Im thinking about ordering my cam next week. Im going to start putting together my bottom end and want everything ordered. I was either going to get the xe268 or the xe274.i really need help in what cam i should get so i dont regret it.heres my probable combo.
350 bored .020 with .010 deck surfaced
heads-edelbrock rpm or pro dart 180 aluminum(thats another thing i cant make my mind on)
3:73 gears with 2400 stall and 2:55 tires.
msd/hei
holly 750 double pumper

Its my #2 chevelle so it wont be driven much and when it is i want it too be fun. Im looking for good bottom with gobs of torque. I may take it to the track but i want it to be a rocket from light to light on the street.

I used the ex274 in a '79 Corvette with a L82 350 bored .030. I had the Edelbrock RPM's 64cc heads, performer RPM intake and a Holley 750dp. This was in a 4 speed car with 373 gears also. The only part of the project that never was right was I didn't want to put headers on the car (they hang so low on a vette) so I had 2 1/2 exhaust manifolds. That cam made good power and sounds awesome...I had 2 chamber flowmaster mufflers on this vette and that cam sounds fairly radical. graemlins/thumbsup.gif

What was the low end like?

I say go for the Xe274 . Im runing the Xe268 and would like to try the Xe274. I think your stall and the Xe274 would be a good match, the stall would lock right when the power starts to come on strong and pull for a long time. These darts I have are a bit too big for my motor but they still work great. Last summer my best ET in the 8th mile was a 8.8 @ 81mph which is like a stop light to stop light. But if your only going for stop light speeds get some 4.11's and an even bigger cam. I ran last year on steet tires so my 60' times are prety bad. the idle sounds great with the Xe268. I think my car in the 1/4 mile would run 13.30 round there on street tires. If it isnt going to be driven much go for the Xe274 I'd say.

good luck with what u decide I dont think you can go wrong with the parts you have in mind.

The XE274 and Edelbrock RPM heads are a great match. That's what I run in my 383. What compression?

I bought the speedpro hyperectectic pistons. They are the 9.5.1. My block has been decked .010 and its .020 over. I also have the summit rebuild felpro kit so im not sure what size the head gaskets are. What compression will it end up?

an xe274 is like 230/236 @.050 isn't it? i would go with the xe268 with your convertor. if you had 400-500rpms more of stall i would say the xe274. i think that either head would work great, the Edlebrock's are a little cheaper i believe.

definately the 268. I had a 2500 stall behind my 350 with a xe274 and my best 60' was 2.12 with a 3000 stall it was 1.8

The engine doesn't even come alive until 3000-3500.

I have built many an engine with the XE274s and XE268s with great performance from both. I really don't think there is enough information here to make a for sure recommendation.

First, you might want to figure how much SCR and especially DCR you really have and that might make things a no brainer for you if it's too high. Get the quench right too. Start with the basic math first.

Next, a 2400 stall for the XE274 is enough unless you are pushing a 5000lb car or have extremely large diameter tires. I used 2400 stall on all my XE274 automatics.

Next, the low end is great but better on a 268. The difference in hp and torque between the two will depend on the DCR.

If you have your 353 already built and parts bought ignore my next statement. If you want torque rebuild a 383. It's a wash these days if your starting from scratch.

One other point. The 750 will be sloppy down low compared to an Eldo 600 or Road Demon 625. Since you are wanting low end throttle response I just thought I would mention this. Also, definitely a dual plain intake. ;)

There isn't that big of a differance in the two cams. The bigger might get you 5-10 more hp at 6000rpm but you might loos 10-15hp under 3200rpm. I'm running the 268 in my 72 Nova with a 355 and throughing down constant 13.2's. My 2500 stall is perfect in the TH-350. Whatever cam you get, ditch the 750. You'll kill your low end. I was running one for about a year, then got a 650dp. My 60' dropped and the engine responded way better than with the 750. You should put down around 13.75 in the quarter in your Chevelle, which is nice for a car that you could daily drive.
Just to let you know, I'm running 3.90 gears and 255/60/15 T/A's and still getting 14.1's, 13.2's with 26/9/15 slicks.

with a 2400 convertor, definately use a 650dp. you need around a 28-3200 stall typically, to run a 750dp in a chevelle with your set up. i had the Lunati 292/.480/230@.050 cam in my 355, with 4.10 gears and an 800dp it ran 8.50's with 1.76 60ft times. but i had a 3000 stall. with a 2200 stall it would only 60ft high 1.90's, also with a 3310 carb. i put the 10" 3000 stall in it and it picked it up to a 1.80 60ft. then i swapped the dp on and it picked up another 4 hundreths. the XE274 appears to be even bigger than the cam i had so i still recommend the xe268 with that stall.

We ended up putting the xe274 in my sons 81 p/u 355,th350,4.11's @ 3860lbs with him in it, it ran a traction challenged(2.13 60ft) 13.89 @ 95mph.

Well, im even more confused now! Both cams seem good. My other chevelle has the xe262 with small chambered heads and runs stock converter with tons of torque and after 2nd gear theres not much left. I wanted something that will come off the line hard but really hit hard from 1-2 and 2-3. i also wanted a nice lope but dont want to sacrifice low end for it.

Blaster,
I'll give my 2 cents too. I ran my 13.0 sec and 103 mph with the XE268, AFR heads, 3000 rpm converter and 373's. I agree with others about needing the slightly higher stall and dual plane (i ran the perf RPM) with the XE268.
If in doubt between the two cams, i'd pick the smaller one. You'll enjoy more low end at the expense of very little loss on the high end.
Good luck

The xe274 seems to have plenty of low end,my son can't hook it up and gets a mean 2nd while racing smile.gif and it sounds great too,a little meaner sounding than the Lunati BM II that we just replaced.

What heads is he running and compression?

Vortec heads,flat tops with 4 valve reliefs, right at 10-1 comp.ratio

As long as the edelbrock rpm heads run like the vortecs then the xe274 will be perfect.

Originally posted by knudsonm:
definately the 268. I had a 2500 stall behind my 350 with a xe274 and my best 60' was 2.12 with a 3000 stall it was 1.8

The engine doesn't even come alive until 3000-3500. I have gone through the same thing.

Sure the 2400 stall speed will work.But your 60ft performance will suffer.Trust me, the 60ft is not where you want to compromise performance with a heavy car.

Lonnie67 has a great performing combo with those RPM heads and the XE274,but it is on a 383.
There is a big difference in the low end torque production between a 350 and a 383.The 383 makes a lot more low end torque so you can get away with less converter.

From the sound of it you will end up with a compression of 9.5-10:1 when it is all said and done.That's another reason to go with the smaller XE268 cam.

If you are only going to use a 2400 converter then I would stick to a 650DP.

My sons best 60ft. time was 2.13 on true radial street tires, the truck has plenty of low end for a 355. It is not a dog out of the hole,he'd be running mid/low 13's easily if we could figure out how to hook a truck.

Would it be best then if i ran a slightly higher stall or just stuck with the 2400 stall and went with the xe268?

70 chevelle
xe274 cam in a SB408ci
trickflow G2 heads
C/R 10.0:1
dual plane
750 vacsec.
stock crank,PM rods, hyper pistons
TH350 w/9" 3000rpm TC
3.73 stock posi 12 bolt
4000 lbs with me in it.
shift at 5500-5600
1/4 = 13.01 w/9" slicks in UTAH (4500 elev.)
drive the car regularly on the street as well

Originally posted by blaster:

Its my #2 chevelle so it wont be driven much and when it is i want it too be fun. Im looking for good bottom with gobs of torque. I may take it to the track but i want it to be a rocket from light to light on the street. Either cam would be a rocket from ligh to light with slightly more converter.The 274 is going to have more top end by design.

If you end up with a TRUE 10:1 COMPRESSION,
not 9.7:1 or around there, either cam would be fine.With lower compression you should use the smaller cam.
Base the choice off the compression.
It is the key to good performance.
It is also the difference between :D and :(

To be a rocket from light to light...
XE268 and a 3000 stall speed.

The XE274 is best used with a 10inch converter with a 3500 stall speed.

Like I said you can use a lower stall speed with either cam,but the 60ft will suffer
And remember,it is 60ft that makes a big difference from light to light.

i agree with thrasher 100%. graemlins/thumbsup.gif

I ran my 383 in my Chevelle also. Stock converter and 2.73 gears. 13.33 @ 107mph. Car weighed 3635 with me. Timeslip here: http://geocities.com/lonnie67_1966/white.html That timeslip is with the xe274 and slightly less compression than now at 9.45 with .058 quench. Perfect traction.

I also ran it with a xe268 cam, best was 2.07 60ft 13.36 @ 104 mph. Also perfect traction. My stock converter stalled at 1900. With more stall 2400+, the ET differences would be a lot more, IMO. Favoring the 274 cam.

I took the car to the track several times during the year with both cams. The 274 really woke up the 383 with the Edelbrock heads mid and topend. I can't say if it would gain 3mph with any other head. I ran 1.6 rockers with both cams. The 274 is the third cam I had in my 383.

Yes, I have a 383, but you have 2400 stall and 3.73 gears. I also agree that a 650 Holley will be better for you.

If you are just going to run regular street tires, they will just go up in smoke on the street anyway. More so with the 268 cam. More than 2500 stall will make the problem worse and will not launch as good on the street.

If you go with the xe268 cam consider this: My buddy in a 79 Z28 swapped from the HE268 to the XE268 and lost .1 and almost 1 mph at the track in his 350.

Ditto making sure your compression matches the cam you pick..

IMHO, above 270, you need 10 to 1 and up!

Below 270, 10 to 1 and down will work!!

That's why the good old 268HE runs so good in the milder CR. motors such as at 9.5 to 9.75CR. and a 280 needs at least 10.25 on up to 11 to 1 to really do it's best.

THIS to me, is what the cam people try to tell us when they say you need a bigger stall, which really means more rpm OR CR.!!!

pdq67

Whats the difference between a XE268 and a 268HE?

You dont want the HE line of cams unless yer racing mini-vans.
the HE268 is 218/218 @.50 your geting this cam confused with the Xtreme Energy XE268 which is 224/230 @.50 rpm range 1600-5800
the XE274 is 230/236 @.50 rpm 1800-6000

Xtreme Energy is also a dual pattern.

I used to run a 222/222 @.50 made by Speed Pro Federul mogul that worked great plenty of torque and used a stock stall and 2.73's and could burn out off the line lightly. That was with 882 heads and stock intake and a small carb. I think it was an all torque engine by mistake was the 1st engine I put together.

anyway im using a 3,200 stall and that cam and on street tires they stop spining when you want them to. :D

Since alot of you can figure how much my compression would be quickly, can i just give you what i know and let you figure it?
crate 350 4 bolt main
block decked .010
bored .020
stock rods
9:5:1 speedpro flattops
edelbrock rpm heads 64cc
felpro gasket from summit rebuild kit(i can buy another if needed)

Still need the piston number and the deck height with piston installed.
Without these it's still prety much a guess.

I liked xe274h too.
i had it in my:
-327 .03"
-performer intake.
-performer 600.
-#291 with my own port job 1.94/1.5.
-shorty headers + 2.25" dual + flowmaster 40.
-4-speed manual.
-3.36 gears.
-10.5 compression (polished comp. champers & piston tops.)

now im building:
-388.
-weiand x-celerator 7547
-performer 600 (smoothed venturi area + choketower cutted.)
-#291 heads with 2.02/1.6 and little more port job & comp chamber modified to high swirl.
-cr 10.3 quench 0.035"

exchaust is the same.. my goal is to go high 12 1/4mile.
impossible?

Blaster- I'd put the pistons in and assemble the bottom end and then figure out what CR you will have then choose your cam. You put the cam and intake on last anyway. graemlins/thumbsup.gif

The pistons i have are 9.73.1 not 9.5.1. so i imagine i will be around 10.1 Once i get it together how will i tell what my C.R. is?