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phil400
Cochise

Canada
456 Posts

Posted - 01 Nov 2017 :  9:17:50 PM  Show Profile  Reply with Quote
I?m looking the XE268 or better yet the Lunati version of the same cam, but I?d like to keep valve lift around .450?. Will comp or Lunati grind it?

78T/A 4-SPEED Marty blue 400/milled 6x-4's/268H,comp roller tip rockers/ performer Q-jet/RA manifolds 2.25" exhaust with x-pipe/ mine since '99 3rd & final owner as long as I'm alive
"sometimes I do what I want to do,rest of the time I do what I have to"

tjs44
Cochise

USA
412 Posts

Posted - 02 Nov 2017 :  09:16:15 AM  Show Profile  Reply with Quote
You need to get their lobe book to see what is avail.Tom
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Steve C.
Crazy Horse

1675 Posts

Posted - 02 Nov 2017 :  09:55:06 AM  Show Profile  Reply with Quote
First, why do you want to limit your valve lift to 0.450" lift ?

If you want to mimic the XE268H cam call Bullet Racing Cams and talk with Tim. Consider a custom cam using their lobe number H270/300

270
224
0.3000" libe lift x 1.5 = 0.450" lift

Use a exhaust lobe suitable to work with your cylinder head intake-to-exhaust flow ratio. In addition it can be ground with any lobe separation desired.

http://www.bulletcams.com/Masters/Hlobes.htm

If you want to work with Comp Cams their Magnum lobe number 5202 is similar to the Bullet lobe above.

.

Edited by - Steve C. on 02 Nov 2017 10:00:31 AM
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Blued and Painted
Chief PONTIAC

USA
3407 Posts

Posted - 02 Nov 2017 :  10:36:40 AM  Show Profile  Reply with Quote
Comp cams has a great web sight and builds fast race cars but
There have been so many threads about valve train noise and spark knock associated with the flat tappet XE lobes.

The shorter stroke 400 is capable of some rpm's where the XE cams build allot of bottom end power.
Generally speaking, increase duration helps rpm's where more lift increases power.
.500 lift is 1/10 of an inch more than factory.
IMO It would be worthwhile to have the heads set op for .500 or more lift.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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Steve C.
Crazy Horse

1675 Posts

Posted - 02 Nov 2017 :  11:35:45 AM  Show Profile  Reply with Quote
"IMO It would be worthwhile to have the heads set op for .500 or more lift."

Good comment. And that works with what I've posted on many related conversations.....

"If you want to build a street motor with the most power without a sacrifice of idle and low speed qualities, then lift is the most important factor to maximize, not duration. The best street cams are those that seek to maximize valve lift while only adding a minimal amount of duration."

David Vizzard


.
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phil400
Cochise

Canada
456 Posts

Posted - 02 Nov 2017 :  11:53:24 AM  Show Profile  Reply with Quote
Ok thanks for the info.

78T/A 4-SPEED Marty blue 400/milled 6x-4's/268H,comp roller tip rockers/ performer Q-jet/RA manifolds 2.25" exhaust with x-pipe/ mine since '99 3rd & final owner as long as I'm alive
"sometimes I do what I want to do,rest of the time I do what I have to"
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Steve C.
Crazy Horse

1675 Posts

Posted - 02 Nov 2017 :  6:46:43 PM  Show Profile  Reply with Quote
Upgrade valvesprings to increase the maximum spring travel.

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