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#1
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Comp XE 256 cam in an 8.0 to 1 400
I have a Comp XE256 cam and lifters that I am thinking of putting in a '73 low compression 400 (6X-8 heads). Car is a 73 LeMans, stock turbo 400 trans and 3.23 rear gears. Has anybody used this cam in a 400 like this.
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#2
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This Cam duration wise at .050" is similar to a factory 068 Cam, but with more lift.
Because of lack of compression the factory stopped using the 068 Cam once compression ratios dropped below 8.5 as is the case with your motor with the dash 8 heads.
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#3
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I have not run this cam. But while it looks to have around the same 0.050" duration as a 068 it also looks to have less seat-to seat duration which should help it with your 8.0:1 CR. What LSA is your cam?
Stan
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Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm |
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#4
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The XE256 has a 110* lobe center, and short seat timing at 256/262 degrees. I found some old threads where they were used in 350 motors. I was wondering if anyone had put one in an 8 to 1 compression 400. Thanks.
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#5
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I used a XE 262 in one(low CR 400) that worked fine mild idle.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
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#6
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If you want to go a step bigger I have a Comp Cam XE 262 for sale here
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1968 LeMans conv. 350 HO - 4 speed triple white (hear it idle here) https://www.youtube.com/watch?v=eVmq...ature=youtu.be 1968 LeMans conv. 350 - 4 speed Solar red/pearl |
#7
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Quote:
What are looking for out of this 400? While I see it making good mid range torque, but I see it making peak HP at a lower RPM than a 068 cam. Stan
__________________
Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm |
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#8
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I use the car daily driver/ street use, it's got working A/C. I just dont want to put another 066 in it if this one I have will work. I'm not concerned about power over 4500 RPM
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#9
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I use the car daily driver/ street use, it's got working A/C. I just dont want to put another 066 in it if this one I have will work. i'm not concerned about power above 4500 RPM.
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#10
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212/218 @ .050 isn’t too bad on the cam you have available but if I had to put up with a low compression 400 as my daily with A/C I’d much prefer something like the Summit 2800 with 204/214 @ .050.
Don’t use a cam that might be okay and might not, it’s the heart of your engine. I ran the 2800 cam in a 400 with 6X-4 heads with around 8.2:1 and it was a great cam, the car was a 1969 GP with factory A/C, a TH400 and 3.23 gears.
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1964 Tempest Coupe LS3/4L70E/3.42 1964 Le Mans Convertible 421 HO/TH350/2.56 2002 WS6 Convertible LS1/4L60E/3.23 |
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#11
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Different low CR 400 in the 81 now has the Summit 2801 a mild cam also. 3.08s A/C etc.
__________________
Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#12
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The XE cams seem to work well with lower compression. Helped build a 389 with 8-8.5 CR ten or 12 years ago with an XE268 cam and it'll rip your head off, and do it with 89 octane fuel, too.
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Jeff |
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#13
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I'm looking to get a little more power out of the engine and keep the idle smooth.I had this cam in a 9.5 to 1 455 and it idled dead smooth and was done by 3500/4000 rpm.
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#14
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That cam is going to be a "turd" in a 400 build at any compression ratio....IMHO
I've had quite a few Pontiac 400's, and a few Olds 400's brought in here for "custom tuning" using the larger XE262 cam in them. A stock 067 cam would do better, at least from my basic impressions of how those 400 Pontiac engines ran. They idled OK, deep/heavy sound, thru a little power at you then fizzled away past 4500rpm's or so. Not enough seat timing and those "fast ramps" work against you with 30 degree intake seats as they thrive on low lift flow numbers, longer duration, and wider LSA. The best cam I've found for low compression 400's is the Crower 60240, it's 270/276 seat timing, 210/222 @ .050" and 112 LSA. Runs best with the ICL around 108-109 degrees.......
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#15
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Quote:
i dont have any other cam to compare it to & im sure there might be a "better" cam but in my experience i dont see what all the xe bashing over the years is about on low compression engines, they seem to run great from majority of user reviews & butler has pushed the xe cams in FT or hyd for a long time. mid 13's @ 103mph is pretty decent for a mostly stock engine. being the OP doesnt care about power over 4500 it doesnt really matter if the cam is a turd above that rpm if it runs good for his low rpm street cruising with the a/c on. |
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#16
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Quote:
Stan
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Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm |
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#17
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A reality check is in order here. The OP is asking about the tiny XE256 here, not the larger ones. The XE268, and XE274 start to have enough seat timing in a 400 build to make decent power. The XE256 camshaft isn't big enough for a 350 build at 8 to 1 compression IMHO. It will still probably make enough power to do a decent burnout in a hard right hand turn leaving Dairy Queen, so all is well in the big scheme of things.......
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#18
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Note I have not run this cam and so this is a JMO.
The XE256 in a 400 ci engine even installed on a 110 ICL will have about 155 PSI cranking compression. IMHO I see the XE256 making more lower RPM and peak torque (at a lower RPM) than a 066 cam. Where the short seat_to_seat duration will play out is in where the engine makes peak HP and is done pulling, IMHO around 4300 RPM. Stan
__________________
Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm |
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#19
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I agree with Cliff . I did run an XE 262 in my original 78 180 HP 400-I think specs are below 8:1. It was very mild -a step smaller will make less power and be done even sooner.
__________________
Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
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#20
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" The OP is asking about the tiny XE256"
"That cam is going to be a "turd" in a 400 build at any compression ratio" My old Comp book states that cam has 212 degrees on the intake. My Crower book says the 60240 is even smaller... MORE tiny at 210 degrees on the intake. Both are tiny. Won't both be turds ! .
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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
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