I have a 1996 Z28 Camaro and was recently informed that I need a "valve
job." The shop told me it would cost around $1500 for them to do it.
That price sounds reasonable, but I'm thinking that I can do the job
myself and replace everything with performace parts for around the same
amount. I was hoping to get people's opinions of options for the
Roller Rocker Arm
I'm pretty handy, but have not replaced heads before. Because I am a
noob to this, I wanted to get the experts opinions before I buy
anything. What company has the best options for parts (i.e., highest
quality for best price). Also, what shop should I buy from. I hear
Summit Racing is pretty good. Thoughts? Thanks up front for your
Here is the cars present situation suggesting that it needs a valve
The car has been running like crap since I purchased it 500 miles ago.
It is missing on cylinder #3 and occasionally on #6. The cylinders are
getting good spark from the opti and the injectors have been tested and
are functioning properly. The fuel pressure for the line is fine and
the fuel pump has been checked. The car has new plugs and plug wires
and is wired correctly. The problem is that there is a funky vacuume
pattern suggesting a valve problem. The car has 160,000 miles on it
and is due for some major work.
What is a "funky" vacuum pattern, and why would you have your heads
messed with over it?
Vacuum comes from the manifold, not the heads. If you have a vacuum
leak, on a fuel injected engine, the RPM's will go higher then normal.
Have you had a compression test? If you can change the plugs you can
test the compression on each cylinder.
Has the valve lash been checked? have the valve covers even been removed?
I hate to see someone suckered in to a head service when it is not
needed. Your vaccum issues could all be EGR related. If the EGR pentle
is clogged with carbon your engine will do everything from lose power,
The mechanic who worked on the vehicle told me I needed a valve job.
When I asked him how he knew I needed a valve job, he informed me that
he had checked cylinder compress and that the cylinders were getting
good compression, but that my vacuume was going up and down
speradically. He insisted that it meant I needed a valve job. He said
that he had not had an opportunity to take off the valve covers but
that he was sure that the valves were my problem.
I, personally, have not had an opportunity to remove the valve covers
to take a look at things. As you know, these engines are a pain in the
@$$ to work on so its a full days work just to get the valve covers
off. Before I tear everything down to get at the valve covers, I want
to make sure I have everything I need to fix the problem once I
I appreciate your interest in my plight. Since fuel and spark have
been checked and there doesn't appear to be a vacuum leak, what would
you suggest I do next? Any advice would be appreciated. Also, if I do
need to replace the valves, what heads/rockers/rods would you suggest
for an upgrade?
Charles Bendig wrote:
that if you had a valve problem causing missing, you would have a
compression problem on the missing cylinders. The optispark IIRC is
well known for causing symptoms like you describe if it's bad. I would
certainly get a second opinion since it sounds to me like the mechanic
is trying to rip you off or doesn't know what he is doing. As I
understand it, the fact of a miss happening will cause the vacuum to
Ok, here's what you do. First, since you bought the car 500 miles ago,
I'm assuming you have a comprehensive deductible on it. Lower it. REAL
low; like $250 low. Second, find a different idiot mechanic who will
tell you you need new heads, especially if he overprices it. Take that
estimate, file a claim, and with your fat check, buy yourself the LT4
conversion kit(GM PART # pk12550630). Have a friendly mechanic install
the goodies for you, and while your at it, take charles' advice and fix
your EGR system. 160k is a good time to swap heads and rebuild the top
half of the motor anyways; might as well make a good deal on a huge
upgrade if you can afford the cost of the difference from the insurance.
Im far from the best, I just happen to do it more often then some here.
You would not believe the number of 1992 up GM vehicles with odd ball
problems that lead to a mis-diagnosis because of one problem.
Very Often on cars & trucks with the 1992 up style electronic EGR
Valve. The Pintle (the moving part inside) Gets clogged up with a chunk,
or fleck of carbon. This hold the Pintle open, Thus keeping the EGR
Valve Open all the time. This causes false/ghost trouble codes, the ECM
will cycle vacuum switches, giving odd vacuum readings with a gage, and
will cause miss-fire situations.
This year alone I have seen 20 cases of this issue, all in GM RWD
vehicles with over 100,000 on them. The problem is found often enough
that a few companies (Standard Motor Products, Help/Motormite and
others) make a EGR gasket with screen. The Screen catches large carbon
chunks or Flecks, and prevents them from hanging the pintle open.
Even some Ford engines have this problem (mostly 1993 up Trucks). Yet
for a Mechanic who does not see this issue often, it can be hard to
diagnose. I know a few master techs who were doing intake gaskets, fuel
spiders, even new EGR valves trying to figure out why the cars and
trucks would come back in a week or two with the same issue.
I was just fortunate enough to learn from there mistakes.
I take September 11th off work every year.
Well the verdict is in... I took off the valve covers, examined all
the springs and found that the cylinder 3 spring on the front valve had
cracked near the base and was loose enough for me to spin it around
with my fingers without alot of resistance. So its time for a valve
job. Anyone want to chime in on the best cylinder head question?
BTW... thank you all for your feedback. I am going to take peoples
advice and replace the EGR valve also.
Gary - KQ6RT (NoMoreSpam) wrote:
.....or, you could just replace the valve spring.
Seriously, unless you have a broken valve you can't tell anything about the
condition of the valves by looking under a valve cover. A compression test
is what really tells the story.
Second of all, I wouldn't recommend anyone pull the heads off any fourth gen
f body until it's time to drop the motor out and do a complete rebuild. I
own a '96 Z28 myself and over the last five years I've taken apart about
everything on the car there is to take apart. Pulling the heads off while
the engine is in the car would be a nightmare of a job. There is a reason it
cost so much.
I dropped the motor out the bottom of my car a few months ago, rebuilt it,
and put it back in. I'm very familiar with everything you would have to do
to pull the heads. It certainly can be done, but I wouldn't want to do it!
to work on so its a full days work just to get the valve covers
I would not pull the head because of a bad valve spring. They can be
changed with the head in place. You use compressed air @ 80 psi to hold
the valve in place while you change the spring.
A few companies make adapters for doing this that thread in the spark
plug hole. I have a compression tester that the gage head removes from
the hose, and has a Milton type M connector. If I remove the shader
valve from it, I can use it to put compressed air in to a cylinder (the
quick way to verify a valve, hole in piston or blowby).
At 160,000 miles, things like valve springs get weak. If you want to
improve your engine, replace all 16 springs, go with roller tip rocker
How difficult can it be to change the heads? I've already removed the
exhaust headers since I'm changing them out, and I'll have to take off
the intake manifold. How much more difficult can it be to yank out the
Charles Bendig wrote:
How Difficult? For me not that hard. But then I have a Shop, with a
Lift, a small (twin stage, single phase, 7&1/2HP motor) air compressor
that will give me up to 200 PSI to bust lose bolts when need.
For you? Probably a royal nightmare with the engine in the car. Taking
the engine out might be a bigger nightmare for you.
As for changing over to after market heads, your not going to gain
much, even with headers & a after market intake. Not till you change the
Cam. Yet if your going to change the cam, you might as well get the
motor professionally built.
How difficult is it to drop the engine out of the bottom and replace
it? I can get a brand new engine for the car for $1750 at this place:
Since the car is high milage, do you think it would be worth it to
trade it out? I just hate having to redo work when it is not
necessary. I wouldn't want to change the heads or change out the
springs only to find that my rings have 10,000 miles of life left on
them. Thoughts anyone? BTW... thanks for all the input. I am
Charles Bendig wrote:
These links will explain the project in detail. This is what I used to do
To answer your original question, AFR makes what is considered to be the
best high performance heads for the LT1. You may be tempted by the LT4
heads, which are even better, but you would also need to get an LT4 intake
manifold. Chevrolet has stoped offering these pieces, and you would be lucky
to find one on Ebay for under $1000.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.