L88 cam in L78?

[Born30YrsLate]

Rob - yup I'll be running headers that go into mid year corvette side pipes with the capability of running the headers open.
Another quick question - will the L78/L72 cam perform just as well as let's say a Comp Cams Magnum mechanical camshaft which has the same powerband range? I noticed that that Comp Cam has a significantly higher lift for the same rpm range?
Thanks again....... [img]/ubbthreads/images/graemlins/beers.gif[/img]

[Chevy454]

Fred:

Some quick guestions on the engine combo. What intake/carb are you gonna run (L-88 stuff?)? And this car will mainly be a street car, with a trip to the track once in a while?

The thing with the magnum muscle cam is there is just a tad more duration (242 vs. 250) on the exhaust side, but is identical on the intake, but it's got a TON more lift and a LOT tighter LSA (110). That LSA worries me, as that's a borderline race car spec. That means it's gonna have a choppy idle, and may have a vacuum problem. But, I'd give Comp a call and ask. Also something to consider is the more RPM you wanna run, the better your valvetrain has to be, and the more wear and tear on the engine. Just food for thought.

[JoeG]

Born30YRSLate, Just some seat of the pants info that was tried aways back,
With the 143 cam you get very good street response with a 456/410 of course the steeper the gear the better the low end response with the 143 cam. The higher the lift and close LSA ,you are going to have to stay with 456/488 to give you that acceptable low end response.Bottomline as everyone has more or less agreed the 143 is an excellent compromise between street and strip.Listen to what the fellas are saying you won't be dissappointed,-----if you are only going to make an occasional trip to the track and mainly street drive it. .Just some input,-----JoeG [img]/ubbthreads/images/graemlins/[/img]

[VintageMusclecar]

If I may chime in;

FWIW, the 2 smallest solid grinds Crane makes work extremely well on mild BBC applications.

P/N: 133841
3000-6500 rpm
238*-248* @ .050
304*-314* adv. dur
114* LSA
.544-.567 lift (gross)
.022-.022 lash

P/N: 134781
3800-7000 rpm
248*-258* @ .050
314*-324* adv. dur.
110* LSA
.567-.590 lift (gross)
.022-.022 lash

The first of these 2 cams provides a nice flat power curve and a fairly mild idle. The 2nd cam is a bit "peaky" with a noticeable midrange charge, and a somewhat more noticeable idle.

I ran cam #2 in a well-worn LS6 "clone" motor (it did have a Dart intake and 2" Hooker headers) in my `67 Chevelle years ago, and it's 1 of the best street/strip cams I've ever used. Blowing through a "way-too-small" 2 1/2" exhaust, with only a 2500 converter and 4.10 gears, this was an easy low-12-high-11 second combination. In a 396 with OEM manifolds, I'd opt for the smaller cam.

Re: The advertised rpm ranges Crane recommends... I've found that these cams often come in sooner than Crane advises; perhaps this is an attempt on Crane's part to keep people from "over-camming" their engines, I don't know.

Just throwing my .02 in. [img]/ubbthreads/images/graemlins/beers.gif[/img]

Eric

[Born30YrsLate]

Rob - the car will have the 198 L-88 intake and a Holley 950 cfm 3-barrel. Because of the kind of car the motor will be going in to, I feel it needs to be feared/respected on the street as well as the track. The car will be driven no more than a couple times during the year....local shows and local cruises.
I appreciate everyones input so far....... [img]/ubbthreads/images/graemlins/beers.gif[/img]

JoeG - what size cam do you have in your 396 Phase III Chevelle?...... [img]/ubbthreads/images/graemlins/[/img]

[JoeG]

Born30YrsLate,
Everybody is right with these different cam combinations, it just depends on how much cam you are willing to live with on the street. I had installed a PHASE III cam from Motion 535/555 lift, and the extra lift with the open plenum and three bbl really came alive mid -range ,kept it in for about a year. I went back to the 143 because with the auto there was less creep and loping in traffic.It sounds like you want to step up a little with your cam selection,go ahead ,with the setup your talking about your engine would welcome the extra air., you can always change, at least you can say you tried it--Just my opinion--JoeG

[Chevy454]

Some things to consider...

The L-88 intake is gonna be a single plane (open plenum), as opposed to the 163 dual plane of the L-78/L-72. The open plenum is geared towards the upper RPM range, and is gonna hurt anything geared towards the low end or lower-mid range. Also, I'm gonna *guess* the 950 is a double pumper? If so, it's not exactly the optimum street carb...I myself favor a vacuum secondary carb. The 4.56 gears will help keep the revs up for the big intake/carb combo, so the rest of the combo is geared towards revs. That means you'd better have a good valvetrain, and you're almost gonna have to have a fairly healthy cam to make best use of the other components. Now, being in a relatively light car and being a 4-speed will help.

Like everyone has stated, the 143 or something equivalent is gonna be better for the street and will have vacuum, but as you start edging towards the L-88 range of cams drivability and vacuum become concerns. And, some people can tolerate more/less than others. But, you may need to turn some RPM's to fully use the intake/carb combo. Wayne's pure stock L-88 Corvette made 571hp with a custom grind. Shoot him an email and see what cam and vacuum he's got: nelson66@REMOVE_ME_ecenet.com

Now, my recommendation. The rule of thumb on carbs and cams is that it's better to go too small as opposed to too big. I think you'd be fine to go with the 143 cam, and it would do what you want. But, a call to Comp and Crane would be your best bet, if nothing more than to get another opinion. I'm gonna guess Comp will steer you towards the Muscle Magnum cam, but be sure and ask about idle and vacuum quality.

[GMH454]

Am rebuilding the driveline of a local A/Mod car that ran LS7 074 alloy head BBC back in 1974. Car was 3700lbs usually with 4.56 (12 Bolt also ran a Hone OD ) Car track raced with dual 660s but street raced ( he was a BAAAD boy )with Weiand intake and a 780 vac.
Reason was that it produced better torque out of the hole, and with 3700 lbs it was a factor.
850DPs were made for the Vette A Prod wars with the Cobras.
Great carb but originally designed for the race track (read one with corners )
There is a school of thought, that the the bigger the carb, the better the carb, but ain't always so.
[img]/ubbthreads/images/graemlins/[/img]

[JoeG]

Something also to consider--The L /88 manifold is completely gutted open. The edelbrock C-427x,has only a section cut out of the plenum divider,for the 3bbl sec throttle plate, giving it a little better low end response.I think you got what you wanted from everyone input---O.K. Flip a coin [img]/ubbthreads/images/graemlins/grin.gif[/img]--If you call the cam doctors like to hear what they say.----JoeG.

I,m just going to add to GMH454,---He's right the 3bbl in the beginning was not a street friendly carb, but Edelbrock did make it more streetable thru some modifications and I did have to play with mine a bit to get it to work properly.--To make the car more streetable,after awhile I changed to a Tarantula man .and a 3310 Holley.The car had some manners then.Whatever you decide I would like to see photos if possible [img]/ubbthreads/images/graemlins/beers.gif[/img]---JoeG

[Chevy454]

Milling the divider down a tad on the 163 intake is supposed to be the hot ticket. Kind of a "best of both worlds" scenario.