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Cam lift and duration

Discussion in 'Chevy Trucks' started by MTCK, Feb 24, 2002.

  1. MTCK

    MTCK Senior Member
    Messages: 346

    I have decided to put a different cam in my truck and am a big overwhelmed by my options. The motor has stock guts in it, and is just a 305 that I'm looking to get a little more poop out of since I don't see myself buying that 383 I'd love to have any time soon. It has an Edelbrock performer intake and carb, GM HEI ignition with no ESC, hedman hedders 4 to 1, and dual exhaust. Right now it's not bad, but I have read lots of places, that motors with the basic upgrades I've done can really wake up when you add a cam, and they are fairly inexpensive. In the next week or so I will be replacing the transmission, so I was thinking I'd just pull the motor at the same time, and put it on the stand, which would make the job pretty easy. OK, to the questions:

    I'm not looking for a tempremental race motor, just a little more poop, good low end still and maybe a bit more up top.

    How much lift can I go with and not have problems with the stock valvetrain, such as rocker arms and springs.

    Some of the cams have a little more duration on the exhaust lobe than the intake, what's the advantage of this?

    Basically, if some of you guys had the specs of the cams you've put in, and how you like them, don't like them, ect, that'd be great.

    Thanks,
    Marcus
     
  2. Alan

    Alan PlowSite.com Addict
    Messages: 1,393

    I'd tuck an Edelbrock Performer cam in there. The cam and manifold are optimized to work together, at least according to Edelbrock propaganda. I put the big block version in a low compression 396 and the low end was awesome.
     
  3. OBRYANMAINT

    OBRYANMAINT PlowSite.com Veteran
    from ohio
    Messages: 534

    i agree with alan on matching up with the intake.........when i redid the top end of a 305 in a blazer i put in an "rv or towing " cam as it was called and then put some bigger bore heads on it.....with the slightly bigger cam and better "breathing" through the head it ran exceptionally well..........with soo many options with reguards to the top end you could go crazy trying to get the ideal match
     
  4. John DiMartino

    John DiMartino PlowSite.com Veteran
    Messages: 2,154

    I agree on the edelbrock performer cam.I must tell you though,when i used to hotrod gas SB chevys,i had great luck with Competition cams,i put a 252H in a tow truck with a 350,man did it run good,power everywhere,it had the performer intake,and a tuned Qjet,2 1/2" dual exhaust.I ran a 280H inmy Toyota landcruiser's 350,it is to much for an auto,but that thing ran.I have not looked at cam specs in a while,but I remember that the intake duration shouldn't be any more than 206degrees@.050 lift,for low end,and good driveability.
     
  5. MTCK

    MTCK Senior Member
    Messages: 346

    Thanks guys. The Edelbrock Performer for SB chevy has 204 degrees duration intake and 214 exhaust (@ .050") and .420" and 442" lift respectively. Comp cams sells a cam with .206 214 duration and .432 .453 lift "designed just for my truck." Price is comparable. What will I see with more lift, and do you think I'll see any problems with my valvetrain with this small difference? Those of you who swapped cams, did you leave the rest of the rocker ratios and valve springs alone when you did it? Appreciate the expertise.

    Marcus
     
  6. reallyrusty

    reallyrusty Member
    Messages: 71

    Go to www.amotion.com. They have a great site to explain camshafts. You also need to consider lobe center separation. This site does explain it all. Hope this helps
     
  7. John DiMartino

    John DiMartino PlowSite.com Veteran
    Messages: 2,154

    If your valvetrain is in good condition,you should be able to leave it stock.If you were running a larger cam,with a power range into the 6000+RPm range,yopu would want to use scew in rocker studs,moly pushrods,stiffer springs.You shouldnt need them with your lift,and rpm range,save your money for other things.If however your springs/rockers have 100+K on them,you might want to upgrade them at this time.