EXPERIENCED engine builders,, help!
Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
EXPERIENCED engine builders,, help!
Guys I have a problem with my '85 L98 that has me completely baffled. I have had a ticking sound like a loose rocker(s) now for quite some time. I have set the rockers at least a dozen times and have never found one not right. I finally decided it must be a lifter so I bought a complete cam & kit to replace everything. I do NOT just throw money at my car, I wanted to do this change anyway. I have the later aluminum 128 heads on my car which have the small pushrod holes & guide plates. I am running a set of the old Crane Energizer non-self aligning full roller rockers 1.6 ratio that are in perfect condition and I have set preload anywhere from 1/4 to 1 full turn. At 1 full turn the car would not even start. Anyway, after the cam change along with new lifters, springs, retainers, & locks I still have this damn noise. I have even changed back to the stock rockers but the noise is still there. I have also checked pushrod length and installed proper length p-rods. Any ideas at all??
Team Owner
Joined: Oct 2004
Posts: 81,242
Likes: 3,061
From: altered state
St. Jude Donor '05
Was the cam stock before, what is it now?
Remove the belt on the accessories and try to start it?
Check for exhaust leaks? That one can fool you. Check the EGR tube going to the intake too.
Remove the belt on the accessories and try to start it?
Check for exhaust leaks? That one can fool you. Check the EGR tube going to the intake too.
Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
Took the belt off tonight, no change.
No exhaust leaks that I know of but I will check that tomorrow, and no EGR.
Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
I am suspecting that the Valve Stem Tips are no longer square.
At exact 90 degree flat angle in relation to valve stem.
That would cause a similar or exact sounding lifter noise.
Sometimes reground incorrect by engine rebuilders.
Their valve grinder stem resurfacer is out of wack.
Seen that several times in the past.
Or the engine rebuilder machinist does not even regrind the valve stem tip after a valvejob.
B
At exact 90 degree flat angle in relation to valve stem.
That would cause a similar or exact sounding lifter noise.
Sometimes reground incorrect by engine rebuilders.
Their valve grinder stem resurfacer is out of wack.
Seen that several times in the past.
Or the engine rebuilder machinist does not even regrind the valve stem tip after a valvejob.
B
Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
I'll check them out first thing tomorrow, I know I sure as hell can't get under my car,,,, even if it is raised up a bit. 
Had some real thunderboomers last night, I don't normally get seepage in my basement but I did last night. Supposed to get it again today, (saturday)
Had some real thunderboomers last night, I don't normally get seepage in my basement but I did last night. Supposed to get it again today, (saturday)
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Drifting
Joined: Mar 2009
Posts: 1,253
Likes: 4
From: East Wenatchee (2hours from n e where) WA
I would try to find exactly where the noise is coming from. get a automotive stethoscope or a long screw driver pressed to your ear and the engine. also a 2' piece of heater hose like a megaphone. once you find where the noise is coming from it will be much easyer to diagnose.
Instructor
Joined: Mar 2010
Posts: 216
Likes: 4
From: Shrub Oak NY
On a customer's stock 350 I once had a valve tap that would not go away. Adjusted lifters, moved rockers around, the same valve kept making noise. It was a bad stud. Pulled the stud out by using a deep socket and washer over the stud then tightening up with the nut to pull it out of the head. Stud did not look bad either. Weird.
Melting Slicks
Joined: Sep 2008
Posts: 2,376
Likes: 110
From: Cherokee National Forest TN
Probably a worn valve guide, it will sound like a lifter tick.
Check one cylinder at a time, both valves closed, use a long screw driver in the head valve cover rail & lever the retainer while watching the valve stem. Stem movement & worn guides will be apparent.
Check one cylinder at a time, both valves closed, use a long screw driver in the head valve cover rail & lever the retainer while watching the valve stem. Stem movement & worn guides will be apparent.
Last edited by Churchkey; May 5, 2012 at 07:45 AM. Reason: got coffee, corrected spelling
Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
On a customer's stock 350 I once had a valve tap that would not go away. Adjusted lifters, moved rockers around, the same valve kept making noise. It was a bad stud. Pulled the stud out by using a deep socket and washer over the stud then tightening up with the nut to pull it out of the head. Stud did not look bad either. Weird.
Thanks, I'll check this out but I'm 99% positive they are good.
Suckin' gas, haulin' ass.
Joined: Apr 2010
Posts: 1,100
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From: Newport News Virginia
Racer
Joined: May 2011
Posts: 293
Likes: 4
Put the stock rockers back on.
I have had many older crane rocker sets sound loud. Had a few customers what them removed. They brought them to me sooo I had to charge to R&R 2 times but they didn't like the ticking/tapping at all.
I have had many older crane rocker sets sound loud. Had a few customers what them removed. They brought them to me sooo I had to charge to R&R 2 times but they didn't like the ticking/tapping at all.
Team Owner
Joined: Oct 2004
Posts: 81,242
Likes: 3,061
From: altered state
St. Jude Donor '05
You know what it could simply be the injectors ticking away.
They can fool you and sound just like a loose rocker arm.
Churchkey chasing a similar noise on mine...worried a guide could be bad. Have to check that one out. They were imo loose when it went back together thought the machinist swore they were within spec. Hmmm.
They can fool you and sound just like a loose rocker arm.
Churchkey chasing a similar noise on mine...worried a guide could be bad. Have to check that one out. They were imo loose when it went back together thought the machinist swore they were within spec. Hmmm.
Melting Slicks
Joined: Sep 2008
Posts: 2,376
Likes: 110
From: Cherokee National Forest TN
You know what it could simply be the injectors ticking away.
They can fool you and sound just like a loose rocker arm.
Churchkey chasing a similar noise on mine...worried a guide could be bad. Have to check that one out. They were imo loose when it went back together thought the machinist swore they were within spec. Hmmm.
They can fool you and sound just like a loose rocker arm.
Churchkey chasing a similar noise on mine...worried a guide could be bad. Have to check that one out. They were imo loose when it went back together thought the machinist swore they were within spec. Hmmm.
stems of .003, .015 or .030 dependent on wear.
113 heads on my 89 lost #5 exhaust guide @ 110K, Installed new heads. Might have been #7 exhaust, don't recall exactly its been 10+ years & that ride is long gone (regretfully as it was the best of 3 Vettes).
Racer
Joined: Sep 2007
Posts: 493
Likes: 0
From: Eden Utah
Team Owner
Joined: Oct 2004
Posts: 81,242
Likes: 3,061
From: altered state
St. Jude Donor '05
Will check it Churchkey.
These damn Dart heads have eaten so many guides in a short period of time its not even funny.
No matter how perfect you make the geometry they still go away fast. God I hope thats not the case. lol
HAve to lash them this morning so Ill find out.
These damn Dart heads have eaten so many guides in a short period of time its not even funny.
No matter how perfect you make the geometry they still go away fast. God I hope thats not the case. lol
HAve to lash them this morning so Ill find out.