1968 L78 cam replacement - Team Camaro Tech
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  #1  
Old Sep 24th, 07, 05:31 PM
mstehle mstehle is offline
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Mark
 
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Default 1968 L78 cam replacement

My buddy is going to help me replace the cam on my L78 car. The previous owner went to a hydraulic cam and lifters and I want to change back to the solids. My searches have not shown what cam specs or a mfg and part no. for the stock cam. Can anyone point me in the right direction? I want to be true to the stock originality of the motor, (but monkey coming here), BUT, I wouild also consider going a little more radical on the cam. Any advice is appreciated.

Thanks

Mark
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  #2  
Old Sep 26th, 07, 11:51 AM
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Vintage 68 Vintage 68 is offline
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Default Re: 1968 L78 cam replacement

The original GM performance cams are still available from GM Parts Direct - http://www.gmpartsdirect.com/perform...CATID=486.html
These cams are manufactured for GM by Crane Cams and are also available directly from them. Call them or go to their web site to find their part number(s).
Summit lists and sells the Crane replacements.

The original RPO-L78 (396/375) cam was part #3863148 - the new GM part number is #12364057 - http://www.gmpartsdirect.com/perform...CATID=486.html
Cam spec.s are;
Duration @ 0.50" = 242/242
Lift = .520/.520
Lobe Center = 114

You can of course go to a 'Bigger' cam, but be sure you discuss the application with the cam manufacturer as it may require some other changes.
Trying to go to the RPO-L88 type cam for instance usually requires a compression increase and other changes to take advantage of the cams grind.

There are also some really good Hydraulic cams that deliver nearly the same results with less upkeep than the original Solids.
The GM/Crane #12353922 (@0.50"=218/228-lift=.500/.500-114) works well with higher compressions (9.5~10.5:1).
Discuss your engine set-up with the cam advisors to get a recommendation closer to your exact needs.

BTW - these cams require the GM performance valve springs.
Make sure your springs weren't changed to accomidate the Hyd. and are no longer compatible with a new Solid cam, bad things could happen ...

Hope some of this helps
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  #3  
Old Sep 26th, 07, 05:24 PM
WILMASBOYL78 WILMASBOYL78 is offline
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Default Re: 1968 L78 cam replacement

The 143 replacement cam is the way to go...be sure your valvetrain is up to the task...make sure you change gears and use a steel roller chain...if the heads still have the factory valves in them consider freshening up the heads as well...the oem valves were actually 2 piece and prone to failure...the factory valves were responsible for most of the CE engines floating aroundout there.

wilma
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  #4  
Old Sep 27th, 07, 04:11 PM
mstehle mstehle is offline
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Mark
 
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Default Re: 1968 L78 cam replacement

Guys:

Thanks for the advice. I talked to Summit and ordered the Crane Blueprint cam and lifters for the car. In fact I just got home and see that it has arrived already . Just opening the box now.

Thanks for the advice on the valves. I will have to talk to the previous owner and see what he has done with the valves. He owned the car since 1972 until last year so he has a good history. He is also a mechanic and did all his own work except for machining. From everything I have seen so far he did good work. I do know that he put the 427 crank in the car, same specs, just cross drilled for better oiling. The bottom end is also nicely balanced so his shop did a good job with that too.

Can't wait to get the new cam in. Got a skip in the motor so I am putting all new wires, cap, rotor etc too. I will also do a compression test and put a vacuum gage on her to see what we find there.

Thanks again

Mark
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Team Camaro Tech > First Generation Camaro Info and Tech - 1967- 1969 "Where it all started" > Engine      Current Topic: 1968 L78 cam replacement
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