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Cam Shaft upgrade question

Tepot

Well-known member
Joined
Sep 13, 2005
Messages
307
Location
Moncton, NB, Canada
Corvette
1974 Metalic Blue L-48 Coupe 4 speed
Hi,

I'm thinking of buying the Extreme energy 268 Hydrolic cam kit from COMP CAM.

They say it's the biggest cam for stock engine.

Is there anyone that already has that cam? I would like to know if it sounds alot better than the stock cam. How much horse power or torque did you gain. Did you felt a big difference on performance or barely noticed the difference?

If it's sounds good, please send me a sound clip or video so I can ear it if you happen to have one

my e-mail is tepot@nbnet.nb.ca

the specs of my engine is as follow:

L-48 stock engine 195 HP and 275 foot pounds torque
The 2 bolt main block as been replaced by a 4 bolt main
Intake manifold is now an Edlebrock performer
I run on headers true dual exaust to flowmasters 40's mufflers no cat.
4 speed manual transmission with I think 3.08's rear end gear ratio
I'm also thinking of changing gear ratio to 3.55's.

I might have more HP and Torque now with all those modifications but never got it on the Dyno. I will also change the point system to electronic. I might run better after that too.

Can anyone answer a few of my quesions? does anyone has the same setup?

Thanks in advanced

Daniel
 
V

vmrod

Guest
Depending on the cam, your engine will likely produce less vaccuum than your stock engine. Headlights and brakes may not work like they used to.

I had a radical Lunati cam in my engine, but traded it out for an Edelbrock Performer cam. don't remember the cam specs though.
 

Tepot

Well-known member
Joined
Sep 13, 2005
Messages
307
Location
Moncton, NB, Canada
Corvette
1974 Metalic Blue L-48 Coupe 4 speed
They have that cam for sale on www.ecklers.com and they say in the description "This cam has a slight lope at idle but does not affect power accessories" so If ecklers says so. it must be good for my corvette right?

Ecklers only sells corvette stuff so they wouldn't sell that cam if it would affect vaccuum in our cars. I assume anyways.
 

Jerrylee

Member
Joined
Dec 23, 2006
Messages
24
Location
dolomite,alabama
I'm using the 268 but the one 4 the big blocks.....I am very happy with it .....Combined with a set of Hooker super comps It produces an awsome low end sound......I'm extremely happy with this set-up...Hope this helps...Jerrylee///
 

fine69

Well-known member
Joined
Dec 12, 2004
Messages
975
Location
Maryland / D.C.
Corvette
'69 Convertible Vette; '72 Z28 Camaro Rally Sport
... so If ecklers says so. it must be good for my corvette right?....
Ecklers only sells corvette stuff so they wouldn't sell that cam if it would affect vaccuum in our cars. I assume anyways.

Hey Tepot,

Be careful. I got recommendation from Edelbrock for a .510 lift cam to go with my rebuild. It was awful... It had a nice lope alright, but vacuum suffered ( approx 8-9 in Hg), and unless I was going like 80 mph, or at high RPMs, it ran like garbage... not very practical for the street.

With help from Jack and others here at CAC, I ended up replacing it with one that was more "streetable". The result? The first time I punched it, the torque and power was so awesome that my knees were shaking! I guess I could describe it as "scary fast!" Also vacuum is approx 15 in Hg.

With respect to Ecklers only selling Corvette stuff... not true. I get my Camaro stuff from them as well.

ADDED 11:12 p.m.:

Hey Tepot, I checked out the specs...

COMP Cams Xtreme Energy Camshafts - Camshaft, Hydraulic Flat Tappet, Advertised Duration 268/ 280, Lift .477/ .480, Chevy, Small Block. "...COMP Cams Xtreme Energy camshafts are built to take advantage of the latest cam technology, to provide maximum performance. Whether your use is off-roading, towing, or street performance, there is an Xtreme Energy cam available for you. By using an aggressive lobe profile, these cams provide better throttle response and more top-end horsepower than equivalent cams from other manufacturers, while delivering increased engine vacuum..."

Anyway, it looks like good cam !-- I hope you get the most out of your mill with this setup!

BTW, Summit has this camshaft kit for $103.95 (# CCA-12-242-2).

Ralph

:w


.
 
M

magoo

Guest
I am running this cam in my 62. It was put in 3 or more years ago when I built a new 350 for it so I can't tell you anything about any improvement to an existing motor. I love it. The idle is excellent if you like to hear a lumpy idle which I do. My car is tucked away for winter and I'm not to good on pictures and videos anyway, but I can tell you that I like the way it runs and it is considerably lumpier at idle than the 350 HP GM hydraulic cam. I am running it with ported and polished 2.02 heads and about 9.5 to 1 compression. I'm using a polished GM aluminum hi rise, an MSD distributor and coil and a 650 Holley double pumper. I am running it through a stock exhaust system and Thrush mufflers which is bad for my performance, but I love how it Idles. I don't remember if I needed head work done because of the lift to keep the springs from binding but there is a max lift you can go without head work or at least changing valve springs. I know I did use the Comp Cams 981-16 valve springs. I think the cam is ground to perform between 1600 and 5800 RPM which is pretty good for a stick hydraulic lifter car. This past summer I think I sucked an intake gasket so I plan to pull these heads and put on something with smaller runners, hoping for better performance in this RPM range. While diagnosing this problem I had 12in. of vac at idle, so without the leak I think there is enough vac to run your headlights etc. The only thing I did not like from Comp Cams was there gear and chain set. It seemed sloppy to me, much more than others I've seen. I hope this helps. I'll be glad to answer any questions I can. I'm sure no expert so I hope someone else will jump in so we can both learn. I too am interested in knowing if this cam can be used on stock heads.

Mike
 

Tepot

Well-known member
Joined
Sep 13, 2005
Messages
307
Location
Moncton, NB, Canada
Corvette
1974 Metalic Blue L-48 Coupe 4 speed
wow thanks for the feedback guy's. I'm gonna order the complete cam kit and put it into my engine. Can't wait to see the difference and mostly important how it sounds when it idles.
 
M

magoo

Guest
I dug out the spec. card for my extreme energy 268. I think the magic number for needing head or spring modification is .500 lift. Ralph already listed most of it but I noticed the lobe seperation of 110 degrees as opposed to 112 or I think some are even 114 deg. I believe this is one of the ways they keep the vac up. You're gonna love the idle. That 308 rear may hurt you some but you may be changing that anyway. My 62 is running 373 gears. Get some gear ratio and tire diameter formulas and do some research before you change. Unless you do a lot of highway driving, you too might like the 373. I hope someone else will jump in here with some good info. Maybe this post will bring it back to the top of the list.

Mike
 
Joined
Apr 29, 2001
Messages
2,141
Location
Rio Rancho, NM
Corvette
1981 HD Suspension; ZN1 Option
Tepot,

I like the XE-268H so much, that I used it on my L81.

On my play 1968 engine that I was running, the 268 worked great (Performer heads, 0.040" over 4-valve relief pistons, Holley single plane intake, 650 Holley double-pumper, straight HEI distributor, approximately 9.2:1 CR, 0.090" quench). I believe that some of my best 1/4 miles times were in the 14.9's THAT IS AT 5,000 FEET OF ELEVATION, THOUGH. The calculation comes-out about a second faster at sea-level).

I later changed it to the XE-274H, and with the 274 I liked the top-end power, but the bottom end suffered somewhat (the overlap was more aggressive, so a lower vacuum signal was obtained). The 274 did help in the 1/4 mile time slips though. My best was 14.602 (again @ 5k feet of altitude).

I knew that the 274 was going to give the L81 computer some problems, and therefore, I installed the 268 instead. You see, I cheated just a bit.

I am using all the original components of the L81 engine, except for two items:

1) Installed Hyperutectic 0.020" over pistons with a .210 dome. (sticker shock on
the authentic L81 pistons really caused this -$150 EACH L81 PISTON :eek )

2) Installed the XE-268H cam. (It only had 500 miles on it, so it was good and
seasoned already).

The combination above with the L81 components produced a TRUE 9.5:1 CR, a Quench of just 0.045", and with the 268 a dynamic compression ratio of 7.86.

I will report later on what this combination actually produced at the rear wheels when I take it to the dyno soon (with 3 snow storms passing through, and another on its way in time for this weekend, chances are that I won't be able to take the Vette to the Dyno until the last week-end of January at best). I tip my hat to all of you who reside in snow-prone-bound-stuck areas. :pat I can't wait for El Niño to move-on and bring back our mild winters back.

GerryLP:cool
 
Joined
Oct 7, 2006
Messages
295
Location
South Dakota
Corvette
76 Coupe
Hey
tepot, I think you will like the XE262 better than the 268. although the idle quality is smoother withthe 262, it develops more torque than the 268 whil only losing aroun d10 HP on the top. I am not sure how it will work with the stock heads. I run the vortecs and get 425 torque and 390 HP with the 262. The stock heads on your motor will have considerably less midrange flow and a larger combustion chamber which will both lower your total output numbers. I have desktop dyno which has given me the same results as the magazine tests and will be happy to try and simulate your engine for you. The biggest thing I would need is the casting number offf your heads.
 

Tepot

Well-known member
Joined
Sep 13, 2005
Messages
307
Location
Moncton, NB, Canada
Corvette
1974 Metalic Blue L-48 Coupe 4 speed
I dug out the spec. card for my extreme energy 268. I think the magic number for needing head or spring modification is .500 lift. Ralph already listed most of it but I noticed the lobe seperation of 110 degrees as opposed to 112 or I think some are even 114 deg. I believe this is one of the ways they keep the vac up. You're gonna love the idle. That 308 rear may hurt you some but you may be changing that anyway. My 62 is running 373 gears. Get some gear ratio and tire diameter formulas and do some research before you change. Unless you do a lot of highway driving, you too might like the 373. I hope someone else will jump in here with some good info. Maybe this post will bring it back to the top of the list.

Mike

Hi Magoo,

Thanks for the info. much apreciated, I do alot of Highway with my car so I might consider 3.55 gear ratio. I think 3.73 will give me poor gaz milleage. I know for highway I should keep 3.08's but I kinda like a quick take off and 3.08's just don't work for me. I love to squeel tires and 3.55 will probably work alot better. Can't wait to put this cam in my engine. probably will at the end of the month.
 

Tepot

Well-known member
Joined
Sep 13, 2005
Messages
307
Location
Moncton, NB, Canada
Corvette
1974 Metalic Blue L-48 Coupe 4 speed
Hey
tepot, I think you will like the XE262 better than the 268. although the idle quality is smoother withthe 262, it develops more torque than the 268 whil only losing aroun d10 HP on the top. I am not sure how it will work with the stock heads. I run the vortecs and get 425 torque and 390 HP with the 262. The stock heads on your motor will have considerably less midrange flow and a larger combustion chamber which will both lower your total output numbers. I have desktop dyno which has given me the same results as the magazine tests and will be happy to try and simulate your engine for you. The biggest thing I would need is the casting number offf your heads.

Hi Curtis,

If the XE262's idle quelity is smoother, well I don't want it. ahah lol. I just love the sound of a rougph idle engine and that's the big reason why I'm changing to the XE268. My car is actually in storage right now because of the snow. But I will get to it probably this weekend. I'm gonna try to get those cast numbers off the heads for you. I would really want to have an idea how much HP and torque this engine can produce.

In case you need more info. The engine as been rebuilted once. It's the original L-48 with a 4 bolt main small block, edelbrock performer intake, 4 barrel quatra jet carb, I'm changing the points system to that "1957-1974 Breakerless SE Ignition Kit" , Hopefully will run better with electronic ignition. Also I have an ACCEL performance ignition coil and I'm running on headers true dual exaust with no cat on flowmasters 40 series mufflers. I run a 4 speed manual transmission.

Hopefully you can guess the HP and torque that my engine produce

thanks
Daniel
 
M

magoo

Guest
Daniel,
Please post your results after the installation. I am very interested since my 74 cp. is also an l-48.
Thanks,
Mike
 

Tepot

Well-known member
Joined
Sep 13, 2005
Messages
307
Location
Moncton, NB, Canada
Corvette
1974 Metalic Blue L-48 Coupe 4 speed
Daniel,
Please post your results after the installation. I am very interested since my 74 cp. is also an l-48.
Thanks,
Mike

Yup, I'll do for sure. As soon as the cam goes in. I'll probably make a video with the sounds and maybee a burnout.

I do alot of Audio/Video Montage. If you guy's want's to see some corvette videos I've got a few on our web page. It's videos of the corvette club when we go on trips. check it out if you want to. Let me know what you think.

http://www.greatermonctoncorvetteclub.com/Videos.htm

There another small one with less quality here:

http://www.greatermonctoncorvetteclub.com/Movies/Vettes hopial.wmv

another one that I made but not of a corvette right here. this one is pretty cool

http://www.greatermonctoncorvetteclub.com/Movies/1970Mach1.wmv

have fun !!
Let me know what you think
Daniel
 

Bill75

Well-known member
Joined
Jan 1, 2004
Messages
698
Location
Somers CT
Corvette
75 Coupe ZZ4, Brodix IK-180's, Headers,TK0-500
Hi Daniel,

Cool videos, looks like you guys have a good time. Nice Mustang video!!:beer

Bill
 
Joined
Oct 7, 2006
Messages
295
Location
South Dakota
Corvette
76 Coupe
I once had a 1966 Rambler that fried the tires every bit as well as that pony. It was a cool video to watch though. Brought back a lot of memories. Thanks.
 

Tepot

Well-known member
Joined
Sep 13, 2005
Messages
307
Location
Moncton, NB, Canada
Corvette
1974 Metalic Blue L-48 Coupe 4 speed
Hi Daniel,

Cool videos, looks like you guys have a good time. Nice Mustang video!!:beer

Bill

Thanks Bill,

It's only my first year with the vette. so next year I plan do have a lot more videos, I'm gonna make one of my vette like the mustang one that I did.
 
Joined
Oct 7, 2006
Messages
295
Location
South Dakota
Corvette
76 Coupe
Excellent idea sharkcar. Then we could run the numbers on my Dyno Sim and see if it corresponds to the retailers claims. they probably would have an excellent idea of what to expect.
 

Tepot

Well-known member
Joined
Sep 13, 2005
Messages
307
Location
Moncton, NB, Canada
Corvette
1974 Metalic Blue L-48 Coupe 4 speed
Id call Comp Cams cam help line and see what they think about your combination.1-800-999-0853

It's exactly what I've done in the first place. that's why I've asked you guy's your opinion after. they told me the XE268H would be the best fit for me. But i needed to here it from you guy's.

I normally don't trust salesman. as long as they make a buck they don't care if it works or not. Note that not all salesman are like that.
 

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