1968 327/350HP Valves
Thread Starter
Heel & Toe
Joined: Jan 2015
Posts: 16
Likes: 0
From: Whitby Ontario
1968 327/350HP Valves
Following a rebuild of the original engine (previous owner), I heard a loud clicking noise. Took the valve covers off to find severely bent push rods and twisted valve rocker on cylinder 2. A few other rockers were unusually loose so thought it was a poor lashing job and thought I got lucky before a disaster. Relashed and all felt nicely fitted into cam. Valve movement was nice and engine running beautiful. I drove approximately 100 miles before a loud metallic clunk and the same loud clicking. Took valve covers off to find the same problem. Any ideas?
Thread Starter
Heel & Toe
Joined: Jan 2015
Posts: 16
Likes: 0
From: Whitby Ontario
I don't see any sign of the studs pulling out of the head. There is a small groove in the cylinder 4 exhaust stud. The rocker from #4 Intake has pushed the rocker on #4 Exhaust onto an angle and the edge of the rocker caused the groove.
Melting Slicks
Joined: Nov 2002
Posts: 2,884
Likes: 260
From: Jamison Pa
St. Jude Donor '11-'25
Loose Nuts
Were the rocker arm nuts replaced when the heads were rebuilt?
They might be backing out of adjustment. If the studs are all even in height, I would suspect the nuts. When you set the adjustment before were the nuts tight?
I would replace them. It might end up being a cheap easy fix.
Bob K.
They might be backing out of adjustment. If the studs are all even in height, I would suspect the nuts. When you set the adjustment before were the nuts tight?
I would replace them. It might end up being a cheap easy fix.
Bob K.
Thread Starter
Heel & Toe
Joined: Jan 2015
Posts: 16
Likes: 0
From: Whitby Ontario
Certainly can't hurt to try new nuts although the "crush" ends seemed tight.
Were the rocker arm nuts replaced when the heads were rebuilt?
They might be backing out of adjustment. If the studs are all even in height, I would suspect the nuts. When you set the adjustment before were the nuts tight?
I would replace them. It might end up being a cheap easy fix.
Bob K.
They might be backing out of adjustment. If the studs are all even in height, I would suspect the nuts. When you set the adjustment before were the nuts tight?
I would replace them. It might end up being a cheap easy fix.
Bob K.
Le Mans Master
Joined: May 2007
Posts: 5,031
Likes: 1,121
From: North tonawanda NY
my 74 had the same issue when I bought it with a couple rockers. Someone replaced the arms right before I bought it too which was an indication they knew about the problem.. I have yet to pull the cam since I replaced the motor but I assumed its wiped lobes on the cam from the PO using regular modern ultra low zinc motor oil in it without a zddp additive...
Last edited by augiedoggy; Jun 23, 2016 at 08:11 AM.
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Le Mans Master
Joined: Aug 2005
Posts: 6,542
Likes: 1,976
From: Temple Terrace Florida
Studs
Just for added protection, I had my machine shop drill and pin the rocker arm studs. If I remember correctly, it was $3 per stud. I also added roller tipped rockers to both of my L-79 engines. I would either use a dial indicator on the valve train to see if any of the cam lobes are wiped or use a vacuum gauge to determine valve train condition. Good luck. Jerry
Racer
Joined: Nov 2010
Posts: 310
Likes: 25
From: Brisbane Australia
Similar thing happened on my 68 327 after I replaced the valve springs. Turned out the one rocker nut was bad and backing off just enough. Coincidentally I'm pretty sure it was the same one you show in your pic. New nut and all has been good since.
