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Vortec Heads, TBI and Intake, What Cam?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by zcarczar, Dec 10, 2002.

  1. zcarczar

    zcarczar 1/2 ton status

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    I sent Comp Cams the nifty little cam form they had on their site and they recommended me this cam Link. I was also looking at LT1 cams because the guys over at www.thirdgen.org said they would make a good truck cam.

    Also with the Vortec heads is it a good idea to get them studded or pinned to use with the larger than stock cam and valve springs?
     
  2. Blazerfun

    Blazerfun Registered Member

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    A dual pattern cam is better for a 4x4. I went with the Cam Dynamics x-treme dual pattern with a gross lift of 480 on the intake and I think 472 on the exhaust. The duration is around .250 at .50 & 260 at .50. It lopes a little at idle, but its crisp of the line, I kept great vacum and gained torque. You dont need to do a thing to the vortech heads as long as you stay under .500 lift and .300 gross duration. Try going to 1.60 or 1.70 ratio rocker arms, the valve train will rotate easier and live longer.
     
  3. solowookie

    solowookie 1/2 ton status

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    I did vortec's - I with I would of gone with some S/R Torquers... for the same cost as the intake & heads you can have yourself a set of heads that will work with any intake, and don't have to get into all the vortec specific crap.

    can't have more then .5 lift with the vortec's too.
     
  4. Derf00

    Derf00 1/2 ton status

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    I am running an LT1 cam in my 383 w/Vortec heads. It produces a good idle, computer friendly, great low end torque, and I stayed emmissions legal.
     
  5. zcarczar

    zcarczar 1/2 ton status

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    I think im leaning more towards the LT1 cam. The one that comp recomended seems to radical for me and the comp. Maybe I will make a post over on thirdgen.org.

    Solowookie, I got a whole vortec engine but the block was bad and the heads had about 10 miles on them before I got them.
     
  6. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    Call and talk to one of the guys at Scoggin Dickey . For a while they were selling a 270HP TBI motor. I called and got the cam specs from them. I put this cam in a friends '89 K5 with TBI and Vortec's and it is VERY strong.



    Mike
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    The first cam here http://www.cranecams.com/master/apps/chevy18.htm#1.%20PowerMax

    Makes a LOT more low end power than any other cam out there that I could find. (compare its lift and duration with others, nothing else is a copy even, and the lift will keep you safe with the Vortecs)

    Now mind you, thats a roller retrofit, and the one comp sent you a link to is also a roller cam, and if you are dealing with a retrofit set of lifters (for roller cam in older block) you are looking at $400 for lifters alone.
     
  8. Diesel Dan

    Diesel Dan 1/2 ton status

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    Anyone running a L31 Vortec roller cam in their TBI setup? I can get the cam, lifters, retainers and pushrods for $175. Need to find the specs on the cam first.
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    If anyone can find the cam specs on it, I'll run it through DD2K to compare to the Crane cam I posted.

    I sure wish I had known about the later block option before I started on mine, it makes so much more sense to go with a 1 piece rear main seal/factory roller equipped block than to retrofit the roller cams into the older blocks. /forums/images/graemlins/frown.gif
     
  10. Derf00

    Derf00 1/2 ton status

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    Correct me if I am wrong here, but zcar's Blazer is a '89, which is comp controlled & from the looks of it, he is running it on the street, which probably require the emmissions to work. The Crane Cams shown are for non emmission and non computer controlled applications.

    I won't dispute the power that these cams may make, but the LT1 cam allows you to use the stock computer with some chip mods, and you can maintain you emmissions.
     
  11. solowookie

    solowookie 1/2 ton status

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    Darth Blazer is all stock, but internally balanced with comp cam # 12-249-4. then in Jedi Mind trick it's running vortec's with crane cam #114122.

    I love the comp cam, and hate the crane cam... don't know if this will help you at all, but I'd highly recommend that comp cam. crowers suppose to have some pretty decent cam's too. I've been looking into these for the TPI 383 I'll be dropping in my hotrod. /forums/images/graemlins/thumb.gif
     
  12. solowookie

    solowookie 1/2 ton status

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    (both those engines are TBI engines)
     
  13. dyeager535

    dyeager535 1 ton status Premium Member

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    Bah, Crane says no emissions/computer because its illegal more than likely. The thing has no CARB/EO is my guess, and they don't want to get themselves in trouble.

    Any time you change things on a computer controlled vehicle, some fine tuning (PROM burning, what have you) is necessary to get the *most* out of it.

    The cam won't have any affect on visual emissions components, the only thing the cam would affect is a sniffer test, and with a properly running engine (system actually) the thing will pass.

    You are looking at over 400ft lbs down low with the crane cam I speced, and right around 275HP. (all numbers cited via DD2K using vortec flow #'s and TPI)

    It's kind of funny, if you look at Comp's LT1 cam selection,( http://www.compcams.com/catalog/086_087.html ) the "stock replacement" LT1 cams have too much lift for stock Vortecs, and the "more power" LT1 cams have less lift and a 112* lobe seperation, with almost the exact same duration numbers as the mentioned crane cam. Still, lift that IMO is too much for the Vortecs, stock.
     
  14. zcarczar

    zcarczar 1/2 ton status

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    I dont have to worry about emmisions, I know a guy that will make it pass. I also emailed comp cams and tried to get the L31 stock cam specs from them. I think they might be the best shot.

    I was also figuring on having to do some PROM tuning to get this thing to run right, Im hoping it will be a little easier with the Holley TB because of the adjustable fuel pressure reg.

    dyeager, did you run the Comp cam they sent me? if so what were the numbers compared to the crane?

    Also I have all of the stock L31 valvetrain parts, My block should already be machined to accept it, except for the 3 holes I have to drill and tap. But will I have to buy new lifters to run with the new cam?
     
  15. dyeager535

    dyeager535 1 ton status Premium Member

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    Yes, I ran that comp cam through DD2K. It shows more HP (about 25 more peak) and a hair more TQ, about 7ft lbs.

    DD2K doesn't show anything under 2000RPM, however, the comp cam TQ is climbing at 2000RPM, while the crane has already peaked and is starting to head down.

    This is important to me with a manual transmission, the lower in the RPM range that the motor has strong torque, the easier it is to get moving, and will help out when crawling along. Less of a factor with an automatic since 2000 is almost where most of them stall to anyways.

    The difference between the two cams, either at 2000RPM or 3000RPM, is 15 ft lbs or less though, so not a LARGE amount. Under the curve though, (before 2000RPM) I'm assuming the crane performs quite a bit better, based on the difference at 2000RPM, and the fact that the Crane has already peaked before that RPM.

    I believe Engine Analyzer shows under 2000RPM, but I don't have it.

    As to lifters, should be no reason you can't reuse the stock ones, but they need to be checked out of course, to make sure they aren't worn.

    If the L31 cam is any good, I'd suspect ebay would hold a few takeout L31 cams, maybe lifters too...the stock lifter/roller lifter combos aren't that expensive comparatively.
     
  16. solowookie

    solowookie 1/2 ton status

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    Email me Dorian & I will get you engine anyalizer... that comp cam I listed I'm running with the sm465. I really like the torque range. it is plenty strong down low, and seems to top out around 4,000 RPM's.

    I'm running it with the stock chip, and this engine is the smoothest running engine I think I've ever heard. it was internally balanced too, but you should check the cam out.

    I don't think DD2000 is very accurate on the torque range. you will get a drastically different torque curve with DD2000 vs. Engine Analizyer.
     

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