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Biggest Cam for TBI

This is a discussion on Biggest Cam for TBI within the TBI Tuning (87-95 / OBD I) ECM/PCM forums, part of the Performance category; I'm considering swapping out my cam for a bigger one. When looking around at cams I keep seeing 'computer friendly' ...

  1. #1
    Registered User sdmorrison's Avatar
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    Thumbs down Biggest Cam for TBI


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    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 at 05:21 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

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    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.

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    Registered User sdmorrison's Avatar
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    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 at 07:43 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

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    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.

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    -Jeremy XLR8N's Avatar
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    Re: Biggest Cam for TBI

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

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    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.
    Quote Originally Posted by Quyonmob View Post
    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, TB mod, UDs, block, crank, 285s, and a lot of stuff on the shelf.

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    Registered User sdmorrison's Avatar
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    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 at 10:34 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

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    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

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    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

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    Re: Biggest Cam for TBI

    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.

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    Registered User sdmorrison's Avatar
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    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

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    -Jeremy XLR8N's Avatar
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    Re: Biggest Cam for TBI

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

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    Re: Biggest Cam for TBI

    Quote 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 at 05:37 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.

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    Re: Biggest Cam for TBI

    Quote 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 at 11:11 AM.
    1997 G1500 Cobra Conversion, 5.7, 4L80E, 3.73 14-bolt 9.5", L31 Marine Intake, CFM TB, 02 MAF, 0411, Custom cam. Doug Thorley Tri-Ys, full exhaust soon.

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    Re: Biggest Cam for TBI

    Quote 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.

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    -Jeremy XLR8N's Avatar
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    Re: Biggest Cam for TBI


    hope fast doesn't blush!
    Quote Originally Posted by Xander Berkeley
    I'd better make hay while the sun shines.

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    Registered User sdmorrison's Avatar
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    Re: Biggest Cam for TBI

    Thanks for the feedback guys. I guess I won't worry too much about a cam being 'computer friendly' or not then. I'll just have to take my time tuning it.

    After playing around with Desktop Dyno a little, I think I may be better off sticking with my current cam and getting it tuned as best I can since my heads seem to be limiting me. Oh well. By chance does anyone have flow numbers for heavily ported swirl port 187 casting heads?

    Thanks again guys
    '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

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    Re: Biggest Cam for TBI

    Quote 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?
    To be honest, I had lots of trouble tuning, but none of it was cam related. I've never heard of any relationship between false knock and cam size. To continue with the honesty, my knock sensors don't work right, but that's got nothing to do with the cam I'm using and ever thing to do with the Memcal I'm using.
    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.

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    Re: Biggest Cam for TBI

    im running a 230/232 at .050, 550/554 with a 109LSA.

    Truck is built pretty well tho, and runs like a champ.

    people told me that it wouldnt run... well, its out running most of the 5.0's in town, and a few others.
    bobbyjames likes this.

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    Re: Biggest Cam for TBI

    Quote Originally Posted by Derek1387
    im running a 230/232 at .050, 550/554 with a 109LSA.

    Truck is built pretty well tho, and runs like a champ.

    people told me that it wouldnt run... well, its out running most of the 5.0's in town, and a few others.
    Quote Originally Posted by Xander Berkeley
    I'd better make hay while the sun shines.

 

 
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