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66 coupe with a 302 mystery motor
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Discussion Starter · #1 ·
Anyone know what could’ve caused this damage? Bent push rod and rocker damage on one cylinder and broken rocker arm stud on another
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. Bought this car in this condition so I don’t know what happened
 

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Looks to me like you may have to dive a little deeper into this motor to find the smoking gun...but check the other pushrods for different sizes? also from the pics it looks like the rockers are different?...some have oiling holes and othes appear not to have them? Something is wonky....need more pics...and info. Keep going. You may have an assortment of parts, as it appears that you have 3 kinds of rockers in photo....but it could just be my old eyes....
 

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66 coupe with a 302 mystery motor
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Discussion Starter · #3 ·
Looks to me like you may have to dive a little deeper into this motor to find the smoking gun...but check the other pushrods for different sizes? also from the pics it looks like the rockers are different?...some have oiling holes and othes appear not to have them? Something is wonky....need more pics...and info. Keep going. You may have an assortment of parts, as it appears that you have 3 kinds of rockers in photo....but it could just be my old eyes....
Nope. You’re absolutely right! I noticed the difference in rockers immediately after posting. They’re not even close to the same size. I have no idea what he was doing. Other than new pushrods and rockers anything you would recommend checking? He had a cam put in it with a 471 lift I’m thinking maybe he just tried using the stock pushrods and what ever rocker fluster cuck is happening might have been the issue
 

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When you put random stuff together, random things happen. I'm guessing that with this lack of attention to detail, geometry at the valve was not carefully considered.

When you put it back together, I would urge you strongly to consider linkbar roller rockers and a roller cam (if it doesn't already have that setup). Modern flat tappet lifters are suffering major reliability and build quality issues. All of them.
 

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66 coupe with a 302 mystery motor
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Discussion Starter · #5 ·
When you put random stuff together, random things happen. I'm guessing that with this lack of attention to detail, geometry at the valve was not carefully considered.

When you put it back together, I would urge you strongly to consider linkbar roller rockers and a roller cam (if it doesn't already have that setup). Modern flat tappet lifters are suffering major reliability and build quality issues. All of them.
I have no idea what kind of cam is in it I’m only going off the sticker in the engine bay. I’m trying to avoid pulling the entire motor if I can help it
 

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At the very least here, I think I'd pull the intake and look down through the lifter valley at your cam and lifters. Frankly, you're going to have to pull the head to fix that valve anyway - and almost certainly some of the others, even if their rockers haven't fallen off. If you have this level of hanky-panky going on at the head, who knows what it's like in there? As @64-1/2 first.... 66 now mentions, the rocker that died was not compatible with your heads; it needs an early slotted 289 head, or guides. It was bound to fall off the valve and die.
 

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I see at least two style rockers as well. The stud is broken, right? You can't judge from most of that damage on the rocker as it may have bounced around in there and did all that after it broke off the stud while it was running high RPMs.
It could be the simple case of too much cam on stock springs.
Best wishes.
 

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66 coupe with a 302 mystery motor
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Discussion Starter · #10 ·
I see at least two style rockers as well. The stud is broken, right? You can't judge from most of that damage on the rocker as it may have bounced around in there and did all that after it broke off the stud while it was running high RPMs.
It could be the simple case of too much cam on stock springs.
Best wishes.
that’s the thing, the broken studs respective rocker and pushrod are undamaged. I checked them when I bought the car. It was when I pulled the head i found the damaged rocker and pushrod on a completely different cylinder
 

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66 coupe with a 302 mystery motor
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Discussion Starter · #11 ·
At the very least here, I think I'd pull the intake and look down through the lifter valley at your cam and lifters. Frankly, you're going to have to pull the head to fix that valve anyway - and almost certainly some of the others, even if their rockers haven't fallen off. If you have this level of hanky-panky going on at the head, who knows what it's like in there? As @64-1/2 first.... 66 now mentions, the rocker that died was not compatible with your heads; it needs an early slotted 289 head, or guides. It was bound to fall off the valve and die.
Yeah I’ll do that. I actually already bought some aluminum heads to throw on it.
 

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I would personally remove heads for repair/replacement as needed and inspect pistons and walls for any other issues.
The 65 and early 66 heads have a slotted hole (oval) that pushrods go through and act as guides.

From what I see, the holes in your cylinder head are round which require different rocker arms.
 

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My Mustang had a rebuilt engine with less than 1/2 hour of running time on it. The only undamaged part was the intake manifold.
If I were you I'd pull the engine for disassembly and inspection. The lesson I learned from my engine is that stupid follows stupid.
 

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'65 convertible, A code 289, CR 4 spd, factory front discs.
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Looks like a case of no oil supply to the rocker, valve stem ate into the rocker, steep rocker angle snapped the stud.
 

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66 coupe with a 302 mystery motor
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Discussion Starter · #15 ·
My Mustang had a rebuilt engine with less than 1/2 hour of running time on it. The only undamaged part was the intake manifold.
If I were you I'd pull the engine for disassembly and inspection. The lesson I learned from my engine is that stupid follows stupid.
If I am to pull this motor it won’t be going back in it :LOL:
 

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Yeah I’ll do that. I actually already bought some aluminum heads to throw on it.
If you're going to install aluminum heads, why are you worried about it? You're going to need all new rockers and pushrods anyway.
 

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1965 Mustang GT. 11.898 @ 113.646, all motor, three pedals
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Anyone know what could’ve caused this damage? Bent push rod and rocker damage on one cylinder and broken rocker arm stud on another
View attachment 842869
. Bought this car in this condition so I don’t know what happened
A grinder or cutoff wheel did that^
 
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