new cam or not?

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redfastback

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since i have my engine out, i was thinking about having some work done. not much though.
i am running a 284/484 mp cam right now and was thinking about going to a comp 274xe 274/286 .488/.491 lift. do you think i will see a difference? the car has 3.55 gears and a 2500 stall.
the intake is gonna get fitted better, i think it has always sat to high. probably just a few 1000ths off each side.
 
redfastback said:
since i have my engine out, i was thinking about having some work done. not much though.
i am running a 284/484 mp cam right now and was thinking about going to a comp 274xe 274/286 .488/.491 lift. do you think i will see a difference? the car has 3.55 gears and a 2500 stall.
the intake is gonna get fitted better, i think it has always sat to high. probably just a few 1000ths off each side.
Click to expand...


The exhaust will work better with the Comp cam that's for sure. Your guess is as good as mine on HP/TG but I bet you will gain with the Comp Cam.
 
redfastback said:
i am running a 284/484 mp cam right now and was thinking about going to a comp 274xe 274/286 .488/.491 lift.
Click to expand...


I have the same Comp Cam in my new engine, the .488/.491 dual pattern. And the funny thing is the old cam was the same one you have now, the MP 284/484. Unforntunately, I can't give firsthand results because mine is STILL an in-animate lump of expensive parts and labor.

If you do it, let me know how it goes.... :-D
 
This might be a little bit of a crap shoot in terms of what you will gain vs the cost and time but I have a feeling you want to do this. When you, crackedback & I went to lunch, I remember you bringing up the old technology of the MP cam you were running and the desire to try a Comp dual pattern. As we all know, this is the perfect time to do it (while the motor is out) and, you get to address the intake manifold (which knowing you, is driving you nuts)..
 
The comp cam should run better down low and have a broader torque curve.
 
i am shooting towards changing it. i agree that my bottom end torque will be better but i think the acceleration curve might increase as well due to the split duration.
 
I don't know how much faith you have in desktop dyno but when I was rebuilding my engine I got the info for allot of different cams including the ones you mentioned and ran them all as a comparison. I don't remember exactly how much difference there was but it was a significant low/mid torque gain. On the top end the Mopar cam had a little hp more but not much and that wasn't until after 5,000 rpm.

Allot of guys talk about the Mopar cams being old technology. Well in rate of lift comparison they are right up there with the comp xe series. The only thing they are not split duration/lift cams that seem to work better on cars with full exhaust. The exhaust port flow is weak on the LA heads anyway. When you combine that with full exhaust I believe the split cam is the only way to go on a street car.

The XE274 I had in my engine was pretty torquey and pulled right past 6500 with ease.
 
Do it !!!!!!
The xe274 cam is bad to the bone.The modern technology of the xe cams is superior to the old purple shaft.As far as I know,you will have to change springs.Match it with a pair of there lifters.Very nice !!!!!
 
well the springs that are stock in the eddy heads can take a .575 lift but are not a dual spring like comp recomends with this cam.
eddy springs- coil bind=1.130 single springs
comp springs-coil bind=1.050 dual springs
 
redfastback said:
well the springs that are stock in the eddy heads can take a .575 lift but are not a dual spring like comp recomends with this cam.
eddy springs- coil bind=1.130 single springs
comp springs-coil bind=1.050 dual springs
Click to expand...

Looks like your fine as far as lift goes but do you know the pressure ratings of the Eddy springs? I tested the springs for the comp EX274 and at 1.69 installed height were 110 lbs. and at .500 lift were 320 lbs. If your Eddy springs are close to that they'll work fine.
 
for the eddy springs 5767 , they list it at
installed height 1.830 in., seat pressure was 120 lbs.

open height 1.250, open pressure was 330 lbs.
 
OK. Looks like the spring rate is a less than the comp springs but I think they'll work fine. The only bad thing is that's quite a bit of pressure for break in. Hopefully not too much. If you have some lighter springs you could put on for break in it would be better.
 
Theres nothing wrong with m.p. cams,they are agressive-and they make power,the main difference Ive found with todays grinds is they offer better driveability/idle,and a broader power curve while still making comparable power on the top end.With your setup I would say the car will respond and run alot stronger below 3-3500,I would do it personally.
 
I agree with Fishy68 in post #7. Also, the Desk Top Dyno is a sim. It may not be exact or as some would say, generous in upper HP. It really doesn't matter to much. The reason being is it gives you a good idea of how things are going to go. Maybe not perfectly, but it is good enuff to get going on.
Second, the abilty to compare cams is a very good one and the program will show you how things react. This will help in a decideing what direction to take.

MP cams do have a fast rate of lift. (Duration X's .850 for a @ .050 duration.) But there single pattern grinds that work well with well ported heads. When the head flow balance gets more evened out after porting, a split duration cam can actually hurt performance. It becomes a case of too much of a good thing.

The amount of duration difference can also have an effect. More is not allways beter. Peak at a Comp cams catolog and notice the diference in the XE line and the few grinds designed to work with exhaust manifolds.


Click here for Comp Cams on-line; http://www.compcams.com/DefaultWide.asp
and go to info, cam lobe master catolog and scroll down to view cam specs between grinds. (Beaware of advertised lift @ tappet rise variables)
 
i agree that this 284 cam runs good at 3k and above. its a runner. but the amount of torque gain from this split duration cam seems to be enough to change it. the duration @ .050 isn't all that bad at 230/236.
 
I like the cam. That ought to be nice in there.
 
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