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Something that popped into my head is that a cam lobe/lifter could have wiped. That would have loosened the rocker enough to allow it to hammer the vlv tip. I'd say the lifter needs to be inspected also. I know that's more than my 2 cents worth but hey you get 4 cents worth now - what a deal.
Something that popped into my head is that a cam lobe/lifter could have wiped. That would have loosened the rocker enough to allow it to hammer the vlv tip. I'd say the lifter needs to be inspected also. I know that's more than my 2 cents worth but hey you get 4 cents worth now - what a deal.
Cheap enough at twice the price. Everything that you and everyone has mentioned will be checked during tear down and rebuild. Thanks again!!
Old head bolts like those used on the 327 are reusable. The only thing to watch as you torque them, they should all feel the same. If one feels like it is not tightening it may be stretching. Try another bolt in that hole and feel how it reacts.
99.9% of the time your head bolts will be fine.
Newer cars starting in the late 90's started using TTY head bolts. Torque to yield. These are built to apply a limited clamping force and then they fracture.
TTY Bolts were designed to protect the new light casted engines. It was found that light casted engines will distort when over torqued. This distortion could cause out of round cylinders, or in the case of one Ford Engine the Main Caps could pull .0015 up towards the heads if the heads were over torqued. A TTY bolt properly installed will break before it over tightens and protects the block from distortion. Properly installed you will feel these bolts starting to stretch when you reach proper torque.
Engineers like TTY bolts because they give predictable torque every time.
Old head bolts work in the elastic zone, meaning they always bounce back and you can re use them.
TTY head bolts work in the plastic zone, you stretch them till they give proper torque but will not bounce back.
Actual tests of TTY bolts have proven that 80% of them will bounce back and can be reused but there is no reasonable way to prove which ones will work and which ones will snap so new bolts are always recommended for TTY applications.
They, AERA, have come out with info that says LS bolts are reusable as they are torque to angle and not tty. Personally I hate tty bolts. On the LS engines I've built I've never gotten all of the way to the second 90* pull because they feel WAY TOO tight. And once you pull the threads out of the block they aren't easy to put back.
On a 327 if the thread feels spongy you're more than likely either pulling the threads out of the block or splitting the outer head bolt boss due to the under head ring made in the head bolt to help seal. You'll notice an indention in the heads where all of the head bolts torque. Often times this indention after repeated installations wil split the outer bosses.
You'll notice an indention in the heads where all of the head bolts torque. Often times this intention after repeated installations wil split the outer bosses.
Update. More issues than were first thought. Pictures below. When we removed the heads (which had several wallowed out push rod holes, we discovered the lifter for the offending valve had come apart. Took the heads to Kim Barr Racing Engines for him to work his magic on. Pictures show the condition of the valve seats on many of the valves. Many of the valve edges were razor sharp, as well. Going to install stellite valve seats, stainless steel valves, push rod guide plates, chrome moly push rods, rockers and a new Comp Cam, lifters, timing chain and gears. The water pump was also weeping, so that has had a complete rebuild...it is the original piece.
Can someone identify the pistons that are installed in the engine. They don't look like typical stock L79 pictures. The lifter than came apart contributing to the pushrod bending and the destruction of the valve head. Look at that exhaust valve seat. Valve seals were shot. Valve guides were worn. All to be replaced. Can someone identify this piston?? Can you say weeping?!? Rebuilt and ready for re-install.
But but we don't need hardened seats, that's just a myth!
Sorry Leif, I'm not picking on you or making fun of your situation in any way. It's just spouted over and over and over that hardened seats are an unnecessary evil foisted on Corvette owners by shady machine shops looking to increase their bottom line. Hopefully they'll have you up and running shortly. Remember you have to run hardened pushrods with guide plates. And not that you'll ever notice it but good pushrods will make about 7 hp more than stock pushrods on even a slightly modified engine.
Well duh I didn't notice you said chromoly pushrods. I would suggest Chevrolet Performance lifters. Nowadays with the after market you really don't know what part of China your parts may come from.
Leif, I went back and read your initial post again as it is very odd that you heard or felt nothing until that fateful stop sign given how much damage you have discovered. Your plan sounds solid and you should be back up and running soon!
Could be. I can't find any pics online to match-up with what I have. Looking at both L79 pistons and L76 pistons. Lots of variations. They're staying in, I was just curious as to what they might be and manufactured by who.
Leif, I went back and read your initial post again as it is very odd that you heard or felt nothing until that fateful stop sign given how much damage you have discovered. Your plan sounds solid and you should be back up and running soon!
I think my guardian angel was riding with me that day. There was, literally, nothing wrong sounding prior to the rocker sliding off the top of the valve. That rocker could have easily dislodged the keepers on the spring and allowed the valve to drop into the cylinder...makes me sick just thinking what would have happened next. I should be back riding next week. This being a completely original to the car engine, I'm doubly lucky she didn't suffer anything worse. Must be living right.
When a machine shop states It's possible they may cut into water jacket when machining for hard seats that's a no brainer for me, especially with correct number/dated heads. I will just add lead to the fuel.
My car came all original except the heads had been changed at some point and did not match. I found a set of date matched heads but with 1.94 1.5 valves and had them converted to 2.02 1.6 with the proper head and bowl work done to make them same or better as the L79 originals.
Did not need to add hard inserts because opening up to the larger valves put me in 100% original new material in the heads. With so many people upgrading to aluminum newer designs there are a glut of old 461 and 462 castings around today.
Maybe not in the future, but I see them on Craigs list almost every week.
An option to look at if you are afraid the heads you have will end up with leaks due to hard seat installation.
Wow! Thx for the follow-up. I love those pics. Reminds me how resilient the sbc is. With gas and ignition it keeps on moving even with less than 8 cylinders.
I think you got off easy as the bottom end is still usable unless the cam has wiped lobes and metal cam fragments/particales got into the bearings. But a re-ring and bearing should be the worst case. Not many mechanics do a re-ring and bearing overhaul now days but when the car was built they sure did. FWIW an overhaul can be done with the block in the car. Transmission bolted on too.
Those pistons look pretty fancy to be stock items.
Wow! Thx for the follow-up. I love those pics. Reminds me how resilient the sbc is. With gas and ignition it keeps on moving even with less than 8 cylinders.
I think you got off easy as the bottom end is still usable unless the cam has wiped lobes and metal cam fragments/particales got into the bearings. But a re-ring and bearing should be the worst case. Not many mechanics do a re-ring and bearing overhaul now days but when the car was built they sure did. FWIW an overhaul can be done with the block in the car. Transmission bolted on too.
Those pistons look pretty fancy to be stock items.
03-23-2019, 09:33 PM
