Cam change...change heads also?
Thread Starter
Instructor
Joined: May 2007
Posts: 130
Likes: 0
From: Houston TX
Cam change...change heads also?
I'm considering a cam upgrade on my stock L-48. Will change the intake manifold also, probably use an Edelbrock Performer. My question is whether I should change the heads also or can I get most of the HP increase w/o new heads. The cam I'm considering is a Comp 218/224 Dur, .462/.469 Lift Xtreme Energy. I read somewhere the L-82s stock heads have a 76cc chamber and 202/106 valves which I think will work well with this cam; but don't know if those heads were also used on the L-48. Does anyone know the L-48 head specs? 
Thanks for any input...
Thanks for any input...
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
L48 heads Essentially same as L82 except L48 has smaller 1.94 & 1.50 valves.
The smaller valves are NOT a bottleneck with the cam you're considering ... same goes for your OE intake manifold ... go ahead & use the L48 heads but have NEW valve springs installed and ensure springs're setup for your NEW CAM's LIFT. Do NOT go to bigger cam than the cam you're considering without first raising compression via pistons / small chamber heads.
You're gonna need all the compression you can get ... install iron heads with thin shim felpro p/n 1094 head gaskets (0.015" x 4.100" ~ 3.2cc)
The smaller valves are NOT a bottleneck with the cam you're considering ... same goes for your OE intake manifold ... go ahead & use the L48 heads but have NEW valve springs installed and ensure springs're setup for your NEW CAM's LIFT. Do NOT go to bigger cam than the cam you're considering without first raising compression via pistons / small chamber heads.
You're gonna need all the compression you can get ... install iron heads with thin shim felpro p/n 1094 head gaskets (0.015" x 4.100" ~ 3.2cc)
Last edited by jackson; Jun 28, 2008 at 10:31 AM.
Drifting
Joined: Apr 2008
Posts: 1,305
Likes: 2
From: Lewisburg WV
thegazman
If you can afford new heads there is a lot of HP to be gained. If you decide to keep your existing heads follow Jackson's advice. Chevy sells a little stronger valve spring designed for their 300 HP 350 engine. Also match the flow of your intake and exhaust to the heads. The ports on your existing heads will be smaller. Scribe them and grind the ports to match your manifolds flow. Have your machine shop true the head surface and use the gasket Jackson recommended. That will give you a little more compression without getting you into trouble.
Thread Starter
Instructor
Joined: May 2007
Posts: 130
Likes: 0
From: Houston TX
Thanks for your input. I didn't tell the whole truth on this engine. :o It was rebuilt about 5 yrs ago at 95k miles. The rebuilder put in flat top pistons and a "mild cam". It was reported to have a 9.5:1 compr ratio. But, it has never run to it's potential...maybe because of a mismatch of this cam (no specs) and the stock heads.
Anyway, with the better pistons can't I expect much better performance by going to a better CI head with matching cam?
I don't want to get crazy or carried away with this change($$$) but would like to get-it-right-the-first-time if I do anything.
Thks, again.
Anyway, with the better pistons can't I expect much better performance by going to a better CI head with matching cam?
I don't want to get crazy or carried away with this change($$$) but would like to get-it-right-the-first-time if I do anything.Thks, again.
Racer
Joined: Feb 2006
Posts: 324
Likes: 0
From: South Elgin IL
If you have the money for new heads, I would change them. You mention that you are going to swap the intake. If you are going to do that, then why not make a vortec conversion since the intake is going to be changed. The Vortecs flow much better than stock and have better compression. This kit already has upgraded springs:
http://www.sdparts.com/product/SD806...merIntake.aspx
http://www.sdparts.com/product/SD806...merIntake.aspx
Team Owner
Joined: Jun 2001
Posts: 43,136
Likes: 155
From: Thomson Georgia
L48 heads Essentially same as L82 except L48 has smaller 1.94 & 1.50 valves.
The smaller valves are NOT a bottleneck with the cam you're considering ... same goes for your OE intake manifold ... go ahead & use the L48 heads but have NEW valve springs installed and ensure springs're setup for your NEW CAM's LIFT. Do NOT go to bigger cam than the cam you're considering without first raising compression via pistons / small chamber heads.
You're gonna need all the compression you can get ... install iron heads with thin shim felpro p/n 1094 head gaskets (0.015" x 4.100" ~ 3.2cc)
The smaller valves are NOT a bottleneck with the cam you're considering ... same goes for your OE intake manifold ... go ahead & use the L48 heads but have NEW valve springs installed and ensure springs're setup for your NEW CAM's LIFT. Do NOT go to bigger cam than the cam you're considering without first raising compression via pistons / small chamber heads.
You're gonna need all the compression you can get ... install iron heads with thin shim felpro p/n 1094 head gaskets (0.015" x 4.100" ~ 3.2cc)
Pro
Joined: Feb 2006
Posts: 718
Likes: 7
From: Jacksonville , NC
My recomendation is to find out what you have. Get the casting numbers for the heads and the P/N of the pistons to figure out with out a doubt what you are working with. Cam isnt going to change your static CR. A stock L82 with flat top (6cc cutout) pistons with 76cc heads has a compression ratio of 9.1:1 . When I stroked my L82 with 64cc heads the CR was only 9.8:1 with reverse dome pistons. Im not an expert but not seeing 9.5:1 CR with your set up, hence the lack of performanc expected. You can get HP gains but you have to find out where you are now to correctly select parts. Good luck.
Advanced
Joined: Feb 2008
Posts: 88
Likes: 0
From: PORT ST LUCIE FLORIDA
i have the same cam xe262 but i put a set of rhs pro action heads on with 72 cc chambers,and 180 intake runners the stock heads L82 have 76 cc chambers and 160 intake runners, you would not believe the difference in port and chamber design from old to new
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Thread Starter
Instructor
Joined: May 2007
Posts: 130
Likes: 0
From: Houston TX
Many thanks for all the great input! I've got alot more to think about and appreciate the suggestions, links and knowledge. Will report decisions, directions and maybe good results later.
Cheers,
Cheers,
Melting Slicks
Joined: Apr 2004
Posts: 2,008
Likes: 38
From: Space Coast Gator Territory
I have a 79 L-82 engine with a 327-350 HP cam and the stock heads. I wouldn't waste any money on those stock heads and would recommend vortec heads. Here are two links that might help your decision. Notice the kit comes with an intake and the heads are already machined and with the Z-28 springs.
http://www.nastyz28.com/forum/showthread.php?t=56505
See the head choices listed in this link, then look along the top to move to illustrations of the various combinations they offer.
http://www.sdparts.com/catalog/engin...cHeadKits.aspx
http://www.nastyz28.com/forum/showthread.php?t=56505
See the head choices listed in this link, then look along the top to move to illustrations of the various combinations they offer.
http://www.sdparts.com/catalog/engin...cHeadKits.aspx
Thread Starter
Instructor
Joined: May 2007
Posts: 130
Likes: 0
From: Houston TX
WOW! Great info from thread on Vortec heads. And your link to SD and the Vortec kit is the same listed by My Mach 5. The price looks very good as I've seen the assembled Vortec heads listed elsewhere for $500 each. I'll probably call them to determine what version of Vortec design is in the kit.
The info from the GM guy in that thread indicated several designs and the kit is not detailed on that. He mentioned a fast-burn design and I see one in Pace Performance's cat that is designed for flat top pistons and the early SB. Their price is $640ea.
Thks, again
The info from the GM guy in that thread indicated several designs and the kit is not detailed on that. He mentioned a fast-burn design and I see one in Pace Performance's cat that is designed for flat top pistons and the early SB. Their price is $640ea.
Thks, again
Race Director
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It will run better with the new cam maybe...depends on what the old one is.
Heads are where the power is. I also wouldn't spend much if anything on the stock ones..I'd just get something decent. The Vortecs will carry you well into the 400-450Hp range.
Aluminum heads are getting cheaper and cheaper..even the non-Chinese versions. Lots of power right there. $1000 will buy a lot of power.
JIM
Heads are where the power is. I also wouldn't spend much if anything on the stock ones..I'd just get something decent. The Vortecs will carry you well into the 400-450Hp range.
Aluminum heads are getting cheaper and cheaper..even the non-Chinese versions. Lots of power right there. $1000 will buy a lot of power.
JIM