Comp XE256H-10

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ir3333

ir3333

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Anyone using this cam?
256/212 268/218
.447 .455
..how does it perform
..looks to be a more aggressive stock style cam
 
I have one in my 1986 318 with EQ Magnum heads, Performer intake and 1406 carb in a 68 Coronet wagon with 904 and 2.76 gears. I asked Comp Cams for a recommendation based on wanting a little more power on the low end with an eye on fuel economy. I still have to replace the single exhaust with a set of modified Magnum manifolds and duals with an H pipe. I am very happy with the cam, the engine pulls 15" Hg and has decent acceleration in a 4000lb car. FYI I degreed the cam.
 
That's pretty much the 340 cam with a tighter LSA.
 
One thing I found about the Isky E4 is that it is a 108° lobe center cam. 216° @ .050 and only .425 lift but it has a little attitude. Really a mild cam but it works.
 
I would be willing to bet a dollar that one ground on a 112 or 114 would be faster on the street.
 
RustyRatRod said:
That's pretty much the 340 cam with a tighter LSA.
Click to expand...

.. this extreme energy cam would have more aggressive ramps than a stock 340 grind,
and more lift.
wondering if there would be a noticeable improvement over the stock 340 piece..
 
ir3333 said:
.. this extreme energy cam would have more aggressive ramps than a stock 340 grind,
and more lift.
wondering if there would be a noticeable improvement over the stock 340 piece..
Click to expand...

Yes , it would be in most circumstances. I've got one for the replacement engine for my truck LA360/Magnum head hybrid).
 
ir3333 said:
.. this extreme energy cam would have more aggressive ramps than a stock 340 grind,
and more lift.
wondering if there would be a noticeable improvement over the stock 340 piece..
Click to expand...

That's why I included "pretty much".
 
RustyRatRod said:
That's pretty much the 340 cam with a tighter LSA.
Click to expand...

RustyRatRod said:
I wouldn't want it in my stock 318. Now if it was the same specs ground on a 114, then yeah.
Click to expand...

RustyRatRod said:
I would be willing to bet a dollar that one ground on a 112 or 114 would be faster on the street.
Click to expand...


X2


Same specs with a tighter LSA will mean less idle quality and peaky power band. The wider centerline on the street gives you more power across the board because it flattens the curve. It will also improve idle quality. It will be more octane friendly too.
 
I haven't brought this up because I didn't want to start WWII.......but this thread seems a good place to do it.

I have spoken with Oregon Cam A LOT on the phone since I have had them grind a few. Those guys have been in the business since the early 80s I believe, so they are far from stupid.

They tell me the exact opposite of what everything else says about lobe separation. They say that the wide LSA jacks up cylinder pressure, while the tighter LSA decreases it.

I can see on the one hand how the wider LAS would do that. When you grind on a 114 for instance, instead of a 108, you are reducing overlap. Overlap is the period when both valves are hangin open. So reducing overlap will generally make cylinder pressure go up.

It would be a good topic for discussion for sure. I "think" what "THEY" are trying to say is that all things equal and unchanged, a wider LAS will result in more cylinder pressure.

'Tis interestin' fo sho.
 
Tighter LSA increases cylinder pressure and increases change of detonation.

I know it seems backwards but that's how it works.


I can tell you I wouldn't go near this Oregon cam in a million years after reading what they told you.

Straight from com cams. http://www.compcams.com/Pages/413/cam-timing-lobe-separation-angle.aspx

And I've also discussed this with jim laroy as well. Email from Jim.. "The wider lobe separation angle closes the intake valve later and reduces cylinder pressure, so that is where it's detonation resistance comes from. Really wide lobe separation angles are used in boosted applications. Many later model engines use wide lobe separation angles to reduce overlap for idle quality and fuel economy. "
 
I've read all that. Ant TONS more. I have been online since 1997. Read technical manuals since I could read.

There's "more" involved than "just" the LSA. That's what I am getting at.

....and while you may not go near Oregon, I take what Comp says with a grain of sand.

I have had those guys give me some colossal bad advice before. ....and I am not alone.
 
RustyRatRod said:
I've read all that. Ant TONS more. I have been online since 1997. Read technical manuals since I could read.

There's "more" involved than "just" the LSA. That's what I am getting at.

....and while you may not go near Oregon, I take what Comp says with a grain of sand.

I have had those guys give me some colossal bad advice before. ....and I am not alone.
Click to expand...

Been here,done this.Not going back...
 
RustyRatRod said:
I've read all that. Ant TONS more. I have been online since 1997. Read technical manuals since I could read.

There's "more" involved than "just" the LSA. That's what I am getting at.

....and while you may not go near Oregon, I take what Comp says with a grain of sand.

I have had those guys give me some colossal bad advice before. ....and I am not alone.
Click to expand...

That's fine and dandy but I'm hard pressed to dispute what Jim Laroy has to say about it. I'd say he knows his stuff.
 
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