trailblazr81

So Ive narrowed my cam choices down to the 261c and 268. But I have a couple questions...

268C/T: I would suggest the 268C/T for best combo of econmy/power in the
midrange. It is 218° & .425" lift, 110° center.

261C: duration @.050" lobe lift, 222°. lift .410", has more
RPM portential..Perhaps 3-4 H/P less at peak but longer powerband.

Now from what Ive been reading the 261c cam has more duration, but better low end torque, a wider power band and a little less peak hp. While the 268 has less duration, a narrower power band, runs out of steam earlier, but gives a few more ponies.
If this is all true I think for my rebuilt motor I want to use the 261c with stock gears and 31's. I DD with some fun on the weekends and have a couple hills to deal with during my commute.

Matt16

Horsepower is way over rated. Its torque that matters. From what you say, the 261* will feel like it has more power. If you don't believe me, test drive a diesel vehicle. When was the last time you actually needed power at high rpm?

trailblazr81

Oh I understand the importance of torque. I own a turbo diesel Chevy. I'm just kinda confused on why the 261 cam has more duration but better low end. More duration usually means more high RPM HP. Ive played with a couple small block Chevy's from smooth idle cruisers to big cam choppy idle hot rod's. I think I need a cam card for both these cams.

Matt16

Oh, I see what you're saying. I'm out of my depth a little, but it might be that it has less lift and thus you maintain a little more back pressure to aid your torque. I really don't know what I'm talking about, but it is a possibility.

abecedarian

it's possible that in spite of the longer duration, the lesser lift may be increasing the intake velocity and tubulence in the chamber and giving more efficient combution at lower rpms. also plausible, and not evident from what you've stated is that the 261 cam may have slightly advanced lobe centers compared to the 268 which could result in the valve events occuring sooner and consequently would move the powerband lower.

Matt16

Listen to abecedarian, because he probably is a lot more informed than I am.

abecedarian

No! don't listen to me! I just like to throw out theories and postulations!
I'm here trying to help answer questions, not trying to answer them directly.

Team420

Well, what if ur just learning as much as possible...and still agree?

abecedarian

Don't agree with me?

just kidding.

Camshafts are one of the most secretive parts of engine tuning. And the 'standards' the cam makers have agreed on don't tell you everything a knowledgable person should know in order to make a decision, and what they do tell you is vague enough to raise questions such as the topic of this thread.

So that leaves people stuck with interpreting the opinions of other people that have purchased and used the cam.

For lack of a better analogy...
why not ask who has the best coffee?

Matt16

double post

Matt16

We have a donut shop called Tim Horton's (he was a hockey player who started a franchise, pretty Canadian eh?). They make great coffee. Unlike like the Starbucks crap, were there are a billion way to order a coffee, at Timmy's there are three sizes, Small, Medium, Large (vs tall, grande and some other stuck up names for sizes). Then you can have your coffee with extravagant options such as cream, sugar or double-double (2x cream, 2x sugar).

Yota82

edit- nevermind

n8hunt23

I can give you my personal experience with the 268 cam. Note that I also installed engnbldr's street rv head at the same time.

I chose the 268 cam because I has looking for stronger midrange and wanted more power while cruising on the highway. I run 31" tires with 4.56 gears and typical highway rpms for me are 3000-3500 (65-80 mph).

Compared to stock, bottom end (1000-2500 rpms) is better, midrange (2500-4500rpms) is about the same and top end (4500+rpms) is worse. There was no improvement pulling hills on the highway, I have tested it on a number of hills where I know exactly how the truck performed before and after. Up very steep grades on the highway it is worse than stock because once I downshift and my rpms are 4000+ the engine does not pull as hard. Peak torque feels about the same as stock and peak power is worse.

I have an adjustable cam gear so I have experimented with retarding the timing. This seems to take away from the bottom end without really improving
midrange while overrev is improved (but still worse than stock).

norcalsvx

i run the 261c (with other mods) and am very happy with it much faster than stock. (pulls well up top)

Tsquare

This is good info guys, I just ordered the 261 on Monday. I'll post up after I install this weekend....hopefully.