Damaged cylinder head repair
#3082292
10/01/22 04:14 PM
10/01/22 04:14 PM
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Joined: Jun 2014
Posts: 3,164 Md.
carnut68
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master
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OP
master
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Md.
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Since I dropped a valve and damaged the head [Indy SEZ] the guide is split open for sure haven't pulled the head just intake. I'm weighing options here. Try to repair, it looks pretty bad. Replace the single head. Or buy a pr of Edelbrock E Streets and be done with it. With the economy taking a crap I want to be careful with $, but I also don't want it to sit for months not running. Thoughts? The 446 is probably toast hint of water in the oil. I have another shortblock ready..512 with a smallish roller. This happened yesterday, but I did make my quickest passes ever. 10.66@125.4 1.47/60 and picking up with each pass.
America First!
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Re: Damaged cylinder head repair
[Re: carnut68]
#3082299
10/01/22 04:30 PM
10/01/22 04:30 PM
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Joined: Feb 2005
Posts: 20,163 PA.
pittsburghracer
"Little"John
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"Little"John
Joined: Feb 2005
Posts: 20,163
PA.
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You won’t know till it’s taken apart and stripped but I’m betting it’s fixable. Jump on it and get it to a shop before everyone else. Winters coming. Indy may even fix it.
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27
Livin and lovin life one day at a time
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Re: Damaged cylinder head repair
[Re: carnut68]
#3082322
10/01/22 06:17 PM
10/01/22 06:17 PM
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Joined: Jan 2003
Posts: 14,493 So. Burlington, Vt.
fast68plymouth
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So. Burlington, Vt.
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A head broke off a valve? Intake or exhaust? The most common reasons I see that are usually because there was something unhappy in the valvetrain, valve to piston contact, or in the case for exhaust valves, it can be a corrosion issue.
I would carefully inspect the cam & lifter that correspond to that valve, along with checking to see that the spring hasn’t given up.
Also, I’d look for witness marks in the heads near where the pushrods go. It’s pretty rare that a valve breaks “for no reason”...... as in just fatigue. With some detective work, you can usually find the reason.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Damaged cylinder head repair
[Re: fast68plymouth]
#3082326
10/01/22 06:24 PM
10/01/22 06:24 PM
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Joined: Jun 2014
Posts: 3,164 Md.
carnut68
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A head broke off a valve? Intake or exhaust? The most common reasons I see that are usually because there was something unhappy in the valvetrain, valve to piston contact, or in the case for exhaust valves, it can be a corrosion issue.
I would carefully inspect the cam & lifter that correspond to that valve, along with checking to see that the spring hasn’t given up.
Also, I’d look for witness marks in the heads near where the pushrods go. It’s pretty rare that a valve breaks “for no reason”...... as in just fatigue. With some detective work, you can usually find the reason. Intake valve. Broke all the way off. Valve spring is not broke as far as I can tell.
America First!
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Re: Damaged cylinder head repair
[Re: carnut68]
#3082327
10/01/22 06:25 PM
10/01/22 06:25 PM
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Joined: Jan 2003
Posts: 14,493 So. Burlington, Vt.
fast68plymouth
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I Live Here
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So. Burlington, Vt.
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The head broke off, or it broke up by the retainer?
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Damaged cylinder head repair
[Re: fast68plymouth]
#3082329
10/01/22 06:32 PM
10/01/22 06:32 PM
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Joined: Jun 2014
Posts: 3,164 Md.
carnut68
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The head broke off, or it broke up by the retainer? The head of the valve. You can see it with intake off. The guide is split open.
Last edited by carnut68; 10/01/22 06:34 PM.
America First!
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Re: Damaged cylinder head repair
[Re: carnut68]
#3082333
10/01/22 06:52 PM
10/01/22 06:52 PM
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Joined: Jan 2003
Posts: 14,493 So. Burlington, Vt.
fast68plymouth
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I Live Here
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It’s very rare for an intake valve to “just break”....... without some sort of help.
Look everything over carefully when you pull it apart.
The last broken intake valve I can think of was in a 452 head. That motor was running an aggressive SFT cam with 1.6 rockers.
The actual failure that resulted in the broken valve was the tangs got sheered off the locks from the valve hammering shut repeatedly. The locks had actually worked there way towards the top of the valve, and the roller wheel from the rocker had pounded a trough into the top of the locks. When the tangs finally let go, the valve slid down the guide, the piston whacked it, and then the head of the valve snapped off.
The cause of the valve hammering shut and pounding the locks into oblivion was that the spring had died. Only that one spring was dead........ down like 30-40lbs. The other 15 tested within a few pounds of new.
Why that one spring died was the unanswered question on that failure.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Damaged cylinder head repair
[Re: fast68plymouth]
#3082384
10/01/22 11:04 PM
10/01/22 11:04 PM
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Joined: Jun 2014
Posts: 3,164 Md.
carnut68
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It’s very rare for an intake valve to “just break”....... without some sort of help.
Look everything over carefully when you pull it apart.
The last broken intake valve I can think of was in a 452 head. That motor was running an aggressive SFT cam with 1.6 rockers.
The actual failure that resulted in the broken valve was the tangs got sheered off the locks from the valve hammering shut repeatedly. The locks had actually worked there way towards the top of the valve, and the roller wheel from the rocker had pounded a trough into the top of the locks. When the tangs finally let go, the valve slid down the guide, the piston whacked it, and then the head of the valve snapped off.
The cause of the valve hammering shut and pounding the locks into oblivion was that the spring had died. Only that one spring was dead........ down like 30-40lbs. The other 15 tested within a few pounds of new.
Why that one spring died was the unanswered question on that failure.
The valve stem is still attached and the keeper still holding retainer. With the spring pulled tight. The head is off and there is a hole in the piston luckily it didn't scar up the cylinder. The head of the valve is wedged in the port and the guide is cracked, the exhaust valve looks to be bent also. The chamber and seat is scarred up.
America First!
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Re: Damaged cylinder head repair
[Re: Cab_Burge]
#3082391
10/01/22 11:50 PM
10/01/22 11:50 PM
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Joined: Jun 2014
Posts: 3,164 Md.
carnut68
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Weak valve springs lead to death and destruction in high performance engines when driven aggressively No arguments here. I'm just glad it ruin the block. Especially since it's a 65 year block.
America First!
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Re: Damaged cylinder head repair
[Re: carnut68]
#3082433
10/02/22 10:31 AM
10/02/22 10:31 AM
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Joined: Jan 2003
Posts: 14,493 So. Burlington, Vt.
fast68plymouth
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I Live Here
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My main point was, especially with regards to intake valves........ they very rarely break without a reason.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Damaged cylinder head repair
[Re: fast68plymouth]
#3082439
10/02/22 10:57 AM
10/02/22 10:57 AM
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Joined: Jun 2014
Posts: 3,164 Md.
carnut68
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My main point was, especially with regards to intake valves........ they very rarely break without a reason. I understand. I didn't see any obvious, that point to any one thing. I need to drop the pan and check #5 rod bearing since it was that cylinder. There is a small witness mark on #7 piston. So it's possible the springs lost control of the valves. It happened at 1-2 shift [6400 rpms] a friend said he could hear the engine sound change.
America First!
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Re: Damaged cylinder head repair
[Re: Cab_Burge]
#3082647
10/03/22 09:17 AM
10/03/22 09:17 AM
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Joined: Sep 2014
Posts: 4,457 Washington
madscientist
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master
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Washington
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I’ve fixed way worse than that. That’s a relatively easy fix. As Cab said replace all the valves. And I would double check the spring load.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: Damaged cylinder head repair
[Re: carnut68]
#3082838
10/03/22 01:23 PM
10/03/22 01:23 PM
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Joined: Dec 2021
Posts: 1,118 Loudoun County, VA
Brad_Haak
super stock
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super stock
Joined: Dec 2021
Posts: 1,118
Loudoun County, VA
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I've seen worse that were repaired successfully... but they weren't mine
Regardless, ouch!
2021 Challenger 6.4L Scat Pack 1320 100% stock: 1.680, 11.894 at 113.75 (DA 175 ft) weight reduction, wheels, tires, Hellcat air box: 1.661, 11.686 at 115.97 (DA 710 ft)
1973 Challenger 452 ci street/strip [2008] pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
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Re: Damaged cylinder head repair
[Re: Brad_Haak]
#3082848
10/03/22 01:58 PM
10/03/22 01:58 PM
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Joined: Jan 2003
Posts: 14,493 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
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So. Burlington, Vt.
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Well, I see what’s 99% likely the cause of the failure.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Damaged cylinder head repair
[Re: fast68plymouth]
#3082850
10/03/22 02:02 PM
10/03/22 02:02 PM
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Joined: Aug 2011
Posts: 2,853 Pattison Texas
CSK
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master
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Posts: 2,853
Pattison Texas
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Well, I see what’s 99% likely the cause of the failure. Yep, & replace ALL the intake valves, new springs & double check PV clearance
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
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