to 34*. It seems to like that best. This is all seat of the pants, no dyno to look at.
Thread Starter
Racer
Joined: May 2013
Posts: 421
Likes: 6
From: Chicago IL
I had it back to 16* last night and it drove very well. Not highest vacuum, but that is the max I want to go and should go. That makes 36 and another 16 with vacuum. Just broke my carb today (started a new thread) so adjustments or not, I am dead in the water. 
Thanks for all the help - this forum and it's members are great!
Thanks for all the help - this forum and it's members are great!