Recommend me a camshaft

SadbutTrue

Founding Member
May 1, 2002
2,390
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49
Granada Hills, California
Rest of combo as follows: 351w, ~9-9.5:1, Weiand Stealth, Trick Flow TW heads, Heddman headers/2.5" exhaust, 650-700 cfm Holley based carb (street avenger or demon, I think... though I might give mechanical secondaries a shot). I plan to make power to about 6,000 rpm, but I also want the cam to have decent street manners.

I have my eyes on the compcams xe268h, which specs out as follows:

Advertised Intake Duration: 268
Advertised Exhaust Duration: 280
Duration at 050 inch Lift: 224 int./230 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.510 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.512 in.
LSA: 110
RPM range 1600-5800

Compcams recommended that and the xe262H, which looks like:
Advertised Intake Duration: 262
Advertised Exhaust Duration: 270
Duration at 050 inch Lift: 218 int./224 exh
Intake Valve Lift with Factory Rocker Arm Ratio: 0.513 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.520 in.
Lobe Separation (degrees): 110
RPM range 1400-5600

(strangely, summit seems to list another xe262h-10, with the same duration specs but .493/.500 i/e lift, basically the same rpm range).

The maximum lift the springs can handle is .540, which both of these cams clear, but both get pretty close to that limit if I were to mill .020 off the bottom of the heads (and I wanted to mill a bit more than that).

I know Lunati and Crane have similar grinds. Was wondering if anyone had a cam that woudl work better for me than the 268 and why?
 
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IME there is no real gain with an XE262 over an XE256, which is why the XE256 has become my personal favorite for an all-purpose 289/302 cam, as far as Comp goes, and the best part is, it never seems to leave a whole lot of HP as untapped potential.

The new Lunati Voodoo's are probably my overall favorites though, they seem to result in a better driving car than a Comp XE and make a hair more power.

All said and done, I'd probably go with a Lunati 61001
HTH
 
IME there is no real gain with an XE262 over an XE256, which is why the XE256 has become my personal favorite for an all-purpose 289/302 cam, as far as Comp goes, and the best part is, it never seems to leave a whole lot of HP as untapped potential.

The new Lunati Voodoo's are probably my overall favorites though, they seem to result in a better driving car than a Comp XE and make a hair more power.

All said and done, I'd probably go with a Lunati 61001
HTH

I looked on summit for a 'Lunati 61001' but didn't see it. i checked the Lunati line and didn't see any part numbers with 61001 in them. Link?

Is there a rule of thumb for how LSA and required compression ratios work?
 
LSA: Not one that I know. Of course, you know that the smaller the LSA, the more overlap you will have. Low compression and too much overlap don't mix well. You had two cams listed and both have 110 degrees of overlap, which is a good number for a 351. The smaller cam will just make better dynamic compression with that LSA.

If you were to start with more compression, you could afford to bleed off a bit with the larger cam and performance would improve. With low compression, you may not see any difference between the two, and it may get a little lazy. I'm probably overstating the case here, though, as neither cam is all that big. I really like the bigger can if you shave the heads.
 
LSA: Not one that I know. Of course, you know that the smaller the LSA, the more overlap you will have. Low compression and too much overlap don't mix well. You had two cams listed and both have 110 degrees of overlap, which is a good number for a 351. The smaller cam will just make better dynamic compression with that LSA.

If you were to start with more compression, you could afford to bleed off a bit with the larger cam and performance would improve. With low compression, you may not see any difference between the two, and it may get a little lazy. I'm probably overstating the case here, though, as neither cam is all that big. I really like the bigger can if you shave the heads.

I am planning on shaving the heads. Even if I do shave the heads, unless the pistons in my 351w aren't the type that came with that year block (possible), the maximum I'll probably see is about 9.5:1. If I don't mill the heads, and its got stock 72 compression, its probably about 8.8ish:1. :( :nonono:

So in general if I find a cam with similar specs but with a 112 or 114 LSA, it might work a little better?
 
Yes, the wider the LSA, the less overlap and more dynamic compression.
Don't get me wrong, overlap can be a good thing for cylinder filling, it just requires more static compression in order to produce good dynamic compression.
 
I will start by saying I am not an expert, but I am well read. I don't think that running wide lsa is good for a motor like your's. N/A motors tend to like them on the narrow side. Most cams are ground for 302ci motors and a 351 might like a little less lsa, like 108. A Vizard article I read said lsa is set first and that duration is then picked to get the right overlap.
 
Wide LSA's work great with carbs. I'm running the F4TE roller with a carb and it runs exactly like EFI. Power is from idle to 6000. Running the Z303 with carbs. Same story but power is from 1500 to 7000. The only thing a narrower LSA will do is trash the fuel mileage.
 
even with 9-5 compression I would still run the 262 cam, I ran a comp 268h cam in a 351w, ported 69 heads, performer and a 670 holley tbi in my 67 vert and it hauled ass and it got 19 mpgs consistantly with a c4 and 3.00 gears.

I would definetly stick with 110 lca, after that I switched to a hyd roller with 4 degs less duration int but 2 degs more ex and a ton more lift, 112 lca and TW heads, there wasnt alot of differnce.

The xe 268 will give some more upper rpm power but may kill some low end and idle quality and vacuum will suffer as well as economy.

On a street driven 351w I would keep int duration between 218 and 224 @0.50 and you should be happy.

As for a carb I would run a 650 speed demon with annular venturis, if you have steep gears/3000 converter or man trans run mech secondaries other wise run a vac secondary carb and tune the secondary spring.

The comp cams 270 magnum cam is a great compromise, great streetability but just on the edge.

my vert http://htwheelz.smugmug.com
 
Compcams just recommended the 274XE, for reference. The 268 would be a good compromise in general.

I'm okay with more high end than low end... my tranny doesn't need any off idle torque than necessary.

Any competing companies grind #s that I should look at?
 
Any reason not to look at a custom grind? Maybe something from camshaft innovations, or similar?


Cost and my combo not having any real 'special needs'? If I was running a less common or more radical application a custom cam might be more appropriate, but mine is a pretty run-of-the-mill performance build.

Of course, i've never really seen a dyno showing how much difference a custom grind will make over a well-matched mass-produced grind...

My only concern with the 274 is whether it'll be okay at 1800-2200 rpm on the freeway (where my car spends most of its time). If its reasonably happy and gets decent economy at those engine speeds, i'm sure it'll work.

If not, the 268 should be okay.

Still wondering about competing grinds though, for you Crane and Lunati fans...
 
Well, for giggles, why not talk to the master over on s b f techdot com. Or, just do a search on Jay Allen camshafts.

Had I known in the beginning what I now know about valve train and related components, a custom is the only way to go!
 
Well, for giggles, why not talk to the master over on s b f techdot com. Or, just do a search on Jay Allen camshafts.

Had I known in the beginning what I now know about valve train and related components, a custom is the only way to go!

But have you actually run an off the shelf grind,(chosen thru an intelligent process, not something picked "off the wall" with no regard to what your combo was and what you expected it to do) then swapped in a custom cam with no other changes? If you did, how close were the two cam's specs?
 
A properly designed custom cam on average will give approx 30 hp/tq, more low end,smoother idle, better vacuum and better bsfc than a larger off the shelf cam. A custom cam may just be an off the shelf cam with a different LCA or it may be picking int/ex profiles from off the shelf grinds. If you choose to go with a custom cam guru like CI or alike and you give your exact combo(even mismatched combo), usage, expectations etc... you will find you will get a cam usually with 8-10 degrees less duration than what you thought you needed and will make as much or more power than the bigger cam but with much more drivability.

on the other end a custom race cam will do the same but really shine on the top end.

I have built many engines, and basically for a street driver "less is more" if you match the components properly and drivability is way better.

My custom cam on my 408 with 205cc TW cnc ported heads is 231 242 578 576 with a 113.8 lca because I will be efi'd at some point, it pulls 14hg vac at idle, will idle at 750-800, has unreal low end TQ even with 3.00 gears I havent been to the dyno yet but FWHP will be way over 500 and my last cruise on the fwy was 18.2 mpg's with 600 miles on it. bUt racing around......maybe 8 mpg's.

my vert http://htwheelz.smugmug.com
 
While I've never had the opportunity to dyno it, my 331's street manners and track performance is stellar with an off the shelf Ford Z303 cam. Plenty of vacuum for power brakes (when I had it in the 89 Ranger) Fuel mileage was 16 highway running 65 mph with no overdrive (2687 rpms @60 mph) I've no doubt it would have pulled down 20 mpg with an overdrive transmission. 1/4 mile with 2+ sec. 60' times was 13.7 @ 103 in the 3800 lb Ranger. So far it's done 13.1@ 106 in the Comet, with a C-4 auto and nearly the same final drive ratio with about 6-8 passes in 3 trips to the track.(and still with those same 2+ sec. 60' times;) ) This is all with a 10.4 to 1 comp ratio, Canfield 1.94 valved heads, no porting, and the thriple duece carb setup. I run em the same on the street as on the track, never took the money to invest in better tires. There's no way you could sell me on a custom cam over a properly picked off the shelf grind. I've learned much of the improved driveability comes from picking a cam with a wider LSA, it works just as well with EFI or carbs. Your custom cam designer has found the same thing works. ;)
 
I have 'cams' in two of my cars.
When I bought the cam for my 69 Coug, is was part of a package parts deal. Apparently another guy had bought these parts (cam&lifters, intake and timing gear set) and couldn't get them to 'fit' in the engine. I got all the parts for less than the cost of the intake. It was a comp cams 'extreme' 519/524 (as I recall from Germany..)
I swapped out the parts, and didn't like the way it worked at all! When I bought it all, I told the guy I didn't want to have to change the gears or torque converter. "No problem, don't worry, you're gonna love it!"
After a 3500 stall TC, and 3.89's in the rear, it's a real hoot around town, no more freeway driving until I rebuid the heads. It goes thru a quart on the interstate in less than a hundred miles.
My other car, my 68 4sp, has an Edelbrock cam. 496/520 specs. (see the how wicked is your cam thread.)
I have had a massive learning curve with that motor! I've been thru two sets of roller rockers, and am on my third set of pushrods. Two complete head 'rebuilds'. (Thanks MR. Machine shop "Subject matter expert").

I bought all my new parts thru summit.
For the money with my gray car, I could have had a custom cam, and new aluminum heads with all I now have invested in the stock cast irons, with all the other parts as well.
My 69 351W however, with 'more cam', has all stock rockers, springs and push rods, and hasn't broken anything!
I have one more cam in a box, waiting for my next 289 project, and after that, customs only!

For the money, you get so much more than just a stick.