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  • Biggest Cam for TBI

    I'm considering swapping out my cam for a bigger one. When looking around at cams I keep seeing 'computer friendly' cams. What exactly makes a cam 'computer friendly'?
    What I really want to know is how big of a cam can I use in my 383 TBI engine? I have a Flash EBL computer, so a custom tune will not be a problem, and I also have a 2" bore TB, matching 2" bore intake, BB injectors, VAFPR, and high volume fuel pump (everything I need to make bigger power).
    I would like to make power up to 6000 rpm. What I have in the truck for a cam now is a 214/224 degree @ 0.050" and 0.443"/0.465" lift hydraulic flat tappet and stock rockers. With this setup, it runs out of steam before it hits 5000 rpm.
    Any help on this would be appreciated.
    Thanks
    Last edited by sdmorrison; 09-26-2008, 06:21 AM.
    '87 Chevy 383 TBI, 700R4, 3.73 open rear diff, stock suspension
    195cc AFR heads, Scat rotating assembly, Lunati Voodoo 268/276 hyd. flat tappet cam, Edelbrock Performer RPM intake, Doug Thorley Tri-Y headers, ported big block throttle body with 80lbs injectors, EBL Flash computer

  • #2
    Re: Biggest Cam for TBI

    sounds like money is not too big of an issue for you. You can do a roller swap and go up and over .510 lift....some guys on here have.
    1993 Chevy 5.7 tbi Z71, vortec heads, GMPP tbi vortec intake, 2" TBI and bored intake, TBI spacer, Comp Cams 08-409-8 XTREME 4x4 roller cam conversion, Hedman full length headers, 3" body lift, 33" tires, Paxton Performance tune (aka 94Blazer383), 4.10's, Hypertech powercharger, built 4l60e.

    Comment


    • #3
      Re: Biggest Cam for TBI

      Money is always an issue! It's taken me a while to get all the parts I have and there is a list as long as my arm of parts I would like to buy but I can't afford them. I like to research all my upgrades as much as I can before spending anything. Also, I have an arrangement with the wife to let me buy the occasional upgrade in place of the usual birthday, xmas, and anniversary gifts... works for me.

      The roller setups I've looked into are pretty expensive. Would the performance gain be worth it? I was thinking of switching over to a mechanical flat tappet cam if it is 'computer friendly' since I hear they can work a lot better than hydraulic setups. Does anyone have an opinion on this?

      Also, I would consider upgrading to 1.6 rockers in the future if anyone could give me a good idea of the improvement I might expect to see.

      Thanks
      Last edited by sdmorrison; 09-26-2008, 08:43 AM.
      '87 Chevy 383 TBI, 700R4, 3.73 open rear diff, stock suspension
      195cc AFR heads, Scat rotating assembly, Lunati Voodoo 268/276 hyd. flat tappet cam, Edelbrock Performer RPM intake, Doug Thorley Tri-Y headers, ported big block throttle body with 80lbs injectors, EBL Flash computer

      Comment


      • #4
        Re: Biggest Cam for TBI

        You can get roller parts (lifters, retainers, spider) cheap or even for free from friends or junkyards. The only thing that costs a lot is the cam ($300) and you get a lot more torque from them. I gained 80 ft/lbs at 2000 rpm. 1.6 rockers aren't needed if you choose the right cam.
        1993 Chevy 5.7 tbi Z71, vortec heads, GMPP tbi vortec intake, 2" TBI and bored intake, TBI spacer, Comp Cams 08-409-8 XTREME 4x4 roller cam conversion, Hedman full length headers, 3" body lift, 33" tires, Paxton Performance tune (aka 94Blazer383), 4.10's, Hypertech powercharger, built 4l60e.

        Comment


        • #5
          Re: Biggest Cam for TBI

          what about a XE268?
          Originally posted by Xander Berkeley
          I'd better make hay while the sun shines.

          Comment


          • #6
            Re: Biggest Cam for TBI

            You wanna rev to 6k on swirlports? I think 5k is as good as it'll get on those heads, especially for a 383.
            Originally posted by Quyonmob
            Straight pipes are for peckerheads. . .
            '98 K1500 ECSB 5.7, 4L80E, 14BSF, 4.10/G80, 7,200# GVW springs, 8600# GVW calipers/pads, 411/EFI Live.

            Comment


            • #7
              Re: Biggest Cam for TBI

              speedracer326, you may be right about the swirl port heads but they are extensively ported. The swirls are ground back to the point where they don't really block the intake runner at all anymore. Also, the downturn in the floor of the intake port has been ground down, so it is a nice straight shot to the valve. Before I put in the stroker assembly, the engine made power up to 6000 rpm with the cam I have in it now.
              If it turns out to be a dog with a bigger cam, I do have another set of heads I could use. They are ported 416 castings with 1.94" valves installed (installed properly with the port opened up to match the valve and the chamber has been opened up to unshroud the valve). And I have access to a victor junior intake that will fit the 416 heads, and a squarebore to tbi adapter plate.
              Last edited by sdmorrison; 09-26-2008, 11:34 AM.
              '87 Chevy 383 TBI, 700R4, 3.73 open rear diff, stock suspension
              195cc AFR heads, Scat rotating assembly, Lunati Voodoo 268/276 hyd. flat tappet cam, Edelbrock Performer RPM intake, Doug Thorley Tri-Y headers, ported big block throttle body with 80lbs injectors, EBL Flash computer

              Comment


              • #8
                Re: Biggest Cam for TBI

                i have a 216/228 .454/.480 lift at a 112 lsa from crane cams and its a computer compatible cam i paid like $188 for cam and lifters and shipped to my door

                350tbi,tbi spacer,injector spacer,lt headers,volant cai,e-fans,tbi performer intake,under drive pullies,216/228 .454.480 at 112 lsa cam,complete build 4l60e w/trans cooler,and a 2500 stall,borla muffler w/no cats,3.73 w/g80

                Comment


                • #9
                  Re: Biggest Cam for TBI

                  sorry bout bad info i didnt read right i got it for my 350 tbi not sure if it fits on a 383.

                  350tbi,tbi spacer,injector spacer,lt headers,volant cai,e-fans,tbi performer intake,under drive pullies,216/228 .454.480 at 112 lsa cam,complete build 4l60e w/trans cooler,and a 2500 stall,borla muffler w/no cats,3.73 w/g80

                  Comment


                  • #10
                    Re: Biggest Cam for TBI

                    Here's the cam I'm using:
                    http://www.compcams.com/Cam_Specs/Ca...x?csid=79&sb=1
                    1993 S10, 355ci.V8, Edelbrock MPFI, 2" TB, 6395 ECM, $0D Mask, Comp 280H Magnum cam, Edelbrock Performer RPM heads, Lincoln Mark VIII e-fan, 4L60E, 8.8 rear, 8.80s @ 79 MPH (1/8 mile), and cost to much.

                    Comment


                    • #11
                      Re: Biggest Cam for TBI

                      93V8S10 - Did you have any problems tuning for the larger cam? I read somewhere (tbichips.com maybe) that the cam lobe separation has to increase when you increase duration to avoid false knock readings. Have you noticed this at all?

                      Thanks guys for all your input.
                      '87 Chevy 383 TBI, 700R4, 3.73 open rear diff, stock suspension
                      195cc AFR heads, Scat rotating assembly, Lunati Voodoo 268/276 hyd. flat tappet cam, Edelbrock Performer RPM intake, Doug Thorley Tri-Y headers, ported big block throttle body with 80lbs injectors, EBL Flash computer

                      Comment


                      • #12
                        Re: Biggest Cam for TBI

                        268 with a 128 LSA
                        Originally posted by Xander Berkeley
                        I'd better make hay while the sun shines.

                        Comment


                        • #13
                          Re: Biggest Cam for TBI

                          Originally posted by sdmorrison
                          93V8S10 - Did you have any problems tuning for the larger cam? I read somewhere (tbichips.com maybe) that the cam lobe separation has to increase when you increase duration to avoid false knock readings. Have you noticed this at all?

                          Thanks guys for all your input.
                          Brian has had trouble tuning the lower LSA cams but it's not impossible. My tuner, check sig, had no problem tuning mine. HaulinAss is the one who convinced me to go ahead with LSA of 111. He said you can tune just about ANY cam with time and patience.....as long as you have a competent tuner. If you're doing mail order, you might wanna try a local tuner or choose an easier cam to tune.
                          Last edited by 93ChevyTBI; 09-29-2008, 06:37 AM.
                          1993 Chevy 5.7 tbi Z71, vortec heads, GMPP tbi vortec intake, 2" TBI and bored intake, TBI spacer, Comp Cams 08-409-8 XTREME 4x4 roller cam conversion, Hedman full length headers, 3" body lift, 33" tires, Paxton Performance tune (aka 94Blazer383), 4.10's, Hypertech powercharger, built 4l60e.

                          Comment


                          • #14
                            Re: Biggest Cam for TBI

                            Originally posted by 93ChevyTBI
                            Brian has had trouble tuning the lower LSA cams but it's not impossible. My tuner, check sig, had no problem tuning mine. HaulinAss is the one who convinced me to go ahead with LAS of 111. He said you can tune just about ANY cam with time and patience.....as long as you have a competent tuner. If you're doing mail order, you might wanna try a local tuner or choose an easier cam to tune.
                            LSA changes the overlap of a cam. Changing the overlap effects engine vacuum, especially at loaded idle. I have tuned 305 TBIs with over 230* @ .050, .500" lift cams in them and setup properly, the run GREAT even with TBI. Ever heard a Vortec head 305 TBI pull 6,500+ RPM?
                            Last edited by Fast305; 09-28-2008, 12:11 PM.
                            1997 G1500, 5.7, 906s 2.02/1.60, GM 395' marine cam, 1.7 RR's, Marine Intake, BBK TB, 85mm MAF, 6.5 aircleaner, Thorley Tri-Ys, Thunderbolt 2.5 cats, Dynomax 22865 muffler, 4L80E, 0411, Hydroboost, 9.5" 14-bolt 3.73s, 8800 GVW front calipers, March 4490 pulleys, AD244 alt, D-Max fan

                            Comment


                            • #15
                              Re: Biggest Cam for TBI

                              Originally posted by Fast305
                              LSA changes the overlap of a cam. Changing the overlap effects engine vacuum, especially at loaded idle. I have tuned 305 TBIs with over 230* @ .050, .500" lift cams in them and setup properly, the run GREAT even with TBI. Ever heard a Vortec head 305 TBI pull 6,500+ RPM?
                              I'm not douubting you at all but do you think Brian can do that by mail order? I think that's the biggest question.

                              To be totally honest with you, I think he'd have better luck with a tune coming from you, Haulin', maybe Pauly than Brian.....assuming you guys have the time to do it. From my experience with TBIchips and learning from you guys on here, ya'll seem to be in the know on more radical set-ups than Brian.
                              1993 Chevy 5.7 tbi Z71, vortec heads, GMPP tbi vortec intake, 2" TBI and bored intake, TBI spacer, Comp Cams 08-409-8 XTREME 4x4 roller cam conversion, Hedman full length headers, 3" body lift, 33" tires, Paxton Performance tune (aka 94Blazer383), 4.10's, Hypertech powercharger, built 4l60e.

                              Comment

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