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03-31-2009, 03:33 PM
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Join Date: Oct 26, 2006
Location: Asheville NC.
Posts: 122
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K8600 vs. Comp 256XE
I have both cams is there really a choice or am I crazy not to use the 256? Please help.
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03-31-2009, 04:21 PM
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Master Mechanic
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Join Date: Jan 22, 2008
Location: Robertsdale Alabama
Posts: 803
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Post the specs. of the Comp. cam.
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88 Grand Wagoneer
99 Camaro z28
73 Honda st 90
79 F250
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03-31-2009, 05:39 PM
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Join Date: Jul 20, 2003
Location: Forney,TX
Posts: 5,476
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The Comp has less lift, says it requires .150 longer push rods and screw in studs. I would venture to say it is a more technically advanced cam than the Summit.
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04-02-2009, 01:34 PM
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Fool-Injected
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Join Date: Jun 30, 2003
Location: The Long Beach area, SoCal
Posts: 3,514
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Quote:
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Originally Posted by Chevelleguy
The Comp has less lift, says it requires .150 longer push rods and screw in studs. I would venture to say it is a more technically advanced cam than the Summit.
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 WHAT? My instructions didn't mention any of that at all! That means I'm probably not making maximum power, right?  I'm not using stock pushrods, but don't know if they're .150 longer than stock (it's been years, can't remember any of it - I just know they're Summit rods). Time to go measure I guess...  |
04-02-2009, 05:46 PM
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FSJ Maniac
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Join Date: Jul 18, 2003
Location: Cullman, AL
Posts: 4,480
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Quote:
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Originally Posted by PlasticBoob
WHAT? My instructions didn't mention any of that at all! That means I'm probably not making maximum power, right? I'm not using stock pushrods, but don't know if they're .150 longer than stock (it's been years, can't remember any of it - I just know they're Summit rods). Time to go measure I guess... |
Yea, mine didnt say anything about that either. I am running stock lengh pushrods and stock rocker arms. Still runs good for me.
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79 Cherokee Chief 401/T18/D20, MPFI fuel injection, hydroboost, otherwise stock.
Future mods: Caddy 500/NV4500/NP205, HP D60 front D60 smooth botom rear, 5.13 gears, 35x12.50's on re-centered H1 beadlock wheels. Warn M12000 winch.
93 Wrangler 4.0L/AX15/NP231,SYE,CV, OME 2.5 lift, WJ knuckles and brakes, 31X10.50's Warn M10000 winch.
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04-03-2009, 08:09 AM
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Moderator
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Join Date: Jul 20, 2006
Location: Left Coast, Right wing. Nor Cal
Posts: 740
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Quote:
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Originally Posted by PlasticBoob
WHAT? My instructions didn't mention any of that at all! That means I'm probably not making maximum power, right? I'm not using stock pushrods, but don't know if they're .150 longer than stock (it's been years, can't remember any of it - I just know they're Summit rods). Time to go measure I guess... |
some do some don't but thats with roller rockers not stock bridges. prime the oil system and turn the engine over doubtful you need longer pushrods if you are running stock rockers. my engine needed 10 thou longer but that was because of my roller rockers not the cam. |
03-31-2009, 05:57 PM
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Member
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Join Date: Oct 26, 2006
Location: Asheville NC.
Posts: 122
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04-01-2009, 07:30 AM
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FSJ Maniac
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Join Date: Jul 18, 2003
Location: Cullman, AL
Posts: 4,480
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I have the comp XE256H in my 401. And I have the stock lifters/pushrods. I have had it in for several years, and the several years ago when I put it in, it said nothing about the screw in studs or longer pushrods.
Cant really help you much, as I have nothing to compare this too. I put the cam in on a fresh engine rebuild, and I dropped the 401 in place of a worn out 360.
I think the member plasticboob has one of these cams in his 401 too. Mabey he will post up. I think he swapped it in a already running 401.
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79 Cherokee Chief 401/T18/D20, MPFI fuel injection, hydroboost, otherwise stock.
Future mods: Caddy 500/NV4500/NP205, HP D60 front D60 smooth botom rear, 5.13 gears, 35x12.50's on re-centered H1 beadlock wheels. Warn M12000 winch.
93 Wrangler 4.0L/AX15/NP231,SYE,CV, OME 2.5 lift, WJ knuckles and brakes, 31X10.50's Warn M10000 winch.
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04-01-2009, 09:29 AM
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Cowboy Up
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Join Date: Jun 22, 2002
Location: Pilot Point, TX
Posts: 12,952
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Quote:
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Originally Posted by JeepsAndGuns
I have the comp XE256H in my 401. And I have the stock lifters/pushrods. I have had it in for several years, and the several years ago when I put it in, it said nothing about the screw in studs or longer pushrods.
Cant really help you much, as I have nothing to compare this too. I put the cam in on a fresh engine rebuild, and I dropped the 401 in place of a worn out 360.
I think the member plasticboob has one of these cams in his 401 too. Mabey he will post up. I think he swapped it in a already running 401.
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Did you run any oil additive for the break in or just use the cam break in lube? |
04-01-2009, 05:18 PM
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FSJ Maniac
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Join Date: Jul 18, 2003
Location: Cullman, AL
Posts: 4,480
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Its been several years ago, so I cant really remember what I used. I cant remember if it came with some lube, or if I used some store bought assembly lube. But I used some type of assembly lube on it and all the other parts. Primed the oil system on the stand with the valve covers off to make sure I had oil out of all the pushrods. Then primed again right before I fired it up.
I broke it in with regular castroil 10w30, then drained it after the break in and have been running regular castroil 10w40 ever since. Nothing else ever added in. I think this summer, I may switch to rotella t 15w40.
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79 Cherokee Chief 401/T18/D20, MPFI fuel injection, hydroboost, otherwise stock.
Future mods: Caddy 500/NV4500/NP205, HP D60 front D60 smooth botom rear, 5.13 gears, 35x12.50's on re-centered H1 beadlock wheels. Warn M12000 winch.
93 Wrangler 4.0L/AX15/NP231,SYE,CV, OME 2.5 lift, WJ knuckles and brakes, 31X10.50's Warn M10000 winch.
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04-01-2009, 05:30 PM
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Grease Monkey
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Join Date: Dec 26, 2007
Location: Kalamazoo, MI
Posts: 512
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I'm getting ready to fire up my 401 with a crane cam. I used assembly lube, primed it and made sure oil in the pushrods as well. I installed a oil valley bypass line which will feed oil to the rear journals. I'm going to use Joe Gibbs break in oil, which comes highly recommended by a race engine builder here in town. Apparently the newer oils are really lacking for breaking in engines. (I hope all goes well, the previous owner lost a piston at start up due to improper ring gaps on the Keith Black pistons. Also, the cam lobes looked pretty worn for only having 10 miles on the engine. Most likely due to lack/poor oil at startup.)
Last edited by sappy76 : 04-10-2009 at 05:24 PM.
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04-02-2009, 01:56 PM
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Fool-Injected
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Join Date: Jun 30, 2003
Location: The Long Beach area, SoCal
Posts: 3,514
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Quote:
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Originally Posted by JeepsAndGuns
I think the member plasticboob has one of these cams in his 401 too. Mabey he will post up. I think he swapped it in a already running 401.
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First I installed the Edelbrock Performer intake on the stock engine, and noticed a slight improvement. But after I swapped in the 256XE cam, I noticed a huge improvement in low/mid range torque! I never have to rev the engine (not that I had to much before), but I can accelerate "briskly" to say the least and not even have to get above around 2000rpm. I also did my "curb test" before and after the cam swap, and noticed that I could climb a curb at significantly lower RPM than with the stock cam. I was also worried that this cam wouldn't play nice with fuel injection, since I had repeatedly read on the internet that "cams with lobe separation angles less than 112* don't work well with MAP sensors". I didn't have that problem at all, I just richened up the idle mixture a bit and things are great. I'm a very happy camper with this cam! 
**I don't know all that much about cams so this is just my subjective, practical, real-world experience with this cam...I did some Desktop Dynos to help me choose it, here they are: http://home.off-road.com/~plasticboob/cams.htm |
04-02-2009, 01:17 PM
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Fool-Injected
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Join Date: Jun 30, 2003
Location: The Long Beach area, SoCal
Posts: 3,514
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Quote:
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Originally Posted by mmcswain
I have both cams is there really a choice or am I crazy not to use the 256? Please help.
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Yes you are crazy!  It's no contest, the 256xe is AWESOME. I have so much torque it's unbelieveable.
Here are some Desktop Dynos - don't pay attention to the actual numbers, just compare the differences and see which makes more power, and where:
Summit 8600: http://home.off-road.com/~plasticboob/t1/amc401cam-sum-8600.jpg
Comp Cams 256XE: http://home.off-road.com/~plasticboob/amc401chart.jpg |
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