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Damaged cylinder head repair #3082292
10/01/22 04:14 PM
10/01/22 04:14 PM
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carnut68 Offline OP
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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!
Re: Damaged cylinder head repair [Re: carnut68] #3082299
10/01/22 04:30 PM
10/01/22 04:30 PM
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pittsburghracer Offline
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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




Re: Damaged cylinder head repair [Re: carnut68] #3082322
10/01/22 06:17 PM
10/01/22 06:17 PM
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fast68plymouth Offline
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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
Re: Damaged cylinder head repair [Re: fast68plymouth] #3082326
10/01/22 06:24 PM
10/01/22 06:24 PM
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carnut68 Offline OP
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Originally Posted by fast68plymouth
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.


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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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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
Re: Damaged cylinder head repair [Re: fast68plymouth] #3082329
10/01/22 06:32 PM
10/01/22 06:32 PM
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carnut68 Offline OP
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Originally Posted by fast68plymouth
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!
Re: Damaged cylinder head repair [Re: carnut68] #3082333
10/01/22 06:52 PM
10/01/22 06:52 PM
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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.



E6B3D31E-46BF-4A52-A5EF-769DF84A31E7.png

68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Damaged cylinder head repair [Re: fast68plymouth] #3082384
10/01/22 11:04 PM
10/01/22 11:04 PM
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carnut68 Offline OP
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Originally Posted by fast68plymouth
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.


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Re: Damaged cylinder head repair [Re: carnut68] #3082389
10/01/22 11:42 PM
10/01/22 11:42 PM
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Weak valve springs lead to death and destruction in high performance engines when driven aggressively whiney


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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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carnut68 Offline OP
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Originally Posted by Cab_Burge
Weak valve springs lead to death and destruction in high performance engines when driven aggressively whiney
No arguments here. I'm just glad it ruin the block. Especially since it's a 65 year block.


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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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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
Re: Damaged cylinder head repair [Re: fast68plymouth] #3082439
10/02/22 10:57 AM
10/02/22 10:57 AM
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carnut68 Offline OP
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Originally Posted by fast68plymouth
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.


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Re: Damaged cylinder head repair [Re: carnut68] #3082479
10/02/22 01:54 PM
10/02/22 01:54 PM
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If I was you, I have broken more than one valve while drag racing whiney realcrazy, I would replace all the valves now instead of later, when one breaks off others are sure to follow. The damage caused by over revving one affects all the rest of them work wrench scope


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Damaged cylinder head repair [Re: carnut68] #3082610
10/02/22 11:48 PM
10/02/22 11:48 PM
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carnut68 Offline OP
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Here’s a few pictures.

38A9AE43-7CF1-4F8F-BFD6-4D275EB4F5B0.jpeg9419F919-8A88-4E72-BDBA-BE02D331F2CC.jpegA0B1CB54-ECCE-4E88-B3F9-D3F09071F2B6.jpegA4883B18-32FD-42BB-BB84-ED0DC01D1D08.jpeg

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Re: Damaged cylinder head repair [Re: carnut68] #3082616
10/03/22 01:29 AM
10/03/22 01:29 AM
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A good machine shop or better yet a good shop that specializes in fixing broken heads can fix aluminum heads with no sweat scope
You might want to compare prices on fixing it compared to replacing with a new one scope up


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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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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
Re: Damaged cylinder head repair [Re: madscientist] #3082763
10/03/22 12:29 PM
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Its a "good" thing that the bowl caught that piece.

Re: Damaged cylinder head repair [Re: carnut68] #3082838
10/03/22 01:23 PM
10/03/22 01:23 PM
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Brad_Haak Offline
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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 (2022)
100% stock: 1.680, 11.894 at 113.75 (DA 175 ft)
wheels, tires, air filter: 1.714, 11.833 at 115.80 (DA 310 ft)

1973 Challenger 452 ci street/strip (2008)
pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
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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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
Re: Damaged cylinder head repair [Re: fast68plymouth] #3082850
10/03/22 02:02 PM
10/03/22 02:02 PM
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Pattison Texas
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Originally Posted by fast68plymouth
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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