comp XE256

-
ir3333

ir3333

Well-Known Member
Joined
Jun 1, 2008
Messages
5,836
Reaction score
1,578
Location
ontario,canada
your thoughts on this small cam in a stock 340?
XE series have a little more modern / aggressive ramp rate.
.447 / .455
212 / 218 @ .050

tx guys
 
What year 340? In a cast crank engine that one should work pretty well, a forged crank engine has more compression and that cam might raise your DCR too much. I'd go bigger in a forged crank engine.
 
T-N-T said:
What year 340? In a cast crank engine that one should work pretty well, a forged crank engine has more compression and that cam might raise your DCR too much. I'd go bigger in a forged crank engine.
Click to expand...

If you look at 340 stock cam at 0.050" specs the comp cam is slightly more aggressive. 340 cam is pretty mild cam.
 
273 said:
If you look at 340 stock cam at 0.050" specs the comp cam is slightly more aggressive. 340 cam is pretty mild cam.
Click to expand...

I was comparing the how many degrees ABDC when the intake valve closes at.

IIRC the 340 cam closes the intake at about 60 ABDC and the XE256 closes at 54 degrees ABDC. This will increase the DCR some which would work well in the cast crank engine.

I'd probably chose a XE268 (or bigger) which closes at 60 ABDC for a forged crank engine. I've run it in the past with great results.
 
I'm not a TX guy either but, I have that cam in my stock 318. It has 30 over flat tops with valve relief. I would think a 340 could use something more aggressive. Stand by and the smart folk will respond.
 
If you were going with that cam, I wouldn't even bother.

If you have 8.5:1, like a low compression 340, maybe use the 262 or 268.

If you have a known engine with over 9.5:1 verified, I would use the 274 personally.
 
goldduster318 said:
If you were going with that cam, I wouldn't even bother.

If you have 8.5:1, like a low compression 340, maybe use the 262 or 268.

If you have a known engine with over 9.5:1 verified, I would use the 274 personally.
Click to expand...

..i'm not a racer..strictly street.
Wouldn't the 268 and 274 be lazy with 3.23: gears
 
ir3333 said:
..i'm not a racer..strictly street.
Wouldn't the 268 and 274 be lazy with 3.23: gears
Click to expand...

Is it a older 340 or the lower compression later one? Are you running an auto(stall speed?) or a stick?
 
I used this in our stock piston, 302 head, comp springs, 318 truck and found it to have lots of grunt and a surprising top end with high idle vacuum.

When running just about any small block on the Camquest program all made the most torque with this one in the XE series, as you went bigger torque dropped as horsepower increased.
 
my5thmopar said:
I'm not a TX guy either but, I have that cam in my stock 318. It has 30 over flat tops with valve relief. I would think a 340 could use something more aggressive. Stand by and the smart folk will respond.
Click to expand...
^^agreed

It's a balancing act; compression, cam, gears, and TC. Without knowing your exact compression ratio, it's hard to figure the rest.
And as usual, what are you trying to achieve?
 
Coronet 500 said:
I used this in our stock piston, 302 head, comp springs, 318 truck and found it to have lots of grunt and a surprising top end with high idle vacuum.

When running just about any small block on the Camquest program all made the most torque with this one in the XE series, as you went bigger torque dropped as horsepower increased.
Click to expand...

...that's what i was thinking.
this will be a stock style build 8.5:1 with 3.23 gears and maybe 2200 stall converter.
want good lo speed torque,smooth idle and have it pull well from 800 to 4800 or so rpm.
also considering the XE262?
 
A lot of folks run the 268 with what your describing. I have the VooDoo version and it's fairly tame on the street.

Are you build a motor from the ground up or putting this in an all ready assembled engine?

What is the application?
 
planning my next project and i will build an engine that will
perform well on the street,sip lo test,and idle 'kinda smooth
and i think that xe256 would be best street light to street light.
 
ir3333 said:
..i'm not a racer..strictly street.
Wouldn't the 268 and 274 be lazy with 3.23: gears
Click to expand...

I have 9.7:1 CR and I have a hydraulic roller that's similar specs to an XE274 but with a roller has faster ramp rates, but slightly less lift. I have 3.23's and a 4-speed and it's far from lazy.

With low compression...go a little bit smaller. The XE256 just doesn't seem different enough from a stock 340 cam to me. AT LEAST XE262 IMO
 
If you want a smooth (it's a relative term...) idle, you may want to consider having them put it on a 112 or 114 LSA. That will smooth it out. For the 262, the overlap at 0.05 lift will be 1 (110 LSA) -3 (112 LSA) and -7 (114 LSA). The stock cam is -13 at 0.05 lift.
 
I would run the 262 or similiar brand X in your motor. Plenty of bottom end for your converter and 3.23 and 87 Octane.

I run a 9.5 340 with a XE262H and must use 93 fuel. J heads, polished chambers, ported/
runs great, but a proper tune ignition and fuel is a must.
 
For a strictly excellent street bound driver. I would not go any larger than a [email protected] intake with an auto trans car and 3.23 gears. At [email protected] the gap in power and a stock torque converter becomes apparent and not so great. This is where I think a higher than stock stall converter comes in.

More compression helps a soft bottom end. A manual trans hides the gap the stock stall converter shows. Like Gold duster 318 has, the larger cam, the manual trans works well. A stock stall converter would kind of suck.

The 268 IIRC! Is advertised as a cam that still works with a stock converter? If not, I like the 2200 stall choice even if the cam doesn't call for its "need." The 212/218 cam is like a standard upgrade over stock to a factory 4bbl. performance like level. A lot like the older Comp cam 212/212 but better. (If not slightly better than some factory packages) I would call it lack luster even though performance will be nice.
 
You must log in or register to reply here.
-

Back
Top