Looking for cam for stock '81 vette

[michael r. brinkley]

Anyone recommend a cam for a'81 L81 w/4-speed manuel.

 

[Flared69]

not too sure.

but, have you checked out this months chevy high performance? Its main feature is regarding cams.

 

[michael r. brinkley]

No,I have not seen it yet. I will pickup a copy. On my vette it breaths alittle easier
with the install of a new free flow catalyst. The computer command control is still hooked up & the original carb is still working .I would like to keep it that way,just
looking to add a few hp w/ a fresh cam .

 

[Robin7TFour]

MICHAEL, go to Competition Cams site. i believe you want the 268H cam grind. good mid-range power and torque increases. also will still give you decent idle characteristics.

Bubba, the boy wonder

 

[Glensgages]

I'm not too sure about the camshaft in L-81s, but the 'standard' 4-bbl cam used in the late-'70s/early-'80s had a profile of:
.390" I / .410" E lift
195* I / 202* E @ .050" lift

I've never run the 268H cam, but a buddy had one in a 400" Poncho, and it had a noticable 'lump' to it's idle;
I'm not sure how the 268H would work with the C.C.C.-equipped Q-Jet, either.
Sorry I can't be more helpful...

 

[GerryLP]

Michael,

I used the CompCams HE268H on my L81 with the computer hooked-up. It worked great, and I did not get any "check engine" light. The cam delivered every time.

The only problem is the nut behind the wheel (me...). Once I got the taste for power, I wanted more. So I opted for a quasi-attainable goal of 300 Hp average to the rear wheels, and I moved-up to the XE274H and disconnected the computer, carburator, and replaced the intake manifold, carburator, distributor, and...and...and...Now I have the L81 in the engine stand, and I run a completely different engine.

If you want stop light-to-stop light performance, then look at the high torque cams (XE252H - XE262H). The XE356H "delivers" 350 ft/lbs of torque at 2,000 RPM, and 400 - 410 between 3,000 - 4,000 RPM.

Good luck!

p.s. Yeah, almost forgot, keep in mind the stock compression ratio of the L81. The 8.5:1 ratio will deliver approximately 10 - 15% less torque or horsepower to the quoted power output in the CompCams website for a particular cam. Its never just one improvement that must come together!!

 

[Glensgages]

Michael,
I used the CompCams HE268H on my L81 with the computer hooked-up. It worked great, and I did not get any "check engine" light. The cam delivered every time.

I'm pleasantly surprised to hear that the HE268H (I assume the prefix 'HE' is different from the 'straight' 268H cam?) works in a C.C.C.-equipped L-81;
can you pass-along the lift, duration, duration-at-.050", and L.S.A. specs?
I'm pondering a CompCams stick for an L-83 Cross-Fire, and have been told that the XE-256H-10 works well with the stock ECM of the Cross-Fire.
Thanks in advance, GLEN!!!

 

[GerryLP]

Glen,


When I slapped the HE in front of the 268H I meant "High Energy" -from the CompCams High Energy line. This line is older, and I believe that they do not have a dyno data for it (I remember asking). The cam I used is this one :http://www.compcams.com/Technical/Search/CamDetails.asp?PartNumber=12-210-2

And they designated it with a CS which I think it means chevrolet Small block, but I am not sure. It would be worth asking them for a comparison between the High Energy profile and the Extreme Energy. At any rate, once I completely go over the L81 engine, I plan to re-use this cam.

 

[Glensgages]

Glen,


When I slapped the HE in front of the 268H I meant "High Energy" -from the CompCams High Energy line.

OK: I thought the 'HE' might-be like the 'XE' line, something 'different'. Back in MY day, it was just '268H'

And they designated it with a CS which I think it means chevrolet Small block, but I am not sure.

I believe you are correct; in-fact, if listed with " -10 " at the end, I think it means a 110* L.S.A.

If the ol' 268H is compatible with the stock ECM of a Cross-Fire, it won't run like a C5, but it'll at least sound mean & nasty!

 

[michael r. brinkley]

Gentlemen- Thanks for all the info. I will give comp cams a look.Afriend of mine told
me to look @ the 327/350 cam from GM for this engine ,anybody ever try it on a L81.
Sorry, I thought the comp. ratio was 8.2: 1 on the engine? Can anyone confirm this.

 

[Glensgages]

Gentlemen- Thanks for all the info. I will give comp cams a look.Afriend of mine told
me to look @ the 327/350 cam from GM for this engine ,anybody ever try it on a L81.
Sorry, I thought the comp. ratio was 8.2: 1 on the engine? Can anyone confirm this.

A buddy ran the #151 cam (327/350) in his LM-1 '80 Z28 motor 'back-then', and another guy w/ a late-'70s Z28 we knew ran the 268H.
Both were relatively the same (heads, intake, carb, etc.) otherwise, and the 268H 'usually' out-ran the L-79 cammed Z28 by a tenth, and sounded MUCH more agreesive.

Just my $.02 worth...

P.S.: I believe that ALL LM-1s, and the L-81, were 8.2:1 CR...

 

[GerryLP]

...Sorry, I thought the comp. ratio was 8.2: 1 on the engine? Can anyone confirm this.

P.S.: I believe that ALL LM-1s, and the L-81, were 8.2:1 CR...

Boy, talk about humble pie...I appologize for my mis-statement...8.2 is correct.
I hope that Bud and the L81 gang go easy on me...:L

 

[Glensgages]

Boy, talk about humble pie...I appologize for my mis-statement...8.2 is correct.

One reason I know is I bought a '79 Z28 new in '78 with a the LM-1...

 

[fdxpilot]

Gentlemen- Thanks for all the info. I will give comp cams a look.Afriend of mine told
me to look @ the 327/350 cam from GM for this engine ,anybody ever try it on a L81.
Sorry, I thought the comp. ratio was 8.2: 1 on the engine? Can anyone confirm this.

The 327/350 cam was a good cam in it's day, but it's day was back in the mid sixties. The cam in L82s was a slightly updated version of this cam, The he268 has similar max lift and duration, but with the newer ramp design will give you much better overall performance. As was previously mentioned, an XE grind like the XE256H or XE262H is an even newer design, and would probably be better for you if you keep the computer controls.

 

[Glensgages]

The 327/350 cam was a good cam in it's day, but it's day was back in the mid sixties. The cam in L82s was a slightly updated version of this cam, The he268 has similar max lift and duration, but with the newer ramp design will give you much better overall performance. As was previously mentioned, an XE grind like the XE256H or XE262H is an even newer design, and would probably be better for you if you keep the computer controls.

Yep; why settle for ancient technology?
The 268H will deliver as-much/more HP, better low-end punch, a healthy idle, all with a modest (at WORST) loss of street-temperment.

 

[Robin7TFour]

Gerry are you running a 4-speed or auto? if auto did you change the torque converter?

 

[GerryLP]

Gerry are you running a 4-speed or auto? if auto did you change the torque converter?

Robin,

Yes! I changed the Torque Converter in the TH350C. It was more a pro-active situation than reactive. The transmission was one of the first components to get overhaul, so I guessed how much of a cam I was going to install, and then I opted for a 2,400 stall converter (to cover more cam options).

 

[GerryLP]

One reason I know is I bought a '79 Z28 new in '78 with a the LM-1...

I hear you, Glen. I have had the Stock 1981 since 1985 (bought it with about 16K miles). That's just it...I should have known better...ad ...