Author Topic: Factory Camshaft spec's for 1967 L48  (Read 1392 times)

57s67

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Factory Camshaft spec's for 1967 L48
« on: August 05, 2022, 10:42:05 PM »
When I bought my car the previous owner had started restoring the car to original.  The guy told me he had the engine rebuilt to factory spec's.  I replaced the cam with a Lunatti Voodoo prior to initial engine start up.  I have receipts for a lot of the parts he purchased but not the cam I think it came fro Classic Industries, as most receipts I have are from there.  I have a brand new cam that I cant use and would like to get rid of it.  What would be the approximate specs for this cam?  If I knew that I might be able to find someone who wants it.   

Chuckman4112

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Re: Factory Camshaft spec's for 1967 L48
« Reply #1 on: August 05, 2022, 11:46:46 PM »
Does this help you?

https://itstillruns.com/305-chevy-vortec-cam-specs-7715400.html

I am new here also, just trying to help.
68 Camaro SST 350/TH400

Stingr69

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Re: Factory Camshaft spec's for 1967 L48
« Reply #2 on: August 06, 2022, 01:39:19 PM »
The factory cam would be the "929" cam.  Specs are published but why bother looking for them?  Anybody that wants the base engine stock "929" cam could care less about the specs. There is only 1 base engine cam used for every base 350 from Camaros to Corvettes, to Caprice Estate station wagons.  Used from '67 and up to at least the early '80's. 

67L48

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Re: Factory Camshaft spec's for 1967 L48
« Reply #3 on: August 06, 2022, 02:33:42 PM »
[...] https://itstillruns.com/305-chevy-vortec-cam-specs-7715400.html [...]
This is in no way a criticism of Chuckman, but I quickly glanced at that article and this jumped off the page at me:

"The Chevy 350 engine was originally released by GM in 1967. It has been featured on the Chevrolet Corvette, Chevrolet Caprice wagon and smaller mobile homes. The engine is still produced in Mexico at the GM Toluca plant."

And this is why we can't have nice things.  No mention of the Camaro.  It's no wonder that people forget that not only was the 350 available in the Camaro in 1967 (yes, they do, I have had heated arguments with Chevy guys who swear the 350 was NOT available in the Camaro in 1967), they forget that is was only available in the Camaro in 1967, and that the engine was specifically designed for the Camaro's launch in 1967.  The 350 SB should be synonymous with Camaro, but, sadly, it's not.  People can write entire articles about the 350, including its history, and fail to mention the Camaro.  [me quietly weeping]

Here's a conversation from a Corvette forum. I don't own a vette and don't know these guys, but I'd bet they're pretty sharp on their cars:  https://www.corvetteforum.com/forums/c1-and-c2-corvettes/1124838-1967-327-350-hp-camshaft-question.html

67L48
1967 Camaro SS 350
PG, factory air, console, fold down rear seat, PS, PB, butternut yellow, #s matching, original manual/warranty/POP, <60K miles
Northeast Iowa

David K

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Re: Factory Camshaft spec's for 1967 L48
« Reply #4 on: August 06, 2022, 03:03:48 PM »
The shipping box is gone?
Are there any stampings on the end?

Chuckman4112

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Re: Factory Camshaft spec's for 1967 L48
« Reply #5 on: August 06, 2022, 03:20:29 PM »
[...] https://itstillruns.com/305-chevy-vortec-cam-specs-7715400.html [...]
This is in no way a criticism of Chuckman, but I quickly glanced at that article and this jumped off the page at me:

[/quote]

None taken. That's something new I learned.

Chuck
68 Camaro SST 350/TH400

CNorton

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Re: Factory Camshaft spec's for 1967 L48
« Reply #6 on: August 06, 2022, 03:58:02 PM »
I raced in NHRA Stock Eliminator with an L48 motor in a '68 Camaro for about twenty years.  The teardown specs for lift on a stock cam called for a maximum .390" on the intake and .410" on the exhaust.  Just dug through my records looking for the duration specs but NHRA stopped checking spring pressure, duration, and overlap in Stock engines in about 1988 and those numbers have escaped my recollection plus they are not in my log books.  The lift was checked at zero lash with a solid lifter, a stamped steel rocker arm and stock pushrod length. 

CNorton

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Re: Factory Camshaft spec's for 1967 L48
« Reply #7 on: August 06, 2022, 04:45:00 PM »
Went back into the GM Heritage Center archives <https://www.gmheritagecenter.com/docs/gm-heritage-archive/vehicle-information-kits/Camaro/1968-Chevrolet-Camaro.pdf> and came up with 280 intake duration/288 exhaust duration with 58 of overlap.

Stingr69

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Re: Factory Camshaft spec's for 1967 L48
« Reply #8 on: August 07, 2022, 01:34:15 PM »
Those numbers seem
I raced in NHRA Stock Eliminator with an L48 motor in a '68 Camaro for about twenty years.  The teardown specs for lift on a stock cam called for a maximum .390" on the intake and .410" on the exhaust.  Just dug through my records looking for the duration specs but NHRA stopped checking spring pressure, duration, and overlap in Stock engines in about 1988 and those numbers have escaped my recollection plus they are not in my log books.  The lift was checked at zero lash with a solid lifter, a stamped steel rocker arm and stock pushrod length. 

Yes, this is the lift spec .390"/.410".  The duration is 296/310 at zero lash.  The whole part number is "3896929".  If these numbers seem strange it is because they are unlike any other aftermarket cam specs.  The Chevy Power Manual has even more info.  Elgin still sells it for about $66 today.

We had another thread on this subject about 12 years ago that you can check out below.


http://www.camaros.org/forum/index.php?topic=7311.0

z28z11

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Re: Factory Camshaft spec's for 1967 L48
« Reply #9 on: August 07, 2022, 08:54:37 PM »
Check the specs on the Comp Cams 195/222 camshaft - listed as the replacement for L48 applications. The 222/222 cam is a 350/325 horse application (L79 327) ala the "151" hydraulic cam. Reliable camshafts to be sure -

https://www.compcams.com/products/comp-camshafts/factory-muscle.html

Regards,
Steve

Engine Family:Chevrolet 262-400 c.i. 8 Cylinder (1958-1998)
RPM Operating Range:600-4,800
Grind Number:929H
Cam Type:Hydraulic Flat Tappet
Lifter Style:Hydraulic Flat Tappet
Camshaft Series:Factory Muscle
Usage:OEM
California Proposition 65:WARNING: Cancer and Reproductive Harm P65Warnings.ca.gov
Advertised Intake Duration:319
Advertised Exhaust Duration:320
Intake Duration at .050 Inch Lift:195
Exhaust Duration at .050 Inch Lift:202
Intake Valve Lift:0.39
Exhaust Valve Lift:0.41
Lobe Lift Intake:0.26
Lobe Lift Exhaust:0.273
Lobe Separation:112
Intake Centerline:112
Exhaust Close ATDC:42
Intake Open BTDC:49
Exhaust Open BBDC:98
Intake Close ABDC:81
Camshaft Gear Attachment:3-Bolt
C.A.R.B. E.O. Number:D-279-5
1968 Z28 M21/U17 BRG/W 1967 Chevy ll Nova SS 
1969 Z28 X77/M20/VE3 LeMans/W
1969 L78 X66/N66 Cortez/BVT
1969 Z11 L48/M35/C60/C06  1949 3100 5wd 235/6

maroman

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Re: Factory Camshaft spec's for 1967 L48
« Reply #10 on: August 07, 2022, 11:45:15 PM »
OK, dum question time. CNorton said NHRA checked lift with a solid lifter. Can someone explain why, with it being a hydraulic cam?
Doug  '67 RS/SS 396 auto I know the car since new

NAPA68

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Re: Factory Camshaft spec's for 1967 L48
« Reply #11 on: August 08, 2022, 12:14:19 AM »
OK, dum question time. CNorton said NHRA checked lift with a solid lifter. Can someone explain why, with it being a hydraulic cam?

Checking with a hydraulic lifter would reduce or " dilute" the readings because of it's ability to adjust lash.

maroman

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Re: Factory Camshaft spec's for 1967 L48
« Reply #12 on: August 08, 2022, 01:11:23 PM »
Couldn't they just pull the lifter and place the dial indicator direct to the lobe?
Doug  '67 RS/SS 396 auto I know the car since new

CNorton

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Re: Factory Camshaft spec's for 1967 L48
« Reply #13 on: August 08, 2022, 03:02:56 PM »
Couldn't they just pull the lifter and place the dial indicator direct to the lobe?

The protocol for an NHRA "teardown" was specified by the organization.  Obviously, there is more than one way to accomplish the same end but NHRA used the solid lifter method during the inspection ritual therefore, that was the most reliable way to avoid unpleasant outcomes.  For example, measuring lift directly off the lobe would have left plenty of room for a knowledgeable builder to capitalize on rocker arm ratios, pushrod length, etc. to beat the specified lift measurement by a few thousandths and thereby gain an edge.  If that seems to be an anachronism, it was really nothing compared to some of the other procedures that were routinely followed.  A casual observer would have been mesmerized by the process for checking camshaft duration and overlap using a dial caliper, a dial indicator, a Sharpie or lead pencil, and a strip of masking tape.  Of course, the problems of attaining an acceptable degree of accuracy using that procedure eventually led to the abandonment of the duration spec for stock camshafts in NHRA competition.  Meantime, in order to compete in their game, we measured the lift/duration and overlap on every cylinder, the open/closed valve spring pressures on every cylinder, sorted through buckets of stock rocker arms to find the 16 that would produce favorable lift numbers, poured every combustion chamber and head runner to determine legal volumes, and a bunch of other factors every time an engine was built or freshened.  In retrospect, it probably wasn't worth the effort but, in order to appreciate it, you really needed to be there.  During the early years, a Stocker "teardown" session at the U.S. Nationals or the Winternationals could have included as many as fifty or sixty cars and the "barn" would have been in operation for at least 10 or 12 hours.

Stingr69

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Re: Factory Camshaft spec's for 1967 L48
« Reply #14 on: August 08, 2022, 03:44:28 PM »
Couldn't they just pull the lifter and place the dial indicator direct to the lobe?

If you look at a cam lobe closely you will see it has a taper going up front to back on the lift portion of the profile.  The taper is there to load the cam in the rearward direction so it does not move forward during engine operation and to facilitate lifter rotation during operation. Because of the taper, It isn't practical to try to take a measurement from a lobe directly.  It is taller in the rear of the lobe.

In addition, the "flat tappet" lifter is not actually "flat" either as it has a 1 degree radius crown on the bottom.  This rounded crown works along with the taper on the lobe to cause the lifter to rotate in it's bore as it is lifted up by the lobe.  In order to measure the NET cam lift with any accuracy you need an actual lifter on the lobe while you rotate the cam.  The hydraulic lifters would bleed down and compress under the force of a valve spring while you rotate the engine slowly.  That would give you an erroneous lift measurement.  You need a solid lifter in there that can not compress to get an accurate running NET lift measurement.

maroman

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Re: Factory Camshaft spec's for 1967 L48
« Reply #15 on: August 08, 2022, 05:04:36 PM »
Excellent explanation. Thank you both for the follow up. I knew there had to be good reasoning to the process.
Doug  '67 RS/SS 396 auto I know the car since new

crossboss

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Re: Factory Camshaft spec's for 1967 L48
« Reply #16 on: August 10, 2022, 10:41:59 PM »
Couldn't they just pull the lifter and place the dial indicator direct to the lobe?

The protocol for an NHRA "teardown" was specified by the organization.  Obviously, there is more than one way to accomplish the same end but NHRA used the solid lifter method during the inspection ritual therefore, that was the most reliable way to avoid unpleasant outcomes.  For example, measuring lift directly off the lobe would have left plenty of room for a knowledgeable builder to capitalize on rocker arm ratios, pushrod length, etc. to beat the specified lift measurement by a few thousandths and thereby gain an edge.  If that seems to be an anachronism, it was really nothing compared to some of the other procedures that were routinely followed.  A casual observer would have been mesmerized by the process for checking camshaft duration and overlap using a dial caliper, a dial indicator, a Sharpie or lead pencil, and a strip of masking tape.  Of course, the problems of attaining an acceptable degree of accuracy using that procedure eventually led to the abandonment of the duration spec for stock camshafts in NHRA competition.  Meantime, in order to compete in their game, we measured the lift/duration and overlap on every cylinder, the open/closed valve spring pressures on every cylinder, sorted through buckets of stock rocker arms to find the 16 that would produce favorable lift numbers, poured every combustion chamber and head runner to determine legal volumes, and a bunch of other factors every time an engine was built or freshened.  In retrospect, it probably wasn't worth the effort but, in order to appreciate it, you really needed to be there.  During the early years, a Stocker "teardown" session at the U.S. Nationals or the Winternationals could have included as many as fifty or sixty cars and the "barn" would have been in operation for at least 10 or 12 hours.


Slightly off topic, but relative...
I have a friend who runs in C/Stock automatic class. 'Back in the day', tear downs were common to check if anyone was cheating. Of course most were. (Smokey Unick said "IF you ain't cheatn', you ain't winning!") Remember, a 'Stock camshaft' in NHRA is not your typical street cam grind. Many factors are 'allowable' such as ramp angles, etc. This is why they sound quite radical. Essentially, they are 'cheater cams' to us. Back to my friend, who was a record holder at many events, was running some 'cheater' heads...aka acid flowed. He sold them to me during the late 1980s. They 'looked' stock to the casual observer...
Just another T/A fanatic. A new project in the works.