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LT1 cam advanced 4 degrees on my L31? Yes, I searched.

This is a discussion on LT1 cam advanced 4 degrees on my L31? Yes, I searched. within the Performance forums, part of the General Discussion category; The subject of camshafts does get beaten to death, but I found no threads on before/after of playing with cam ...

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    LT1 cam advanced 4 degrees on my L31? Yes, I searched.


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    The subject of camshafts does get beaten to death, but I found no threads on before/after of playing with cam timing. I've got an LT1 cam to install and thought if I were to advance it 4 degrees, I could keep all my low, low end torque and realize some slight gains everywhere else. Has anyone here ever played with cam timing and was it worth it?
    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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    Re: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    Quote Originally Posted by speedracer326 View Post
    The subject of camshafts does get beaten to death, but I found no threads on before/after of playing with cam timing. I've got an LT1 cam to install and thought if I were to advance it 4 degrees, I could keep all my low, low end torque and realize some slight gains everywhere else. Has anyone here ever played with cam timing and was it ss worth it?
    Install the LT1 cam straight up, with long tubes and tuning, you will not even notice a torque loss. Any loss is under the stall speed of the torque converter. Before we installed the GM Goodwrench >8500 GVW 350 Vortec into my dads 97 G1500 Express we tossed in a LT1 cam, 1.6:1 full roller rockers, and a set of beehives. His 4L60E had the P1870 code in it, so I pulled it apart, installed new frictions and steels, Transgo HD2 shift kit, and a L35 S10 converter, deleting PWM TCC. Gets 18-19 MPG at 70-75 mph and easily accelerates with the torque converter locked in OD and its pushing 6,000 lbs empty with 3.42 gears.

    Tom and I reflashed the PCM a few years ago with 100% torque management and abuse mode delete, revised shift points, pe air/fuel ratio adjusted, and a B-car LT1 timing map. The F-car LT1 cam is worth a solid 20 HP gain over the B-car/L31 grind.
    Last edited by Fast305; 05-01-2011 at 11:58 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: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    Install the cam straight up like fast said,but I'll add that any cam should be degreed to ensure the timing set is accurately made.

    Case in point:My LT4 hot cam installed straight up was 6-7 degrees advanced when checked with a degree wheel.
    I had to install the timing set retarded to bring the cam closer to install specs,though it's still advanced by 2 degrees.
    A timing set with multiple keyways is a must and will give you adjustability.My 0.02
    DD: 1989 Taurus SHO
    Project:1995 ECSB,Auto-5 speed manual conversion,Vortec 357,LT4 Hotcam

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    Re: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    Fast, were said torque losses below the stall of an S10 converter or would they still be below the stall speed of an L31 converter? Due to the fact that I tow a car trailer, I don't want to cook the trans with a higher stall. I've been looking at the parts to build a stronger 4L60E as I prefer its deeper OD over the 80E's which allows me to run a lower gear. I just feel that this cam would give the truck a good kick in the midrange, so when it does downshift it'll be more significant. I've already got the longtubes and tuning covered.
    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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    Re: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    What are the intake centerlines on both cams? My searches are netting random inconclusive results.

    1994-1996 B-bodies (including L99 4.3L): 191/196 0.418/0.430 lift 111 LSA
    From what I've found, the L31 cam's ICL is also 111, indicating that it's installed straight up.

    1993-1995 Y-body, F-body: 202/207 0.450/0.460 lift 116 LSA
    Pretty sure my cam is a '95, though I'm not home to mic it at this time. ICL appears to be close to the L31's, meaning that the LT1's cam is advanced from the factory.
    Last edited by speedracer326; 05-03-2011 at 10:30 PM.
    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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    Re: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    Back from the dead! Everyone else is doing it, so why not? More research has indicated that the L31 cam is installed at 106.5* from the factory. LT1 ICL is still inconclusive, but if it's like the LS stuff it's probably retarded. Fast stuck his LT4 cam in advanced 4 degrees, and advancing a cam makes more torque, so I'm not seeing a reason not to. Now the question is how was that cam advanced. Time to check Summit for an adjustable timing set.

    http://www.summitracing.com/parts/cl...et?prefilter=1

    This looks like it'll work, but damn $111!
    Last edited by speedracer326; 02-05-2014 at 03:20 PM.
    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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    Re: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    Quote Originally Posted by speedracer326 View Post
    Back from the dead! Everyone else is doing it, so why not? More research has indicated that the L31 cam is installed at 106.5* from the factory. LT1 ICL is still inconclusive, but if it's like the LS stuff it's probably retarded. Fast stuck his LT4 cam in advanced 4 degrees, and advancing a cam makes more torque, so I'm not seeing a reason not to. Now the question is how was that cam advanced. Time to check Summit for an adjustable timing set.

    http://www.summitracing.com/parts/cl...et?prefilter=1

    This looks like it'll work, but damn $111!
    http://www.summitracing.com/parts/cl...make/chevrolet
    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: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    Yeah, I like $60 much better. I found your LT4 cam dyno too Fast, looks nice.
    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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    Re: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    Quote Originally Posted by speedracer326 View Post
    Yeah, I like $60 much better. I found your LT4 cam dyno too Fast, looks nice.
    It pulled hard for what it was in.

    I was doing a little searching and it appears the later OBDII F-car LT1 that runs the 117 LSA cam also runs straight up at a 117 ICL.

    Here is the complete specs for the Mellings MC1336 that is supposidly the stock replacement for a 96 Corvette.

    270/276 @ .006, 201/208 @ .050, .446/.459" lift, 117 LSA, 117 ICL

    That being said the MC1337 is the B-Car and Vortec cam.

    259/263 @ .006, 191/196 @ .050, .414/.428" lift, 111 LSA, 106 ICL

    For comparison purposes.

    The CCS-2 aka the everything flat tappet 350 cam including TBI trucks.

    260/271 @ .006, 193/204 @ .050, .390/.410" lift, 112 LSA, 108 ICL

    My favorite TBI friendly non roller grind the MTC-1. In a TBI application with headers and decent exhaust it gains 20 ft/lbs through most of the rpm range over the stock cam.

    278/288 @ .006, 204/214 @ .050, .423/.446" lift, 112 LSA, 112 ICL.
    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: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    That's encouraging, I'll be able to get it down to a 113 ICL then. The LT4 cam is actually retarded 1 degree, I think I'm about to throw up a WTB ad for one. It has a 115 LSA and 116 ICL, so it becomes a 115 on a 112 when advanced if the retard is ground into the cam and isn't in the proprietary timing chain/gears. Either way I know it pulls good. What's going to be ridiculous is 85mph in 2nd gear with 4.10s.
    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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    Re: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    Quote Originally Posted by speedracer326 View Post
    That's encouraging, I'll be able to get it down to a 113 ICL then. The LT4 cam is actually retarded 1 degree, I think I'm about to throw up a WTB ad for one. It has a 115 LSA and 116 ICL, so it becomes a 115 on a 112 when advanced if the retard is ground into the cam and isn't in the proprietary timing chain/gears. Either way I know it pulls good. What's going to be ridiculous is 85mph in 2nd gear with 4.10s.
    At 5,600 rpm fuel shut-off in 1st gear I am at 53 mph and 2nd gear/locked converter comes in at 92 mph with my 3.73s and P285/50R20s. Yea its 6 lug with Titan wheels now. If I were cammed to rev to 6,000 rpm I would hit 60 mph in 1st and 100 mph in 2nd. Definately needs 4.10s lol.

    The LT4 camshaft is 1* retarded in specifications. I believe it is the cam itself because GMPP makes no mention of the sproket having built in retard when they provide the specs for the LT4 hot cam kit.

    The factory LT4 had a rev-limit at like 6,400 rpm. That being said a stock truck intake puts a strangle hold on the engine before 5,500 rpm. With the marine intake and your headers I think it would pull well all the way to the 5,600 rpm rev-limit even 4* advanced. I think it would peak around 5,300 rpm, given the fact a marine engine with its 196/206, 109 LSA cam peaks at 4,800 rpm. I think torque peak would come in around 3,600 rpm too with strong low-midrange torque.

    I wonder how the tiny L31 roller cam I put in a TBI head engine would run if I retarded it 4* and put 1.7:1 rockers on it.
    Last edited by Fast305; 02-06-2014 at 09:37 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: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    Well, seeing how the heads choke so bad up top, I'd think a cam with a peak hp of 4,600 RPM installed straight up would be the ticket. Everyone who's done 1.6s on the Vortecs has felt a kick in the pants, and 1.7s would get you around 1.6 LT1/LT4 lift.
    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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    Re: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    Quote Originally Posted by speedracer326 View Post
    Well, seeing how the heads choke so bad up top, I'd think a cam with a peak hp of 4,600 RPM installed straight up would be the ticket. Everyone who's done 1.6s on the Vortecs has felt a kick in the pants, and 1.7s would get you around 1.6 LT1/LT4 lift.
    The engine is in a 1981 Camaro with the TBI still on top. Built to pose as the original LG4 305 but with EFI and alot more power. The car still has the 2.73 posi rear-end but runs a stock stalled 4L60E in place of the original TH350C.

    On second look I think the lift would be excessive. With 1.7s the stock L31 cam is .469/.485" lift and roughly 3-4* @ .050 more duration along with a 4* retard. Looking at the flow numbers of a stock swirl port, the only gain would be on the exhaust side with that lift and it already has a good intake/exhaust flow split. Looking at the numbers it might respond favorably to 1.7:1 intake rockers and 1.6:1 exhaust. That would keep me under .470 on both sides as well.
    Last edited by Fast305; 02-06-2014 at 10:05 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: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    The only reason I mention weird rocker ratio combinations like that is I feel a L31 with the factory intake manifold like an intake port restricted TBI does not need as much of an Intake/Exhaust duration split as some other chevy engines. Your Tri-Y headers probably scavenge very well and while the vortec exhaust port is a touch weak I feel the intake flow is probably worse.
    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: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    It's getting prettttty deep in here guys.

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    Re: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    Quote Originally Posted by SUBURBIAN View Post
    It's getting prettttty deep in here guys.
    The all knowing L31 master himself, lol. Do tell us this L31 cam experience based knowledge you posses.
    Last edited by Fast305; 02-06-2014 at 10:20 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: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    Quote Originally Posted by Fast305 View Post
    The only reason I mention weird rocker ratio combinations like that is I feel a L31 with the factory intake manifold like an intake port restricted TBI does not need as much of an Intake/Exhaust duration split as some other chevy engines. Your Tri-Y headers probably scavenge very well and while the vortec exhaust port is a touch weak I feel the intake flow is probably worse.
    Let's not forget that a Marine intake is going in at the same time. I'm only taking the intake off once, and when I do I'm making it worth my while.
    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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    Re: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    Quote Originally Posted by speedracer326 View Post
    Let's not forget that a Marine intake is going in at the same time. I'm only taking the intake off once, and when I do I'm making it worth my while.
    I know you are after torque and cost effective, but I am about to pull out my small 206/210 @ .050, .458/.458" lift, 110* LSA cam and go larger in my marine intake/tri-y headered setup. Even as short as the duration on that cam is, it is sluggish off-idle, and eats fuel around town. I also had alot of trouble with burst knock and detonation on launch and when the torque converter locked at slow speeds. It also falls flat well before redline compared to the similarly speced wider LSA LT4 cam it had before. In addition I am boring the TB opening on the marine intake to 84mm and going to run a BBK 84mm TB I picked up along with my 3.5" CAI setup. Should be feeding a monster with 170cc Etec heads and the 215/220 @ .050, .534/.544 w 1.6:1 rocker, 114* LSA , 110* ICL comp cam I have in mind. Straight up on a 114* ICL they recomeend a 2,600-2,800 stall and I recently picked up a GMPP 4L80E 2,400-2,800 converter that looks to have been built by Yank and painted a different color. Combined with 4.10s it should be fun.
    Last edited by Fast305; 02-06-2014 at 11:16 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: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    Quote Originally Posted by Fast305 View Post
    The all knowing L31 master himself, lol. Do tell us this L31 cam experience based knowledge you posses.
    Haha. Easy, killer. Why throw around words like that...you must think YOU"RE the L31 master or something. I've never claimed to be any such thing. You're still alright in my book, man. We'd probably enjoy hanging and wrenching together.

    Torque converters stall and flash at variable rates based on the output of the engine to which they're fastened; more torque means higher stall & flash, therefore the stall/flash ratings of one converter attached to two different engine combinations (heads/cam/compression/etc) will NOT behave the same. "Advertised" operating ranges for any cam (including all of those being discussed here) are inaccurate and very subjective numbers affected by more variables than you can count with your hands. Vortec heads want 12 to 15 degrees duration split favoring intake, with less lift on the exhaust for optimal performance. Increasing rocker ratio DOES NOT increase the seat to seat timing of a camshaft, EVER. Your favorite TBI flat tappet cam is the oldest, generic, lazy lobed, "RV cam" ever to be marketed? I hope that being your favorite does not also mean it's the best FT grind for a TBI engine. Your asserted 20 horse gain with this cam was also with the addition of headers and exhaust, and by reading this, I've just watched you try to quantify power gains from a certain "mod" that was performed at the same time as other "mods", but attributed to only one of them...AGAIN. Just like the cold air intake you posted about a couple weeks ago that netted you however many more horses, yet you happened to swap intakes to the marine piece at the same time. You didn't post again in that thread after this was identified. It is wrong to make conclusions or statements such as these. If you want to quantify individual "mod" power increases, do it one part or "mod" at a time. You've also contradicted yourself, or maybe confused yourself which I see as possible, while talking about all these different cams and engines and cars and theory. I'm not spelling this one out for you, I'll just say that lift is the ability to make power and duration is the ability to sustain it at a given rpm. Lastly, dynos have a special way of spelling B-O-L-O-G-N-A.

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    Re: LT1 cam advanced 4 degrees on my L31? Yes, I searched.

    Sub you're overlooking the fact that duration's effects can be amplified or covered up by altering the LSA and ICL, those 2 things are absolutely huge. The cam Fast is removing is very close in lift and duration to an LT1 cam with 1.5s, but the LSA and ICL make it sluggish off idle and fall off up top, 2 things the LT1 do not do in stock form. Furthermore, the exhaust ports don't stall even up to .600" lift whereas the intake stalls around .500" lift. Can you provide a reference for your claim that the Vortec heads want less lift on the exhaust side?

    http://www.hotrod.com/techarticles/e...ylinder_heads/

    Can you provide a reference for your claim that the Vortec heads want less lift on the exhaust side?
    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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