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.