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Thread: Help with timing table

  1. #16
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    Ok so I guess I should rephrase my statement, If you are shooting for above say 350 hp then it is best to have more lift and less duration and less overlap to create more vacuum and increase torq to take advantage of vortec's bottom end. As-well as machining the guides down to avoid clearance issues. :-)
    Richard
    1969 C-10 SWB Step
    355 Small Block
    Stock Vortec heads
    Howard's Cam (110951-08)
    Stealth Ram, Holley HP EFI
    700R4 Trans, 2200 stall & 3.73 gears

  2. #17
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    Quote Originally Posted by riche View Post
    Ok so I guess I should rephrase my statement, If you are shooting for above say 350 hp then it is best to have more lift and less duration and less overlap to create more vacuum and increase torq to take advantage of vortec's bottom end. As-well as machining the guides down to avoid clearance issues. :-)
    Tighter LSA cams increase overlap and boost mid-range torque at the expense of torque on both ends of the curve. You can grind the same lobes on a 114* LSA vs 110 or 108* and gain 2-3 in/hg of vacuum and keep pulling an extra 400+ rpm higher than the tight LSA.

    Because of this I have always had great luck with the GM F/Y-car LT1 and LT4 cams with 1.6:1 or 1.7:1 rockers. An OBDII F/Y-car LT1 cam is .477/.490 with 1.6 rockers, .508/.520" lift with 1.7 rockers and combined with a set of slightly worked Vortecs, 10:1 350, 1 5/8" long tubes and a decent intake can make an easy 370-380 HP. LT1 cam is also stupid easy to tune for as it has a high, stable vacuum signal and in most cases will start and run on the stock tuning. The LT1 cams really like being dialed in 4-6* advanced as well as they sit straight up on a 116 or 117* LSA.

  3. #18
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    Just looking it is nearly impossible to find an inexpensive lt1 cam substitute...
    My motor isn't exactly a top notch build... but I can definitely see the merit of putting a cam in that would allow me to utilize more of my map table.
    Just can't justify throwing a $200 or more cam into my glorified junkyard motor.
    Richard
    1969 C-10 SWB Step
    355 Small Block
    Stock Vortec heads
    Howard's Cam (110951-08)
    Stealth Ram, Holley HP EFI
    700R4 Trans, 2200 stall & 3.73 gears

  4. #19
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    Quote Originally Posted by riche View Post
    Just looking it is nearly impossible to find an inexpensive lt1 cam substitute...
    My motor isn't exactly a top notch build... but I can definitely see the merit of putting a cam in that would allow me to utilize more of my map table.
    Just can't justify throwing a $200 or more cam into my glorified junkyard motor.
    A L98 cam would not be bad either. IIRC it has numbers 773" cast into it. Runs about 202/207 @ .050, .415/.430" lift, 117 or 114.5* LSA depending on the year. Also came in the 350 TBI 9C1 caprice cop cars and some 305 TPI engines. 87+ G92 and ALL 90+ LB9 cars.

  5. #20
    LT1 specialist steveo's Avatar
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    an lt1 cam is probably the easiest to find too, someone would probably sell you one for 20 bucks and some freight. anyone that's ever wrenched an lt1 apart probably has a stock cam or two in their basement. i've thrown away probably 6 of them.

  6. #21
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    Quote Originally Posted by steveo View Post
    an lt1 cam is probably the easiest to find too, someone would probably sell you one for 20 bucks and some freight. anyone that's ever wrenched an lt1 apart probably has a stock cam or two in their basement. i've thrown away probably 6 of them.

    I always keep them, to throw in L30/L31 and TBI builds. I have probably thrown 6 or 8 of the L31 cams out.

  7. #22
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    My motor seems ok right now with .470 lift on it. I didn't know to check the stem seal clearance... However if I was to find an lt1 cam, running 1.6 rockers .490 on exhaust would probably be an issue right? So I would have to pull the heads and get the guides machined down?

    Oh and we are talking about roller cams? I have a older block... Can you run aftermarket roller lifters on stock cams?
    Last edited by riche; 08-28-2014 at 09:00 PM.
    Richard
    1969 C-10 SWB Step
    355 Small Block
    Stock Vortec heads
    Howard's Cam (110951-08)
    Stealth Ram, Holley HP EFI
    700R4 Trans, 2200 stall & 3.73 gears

  8. #23

  9. #24
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    Yeah, retro rollers are hi-high! Not going to pull my engine down just to try to modify for stock rollers even though it doesn't look to hard to try... So unless I can find a flat tappet cam just going to work with what I got. It really sounds good just sucks knowing it is all bark and I may be leaving something on the table just to have a cool sounding engine.
    Going to try what you recommended steveo. But first I'm gonna back off some timing before I do just in case I am close to what my motor needs. I got a feeling I may be.
    Richard
    1969 C-10 SWB Step
    355 Small Block
    Stock Vortec heads
    Howard's Cam (110951-08)
    Stealth Ram, Holley HP EFI
    700R4 Trans, 2200 stall & 3.73 gears

  10. #25
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    just add cruise timing while watching tps and map .if you add 2 degrees and tps goes down to sustain the rpm and you gain vacuam keep adding

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