Ordering my Cam then Another Choice??
Thread Starter
Instructor
Joined: Feb 2011
Posts: 205
Likes: 0
From: Laquey Missouri
Ordering my Cam then Another Choice??
All set to order my cam, an XE268H was my final choice. I have Edelbrock E-Street heads, Performer Intake, Hollly 4175 carb, Supercomp Header, 200r4 trans w/2400 stall (stall still to be ordered) and 3.70 rear gear. All on or going on a 76 L82, stock bottom end, new rings and bearings less then 5000 miles ago. Then another forum member suggested I get a XE262H with 1.6 rocker on the intake side only - said it was worth 10HP. Any thoughts before I place my order?
Advanced
Joined: Feb 2009
Posts: 64
Likes: 0
From: medford n.y
I've got a 350 punched out 60 thousands with edelbrock rpm 64cc heads. I first had a 268-110 in it but it was a little to rough for me so I swapped it out for a edelbrock rpm-112 with the same specs and I love it. My 4 speed has a 350 first gear and 370 rear. I've also got 10:1 compression and 1 7/8 headers. I had an air-gap intake with a 800 cfm carb but needed more so I went with a offenhauser dual quad set-up with a pair of 450 hollys and walla 417 hp and a lot of *****. Good luck with what ever you choose.
Race Director
Joined: Oct 2000
Posts: 15,057
Likes: 79
From: central FL, near the beach.
Read posts by Joe Sherman. He has ~30+ years of owning a dyno shop. Says he hasn't seen more power w/1.6 on exhaust, only works on intake.
As for the XE268, it is a great cam for a 383, but in a 355 it made 13hp LESS than the 218/218/110 268h, according to CHP, june 2002 issue. So, going to the more aggressive xe262 should be worth a few hp, and adding 1.6 to intake, another few hp. Maybe 20-25 total, or maybe only 10. You pick the cam, it is your car. Make more noise, or make more power? Tough choice
mako
i see your secret to success with mild roller cams, u pick a doggy FT cam, then proclaim roller cams to "make more power everywhere, even have more vacuum" While that is possible with an aggressive roller, the difference with a mild roller against a better FT is quite small, if any.
As for the XE268, it is a great cam for a 383, but in a 355 it made 13hp LESS than the 218/218/110 268h, according to CHP, june 2002 issue. So, going to the more aggressive xe262 should be worth a few hp, and adding 1.6 to intake, another few hp. Maybe 20-25 total, or maybe only 10. You pick the cam, it is your car. Make more noise, or make more power? Tough choice
mako
i see your secret to success with mild roller cams, u pick a doggy FT cam, then proclaim roller cams to "make more power everywhere, even have more vacuum" While that is possible with an aggressive roller, the difference with a mild roller against a better FT is quite small, if any.
Last edited by Matt Gruber; Nov 15, 2012 at 04:49 AM.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
OP has flat top pistons and smaller chamber heads. Compression is bumped up, Stall convertor, 3.70 gears. Quite likely would have detonation issues with a smaller duration cam.
More duration, More lift with good heads = better cylinder filling = more power. If the powerband of the cam is to high with high gearing and stock stall performance suffers. OP has all these bases covered and will be better off with the bigger cam. I would actually think he may need a bigger cam than the 268 given his build specs. Would need to run the compression numbers and figure intake closing point.
The XE line of cams is already at the max or past the max ramp rate for a flat tappet. Adding 1.6 rockers is not a good idea. Extra loading at the lobe lifter. If you need 1.6 rockers to get your cam where you need it you picked the wrong cam to begin with.
And yes Matt, The right hydraulic roller cam will make more power across the entire operating range with better vacuum, manners and fuel mileage. There is a reason that no automobile manufacturer has made a flat tappet engine in the last 25 years and it is not to save money. Flat tappets are cheaper.
More duration, More lift with good heads = better cylinder filling = more power. If the powerband of the cam is to high with high gearing and stock stall performance suffers. OP has all these bases covered and will be better off with the bigger cam. I would actually think he may need a bigger cam than the 268 given his build specs. Would need to run the compression numbers and figure intake closing point.
The XE line of cams is already at the max or past the max ramp rate for a flat tappet. Adding 1.6 rockers is not a good idea. Extra loading at the lobe lifter. If you need 1.6 rockers to get your cam where you need it you picked the wrong cam to begin with.
And yes Matt, The right hydraulic roller cam will make more power across the entire operating range with better vacuum, manners and fuel mileage. There is a reason that no automobile manufacturer has made a flat tappet engine in the last 25 years and it is not to save money. Flat tappets are cheaper.
Last edited by 63mako; Nov 15, 2012 at 10:19 AM.
Race Director
Joined: Oct 2000
Posts: 15,057
Likes: 79
From: central FL, near the beach.
good reply mako. I'd race you anytime, i'm sure it would be close. 
it all depends on his shift point WOT. a 6500 shift would sway me to the xe268.
xe262 is only good 'til 6000.
He does have a 3.70 and 2400 stall, but he has overdrive.
OD likes strong power at low rpm for cruising at lower speeds. If he is worried about the 1.6 being too much, that dyno test showed +12hp at 5500 218/218 cam and 1.5's. And if he has iron heads and over 10.5 CR, I'd go xe268 too. Details are important! Like, does he have cold air intake?
it all depends on his shift point WOT. a 6500 shift would sway me to the xe268.
xe262 is only good 'til 6000.
He does have a 3.70 and 2400 stall, but he has overdrive.
OD likes strong power at low rpm for cruising at lower speeds. If he is worried about the 1.6 being too much, that dyno test showed +12hp at 5500 218/218 cam and 1.5's. And if he has iron heads and over 10.5 CR, I'd go xe268 too. Details are important! Like, does he have cold air intake?
Last edited by Matt Gruber; Nov 15, 2012 at 11:40 AM.
Drifting
Joined: Dec 2004
Posts: 1,714
Likes: 42
From: Austin Texas
Not sure if you have seen this thread. http://forums.corvetteforum.com/c3-t...mp-xe268h.html
I made that post right after I installed a comp xe268h. Since then I have installed a 2800 converter, 3.55 gears and a 2004R is ready to go in next.
As you can see in that post, our configuration is fairly similar. My heads are 60 cc but only have 165 cc runners. I am bored over .060 but used a cheap thick head gasket too.
60 rear wheel hp from the cam change.
You can see the full torque curve but I wuss'd out and stopped at 5k rpm so you cant see the full HP curve. I don't think you will be disappointing with the xe268. However, my next cam will probably be a Lunati Voodoo just to see what they got.
Just wanted you to see a real life dyno sheet for your cam.
I made that post right after I installed a comp xe268h. Since then I have installed a 2800 converter, 3.55 gears and a 2004R is ready to go in next.
As you can see in that post, our configuration is fairly similar. My heads are 60 cc but only have 165 cc runners. I am bored over .060 but used a cheap thick head gasket too.
60 rear wheel hp from the cam change.
You can see the full torque curve but I wuss'd out and stopped at 5k rpm so you cant see the full HP curve. I don't think you will be disappointing with the xe268. However, my next cam will probably be a Lunati Voodoo just to see what they got.
Just wanted you to see a real life dyno sheet for your cam.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
good reply mako. I'd race you anytime, i'm sure it would be close.
it all depends on his shift point WOT. a 6500 shift would sway me to the xe268.
xe262 is only good 'til 6000.
He does have a 3.70 and 2400 stall, but he has overdrive.
OD likes strong power at low rpm for cruising at lower speeds. If he is worried about the 1.6 being too much, that dyno test showed +12hp at 5500 218/218 cam and 1.5's. And if he has iron heads and over 10.5 CR, I'd go xe268 too. Details are important! Like, does he have cold air intake?
it all depends on his shift point WOT. a 6500 shift would sway me to the xe268.
xe262 is only good 'til 6000.
He does have a 3.70 and 2400 stall, but he has overdrive.
OD likes strong power at low rpm for cruising at lower speeds. If he is worried about the 1.6 being too much, that dyno test showed +12hp at 5500 218/218 cam and 1.5's. And if he has iron heads and over 10.5 CR, I'd go xe268 too. Details are important! Like, does he have cold air intake?
Can't race you right now. Car is torn down again so you win.
Race Director
Joined: Oct 2000
Posts: 15,057
Likes: 79
From: central FL, near the beach.
mako
aren't these same XE lobes used on BBC? do u use 1.5 rockers to limit stress?
are u that afraid of their normal 1.6?
.
How do the roller cams make more power everwhere and not increase cylinder pressure? Don't they run the same risk of detonation? How does a roller eliminate detonation?
And if 10.5 makes you
try less timing, it works. AZDoug in c2 has a 427sbc that has only 21 total WOT. Don't over advance the timing!
aren't these same XE lobes used on BBC? do u use 1.5 rockers to limit stress?
are u that afraid of their normal 1.6?
.
How do the roller cams make more power everwhere and not increase cylinder pressure? Don't they run the same risk of detonation? How does a roller eliminate detonation?
And if 10.5 makes you
try less timing, it works. AZDoug in c2 has a 427sbc that has only 21 total WOT. Don't over advance the timing!
Last edited by Matt Gruber; Nov 15, 2012 at 02:39 PM.
Thread Starter
Instructor
Joined: Feb 2011
Posts: 205
Likes: 0
From: Laquey Missouri
Thank you all for your input. Per Edelbrock Spec sheet for these heads, a roller cam is not recommended. Heads are supposed to be good from off idle to 5500. With that, I saw no need for a cam that makes power beyond that. According to what I read, and I could be wrong, but the 268 cam made it max torque at 3800 rpm (over 400 ft lb) and maxed out HP at 5000 RPMs - this is all in the ballpark I was looking for. I thought it would be a fun car to drive and with the 200R4 trans - I could still hit the Interstate and keep up with traffic without running the motor hard. This cam does seem to be used by several on here, but it's not ordered yet - so I guess I'm still in the deciding stage.
Thread Starter
Instructor
Joined: Feb 2011
Posts: 205
Likes: 0
From: Laquey Missouri
Thanks - I must confess, lift/duration numbers, cam specs, etc. is like me reading a medical journal - I don't understand what I'm reading. Both the XE268H and Lunati 60102 are in the range I'm looking at. I'm not sure what a performance difference there would be - I appreciate your input.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
mako
aren't these same XE lobes used on BBC? do u use 1.5 rockers to limit stress?
are u that afraid of their normal 1.6?
.
How do the roller cams make more power everwhere and not increase cylinder pressure? Don't they run the same risk of detonation? How does a roller eliminate detonation?
And if 10.5 makes you try less timing, it works. AZDoug in c2 has a 427sbc that has only 21 total WOT. Don't over advance the timing!
aren't these same XE lobes used on BBC? do u use 1.5 rockers to limit stress?
are u that afraid of their normal 1.6?
.
How do the roller cams make more power everwhere and not increase cylinder pressure? Don't they run the same risk of detonation? How does a roller eliminate detonation?
And if 10.5 makes you
try less timing, it works. AZDoug in c2 has a 427sbc that has only 21 total WOT. Don't over advance the timing! 
Race Director
Joined: Jan 2000
Posts: 13,018
Likes: 2,262
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
I'd use the 268...it will be fine. That's a good baseline cam for a 350'ish motor. I actually like the original 268H just because they seem to be pretty reliable even though the x's will make more power. The 268H has a sweet sound and will drive fine even with a lot less than 3.70 gears.
JIM
JIM
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
Thank you all for your input. Per Edelbrock Spec sheet for these heads, a roller cam is not recommended. Heads are supposed to be good from off idle to 5500. With that, I saw no need for a cam that makes power beyond that. According to what I read, and I could be wrong, but the 268 cam made it max torque at 3800 rpm (over 400 ft lb) and maxed out HP at 5000 RPMs - this is all in the ballpark I was looking for. I thought it would be a fun car to drive and with the 200R4 trans - I could still hit the Interstate and keep up with traffic without running the motor hard. This cam does seem to be used by several on here, but it's not ordered yet - so I guess I'm still in the deciding stage.
Race Director
Joined: Oct 2000
Posts: 15,057
Likes: 79
From: central FL, near the beach.
another good cam to consider is the 270H Magnum 224/224/110
i have that in my 61, it runs great, But i thought it was old school, until i read posts by jeff swisher. He had one, and when he switched to the xe268, he said the 270h was faster!(drags). He was so unhappy with the dual pattern hype, he now only buys single pattern cams!
So the advantage to the 270h is less chance of pinging, less aggressive lobes, no need for 1.6 rockers. Disadvantage is about a 100-200 rpm higher idle in Drive than the xe262, but this would be a better idle than the xe268.
the 270h comes on strong at 2400, so it is a good match w/2400 stall.
I've seen too many reports of less power w/xe268, i think it just has too much exhaust duration for a 350.
i have that in my 61, it runs great, But i thought it was old school, until i read posts by jeff swisher. He had one, and when he switched to the xe268, he said the 270h was faster!(drags). He was so unhappy with the dual pattern hype, he now only buys single pattern cams!
So the advantage to the 270h is less chance of pinging, less aggressive lobes, no need for 1.6 rockers. Disadvantage is about a 100-200 rpm higher idle in Drive than the xe262, but this would be a better idle than the xe268.
the 270h comes on strong at 2400, so it is a good match w/2400 stall.
I've seen too many reports of less power w/xe268, i think it just has too much exhaust duration for a 350.
Last edited by Matt Gruber; Nov 16, 2012 at 04:41 AM.
Race Director
Joined: Oct 2000
Posts: 15,057
Likes: 79
From: central FL, near the beach.
TEST drive. idle speed was up 25-50 rpm and the lope was gone! and i'm only half done
Let me finish the job before making a final conclusion. But, it looks like guys wanting a lumpy idle w/xe262 SHOULD use E1.6, and guys wanting a smooth idle should use 1.5 on E. It could be that when i lower the idle back to 550 in D, the lump will come back. Will see.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
The camshaft I used is a Crane HMV-272 Max Velocity dual pattern hydraulic cam. The cam has a duration of 216 degrees intake and 228 degrees exhaust @ .050 lift and has a max lift of .454 inches on the intake and .480 on the exhaust.
If I remember correctly the cam is ground on 114 degree lobe centers. I can tell you that it's a really nice cam that idles well down to about 850 rpm and wakes up nicely at around 2200. I didn't give up very much torque down low and can lug the engine around town in 4th at 1200 rpm all day.
I used 1.6 roller tips on I&E with ported 186 casting heads
If I remember correctly the cam is ground on 114 degree lobe centers. I can tell you that it's a really nice cam that idles well down to about 850 rpm and wakes up nicely at around 2200. I didn't give up very much torque down low and can lug the engine around town in 4th at 1200 rpm all day.
I used 1.6 roller tips on I&E with ported 186 casting heads
Last edited by gkull; Nov 16, 2012 at 02:14 PM.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Isky 270 will make more tq than the comp if youre willing to go that big
Ditto on the 268 high energy cam works great
Do like some of the older crane grinds they work well.
Ditto on the 268 high energy cam works great
Do like some of the older crane grinds they work well.