help with my cam specs. I need more low end torq.

[ian75c10]

So the PO of my truck gave me some cam specs and I am not so sure how to read them. I have always felt that the truck is a dog in the streets. I have a 75 c10 SWB with a 327 from a 67 camero. Headers and camel hump heads. built 700r4 and 4.10 gears on 30" tires. at 80 mph it runs about 2650 rpm. The cam specs I got are ( comp cam 277/282, 470 lift at 50 ). Can someone break those numbers down and explain them to me. I would love some better suggestions for a cam to put in my truck. thank so much guys.

[ian75c10]

UPDATE, there is a lazer cam for sale near me for $50. The specs are >>>>>>   Dur. adv .006 int.  & exh is 276 deg.
Intake & Exhaust are the same on everything- duration Aaron  @. 050 TL is 224 deg., Lobe lift is.291, Gross lift is .436?.
Lobe separation is 108 deg.
What do you all think about thee specs working with my 327?

[BADAZ chevy guy]

277 is the Duration in crank degrees for the intake lobes and 282 is the Duration in crank degrees for the exhaust lobes @ .050 lift.
Check this chart. Your cam is second from the bottom. As far as I can tell.
http://www.compcams.com/catalog/COMP2012/pdf/COMP_Catalog_2012_266.pdf

[ian75c10]

Great thanks so much. i am not knowledgeable with cam specs but very much wanting to learn. What are you thoughts on this cam?

[BADAZ chevy guy]

Trying to explain cam specs here isn't the best option. Here's a couple of vids that explain it better than I can.

https://www.youtube.com/watch?v=HrtQVhcTPFc
https://www.youtube.com/watch?v=-iKV3CkfEXQ
https://www.youtube.com/watch?v=4lAL40Q9mQU

[rich weyand]

Read this, too.
http://www.crankshaftcoalition.com/wiki/How_to_choose_a_camshaft

That cam is open about 15-20* too long for torque at lower rpms.  Lots of horsepower up top, but it's not a good street cam.  And that much lift will beat up the valvetrain earlier than a more modest lift.

Those heads have 64cc combustion chambers, with 1.95 intake and 1.60 exhaust valves, so the compression ratio on a 327 should be about 10.5:1, and those larger exhaust valves (most 327/350 are 1.50) will breathe really well.

I ran that combination through Comp Cams' calculator, and you have a lot of choices.  12-234-2 looks nice, with 350+ hp at 5000 and 420 lbft of torque at 2500.  The torque curve is almost flat from 2000-4000 rpm, so that will drive really sweet.

You can download the calculator here, and then try out different stuff yourself:
http://www.compcams.com/downloads/register.asp

[HAULIN IT]

Im going to start with...if much of those specs are correct, the cam isn't near as big as most here are thinking it is, but with that I'm going to say: "Your numbers have some flaws in the way you posted them which leaves some guessing as to what you really have"
I suspect the "277-282" are supposed to be Advertised Duration numbers...not @.050.  The .470 is the lift @ the valve, the "lift at 50" you mentioned doesn't belong here. A cam with 277 @ .050 like BADAZ noted is VERY radical & is not going to be in an "average" small block Chevy. Also a 277 @ .050 can't have .470 lift due to lobe design...there are some basic proportions that as duration increases, the lift must also to some degree...there is quite some room for variations, but not as much as 277 @ .050 & .470 lift.
I spent a few moments on Comp's website hoping to find the cam I'm expecting you have without any success. I'm thinking you have a number or Two incorrect. Many of Comp's "normal" cams are Straight grinds...as in both in. & ex. are the same number. 270-270 with .470 lift for example. Typically the ones that are split...have more split, are usually basic numbers & they like a 5-10 split: 265-270 or 270-280. Not saying it HAS to be, just what I see them doing in most cases without a special grind.
Now on to the whole Advertised vs. .050 numbers.  A cam with a 270 advertised is going to have a mid 220 number @.050
I question if this may be the cam you have & should be a fairly nice match to the engine you describe:  http://www.jegs.com/i/COMP-Cams/249/12-211-2/10002/-1?parentProductId=#moreDetails My Two Cents with the info provided. Lorne

[rich weyand]

HAULIN IT, I agree with your analysis that his cam numbers don't jive.  If he has the 12-211-2 as you suspect, that should be good for 360 hp at 5500, and 400 lbft from about 2500 to 4500 rpm.  The actual torque peak is at 4000 rpm, but that's a little misleading because it is pretty flat in that range.

Another 20-30 lbft or so is easy, giving up maybe 10-20 hp up top, but that is already a pretty strong torque curve.  400 lbft is nothing to sneeze at out of an SBC.  Having the torque curve come on about 500 rpm lower would help.

If he really wants to go for it, the best numbers I can get are with the 12-230-2 cam, giving 340 hp @5000 and 428 lbft @2500.  That's with a .432/.444 lift.  An alternate is 12-300-4, which gives the highest torque number at 432 lbft at 2500 -- it's already above 400 lbft at 2000 rpm -- but drops to 320 hp at 4500 rpm.  The drop in horsepower is because of the lower rpm peak.  You run off the top of the cam above 5000 rpm.  It is a .390/.390 lift, which takes it pretty easy on the valvetrain.  I have this cam (with the stock heads on a 350), and it's great for street stuff, but it won't wind as tight when passing.  I went one size bigger flyweight on one side of the transmission governor to pull the shift rpm down a bit to match the cam, which solves the passing problem, since you are upshifting right into the middle of that beefy torque curve.  I have an extra one of the heavier flyweights around if ian75c10 wants to go that route.

[ian75c10]

Thank you guys so much for all of this info. It really sucks not being given exact info on my cam from the PO. I think you may be right about the cam I have HAULIN IT. It almost has no lope at idle but I did have the mechanic that did my trans say he could hear that it had a cam of some sort. Like I mentioned I have 4.1o gears but i do have an extra rear end with 3.42 for the truck. i have been very tempted to have that put in and see if it helps my milage at all. OR I wait it out a few more weeks until I can afford that true track posi with 3.73. Which is what I really want. Are there any numbers on my cam that if I really had to know I could pull it and see what exactly I have? how does one go about finding out exactly what cam they have if they don't know. Thanks so much again guys I am really happy to be working this problem out.

[Engineer]

Smaller cu/in engines are much more finicky when it comes to cam selection. Your loss of low end torque is also magnified by putting it in a heavy truck. Taller gears only add to the problem.

OP- The advice you have received so far is good advice, but I never like to give anyone recommendations especially over the Internet. I have been building engines for 30 years and I am still learning.

If there is one thing I have learned is that 75% of home built engines are over cammed.

If you are wanting the max out of your engine look at adding 1.6 ratio rocker arms to a shorter duration cam. But be aware that 1.6 ratio rockers require that you clearance the push rods, and the valve springs will need to be checked for binding.

And yes, the manufacturer should have engraved the grind number on the back of your cam. If there is no grind number degreeing the cam is the 100% accurate way of knowing what you have.

[rich weyand]

... It almost has no lope at idle....

Note that a lope at idle means the engine doesn't really like to run there, it wants rpms.  That is, an engine built for horsepower at high rpms will lope at idle, because it isn't really happy at low rpms.  An engine built for torque at lower rpms will idle smooth as glass.  If the torque comes on like gangbusters between 1500-2000 rpm, the engine will be very happy at a 700 rpm idle.

You race horsepower, but you drive torque.  People think they want that lope in a high-performance car, but that's because that's how a race car sounds.  Makes a miserable street driver though.