KMatch

Sigh... I see cams talked about all the time, yet don't see enough addressed to satisfy my poorboy approach of buying one and sticking to it. I don't have a baseline as the 65 I'm building I have a total of 50 ft of driving experience in it with a 6 cyl (from his garage to my trailer, from my trailer to teardown), and now it's a ground up resto project going together with a roller 302, home ported GT40 heads, Hyper U-s in a stock bore, 570 Street Avenger, Eddy or Weiand dual plane intake, aod (25-2800 stall likely), 3.73 8.8 rear, long tube headers feeding Magnaflows probably with no crossover, and 4 wheel manual disks (for now, unless I hate the manuals). A good lope is nice and high on my preferred list, yet I don't want to kill the bottom end. This car won't see a track unless I drive by one, I just want something to impress ME on the highway and light to light.

Cams I've been kicking around in desktop dyno (not TOTALLY useless, I feel the curves, although ridiculously high, seem accurate otherwise): Comp XE266Hr, XE274HR, B303, XE264Hr, TFS 1.

The B303 has a nice healthy idle, but with totally different specs than the XE266HR (my highest pic so far), but the curves according to (ahem) ddyno are real close with the B303 giving away VERY little in low end and making up for it at 5500-6000 plus the 303 looks like it would be easier on the valve train.

So, for the moment, I'm at a tossup between the b303 and 266, but who can shed some light on one versus the other? And to keep me from going blind on inputting specs, how about we stay close to the list onhand unless you've discovered some magic in another brand? One other smallish request! Feel free to chant any 303 rants you want - just do me the favor of backing it up with some useful information so we might all get something out of it without wasting bandwidth.

kalli

desktop dyno is a good piece of software when you're interested to see how different cams change the curves. I decided on mine using the same software and the advise I got here on the forum.

Anyway, how high of a rev do you trust the bottom end? no point having a cam that peaks HP at 6500 when the engine will fall apart at 6 grand.

MBDiagMan

kalli is offering some really good wisdom here. Make sure the engine is good for high rev's if you're going to cam it up.

You gave a really good write up of the car, but didn't say how you will be using it. If just a moderate street car, the XE266 sounds pretty good.

Kotobuki

I don't have the curves you're looking at, but if you're looking for something to have fun with on the street, and don't plan on taking it to the track I, personally, would go with whatever gives you the fattest torque curve. On the street you're going to feel the torque down low getting you off the line more than you'd feel the extra couple ponies while wringing it out at the redline. This is, of course, assuming you plan on shutting it down at a reasonable point on the public roads.

KMatch

6000 tops is my intended goal and my goals change with my mood, so I'm looking at the closest to "one size fits all" performance wise with 6k being the limit in rpms. Bottom end is fresh. Both the b303 and 274 just start to nose over here and the 266 is a bit further on the downward slope at 6k. The XE266Hr keeps coming out on top of my research, but I just haven't ruled the others out, yet. Of course, the b303 can be had for quite a bit less... That doesn't help matters.

stephen.osborne1

I believe the B303 is made specifically for the GT40 heads you are running. I would go with whatever will last longest (easiest on the valve train) as you said you are not racing. The difference in top end power is probably not overly noticeable on the street.

KMatch

OK, I'm down to the B303 versus the XE266Hr. The power graphs are nearly identical. I find this odd since one is more of a duration cam and the other is more of a high lift cam, I'd have figured even with similar power, the power band would be shifted around at the least. Anyway, if the graphs are even close to accurate, it appears the B303 a better choice even if it's stoneage technology - lower price, easier on the valvetrain, similar although longer powerband, stock springs are "doable"... It just gives me more of an impression of a rush job with matching intake and exhaust events while the compcams versions (and nearly everybody else, for that matter) all seem to tune intake and exhaust events separately. Does anyone have any off-idle (stomp it from a dead stop) performance issues with either?

KMatch

Well, this discussion died... I'm still looking for any feedback. How about another cam in the mix? I've since tossed the F303 into the mix and like what I see in it as well. I'm having a hard time believing DDyno shows the XE266Hr, B303 and F303 almost identical in every way up to 5K. Who has real world experience with ANY of these? Likes? Dislikes? Idle lope versus poor low end response? The F cam looks like it would still be easy on the valvetrain with "only" .512 lift. Yep, it's "old" technology, but if old works just as well as new, why not? Feedback and opinions needed! I'm to the point of having my wife and daughter pick one. Don't let them make a bad choice!

Aussie66Fastback

LOL i cant contribute anything meaninful to the cam choice, but I'll provide another bump.

what color are the different cams? do they require accessorising? will you need to purchase new shoes to match the new cam? If in doubt go black

kalli

i never used a roller cam, so not either of those any experience.
However I can't really see off idle performance issues related to cam. off idle issues are either timing or carb.
only thing I could think off is that a cam that should idle at 900 runs at 500 making no vacuum whatsoever and just popping about opening the PV occasionally with the oscillating vacuum... then with any cam.