My left head seized the #5 exhaust valve, snapping the valve stem. The exact reason is not yet known, but heat or some type of binding is suspected. Machine shop says it should be an easy fix.

My question is this: Is it smart money to replace lifters while one head is off?

I do not suspect problems with them, but while access is easy, it may be cheap insurance. I was considering only doing the one side. Are there cam issues I am not aware of as far as new lifters with used cam?

Any thoughts will be well received.

The conventional wisdom is that the replacement of valvetrain components is an all-or-nothing deal. i.e. don't replace 2 or 4 or 8 lifters (or rods or springs or rockers) - do all 16. ALWAYS.

Since you have to pull one head anyway, go ahead and pull the intake, open the other valve cover, loosen the rockers, pull the push rods (be sure to put them back in their original locations) and just do all the lifters. If a bad lifter had anything to do with your snapped valve, you're better off with all new stuff anyway. Lifters are cheap - engine rebuilds are not. Timewise, you're probably only looking at an extra hour. Partswise, heck, you're going to the store anyway.

Do it once - do it right.

John

Thanks John. Makes sense -all 16 it will be.

I have been stuggling with whether or not to put new heads on with all new valve train components. The thing stopping me is that if my broken valve was a heat issue, I don't want to spend the money on new heads only to trash them. I figure, fix the immediate problem at hand and look more closely for a cause.

Thanks again for the imput.

Bret

Not trying to stick my nose where it doesn't belong but replacing the 16 is definately the CORRECT way to do the job.
Just for fun if you have a bit of extra money you might try a set of "Rhodes Lifters". They help cars make a bit more power and also help make more vacuum. They cost more but when I did a one cylinder repair a few years ago the Rhodes Lifters made a nice addition as long as you have to go under the intake manifold anyway.
Do you have a aftermarket aluminum intake manifold yet? A great investment with a big gain in Horsepower. I love the effect (both visual and the seat of the pants) of the Edlebrock aluminum "air-Gap" manifolds with the new silver coating.
Another thing to consider is a set of roller rocker arms while you do this type of repair. These come in many flavors, simple roller tip rocker arms, aluminum full-roller bearing rockers arms (bearings in two places, tip and base).
While you are working on the repairs on your cylinder head you have the potential to make a big difference in the power of the engine which makes the smiles per mile factor increase.

Just a couple of thought while you work on your good habit.
Bye for now,
Chris
P.S. if you have not installed hardened seats in your cylinder heads, good time to do it. I pulled the heads off my big block for an inspection and got both heads "overhauled" (cleaned up and valve faces re-done for tighter compression-happier engine) overhaul cost less than $100 for both heads off the car....

Hi Chris,

Thanks for the thoughts / suggestions. The more imput the better. I do have an aluminum intake. Your right, looks good and runs great. Rhodes lifters sound interesting. I'll look into it. I have considered the roller rockers but not on this engine. I want to get all bugs worked out before an upgrade like that. Thanks again - you got me thinking!

Bret

many would say im an anal retentive mofo..

but I have always replaced pushrods, valve springs and lifters as a set.

I think the valve springs and lifters are most important of the three

I agee with Ben. Actually more and more of the Cam Manufacturers are starting to only warranty their cams only if you purchased new lifters and springs to go with them.

Most if you ask them can sell you a cam kit, which contains, springs, locks, retainers, and lifters.

______________

Thanks Ben / After Shark.

Your points are well taken. New springs etc.. it is.

Bret

Hello again Bret,

It sounds like people are giving advice based on replacing the cam. I thought that I understood that you were simply re-using the cam you have and wanted to know about the lifter issue. If you replace the whole cam setup then you would clearly want to replace the springs, lifters and maybe the pushrods.

For just re-installing the head after a problem like you experianced I would'nt replace the valve springs unless you have a problem with the one from the damaged cylinder. Replacing springs is a fairly big job and is a part of head rebuilds. To do it the right way is a bit of work and takes some time and patience.
When I buy a cam I go for the kits from the big companies that give you the valve springs,valve retainers, lifters and timing chain all designed for each other, it is cheap insurance...

Pushrods are not something that has to be replaced unless one is bent. Be sure that they are clear through from end to end. I had a roller rocker get trashed by a defective plugged brand new pushrod.

Aluminum manifolds are the first thing I do to any car with a stock original. I am glad you have that covered. I spent 50 plus hours polishing a new Edlebrock Air Gap "RPM" manifold only to get a new flyer introducing their new coated ones...boy did I kick myself on that one. It sure does keep that fuel cooler going down the throat of my little 427 on those hot summer afternoons.

After re-reading you note I saw that you have a post 71 car which probably has the hardened valve seats I mentioned yesterday.

I would love to hear what they think happened that would cause the damage that you experianced. When the mechanic comes up with a likely scenario please post it so we can all learn from your experiance.

I have heard of valves sticking in their bronze guides when you lean out a cylinder excessively, but never in a car. I had a Cessna 172 with a Continental 0-300 6 cylinder aircraft engine. When you fly we lean out the fuel mixture as we climb up to higher altitudes. This is done using a Exhaust Gas Temperature gauge (EGT), while flying we lean out the mixture forcing the EGT temp to climb, once we hit a maximum then we richen the mixture to prevent valves from sticking in their guides.

Did your bad cylinder show any evidence of leaning out prior to the "problem". By the way...you are one lucky guy not to have had that valve drop and bang around a bit.

I hope that I can be of some help to you as I have learned so much from others on this forum. It helps to share our knowledge and save our money so we can spend it on our Corvettes....

Best of luck to you!!

Chris McCloskey

Just another note. Sometimes the push rods will wear out at the tips, and not be broken. That also requires replacement.

Ken -

Thanks for the info. I'll check the tips.

Chris -

Thanks for the additional thoughts. I am going to reuse the cam. It is a mild isky I am rather attached to. I am planning on just change the lifters. The machine shop is working on the head and have not finished yet. Exact reason for failure, unknown at this point. Machinist initial survey concluded the other springs were ok to reuse. He thinks it is a heat issue. The work will be completed tomorrow and I'm sure he will have a better idea by then.

One additional issue I have yet to resolve is that the piston below the seized valve has two light cresent moon marks on the top where it contacted the piston. Hmmm.... I am going to dye penetrant the piston top to check for cracks. By the naked eye it looks ok, but the dye check should tell the tale. If it is cracked, the gig is up for this engine. I'll swallow my losses on it and go for a new unit.

Good thing my wife is so understanding. She says it keeps me out of trouble.


Bret

I did make the recommendation based on him having the heads off and not replacing the cam.

When you have a set of valve springs some are stonger and some are weaker. this happens when a car has sat for a while with the vavle train in one position a couple of vavles springs may be weaker than the others or its natural for springs to wear differently over time.

this will lead to some of the hydrauic lifters centering at different locations also. with a new set of lifters and old springs they will often recenter to the exact spot the old did and can lead to engine being slightly out of balance.

but I have also had experiences where i replaced lifters and destroyed cam lobes, ive replaced lifters and then had pushrods bend.

also at the very least while you have the heads off it never hurts to check the valve springs for proper tension. the man I bought my car from rebuilt the engine only about 500 miles before I bought it. however it sat for well over a year. I checked my spring tension and they were way out of spec.

anytime you let an engine sit for long periods of time you should back off the rockers, he did not.

I may just be super cautious but the way i look at it, if you have the heads off might as well fix the heads up right. It may cost some extra money, but it will save you time later and time is money.

with solid lifters id feel ok just replacing the lifters but with hydraulic I generally replaces the springs as well.

remember also spring replacement doesnt require pulling the heads..

Thanks Ben -

You hit on a good point. This engine had been sitting on the sidelines for a over a year while another engine got some duty. It was put back when I got the car. The rocker arms had not been backed off. Changing the springs isnt that much more and I dislike doing things twice. Thanks.

Bret

Bret

If the piston is cracked, don't give up on it so easily. With the heads already off, it's not that difficult to pull the oil pan and remove and replace the piston. It will be a lot less costly. Even if you replace all the rings and bearings while you are there, you save money and have a very good engine. It's not a complete rebuild, but it's close.

Thanks Ken.

Piston is ok. Got the head back today. Heat was NOT the issue. The "doctor's" best guess = Broken spring - kisses piston - binds in head. Thats it. Machine shop replaced the broken stud with a screw in type, resized the one valve guide, replaced the one valve, spring, and retainer, and lapped all the valves. Checked all guides and replaced all seals. I went ahead and purchased a complete lifter set (and assembly lube) as well. All thats left is putting it back together. While it might not be the most complete fix, it should buy me some time to save for.......the next engine .

A big thank you to each of you posting your thoughts and suggestions. I feel your help, helped me make a well informed decision. You guys are great.

Bret

hey it reminded me to go back off my rockers from my own engine since its been sitting for 8 weeks with no ETA in sight

|UPDATED|11/23/2004 10:49:47 PM (AZT)|/UPDATED|

What a lucky Guy!!

Bret you are very lucky and I am glad that you found nothing else major in your way. About 14 years ago after I bought my first Vette I saw too much blue smoke shortly after driving it 200 or 300 miles. It turned out that I lost most compression in my #6 cylinder. The cause was the piston had cracked the glans (SP?) which is the area between the rings. I found broken metal in the cylinder after removing the head. I was then able to replace the piston without removing the engine. It wasn't really much trouble, I just pulled the oil pan and unbolted the rod from below. A piston was easily procurred and installation was a breeze.
Whatever problem you find can always be rectified with a bit of elbow grease and a loving wife at your side to tap the piston down the cylinder while you wait below to line it up.
One trick I was going to mention earlier but forgot was when you are putting the engine back togather and need to adjust the valves it always gets real messy and I have had little luck with the clips made to attach to the rocker arms to keep the oil from going everywhere. I took an old valve cover that I bought at Corvettes at Carlisle and then I took a drill and made a hole which then allowed me to use a sabre saw to cut out the center section. This way when I adjust my hydraulic lifters I simply bolt on the modified cover and start up the engine. This way my driveway looks nice and clean and the oil stays where the oil belongs.

By the way, I tought it was interesting about this concept that has been mentioned about loosening your valves when the engine is not being used for a period of time. It sounds like they are concerned about springs losing their tension. This is totally new to me and I question whether it is fact or fiction. My engine and heads were built and set up by a Winston Cup engine builder and the engine was built very carefully and precisely. The valve springs were all within tolerances after the engine sitting for over 30 months. I had driven the car for almost three years and then I put it in my garage up on stands for the 30 month period. After letting it set I was curious so I tore the engine down for an inspection and when we checked the tesion of the valve springs out loose and in place on the head. They were all almost identical to what they were like 6000 miles before. I even used the same shims under the respective valves.
The heads were removed (and rebuilt) while I was inspecting my pistons. I was concerned since I had seen some marks on my pistons using a boroscope and it appeared that my piston to valve clearance was in question. I am running 12.25 to 1 compression ratio in a 427 engine built using L-88 specs. I was happy to find that I wasted a bunch of time in my case.
It is always scarry to have to go inside of an engine but with its always better to be sure.

It sounds like you are doing the right repairs, I wish you all the best and hope that your engine is purring once again soon.

Regards,

Chris McCloskey



P.S. The only bad part of the above story was when my Corvette friends saw the valve cover I used they came after me and wanted to know why I did what I did to that particular valve cover....turned out it was an original 1966 factory cover..hey I didn't know

ctmccloskey said: I took an old valve cover that I bought at Corvettes at Carlisle and then I took a drill and made a hole which then allowed me to use a sabre saw to cut out the center section. This way when I adjust my hydraulic lifters I simply bolt on the modified cover and start up the engine. This way my driveway looks nice and clean and the oil stays where the oil belongs.

this is the method I use also..

Hey Cris -

Great story. I do have the original valve covers sitting in the attic. You know, I think I now have a plan for one of them. It is a good idea. The original valve cover is worth more to me keeping oil where it belongs than sitting where it is.

Ben - If you are doing it also ( cut valve cover) it must be good.

Thanks again to everyone. I'll post once I have everything back together and running. Keep your fingers crossed. I am really ready to put away the wrenches for a while and cruise.

Bret

i wouldnt cut up an orignal set though.. you could give them to someone building a 73 trailer queen..

you should be able to pick one up at a junkyard for peanuts..

You can also get a set of rocker stoppers. They clip onto the rockers and prevent oil from flying around. They work very well.

I always adjust the valves before putting the covers on. It takes a very praticed touch. But if you turn the engine in sequence like doing a manual valve adjust, you can adjust hyd valves as well. Make sure you are off of the cam lobe and set the adjustment to zero lash, then go one more turn. 1/2 turn on old lifters. And your done. You can put on the valve covers before ever starting the engine.

But it is touchy. If you don't get the exact zero lash with NO preload on the lifter, you will screw it up. Very very touchy.

I always do this. I very rarely recommend anyone else do it. It takes pratice. But done right, it's much easier and cleaner. No smoke. No mess. No hassle. And it's easier to put the covers on a cool clean engine.

Ken is right about the adjustment of the lifters, but you had better be comfortable with the whole idea and be careful doing it. Several times I have done it the way he mentioned and actually had no tapping when the engine was started up. The flip side is that you have to be careful that you don't have them too tight or you will have real problems REAL fast.

I used the rocker oil stopper clips and did not have great sucess with them, I am alwas uneasy with metal parts that might find there way into the top of my engine before I catch them. I adjust the lifter clearance the best I can with the engine off (not running) and then using my "open in the very center covers" bolted down with gaskets in place I still loosen the lifters to hear them just start to tap and then close them up barely just enough for the ticking to stop. I am hard of hearing so I use a engine/mechanics sthethascope and listen to the valve I am fine tuning. After I do one side I take off the modified valve cover and replace it with a permanent one and then I do the other side the same way.

My heads have screens installed in the holes that let the oil flow back down into the block. I have them fastened in securely (epoxied) on the heads and the lifter pan wherever things might find their way into harms way.

I believe that having Volkswagens for many years has helped me with messing with the valve train as you get good at it when you own a VW unless your richer than I was in college. Knowing what zero tolerance is important.

If you are not sure about adjusting your lifters let somebody who has done it do yours for you. It is cheap insurance to pay for experiance.

Best regards to all you fellow Corvetters!

Chris McCloskey

ctmccloskey said: I adjust the lifter clearance the best I can with the engine off (not running) and then using my "open in the very center covers" bolted down with gaskets in place I still loosen the lifters to hear them just start to tap and then close them up barely just enough for the ticking to stop.

my method is very similar but I back off until it rattles then tighten one half turn

UPDATE.

All back together and runs great! I adjusted the rockers individually first by TDC'ing each cylinder, getting zero lash, and then 1/2 turn. ( Kens method) As a second check I did it again with the engine running, an open valve cover, and oil retainer clips. 1/2 turn past clatter. Everything was right on. Thanks again for all the response and suggestions. I'm mobile again and it feels good!

Bret

|UPDATED|12/8/2004 11:55:24 PM (AZT)|/UPDATED|

Hinz-73 said: UPDATE. All back together and runs great! I adjusted the rockers individually first by TDC'ing each cylinder, getting zero lash, and then 1/2 turn. ( Kens method) As a second check I did it again with the engine running, an open valve cover, and oil retainer clips. 1/2 turn past clatter. Everything was right on. Thanks again for all the response and suggestions. I'm mobile again and it feels good!

you used the best method.. you did both.. good luck

|UPDATED|12/9/2004 7:45:07 PM (AZT)|/UPDATED|

Congratulations,

It is always a good day when you can drive your favorite Corvette. By adjusting the valves the way you did you were assured that you did it right. Static adjustment is the best baseline for starting the process and is the recommended way in our good old Chevy service manual.

I wish you a wonderful holiday season (Merry Christmas) and may the new year be filled with new and exciting moments in your C-3!

It's been fun corresponding with you and we all learned a bit doing it. I love the C3 Vette Registry!

Best Regards,

Christopher T McCloskey

I don't do both anymore, but the first several times you do it my way it's a very good idea to double check yourself to be sure it was right. That really tells you if you have the feel for it or not.

Glad to hear all is well. Good Job.

|UPDATED|12/9/2004 12:02:15 PM (AZT)|/UPDATED|