Sigforty

I would like to know what types of setups yall are running with this cam. What size carbs, intake manifold, rough CR, etc... I have a friend who is running this cam with edelbrock performer heads, rpm manifold, 600 cfm holley and his has some issues with lack of low end torque.

VETDRMS

I used this cam with 041 heads, 9.8:1CR, performer eps manifold, performer 600cfm carb, in a 350. Lack of low end torque...YES! :smash: I believe duration is 224/232 @ .050. You need at least a 2400rpm stall. After that this cam pulled real strong right up to 6000. I liked it, but yes, under 2500 rpm it was sluggish.

:cheers:

ukvette72

I have the Edelbrock heads and inlet, a 670cfm Holley street avenger, 9.5:1 compression, 3.36 rear gears and a 2400rpm stall converter. The car pulls well compared to the previous stock set up and will spin the tyres hard from a standing start. I suspect this is down to the converter. I woudn't want too run much more or less stall with this set up.

hope this helps

David :seeya

Sigforty

All of this info helps. I am just trying to help my buddy get his car straight. As far as stall he has a 2200 unit in a 200R4 trans, and a 3.55 rearend. I think he might have carb issues with that little 600 cfm holley. I honestly think he needs a bigger carb around 650-700 cfm. I also think the RPM manifold is too much and that a performer would better suit his set up. I am just trying to get some feedback to help him out.

Lasse

Bigger carb isn't the right way to go, if there is lack of low end torque. The bigger carb just give the engine better breath on high rpms, when the engine needs a lot of air/fuel.

8T1-7T9 BIONIC VETTE

Get a B&M Hole shot Stall...... :hurray: :flag :seeya Cappy

Fevre

Might be a timing or adv curve issue, or the cam might be adv/retarded instead of 'strait up'.

Ryan77

The RPM is a good manifold, and suits the 268XE pretty good, the 268XE has a powerband of 1600-5800rpm, and that intake is good for 1500-6500rpm. In my 350 I ran the RPM, 268XE, and a 670 Holley street avenger. Like Comp Cams says, the cam doesn't come on until 1600 rpm or so. What is your friends compression ratio? Having the car dyno-tuned would also be a good idea to get the timing and air/fuel ratio setup correctly :cheers:


[Modified by Ryan77, 7:43 PM 8/7/2003]

BSeery

I looked at several cams when getting ready to do a cam swap in my '78 Chevy pickup. The engine had a 280 Magnum cam and had zero pulling power. As I wanted a motor for towing, this cam had to go.

I looked at cams from the 255 to 268 sizes all from Comp or Crane. I used desktop dyno and went through many combinations. For pulling power under 5000 RPM, the 260 cam was the best for torque and HP. The 262, 266 and 268 cams all made more HP, but less torque They all moved the HP peak farther up the RPM range and that did work for me.

I would think for a daily driver running 9.5:1 compression, 600-670 CFM, dual plane intake and decent dual exhaust, the 262 range is probably the best. My engine was a 9.5:1 compression running 041 heads, 600 CFM Edelbrock on a Edelbrock dual plane with dual exhaust. It has a very smooth idle and pulls well. It doesn't chirp 2nd like it used to with the 280 cam, but the 280 cam could not idle worth a crap and ricers left me standing still at lights. With the trailer it was so bad that I thought I would roll backwards waiting for the RPM's to build. The 260 was a massive improvement. I think a little bit bigger would be great for a street car with a stall converter, but going to a 268 for street driving is too much, in my opinion. Maybe the use of fast bleed lifters (variable duration lifters) may help some.
I wonder what at 262 with 1.6 rockers would do on desk top dyno.

Sigforty

Well, last night we went to the drag strip for test n tune. I managed to get the timing pretty much set for my friend. He was just still disappointed in the lack of low end torque. He is starting to think the cam is just to big for him. His CR is around 9:1. He may just have to swap down on the cam scale to get what he really wants.

The Money Pit

I saw an article that used Vortec heads and 87 octane gas with the XE-268 and pulled 390 hp/430lbs.Granted most rag stories neglect to show the dyno pull below 2500,but the curve looked pretty stout.

The bottom line is the whole package has to match.If you want low end power,cam small,carb small,run some gear and you can't go wrong. The biggest mistake everyone makes including me,is thinking bigger means better.Nothing can be further from the truth.

The 355 my 406 replaced ran stock heads,a Comp 268H,Performer intake with a 1904 carb.Make no mistake about this combo lacking low end.Even with P295 50's if I launched hard I could easily boil them.

In comparison a friend of mine built a 350 in a Monty Carlo using a Performer cam,2bbl carb,single exhaust and 2.70 rear.I drove that car and let me tell you it was a POS that couldn't get out of it's own way.Could not spin a tire if you stood on the gas and let the brakes slip.So here we have a similar cam,but choked by the intake and exhaust,plus a higher gear.

Charlie C.

I'm runnig the same setup as UKVETTE. I to am not happy with the low end. I contacted comp-cam,they tell me my problem is rear end. I have a 350 trans with a 3:08 gear they say you need at least a 3:55. I'm going to a 3:70 this winter.......sounds good sitting still!

68shark

I have the XE262 in my 327. The 268 gives up too much bottom end in an auto 350 unless you have high rear end gears( ie. 3.70) and a higher than normal stall convertor, plus a good manifold, headers etc. He'd probably be happier with the 262...might give up a little on the top but he'll have better punch down low, which seems like that's what he is looking for. Any of the high perf cams (including the 151 cam from GM) will be a little "soggy" below 2000rpm but the 268 would make it more noticeable. Just my .02!!

Jvette73

I used to have the XE268. For reasons still unknown it wiped a lobe. So since I had to replace it I had the choice again. I elected to downsize to the XE262. With the XE268 and all my other mods listed below it was still a bit sluggish down low. That cam wouldnt start really kickin in till about 3k. I changed nothing other than the cam and the car performs better with the smaller XE262. Better bottom end, better manners better idle...ect. Also got a better ET on a 30 degree hotter day at the track. The sluggish bottom end is just a characteristic of that cam. As mentioned above a bigger carb would make bottom end worse most likely. I run the 600 and it screams well up to 5500rpm where it runs flat. But thats my selected redline anyway so the 600 is perfect for me. Its a built in rev limiter. :yesnod:

L-82kid

I'm putting this cam in my engine tomorrow, am I going to have this same problem? I have a stick car with 3:55 gears. All my other motor mods are listed in my signature. I called comp cams several times and told them my set up everytime they suggested the XE268.

Thanks,
Kevin

71coupe

I have that cam in my 355 and it works great, but I am also using great heads(Dart Pro 1's w/200 intake runners) + a 4 speed.

If I could do anything different I would have used Crower hyd race series cam saver lifters:

http://www.crower.com/misc/m_cat.shtml

Jvette73

The XE268 will work good with yur setup. It worked good with mine too. You will sacrifice some bottom end for some additional mid range power. I didnt hate the cam. I liked it ok. But when faced with the need to change the cam due to wiped lobe, that gave me an op to step down one size. With and automatic trans the XE268 was not very comfortable idleing in gear. The 262 has a noticablly smoother in gear idle. The 268 is probably the first cam(size wise) that you will notice a slight loss of bottom end, whereas the 262 has no noticable loss of bottom end. To get the most out of the 268 you need to plan on reving to about 6000rpm. I never really want to go over 5500rpm with my stock 79kmi bottom end so the 262 fits my mods and my plan better. Why have a cam thats capable of producing useable power up to 6000 when ill never take it above 5500? When had the 268, in my case, i was sacrificing some bottom end while not taking advantage of the cams full potential up top. So the net equaision was a loss with the bigger cam. Thats why the 262 works better for "me". So its not only the mods, but also how the driver plans to use it.