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Re: Comp Cams XE268H vs. XE274H? Opinions?
[Re: Baxter61]
#452340
08/29/09 06:44 PM
08/29/09 06:44 PM
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Joined: Nov 2007
Posts: 21,822
Kirkland, Washington
Pacnorthcuda
Too Many Posts
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Too Many Posts
Joined: Nov 2007
Posts: 21,822
Kirkland, Washington
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Quote:
The hp BB cams in 70 were 268 on the intake so do you want the same size or bigger?
The modern grinds ARE larger. Because of lift. The old-school stuff was high in duration for a given lift so diveability suffered in the true Hi-Po grinds. Now you can get good lift at reasonable duration. A lunati 60303 is .493/.513 at 268/274 (as I recall---if thats not totatlly accurate its close) Look at the lift of the stock 268 lobes, its not even .480.
Modern grinds rock.
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Re: Comp Cams XE268H vs. XE274H? Opinions?
[Re: Pacnorthcuda]
#452341
08/30/09 02:57 AM
08/30/09 02:57 AM
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Joined: Nov 2004
Posts: 2,495
Oregon City, OR
Baxter61
top fuel
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top fuel
Joined: Nov 2004
Posts: 2,495
Oregon City, OR
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Quote:
Quote:
The hp BB cams in 70 were 268 on the intake so do you want the same size or bigger?
The modern grinds ARE larger. Because of lift. The old-school stuff was high in duration for a given lift so diveability suffered in the true Hi-Po grinds. Now you can get good lift at reasonable duration. A lunati 60303 is .493/.513 at 268/274 (as I recall---if thats not totatlly accurate its close) Look at the lift of the stock 268 lobes, its not even .480.
Modern grinds rock.
I dont argue the design of the modern cams is better. However, that doesnt change how long the valve is off the seat.
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Re: Comp Cams XE268H vs. XE274H? Opinions?
#452343
08/30/09 10:11 AM
08/30/09 10:11 AM
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Joined: Mar 2006
Posts: 426
Mid-Atlantic
Scatransit
OP
mopar
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OP
mopar
Joined: Mar 2006
Posts: 426
Mid-Atlantic
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Quote:
Quote:
Your cam question really can't be answered properly without having some idea of your actual CR; that's why someone brought up the issue - they were trying to help you, not harass you.
All I seek is personal experiences with the cams mentioned in the subject line with respect to a basically stock 383 HP. I have pretty much decided on the XE268. I was curious about the 274, that's why I posted...Sorry if I worded it improperly Thanks to all for info in that regard. 
As far as a lecture in automotive math goes, after 33 years as a mechanic - I'm good.
It was never within the scope of this rebuild to delve into the exactness of measure...Were I to build a specialty engine, then that would surely come into play. This little 383 ran like a sewing machine, made great power, and was quiet...Its only problem was burning oil. Taper was excessive so I opted for the .030 over 10:1 flat tops from Sealed Power....That's it...All else measured fine...New bearings and gaskets, double roller chain, cam, lifters, springs and I'm done...Were it not for the oil burning issue, it would still be between the fenders!
Trust me, I do appreciate everyones input...I do not feel harassed, or defensive, or mad, or whatever...I've been doing this a LOT of years...You learn something new everyday...
Thanks 
[oo]======[oo]
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Re: Comp Cams XE268H vs. XE274H? Opinions?
[Re: Scatransit]
#452344
08/30/09 10:48 AM
08/30/09 10:48 AM
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Joined: Jun 2008
Posts: 565
IA
landon1
mopar
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mopar
Joined: Jun 2008
Posts: 565
IA
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my 440 has what are called 10:1 pistons - they aren't even close...more like 9:1. i think they figure the CR with closed chamber heads @ 74cc. i went with the XE268. haven't had a chance to get it out yet - hopefully sometime this week. i think i probably could have gone another step larger and been okay, but i wanted to play on the conservative side as i didn't want to mess with my torque converter or change my rear gears (yet  ) will post back with more info once i get it back together and on the road
'71 Satellite Sebring 440
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Re: Comp Cams XE268H vs. XE274H? Opinions?
[Re: Scatransit]
#452345
08/30/09 10:56 AM
08/30/09 10:56 AM
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Joined: May 2008
Posts: 5,399
Aurora, Colorado
451Mopar
master
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master
Joined: May 2008
Posts: 5,399
Aurora, Colorado
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My stock rebuilt 383, I used the Crower 271HDP #32242. It is simular in size. Advertised duration is 271/284, 222/234 @ 0.050", 0.486"/0.496" lift with 112 LSA. This cam made good power but it really wanted a higher stall converter. I guess I could have installed it advanced for more low end torque?
I think going with the smaller cam is the best choice if you plan on driving on the street.
Also, did your pistons have valve reliefs?
My "stock" replacement pistons had no valve reliefs, and I over-reved the 383, resulting in two bent intake valves.
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Re: Comp Cams XE268H vs. XE274H? Opinions?
[Re: 451Mopar]
#452346
08/30/09 06:05 PM
08/30/09 06:05 PM
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Joined: Mar 2006
Posts: 426
Mid-Atlantic
Scatransit
OP
mopar
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OP
mopar
Joined: Mar 2006
Posts: 426
Mid-Atlantic
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That's good info...sorry about the bent valves...My pistons are flat on top - no reliefs - as were the originals...I'd like to hear how Landon1's car turns out...Let us know...
[oo]======[oo]
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Re: Comp Cams XE268H vs. XE274H? Opinions?
[Re: Baxter61]
#452347
08/30/09 06:29 PM
08/30/09 06:29 PM
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Joined: Nov 2007
Posts: 21,822
Kirkland, Washington
Pacnorthcuda
Too Many Posts
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Too Many Posts
Joined: Nov 2007
Posts: 21,822
Kirkland, Washington
|
Quote:
Quote:
Quote:
The hp BB cams in 70 were 268 on the intake so do you want the same size or bigger?
The modern grinds ARE larger. Because of lift. The old-school stuff was high in duration for a given lift so diveability suffered in the true Hi-Po grinds. Now you can get good lift at reasonable duration. A lunati 60303 is .493/.513 at 268/274 (as I recall---if thats not totatlly accurate its close) Look at the lift of the stock 268 lobes, its not even .480.
Modern grinds rock.
I dont argue the design of the modern cams is better. However, that doesnt change how long the valve is off the seat.
A modern grind 268 is not "the same size" as OEM 1970 268. And thats a wonderful thing! 
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Re: Comp Cams XE268H vs. XE274H? Opinions?
[Re: Scatransit]
#452349
08/31/09 12:11 AM
08/31/09 12:11 AM
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Joined: May 2008
Posts: 5,399
Aurora, Colorado
451Mopar
master
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master
Joined: May 2008
Posts: 5,399
Aurora, Colorado
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Quote:
That's good info...sorry about the bent valves...My pistons are flat on top - no reliefs - as were the originals...I'd like to hear how Landon1's car turns out...Let us know...
That was almost 20-years ago, and the 451 stroker was the replacement motor
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Re: Comp Cams XE268H vs. XE274H? Opinions?
[Re: landon1]
#452353
09/05/09 08:23 PM
09/05/09 08:23 PM
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Joined: Jan 2003
Posts: 1,180
Willoughby Hills, Ohio
gd9704
super gas
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super gas
Joined: Jan 2003
Posts: 1,180
Willoughby Hills, Ohio
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The 268 has a large following of very happy users here. For a largely stock engine (like yours) it seems to be a great upgrade. Like others above have said, a too-big cam for a street car will be less fun to drive. I'd jab in the 268 and have fun! My 
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the old 268 is around 212 @.050
