How do I tell if I have a spring or lifter issue? My gm847 peaks at 5800, which sounds low compared to what some of you guys are saying you get out of a cam that big. It peaks with 358 rwhp and at 6300 it is still at 340. It doesn't look like a valve spring issue to me, just natural hp curve. Am I missing something?

 

Sounds like a good thing to me.

 

Thats why I said I can't tell 100%, if you search for XE cams, many have experiences this.

Yes when I had the cam I did have other issues, and belive me a ton but I'm not comparring just what I had at the time but what many people had. It seems after researching that the 236/242s all peak around 6200rpm, plus a friend of mine had a 230/236 XE that peaked at 6k and then fell at it's face.

Like I said, lighter valve train will help, but that is still a relatively small cam compared to soft ramp cams with same duration at .050. Then again, all XE cams seem to have different stories behind them.

I also mention that my cam has XE style lobes but it's not Comp, I madepeak HP at 7k RPM with steel retainers, I added some Ti retainers so hope that HP there will go up a bit as it doesn't climb much after 6700.

Also, if you have an XE cam on a 114 lsa your power band should move up as well since your IC is later and the lift helps closing the intake later as well.

Again only the dyno will tell, I don't want to argue anything but I remember when this was a big topic for me.

 

How about guys who are running 240-250 duration XE lobes to 7,500-8,000rpm?

977's with Rev Kits aren't that much spring pressure BTW considering that the lifter see's 670+lbs with a 1.6:1 rocker and .600 valve lift with just a 977 itself.

Bret

 

my thoughts on the dyno discrepencies, is that the people who have xe cams that fall on thier face way too early all usually have something in common. they're usually running that crane 1038 or whatever it is kit, or some other similar stock diameter valve spring setup. and while the spring pressures and rates are comparable, it seems to me that the harmonics of a large diameter valve spring would be very different from that of a stock diameter spring which is assume is where the problem is. i also notice that the guy who tend to do things right (imho) like rich and others tend to have very good results with xe cams (myself included).

As for the idea that the older "slow ramp" cams are just better because of the longer adv duration allowing more airflow (i guess thats your arguement). just really doesnt hold up. to truely get the area under the lift curve on a camshaft one would have to develope an equation to aproximate the cam lobe on the base circle using polar coordinates (that is directed distance(r) dependant on angle(theta)) and then use intergration it to find the area. this is both difficult and easy to get entirely wrong. however simple logic tells us that increasing the duration at higher lifts leads to much larger gains in area than increased duration at very low lifts say sub .050" if you dont believe picking up 10-20 degrees in duration at .200" lift (xe lobes) is worth more "flow area" than moving that same amount of duration to bellow .050" (where the heads flow next to nothing) then i dont know what to tell you.

 

Yes increasing duration at higher lift being more advatageous is not bein argued, but when you do this you can't keep the IC the same because we don't have unlimited piston to valve clearances, however if the closing on an XE cam would be slower that would probably help some most situations for higher RPM.

As I mentioned earlier, that is probably one of the reasons why some people run into high rpm issues by running crane 10308 springs yes, but I just haven't seen XE cams off the shelf go past these rpms, you either need to increase lsa or lift to have the cams get up in their RPM ranges.

My cam is an agreesive XE style cam as I said before and I am running high RPM 7k, but this is because in order to get their with an XE style cam I had to have 24X/25X duration, then again my LSA is narrower which doesn't help but its because its a customized cam and I wanted it to rev high, sound lopy, and still make good power down low which it does all those things, but I've yet to see an off the shelf XE cam like the 224/230/ 230/236/ 236/242 make any power up top unless their LSA and lifts were altered, but we're talking about the base ones.

 

No I'm not trying to hear what i want to hear. I don't have a XE Cam I just want to learn about it. I'm running a cc305. You missed what I asked. The guy I quoted said his XE 224/230 made power to 6200rpm. I thought that was normal for a cam that size.
The advertised duration of the 224/230 at .006 is 276/281 which is less on the exhaust side compared to the cc305. But that is expected with a steeper lobe cam. Won't the lift area still be larger though due to the fact that it reaches max lift sooner and drops later.
Could it be that heads with better low lift flow work better with regular cam lobe profiles because they spend more time at low lift then cams with a steep ramp? And on the other hand will heads with better high lift flow work better with steeper lobes?

 

Sorry Musky pulling your leg, the guy running that XE cam has it on a 114 LSA and has over 600 lift thats why he pulls to 6200rpm, I've read many people have theirs drop at 5800 with the regular one, I though you already had a reglar one, if you don't you should try that one, I belive its not the XE but the XE-R that he has with higher lift, those I've seen pull much higher like the 230/236 XE-R high lift one I've seen pull to 6500rpm, sorry thought you had a regular one cuz Payam said that.

Ported heads flow no matter what cam you have, but the valve job/port job could differ for different cams, mostly the valve job so you'd have a different back cut say on the valves cuz you don't care about low lift numbers as much with an XE/XE-R lobed cam, your lift area depends on durration off the seat to the close, things like Lift, overall duration alter that.

 

This is interesting. I have the 230/236/112 off-the-shelf cam (medium lift) and CC 977 springs, Ti retainers, and CC lifters. I noticed that over 6K RPM my valvetrain gets loud and it feels like it stops making power. At first I thought it was knock but my knock sensor isn't picking it up. I was wondering if it was valve float, because I'm not running the times I expected. It feels like I might as well shift at 6K because there's no increase above there.

 

Well if you're running Comp R' lifters, i would check there first, while hot, try setting the lash to "0" (zero), then check the installed heigh of the springs and calculate the spring pressure, the spring rate for those is 441lb/in so it's quite a bit.

If this fails and you've got no other probs then perhaps you're experiencing what most are, I mean you could try retarding your cam 2* or so, but then you may see trouble with the opti timing, but I doubt it, advance the timing table 2* throughout the board, and I'm sure fueling latency won't be much trouble especially at high RPM.

 

I'm not using the Comp R lifters, but I am using the ones CC recommends for this cam. They're lashed at 0 plus 1/4 turn. Do you think the roller may be lofting off the fast opening ramp? How would retarding the cam 2* help the situation?

 

Bunker I currently have the Xe224/230 112lsa.I am using the crane kit springs.I am swapping the XE out for a GM847.Are these spring good for this cam.The springs have about 3000 miles on them.Thanks!

Rob.

 

[QUOTE=WS6T3RROR]my thoughts on the dyno discrepencies, is that the people who have xe cams that fall on thier face way too early all usually have something in common. they're usually running that crane 1038 or whatever it is kit, or some other similar stock diameter valve spring setup. and while the spring pressures and rates are comparable, it seems to me that the harmonics of a large diameter valve spring would be very different from that of a stock diameter spring which is assume is where the problem is. i also notice that the guy who tend to do things right (imho) like rich and others tend to have very good results with xe cams (myself included).
QUOTE]

It's been a while and frankly I don't remember all the details, but I tried everything from adding titanium retainers to changing out the springs…. to whatever! Must have spent at least a half a dozen dyno sessions (or more) trying to figure out the problem. I originally had a 224/230 and complained to Comp Cams regarding the sudden power drop and their only answer was to try another cam. I had them send me another 224/236 which displayed the same virtues.

After another whole afternoon on the dyno with a bunch of buddies to help, the only thing that seemed to work was setting the lash to zero. With zero lash the 224/236 made pretty decent peak power (395.7) for its day, but peak power does not tell the whole story as it hit the wall @ 5900 rpm. After adding new springs the power dropped but the peak went up 100 rpm. Go figure!

After dicking around constantly with it for over a month finally changed over to a 306 cam which made a world of difference. The peak actually dropped by two or three hp from the 395.7rwhp but the torque curve was much better and the powerband flatter peaking @6350 going strong until 6800 rpm. The average power within intended powerband was much better making the car faster by a couple of tenths.

In retrospect the only thing we could figure out is the MTI (really GTP) heads used heavy Ferrio (sp?) valves and some people with lighter stock valves did not seem to have the same problem.

 

If you don't have comp R' lifters I would try 1/8th past 0 lash but no less as most lifters don't use big retaining clips to keep the lifter together like the comp R's do, so going 0 lash I would be a bit worried.

Retarding the cam 2* would help peak power and moving the powerband up because you would be closing the intake later, when you do that you move the power band up.

97WRAITH, I don't see any trouble using those springs with the GM847 cam, I really loved that cam when I had it and the Crane 10308 spring package has very good springs, I belive if you set them at the right installed height you can have huge spring pressure on the seat and still have a high lift cam with high spring pressure at the top.

Those springs only lack a dampner which would help harmonics but they are really good because if you set them I belive at 1.850 installed height, you'll have something like 130 lb on the seat and can have .700 lift or something crazy, and if you set height at 1.800 you'll have 150 lb on the seat range and can still have .650 lift cam, very nice springs

Also, aren't they 1.460 diameter? Thats not a stock diameter spring by the way, I would recommend finding some cup style shims, I know there are a few companies that make cup style shims (look like seats basicly) that fit the stock alluminum lt1 heat (not iron) and will work with comp 977 springs and crane 10308 springs, that would help spring harmonics as well as the spring won't dance around so much.

Most Crane 10308 spring users have just shims, thats not very good, regardless, the trouble with the off shelf XE cams remains from what I've seen and I just wouldn't bother with them anymore.