----- Original Message -----
Sent: Friday, May 03, 2002 9:43 AM
Subject: Re: [Chevelle-List] Cam
If this is a daily driver and will not be used
for racing, I think that you have over camed the car. This does not mean that
it will not run, but you might not like it. I believe you could step down 2
cam sizes myself. This looks like it might be a Comp. Cam is it? Let's
assume that this is a daily driver or show car only, you need to get a cam
that is designed for 2000-5500 RPM range. This would mean that you need to
look at something around 220 duration at .050 with about 515 lift. Let me give
you an example. I had a cam that was 210/216 @.050 with .499/515 lift (1.5
Rocker) on 108 c/l for a small block 350. I now have a cam that is
204/204 @.050 with 484/484 lift on 110 C/l. The car has the stock rear end
which when I checked it is 2.50. I do not think that they had a 2.5 rear end
on a 1971 Chevelle/Malibu so it is most likely a 2.73 rear end (Highway gear)
The first cam run good but was very slow on take off and lost power between
35-45 MPH. It sounded really good on the 108 C/L and still had good vacuum.
The second cam had good power at takeoff and all the way through the RPMs. It
just burns the tire ups when you nail it. The first cam would not spin the
tire too much. The reason the second cam worked better is the car has the
small rear end ratio. I also had an Edelbrock performance intake which is
designed for the lower RPM range. The first cam was in a .040 over motor and
the second cam is in a stock motor. If it is too late to change camshafts, you
can try this. When they do the head work, ask them to make sure the you will
have clearance if you decide to change to 1.6 rockers later. By putting in 1.6
rocker, you will drop both your duration and lift down. This will move your
power range down lower. If it was me I would look at a cam that was around
216-228 range with about 510-530 lift with 110-114 C/l
Something else I do not understand, what do you
mean waiting to hear from them before ordering the correct
lifters. If this is a roller cam then their is only
one type of lifter you want, Hyd. roller lifters. If this is a Hyd Flat tappet
cam then you want standard Hyd lifter. I would not get into using anti-pump,
or any of the other weird hyd. lifters on the market. Stick to the
basic. If you are now confused or you are worried about my advise, call
Crane or Comp Cams and talk to someone on the tech line. You will know after 5
minutes on the phone, what your cam selection should be. I live in Daytona
where Crane is, I will call them if you want me to.
Another thing that I am concerned about is
that the head work must be compatible with the camshaft. The springs must work
correctly with the lift of the cam. Most head shop want to know what cam is
being installed. You must check for coil bind on the springs. You must check
Rocker to Spring binding for the camshaft you are using. The spring pressure
for the cam lift must be know or you will be putting too much pressure on
the nose of the camshaft. You also need to check for pushrod binding. All
these are related to the camshaft being used.
Some facts about camshafts. Duration at .050 will
tell you where the power range will be. Lower duration will usually have lower
pulling ranges. Lift tells you how much air and gas you will have, which gives
you more power. C/L will tell idle features. Also c/l will effect the
power range. Tighter centerlines will pull more at lower RPM and idle rougher.
Tighter C/L (106 versus 110) will also run hotter. C/L will also effect valve
overlap(the amount of time when both valves are open). If you know the
duration at special which is usually around .004-.010 subtract that value from
.050. This is call the Hyd intensity. The lower the number the better
performance. For mild street performance, lower duration values at .050 are
better. Crane cam usually have a lower Hyd. intensity value over Comp. Cams.
The cam spec. are directly related to the rear end ratio and must work
together.
Keith C. Cooper
Sent: Thursday, May 02, 2002 9:39 AM
Subject: Re: [Chevelle-List] Cam
Thanks Keith
The engine is a 396
bored .40, it has a steel crank from a 427, and forged pistons. He is
ordering Roller Rockers, they said something like 1.7. The heads are still
being worked at the machine shop. He is waitng to hear from them
before ordering the correct lifters etc. I'm told that my rear is a
posi 4:10, If so I want to replace it with a 3.55 so that I can take
it out of town. The car is a 4 speed. Right now the car came with P295
50 R15's on the rear. There to big so I'd like to sell them ( hate to
because they're new) and so with something not as wide, maybe a P235 60 R15
on rear with a 70 series on front. This is all that I'm sure of. I
have headers and flowmasters installed.
Craig
----- Original Message -----
Sent: Thursday, May 02, 2002 9:04
AM
Subject: Re: [Chevelle-List]
Cam
What is important when ordering a camshaft is
the other components in the engine. What other changes have you made to
the engine and the block and heads.
This is not a small camshaft. It is
made for 9.5-11.00 compression ratio. RPM range will be about over 3000 to
around 5500. This is a good mid range cam. If the other engine component
and the rear ratio is not right, the cam will be slow on take off. When
ordering a camshaft, BIGGER is not better. This is what some people call a
Bracket Racing cam. You may need a stall converter. Before it is too late,
Let me know your RPM at 60 (if you know). If the block has been
bored and to want. Your rear end ratio, Your rear tire size. If your
running a stall converter. Your rocker arm ratio. Crank information. head
information etc. What do you want to do with this car, city driving,
racing etc. If you have a basically stock motor, this cam will be toooooo
big. You will not like it.
Keith C. Cooper
----- Original Message -----
Sent: Thursday, May 02, 2002 8:21
AM
Subject: [Chevelle-List] Cam
Just had the
guy rebuilding my engine to order the cam for it. I'm glad he
always ask me if the part his is going to order is ok, but hell I know
nothing about engines. It's like asking me to read Chinese.
The one I picked for my Big Block is as follows:
Duration 050 IN
224
Duration 050 EX.
232
Lift
IN 527
Lift EX
553
Lobe Center
114
Says: Lopey idle, Wild
Street/Strip
I'm looking for something that sounds
good, but I don't want something that I can hear myself think when
riding in the car. Can anyone tell me what I just ordered.
Thanks
Craig
