Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Opinions needed on intake and cam choice.

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by outlaw612, May 2, 2002.

  1. outlaw612

    outlaw612 1/2 ton status

    Joined:
    Feb 11, 2001
    Posts:
    2,342
    Likes Received:
    0
    Location:
    Springfield, Illinois
    Well, I decided Im gonna wait on the FI untill I get the 383 done. But I still need to do something for the stock 350 thats in the truck. It needs a little extra power. Im putting the headers on this weekend. I also want to change the cam and intake. What is recommended? Trying to stay on the cheap side.
    I was thinking Performer RPM and this cam:
    Duration @ .050 INT 224* EXH 234*
    Lift INT .465" EXH .488"

    Any opinions? I think this is what a friend of mine was running in his 3/4 ton, but not positive.
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,169
    Likes Received:
    1,372
    Location:
    E-town baby!
    It looks a little aggressive and will probably hurt low end a bit but make great mid range and decent top end. The manifold sounds good though.

    Rene
     
  3. outlaw612

    outlaw612 1/2 ton status

    Joined:
    Feb 11, 2001
    Posts:
    2,342
    Likes Received:
    0
    Location:
    Springfield, Illinois
    Would using a set of 1.6 rockers work good on the stock cam, or just get a different cam? Less aggressive as in lower lift and or duration?
    Maybe like a 214/224 duration and a .447/465 lift?
    Im not good at picking cams so if anyone has a suggestion...
     
  4. bigmack

    bigmack 1/2 ton status

    Joined:
    Jan 3, 2002
    Posts:
    478
    Likes Received:
    0
    Location:
    Tennessee
    I put a Crane Energizer cam in a 350 of mine 2-3 months ago it was .454 lift & 216 @ .050 duration. I also put a regular Edelbrock Performer intake on it. You can get the cam and lifters in a kit from people like Jegs for 99.99, I wish I could tell you what difference they made but at the same time I also put a better set of heads on. All of this really made the motor come alive, no more weak ass 165hp.
     
  5. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,169
    Likes Received:
    1,372
    Location:
    E-town baby!
    Lift is always a good thing, but too much duration hurts low end. Obviously that is way oversimplified but gives you a good idea. 212 to 218 or so duration is probably in the ballpark for a nice torquey cam. .440 to .475 or so would do nicely. For a snappy motor running a shorter duration cam with 1.6 rockers would be the ticket. Also a dual pattern cam really helps compensate for stock heads. Look at Comp Cams Extreme energy series of cams...they make great power without killing low end.

    Rene
     
  6. weisel

    weisel 1/2 ton status

    Joined:
    Feb 22, 2001
    Posts:
    491
    Likes Received:
    0
    Location:
    Laveen, AZ
    I forget who is running them, but I have heard a lot of good things about Comp's Extreme 4x4 cam. Don't know what the specs are on it though. This is what I will probably be doing to my 350 in a month. Anyone know the specs to this cam?
     
  7. Jay73K20

    Jay73K20 Registered Member

    Joined:
    Mar 4, 2002
    Posts:
    67
    Likes Received:
    0
    12-235-2
    210/218 @ .050
    .447/.462
    I love this cam:)
     
  8. BARRAZA

    BARRAZA 1/2 ton status

    Joined:
    Oct 17, 2001
    Posts:
    259
    Likes Received:
    2
    Location:
    USA
    If you are interested in some good cam selection information read these links. There are a lot of variables involved in picking a cam, but in general I would suggest going conservative. It is easy to get into trouble by sticking a cam with lots more duration into an essentially stock low compression motor in a heavy truck with not enough gear and big tires. If you have a later model roller cam compatible block, the cam that comes in the 383 chevy crate motor looks like a good choice: Duration @ .050" In196 Ex206, Lift In431 Ex451. Also, if you are going to build another motor, why not go a head and get some vortec heads now and the matching intake, then swap them over to the new motor when its done.

    http://www.chevytalk.org/forums/Forum64/HTML/006486.html
    http://victorylibrary.com/mopar/cam-tech-c.htm
    http://www.mercurycapri.com/technical/engine/cam/lca.html
     
  9. Donovan

    Donovan 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    524
    Likes Received:
    0
    Location:
    Arvada, CO
    I would not go with a Comp Cam because they are not made correctly. They have to much exhaust duration on them. When you exhaust it to much you are losing hp. I will say this again call Elgin Cams. <a target="_blank" href=http://www.elgincams.com>www.elgincams.com</a> The only real way to pick a cam is to flow the head, manifold and carb at the sametime. You get those numbers and send them to Elgin and they will pick the cam for you. I bet nobody on this board can pick a cam like Elgin can and I bet 90% of the cam companies can't get it as close as Elgin either. I will not get a cam from any other company again. We just built a 327 for my brothers 63 Nova and the cam that was in it was a Ultradyne and the specs was 266-266 with .442 lift on the intake and exhaust. The duration .050 was211 intake and exhaust. The new custom cam from Elgin 270/272 and the lift was .471on the intake and .453 on the exhaust. Now get this the duration at .050" is 224 and 218 on the exhaust. We will see how this cams works in the car. Call Elgin and even if you don't have flow figures I bet he can get you setup right. Talk to John.
     
  10. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,169
    Likes Received:
    1,372
    Location:
    E-town baby!
    I just put your cam spec's through the engine analyser I have here and did a heads up comparison with Comp Cams XE256H-10.

    Interesting results...the CC cam made on average 20 lbs/ft of torque more through 4000 rpm with a higher peak torque. hp numbers were within 4 hp. That was on a 9.5:1 355 with Vortech's. Oddly enough after scrolling through a couple hundred different cam choices I didn't see a single cam the had more duration on the intake side. Lot's of single pattern cams, but all the dual pattern cams had slightly more duration on the exhaust side. Dynamic compression with CC's cam ended up at 7.27:1. The cam you specced was 6.83:1.
    Idle vacuum, CC=17.2" Hg, your's was 15.8" Hg.

    Obviously this isn't real world and you left out the LSA in your spec's. I used 110 degrees...

    What heads are you running on the 327? what CR?

    Rene
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,977
    Likes Received:
    189
    Location:
    Roy WA
    Dual pattern (typically more duration on exhaust) cams are made to "get around" restrictive exhaust systems. I don't think there is anything to use EXCEPT dual pattern when running manifolds IMO. Even the factory runs more duration on the exhaust now that they have gotten out of the single pattern cam technology phase.

    I see Elgin isn't single pattern too, but just plugging numbers into desktop dyno in my config (350, vortecs, TPI, roller cam) my 204/214 .429/.452 cam makes more power than the Elgin 224/218 cam, but it isn't much.

    I would worry very much about low end torque when selecting a cam, and build from there. If its a lot of low speed/stop and go, and street/freeway running, a "small" cam will be better than a "big" cam for the most part...you'll just end up with more power on the bottom end, where you can use it.
     
  12. Donovan

    Donovan 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    524
    Likes Received:
    0
    Location:
    Arvada, CO
    What flow figures are you using in the desktop dyno program? That is very important info for me to know, and I will tell you why once I know.
     
  13. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,977
    Likes Received:
    189
    Location:
    Roy WA
    Well, heres what *I'm* using for the Vortecs:

    Vortec,64cc

    1 1.940000 (valve size)

    1 28.000000 (pressure drop in H2O)
    lift intake
    1 0.050000
    1 0.100000
    1 0.200000
    1 0.300000
    1 0.400000
    1 0.500000
    1 0.600000

    flow intake
    1 40.000000
    1 70.000000
    1 139.000000
    1 190.000000
    1 227.000000
    1 239.000000
    1 229.000000


    1 1.500000 (valve size)
    exhaust lift
    1 0.050000
    1 0.100000
    1 0.200000
    1 0.300000
    1 0.400000
    1 0.500000
    1 0.600000

    exhaust flow
    1 25.000000
    1 49.000000
    1 105.000000
    1 137.000000
    1 151.000000
    1 160.000000
    1 162.000000
     
  14. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,169
    Likes Received:
    1,372
    Location:
    E-town baby!
    Looks like Dorian and I spec'd out almost the exact same motor. So what heads are you running?

    Rene
     
  15. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,977
    Likes Received:
    189
    Location:
    Roy WA
    And heres what the dyno graph looks like:
    http://yeagerd.home.mindspring.com/TablePics/vortectpi350.jpg

    First, don't worry about the 700CFM. That or 500CFM made very little difference, didn't notice until I had already done the work to the screenshot that it was at 700.

    Second, I *know* that this isn't real world, but I believe that any of the dyno software out there is extremely valuable in testing combinations..it may not give you real world numbers, (although in some cases its very close) but the numbers it does come up with can be compared to results with other components.
     
  16. Z3PR

    Z3PR Banned

    Joined:
    Mar 30, 2002
    Posts:
    19,217
    Likes Received:
    0
    Location:
    Everywhere
    I've heard both good and bad about Comp Cams xtream 4x4 cams. I personally have always been happy with Comp cams.
     
  17. Donovan

    Donovan 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    524
    Likes Received:
    0
    Location:
    Arvada, CO
    Lets start off with the heads that we are using and they are the Vortec Heads with just a little bowl clean up and that is it. They are 1998 heads I believe. The flow figures that Dorian put up are for a Vortec head with no manifold or carb on it. We had the vortec head and a Edelbrock Performer manifold with a 650 carb and here is the numbers. These numbers was on a Superflow 600 @28

    Intake Exhaust
    .050 33 20
    .100 65 46
    .150 95 71
    .200 124 97
    .250 148 120
    .300 160 141
    .350 171 153
    .400 179 159
    .450 185 165
    .500 186 169
    .550 186 173
    .600 185 172

    As you can see you lose about 20% of your flow by installing the manifold and carb. Looking at the flow numbers at .400" lift, because that is where I like to look at flow numbers. Even know that your heads flow 227 cfm at .400" lift your engine will never see this because your intake and carb is limiting the flow to only 179 cfm. Looking at those number you will get an exhaust to intake ratio. The exhaust to intake ratio is 89%. Now according to SAE and Elgin you will need 75-80% exhaust to intake ratio. So looking at the cam you guys was taking about you are now going to over scavenge the cylinder because you now have to much exhaust duration. This is the reason he is building the exhaust with less lift and maybe less duration because he is try to get 75-80% exhaust to intake ratio. Now if we install a race type intake we will still lose 5% of the intake flow. So at .400" with the race type intake you will only be flowing around 215cfm. Now maybe you can see why I think that the cams are wrong. Also the cam that I told you that we got was a 327 and not a 350. He might have different specs for a 350 with the same numbers. The 327 that we have has 9.8-1 compression with rams horn exhaust and 2 1/4 exhaust. Me computer program said that this engine should make 340hp at 5200rpms. So tell me what you guys think?
     
  18. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,977
    Likes Received:
    189
    Location:
    Roy WA
    I would *guess* that the desktop dyno programs are compensating flow numbers based on intake/carb/exhaust selected.

    I could be incorrect on this, but if it was *not* compensated for, the final numbers would be way off, and they are not, especially for hydraulic flat tappet cams, when compared to 1/4 mile times/power needed to reach them. (guy going 12.5 in the 1/4 with a 385 TPI motor came out with almost exactly the same HP numbers on the computer dyno as using the calculations that figure out HP necessary to attain that time)
     
  19. Donovan

    Donovan 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    524
    Likes Received:
    0
    Location:
    Arvada, CO
    You guys with the desktop dyno run this one thru you program. Caddy 500 Engine
    Bore 4.375
    Stroke 4.4
    12.9 to 1 compression
    Intake valve size is 2.125 and the exhaust 1.84
    Single plane Victor Manifold with a 1050 Dominator
    Heads flow with the manifold and carb is 270 .550 lift intake and .550 on the exhaust it is 239
    The cam specs are 310/300 duration and 268 and 264 @.050 and the lift is .380 intake and .365 exhaust with 1.72 rocker and lash is .026
    If you need any more info let me know. This engine has been dyno on a engine dyno so we can see how close it is.
     
  20. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,169
    Likes Received:
    1,372
    Location:
    E-town baby!
    Well I had to guess at a couple of things because there was no choice for any Caddy motors in the menu's...

    Anyways...I got 686 lb/ft of torque @ 5000 RPM for peak torque. 692 hp @ 5500 rpm peak horsepower./forums/images/icons/cool.gif

    Rene
     

Share This Page