Cam Selection
Thread Starter
Burning Brakes
Joined: Jun 2007
Posts: 1,062
Likes: 10
From: Dallas TX
Cam Selection
I know this has been talked about many times and I have read tons of posts.
I thought I had narrowed it down to two: the L79H and the 30-30H from CompCams. So I called their support line for some advice. I am not very technical when it comes to cam shafts and specs (I’m sure I sounded like an idiot
) and so I made the mistake of asking the guy would he recommend something else based on the info I had given him. “Absolutely” was his response. “I would go with an xtreme energy 268H cam….you are comparing 30 year old cam technology with new technology”
Here are the specs for the cams:
L79
Duration at .050 lift: 229/236
Valve Lift: 468/462
30-30H
Duration at .050 lift: 239/246
Valve Lift: 483/477
268H
Duration at .050 lift: 224/230
Valve Lift: 477/480
The specs for my engine build are:
+ 327 small journal 040 over
+ estimated 10.5 compression
+ rebuilt 64cc double hump heads
What I want:
Looking for a nice idle but not sounding like a drag car, a nice pin you in your seat power band. Will never rev it over 6k (probably not over 5k). I know there are some good solid lifter cams but I know my comfort zone. Looking at the cam specs, is there anything that I should focus on when making my decision? Anyone ever used their xtreme energy cams?
I thought I had narrowed it down to two: the L79H and the 30-30H from CompCams. So I called their support line for some advice. I am not very technical when it comes to cam shafts and specs (I’m sure I sounded like an idiot
) and so I made the mistake of asking the guy would he recommend something else based on the info I had given him. “Absolutely” was his response. “I would go with an xtreme energy 268H cam….you are comparing 30 year old cam technology with new technology”Here are the specs for the cams:
L79
Duration at .050 lift: 229/236
Valve Lift: 468/462
30-30H
Duration at .050 lift: 239/246
Valve Lift: 483/477
268H
Duration at .050 lift: 224/230
Valve Lift: 477/480
The specs for my engine build are:
+ 327 small journal 040 over
+ estimated 10.5 compression
+ rebuilt 64cc double hump heads
What I want:
Looking for a nice idle but not sounding like a drag car, a nice pin you in your seat power band. Will never rev it over 6k (probably not over 5k). I know there are some good solid lifter cams but I know my comfort zone. Looking at the cam specs, is there anything that I should focus on when making my decision? Anyone ever used their xtreme energy cams?
Le Mans Master
Joined: Sep 2008
Posts: 5,662
Likes: 2,344
From: Lake Minnetonka, Mn
2018 C1 of Year Finalist
I think that the L79 cam is the nicest one ever produced by GM. No muss or fuss with the hydraulic lifters; gives great low to mid range torque and has enough overlap to create a nice sound at the exhaust.
It is much different than the 30/30 which does not have the low to mid range characteristics of the L 79. I have owned both and will always favor the L 79. Just remember that both of them require solid compression (11:1) to make them effective.
It is much different than the 30/30 which does not have the low to mid range characteristics of the L 79. I have owned both and will always favor the L 79. Just remember that both of them require solid compression (11:1) to make them effective.
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
Don't know anything about the L 79H cam but, if you can find one, I'd think the GM L 79 cam would fill the bill for what you need.
Some of these aftermarket replacement cams use the same duration/lift as the GM cam. BUT, once the valve opens, they accelerate the valve very quickly, hold it open longer and then let the valve slam shut. This, they call "modern technology" or it could be called a "cheater cam". There is nothing "new" here.
Those cams sometimes cause problems pulling rocker studs, breaking rockers, having to use stiff valve springs and yes, flat cam lobes due to extreme spring pressure.
Use the real McCoy.
Some of these aftermarket replacement cams use the same duration/lift as the GM cam. BUT, once the valve opens, they accelerate the valve very quickly, hold it open longer and then let the valve slam shut. This, they call "modern technology" or it could be called a "cheater cam". There is nothing "new" here.
Those cams sometimes cause problems pulling rocker studs, breaking rockers, having to use stiff valve springs and yes, flat cam lobes due to extreme spring pressure.
Use the real McCoy.
Race Director
Joined: Feb 2004
Posts: 11,039
Likes: 2,592
From: Del Boca Vista FL
I run a Comp Cams hydraulic retro roller XR264HR. This is one of the xtreme energy cams.
I run Canfield aluminum heads and my block is a 69 vintage 350. My compression ratio is right at 9.5 and it pulls smoothly from about 1100 rpm to over 5000 rpm. Power just keeps coming on until you lift.
I also run TPI so basically what I have is an L-98 with better heads and cam than the factory used. I'm very happy with it.
Rich
I run Canfield aluminum heads and my block is a 69 vintage 350. My compression ratio is right at 9.5 and it pulls smoothly from about 1100 rpm to over 5000 rpm. Power just keeps coming on until you lift.
I also run TPI so basically what I have is an L-98 with better heads and cam than the factory used. I'm very happy with it.
Rich
Le Mans Master
Joined: Dec 2007
Posts: 8,000
Likes: 659
From: Puget Sound
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Le Mans Master
Joined: Aug 2009
Posts: 5,474
Likes: 16
From: Houston Texas
St. Jude Donor '10-'12-'13
Stay away from the re-engineered versions of original cams. No one had more resources than GM to get it right..
The 327-350 and the 350-350hp cams are the best all around hydraulic grind.
You don't need the mech. cams if you aren't going over 6000rpm anyhow.
The 327-350 and the 350-350hp cams are the best all around hydraulic grind.You don't need the mech. cams if you aren't going over 6000rpm anyhow.
Team Owner
Joined: Nov 2005
Posts: 28,220
Likes: 2,872
From: Beach & High Desert Southern California
That 269H grind has been around a long time, more than 26-years, so it's not as "modern" as the guy claims.
We ran a 268H in a 350 back in 1984. The engine ran ~10:1 CR, with well ported 186 heads that used the smaller 1.97 intake valves with 1.6 exhausts. With the 268H cam it would lay down around 5000 rpm. We tried Rhodes lifters and a number of other things to improve the top end, but we did not gain much.
We swapped it out for Engel's version of the L79 cam, basically advanced four degrees from stock L79 specs to work better with the lower compressor, and the car went faster and ran clean to 6000 rpm.
Use the L79 (unless you want to run the 097 solid lifter cam with 1.6 rocker arms).
We ran a 268H in a 350 back in 1984. The engine ran ~10:1 CR, with well ported 186 heads that used the smaller 1.97 intake valves with 1.6 exhausts. With the 268H cam it would lay down around 5000 rpm. We tried Rhodes lifters and a number of other things to improve the top end, but we did not gain much.
We swapped it out for Engel's version of the L79 cam, basically advanced four degrees from stock L79 specs to work better with the lower compressor, and the car went faster and ran clean to 6000 rpm.
Use the L79 (unless you want to run the 097 solid lifter cam with 1.6 rocker arms).
Race Director
Joined: Oct 2005
Posts: 12,470
Likes: 1,548
From: Camp Verde AZ
C1 of Year Finalist (performance mods) 2019
2017 C1 of Year Finalist
I run a Comp Cams hydraulic retro roller XR264HR. This is one of the xtreme energy cams.
I run Canfield aluminum heads and my block is a 69 vintage 350. My compression ratio is right at 9.5 and it pulls smoothly from about 1100 rpm to over 5000 rpm. Power just keeps coming on until you lift.
I run Canfield aluminum heads and my block is a 69 vintage 350. My compression ratio is right at 9.5 and it pulls smoothly from about 1100 rpm to over 5000 rpm. Power just keeps coming on until you lift.
With your experience with the 264, what is your opinion of going a step up to the 270 for a daily driver type vehicle with 200-4r trans and 3.5 rear in a 2500-2700 vehicle?
Logic tells me to go with the 264, and EA shows better low and mid range torque than with the 270, without much sacrifice on top end, but I have always been a sucker for bigger is better, and I don't want too much dynamic compression with the 10.3 CR. IIRC, the 264 gives me 8.18:1 DCR and the 270 gives about 7.8:1 DCR.
Oh, yeah, headers, full exhaust, Edelbrock performer airgap RPM, Holley 650 spread bore 6210 double pumper.
Thanks, and sorry about the thread hijack
Doug
Race Director
Joined: Feb 2004
Posts: 11,039
Likes: 2,592
From: Del Boca Vista FL
I am considering this cam for my old 327 motor which will be going in my '37 Ford pickup, real compression is about 10.3. Bowtie iron heads. I haven't decided if I want the 264 or the XR270HR.
With your experience with the 264, what is your opinion of going a step up to the 270 for a daily driver type vehicle with 200-4r trans and 3.5 rear in a 2500-2700 vehicle?
Logic tells me to go with the 264, and EA shows better low and mid range torque than with the 270, without much sacrifice on top end, but I have always been a sucker for bigger is better, and I don't want too much dynamic compression with the 10.3 CR. IIRC, the 264 gives me 8.18:1 DCR and the 270 gives about 7.8:1 DCR.
Oh, yeah, headers, full exhaust, Edelbrock performer airgap RPM, Holley 650 spread bore 6210 double pumper.
Thanks, and sorry about the thread hijack
Doug
With your experience with the 264, what is your opinion of going a step up to the 270 for a daily driver type vehicle with 200-4r trans and 3.5 rear in a 2500-2700 vehicle?
Logic tells me to go with the 264, and EA shows better low and mid range torque than with the 270, without much sacrifice on top end, but I have always been a sucker for bigger is better, and I don't want too much dynamic compression with the 10.3 CR. IIRC, the 264 gives me 8.18:1 DCR and the 270 gives about 7.8:1 DCR.
Oh, yeah, headers, full exhaust, Edelbrock performer airgap RPM, Holley 650 spread bore 6210 double pumper.
Thanks, and sorry about the thread hijack
Doug
Doug:
I have a 336 gear and run a TH350 in a 3200 lb car. I run Heddman 1 5/8 side exit headers with 3" collectors into 2" factory side pipes. At 70 mph I am running right at 3000 to 3100 rpm because I have no overdrive.
The Canfield heads have 2.055 intakes and 1.6 exhausts. Chambers are 66 cc. I also run 7/16 rocker arm studs and Comp Cams Pro Magum full roller rockers.
With factory 24 lb injectors the TPI ran too rich so I changed to Bosch 22 lb injectors. I run 43 lbs of fuel pressure on the rail at idle. For myself this combination is a winner.
We ran the 270XR in my son's 87 Corvette with a 383 and stock Chevrolet aluminum heads from his car. He had the rear end changed to a 390 and ran a 700r4 trans. Car would come out of the hole like a funny car but wasn't that impressive above 70 mph. Seat of the pants feel was that it kind of flattened out, especially when compared to the hole shot. Might have been the lack of a good cylinder head to go with the rest of the motor.
Comp Camps says the 270 is the largest cam you can run with a stock style converter.
My personal opinion (and that is all that this is) would be to go with the 264.
Rich
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
I think you're making a wise choice in cams for the way you want to use the car. As mentioned in a previous post, the very old Chevy, 097 cam is also a good choice if you want a solid lifter cam shaft. Unfortunately, the original spec cam is no longer available from major suppliers.
Team Owner
Joined: Jan 2007
Posts: 29,063
Likes: 1,839
From: cookeville tennessee
will sun great.
Safety Car
Joined: Nov 2001
Posts: 4,424
Likes: 619
From: northern CA
Don't know anything about the L 79H cam but, if you can find one, I'd think the GM L 79 cam would fill the bill for what you need.
Some of these aftermarket replacement cams use the same duration/lift as the GM cam. BUT, once the valve opens, they accelerate the valve very quickly, hold it open longer and then let the valve slam shut. This, they call "modern technology" or it could be called a "cheater cam". There is nothing "new" here.
Those cams sometimes cause problems pulling rocker studs, breaking rockers, having to use stiff valve springs and yes, flat cam lobes due to extreme spring pressure.
Use the real McCoy.
Some of these aftermarket replacement cams use the same duration/lift as the GM cam. BUT, once the valve opens, they accelerate the valve very quickly, hold it open longer and then let the valve slam shut. This, they call "modern technology" or it could be called a "cheater cam". There is nothing "new" here.
Those cams sometimes cause problems pulling rocker studs, breaking rockers, having to use stiff valve springs and yes, flat cam lobes due to extreme spring pressure.
Use the real McCoy.
.. Flat tappet cams aside the 'new' cam dynamics sound better suited to a roller cam design. The factory engineer boys back in the 60's knew a thing or two about cam design.
Burning Brakes
Joined: Jan 2009
Posts: 922
Likes: 2
From: Delta BC
I think you're making a wise choice in cams for the way you want to use the car. As mentioned in a previous post, the very old Chevy, 097 cam is also a good choice if you want a solid lifter cam shaft. Unfortunately, the original spec cam is no longer available from major suppliers.
Bob
Pro
Joined: May 2010
Posts: 560
Likes: 2
From: North Las Vegas Nevada
Federal Mogul Speed Pro CS113R blueprint of original 097. $76 online from Northern Auto Parts. NAPA is supposed to stock this cam also.
http://www.northernautoparts.com/Pro...entoryId=35007
DT
http://www.northernautoparts.com/Pro...entoryId=35007
DT
Last edited by NOM61; May 27, 2010 at 07:16 PM. Reason: Better price