Essentially, "CC'ing a cylinder head" is a process which measures the volume of the
combustion chambers in the head. Typcially this figure is listed in cubic
centimeters, or CCs, hence the term, "CC'ing". When purchasing aftermarket
cylinder heads, the combustion chamber volume is usually one of the specs
listed. For example, the big block aluminum heads for the Mopar B/RB engines from
Edelbrock are available in both 84cc and 88cc versions. This number
refers to the number of CCs in a single combustion chamber. (Therefore,
an "84cc head" for a standard V8 engine is actually 4 chambers of 84 CCs each, for a total of 336 CCs.)
Why would I want to CC my cylinder heads?
To determine your compression ratio.
You cannot compute your compression ratio if you do not know
the size of your combustion chambers. Although you can
sometimes find the combustion chamber volumes for stock heads
and you can usually find them for aftermarket heads, the only
way to be certain is to check it
yourself. The "advertised" numbers
are often inaccurate, can vary from cylinder to cylinder, and
of course things like machine work to the heads can change
the volume. If you want to compute your actual compression
ratio, you must CC the heads you are planning to use - there
is simply no way around it.
To ensure that all of the combustion chambers in an engine are
the same size. If they are not, then each cylinder will have
a different compression ratio and you will either be limited by
the cylinders which aren't making as much power as the others, or you will be
hindered by pinging or detonation from cylinders with higher than
intended compression ratios. Quality control and CNC machining
has greatly reduced this problem with recent aftermarket heads,
however stock, cast heads are notorious for combustion chamber volumes that
vary from cylinder to cylinder.
How do I CC my cylinder heads?
Usually, you must pay someone to do it,
such as an engine builder or machine shop. Rates for this service seem to
average around $10 per chamber or $50/hr. So, to have a pair of V8 heads CC'd you
could expect to pay around $80-100. If you are porting and polishing the
heads and are looking to equalize the volume of the chambers, you'd have
to do some work, then take them back to the machine shop and spend another
$80-100 to get them CC'd again, and so on. If cost is an issue this is
obviously not a very attractive route!
The alternative of course, is to CC them yourself.
What are the benefits of CC'ing my own cylinder heads?
It saves money - You can CC your own heads as often as you like
and/or CC the heads of your friends and club
members for a fraction
of the cost of CC'ing a single pair of heads at a machine shop.
Speaking of which, you may be wondering how many
times you will be able to CC your heads with this kit. The only part
of the kit that is "used up" as you CC a head is the petroleum jelly
which is used as a seal between the head and the deck plate. Its not
really possible to give you an exact number here since your jelly
usage will depend on the size of the combustion chambers you are
measuring and how liberally you smear it on the head. However, a
generous amount of jelly is included with the kit (around 3oz) and should last you
quite a while. Of course, getting more is as simple as making a trip
to the local department store, pharmacy, or the bathroom medicine
cabinet.
It saves trouble - There's no need to cart the heads to a machine shop
umpteen times (or even once). You will also eliminate worries such as,
"What if I don't get my own heads back?", "What if they are damaged or stolen?",
etc. Also, are you certain that the outfit you
hired do the job will do it correctly? Unless you stand there and
watch while they do it, you basically have to trust their work. Don't get me wrong, there are a lot of fine machine shops and engine
builders out there, but some folks live by the credo, "If you want something done
right, you have to do it yourself."
It saves time - No need to fit the job into someone else's schedule. You can
do it wherever and whenever you like, on your own time, at your own
pace, and as many times as you want!
What are the drawbacks of CC'ing my own cylinder heads?
Somewhat reduced accuracy. A machine shop or engine builder with a large
investment in tooling and equipment along with an experienced staff may be
able to give you readings to the nearest tenth of a CC. With
this DIY kit, the accuracy
will probably be closer to a quarter of a CC. For the vast
majority of applications, the accuracy afforded by the DIY method is more than
adequate. For some, engines built to live on the bleeding edge, it might not be. However, someone
building such an engine is probably not going to consider doing the CC work themselves
anyway. This kit is aimed at shadetree mechanics, rodders, hobbyists, trophy/bracket
racers and folks with street/strip vehicles in general. In
other words, normal folks with normal vehicles.
When I installed Edelbrock's CNC machined 84cc aluminum heads on my 440 powered '70 Barracuda,
I used one of these kits to CC the heads and each combustion chamber came out to exactly
84cc. That's accurate enough for me!
What benefits does this kit have over other "DIY Head CC Kits"?
Ease of use. It isn't necessary to ensure that the head is perfectly level
before injecting fluid. Most kits assume you first level out the
head, then you inject fluid into a hole in the center of the
combustion chamber. However, this is very difficult to do with
many heads because the quench area is just
small enough that capillary action causes the fluid to resist flowing
into this area. You will usually end up tilting the head, tapping
on the plate trying to get the air bubbles out of the quench area, etc.
Also, even without this quench area problem, it is very difficult
to completely fill the entire chamber through a center hole. The air
bubble breaks up and bubbles like to hang to the edge of the chamber,
instead of going out the fill hole.
By contrast, this kit is designed for a "vertical fill"
with a hole right at the edge of the combustion chamber. You basically
stand the head up such that the deck plate is at an angle and inject the fluid
into a hole at the top
near the spark plug. The fluid will flow straight down into the quench
area, filling it immediately. As you continue to fill, the air bubble
will stay at the top, and work its way towards the fill hole instead of
sticking to the chamber sides. The head is only placed horizontally
once the entire chamber is nearly full. This makes filling the chamber
without leaving stray air bubbles inside much easier!
Price! This kit is easily $100 cheaper than most of the generic kits on the
market. The main reason for this is my use of a syringe style fluid
injector rather than a burette. Although a burette would no doubt be
somewhat more accurate (because of the finer graduations), the increased
accuracy in my opinion is simply
not worth the price. Plus, the burette is cumbersome
to handle, easy to break (expensive to replace) and would be very
difficult to use for a "vertical fill" style operation as described above.
Its the little things. I provide you
with a generous quantity
of petroleum jelly so that you are ready to go right away. I have not
seen another kit that does this. I also include a small mini-level just
in case you do not have a level handy but would like to level the head.
I also provide illustrated instructions and a few
copies of my easy to use
worksheets; there is one that you fill out during the head CCing process and
another which makes computing your compression ratio simple. Essentially,
once you receive my kit, you are ready to go. All you need to provide is
the fluid. (water, windshield wiper fluid, antifreeze, light oil, rubbing alcohol, etc...)
Applications
This kit should work with any cylinder head that has a combustion chamber which
begins at the block's deck and has a bore size of up to 5.5" or so. The vast majority of cylinder heads are of this type. If
you have any doubts, check out the
on-line instructions
and you should be able to
determine if this kit will work for you.
