NOT the usual cam advice...

GREAT THREAD NAME OR THIS CHEVY TBI POST
have not fooled with TBI in 20 years but here's some links
Fuel Injected Engine Camshafts

from a comp cams sponsored chevy article
Keeping all this in mind, with a conventional, MAP-based, pure-TBI system, at least 15 to 16 inches of idle vacuum is needed. In terms of camshaft duration at 0.050, that comes out to only about 196 degrees on the intake side with an 8.5:1-compression-ratio engine, about 210 degrees on a 9 to 9.5:1 engine, and about 216 to 218 degrees at 10 to 10.5:1. The exhaust duration should be about 8 to 10 degrees more, with an overall intake/exhaust lobe-separation angle (LSA) of 113 to 114 degrees.
A typical cam for the pure-TBI combo would be Comp Cams' Xtreme Fuel Injection 252XFI HR113

edelbrock breaks out a 244 adv 194 @.050 Intake cam 400 lift 112 lca 107 icl for close to 200$
EDELBROCK PERFORMER-PLUS CAMSHAFT KIT FOR 305-350 V8 T.B.I. & LG-4 CHEVROLET - 3702
from a forum
-Edlebrock 3702 flat tappet uses 194/.398 intake and 214/.442 on the exhaust with an LSA of 112. It will carry about 16 inches of manifold vacuum versus 19 to 20 for the Vortec roller (just a data point.
The long exhaust duration seems built in for stock exhaust manifolds and single exhaust and stock converter and muffler. With headers and duals this long duration high lift exhaust is not so necessary.
This cam is a bit edgy with its long duration, higher lift exhaust combined with a shorter LSA so it can get you into a chip which Edlebrock will supply if necessary.


Be careful, the TBI setups use a speed-density injection type which isn't very toleant to changes such as cams, esp. cams that would "sound" differently. ECM tuning would be required with a lopey camshaft.

That being aid, I know that the 1996 LT4 Production camshaft with 203º/210º duration at 0.050" and 0.446"/0.450" on a 115ºLSA is a strong runner in a TBI truck. I know a guy that installed one in a 1989 truck with a 350 with Vortec heads and it has great street manners, but I wouldnt say its a "lopey" camshaft. But it is the most aggressive of the GEN 2 LT1/LT4/L99 roller camshafts.

For a roller block the GM cams that will work without reprogramming are:
Durations measured at .050 lift. Lift measured with 1.5 rocker add 7% for 1.6.
- 10241264 1996 Vortec 190/.414 intake; 195/.412 exhaust;LSA 116. (The Vortec cam will run with 1.6 rockers without problems)
111º. 0.412"/0.428" 191º?196º duration at 0.050" lift(you will also see 192º/197º duration as well.

This cam was used in the 1996-2003 Vortec 350 L31 (255hp/330lb/ft)
96 L31 Camshaft Profile
Intake:
Opening Closing Duration
.004 14 BTDC .004 61.5 ABDC 255 Degrees
.050 13 ATDC .050 22.5 ABDC 190 Degrees
Inlet Centerline 106.25 Degrees
Max Lift .275 X 1.5 = .412
max lift .275 x 1.6 = .440
Exhaust:
.004 62 BBDC .004 24 ATDC 266 Degrees
.050 31.5 .050 16 BTDC 195 Degrees
Exhaust Centerline 115.75 degrees
Max Lift .281 X 1.5 = .423
maz lift .281 x 1.6 = ..450
Lobe Separation 111 Degrees

- 14093643 350 TPI 97-94 roller 202/.403 intake; 206/.415 exhaust; LSA 115
- 12551705 350 LT1 93-95 roller 201/.447 intake; 208/.459 exhaust; LSA 117
(TBI loves this cam because of the 117 LSA it will also accept 1.6 rockers without issue)
- 12551142 350 LT4 95-97 LT4 203/.446 intake, 210/.450 exhaust; LSA 115 (with more duration and lift with less LSA this cam is a bit edgy with the stock programming, especially if mixed with a 1.6 rocker)
production LT4 cam p/n 12551142 is a very good piece for TBI or any engine that like TBI uses a Speed Density fuel management system. These like high manifold vacuum as seen at idle the 115 degree LSA provides that. Timing of this cam is 203/210 at .050 lift with a 1.5 rocker lift at the valve is .446/.450. .006 duration was 258/265
LT4 cam. It has 46º of overlap while the stock LT1 cam has overlap specs of 41º.
I knew a guy that ran this cam on a TBI/Vortec head combination.
He said it was a great cam and provided lots of vacuum for the TBI.
The LT1 cam is the better choice it times pretty close to the LT4 not HOT but it spreads the LSA out to 117 degrees which makes a very torquey engine and preserves a high idle vacuum that the factory TBI likes. You can run this with 1.6 rockers, actually using 1.6 on the intake and 1.5 on exhaust will offer the best torque and power.
Anybody's aftermarket cam that falls real close to these parameters will work just keep the LSA not less than 111 degrees.

Recommended 350 TBI modifications | TBI



The LT1 can p/n 12551705 trades a couple degrees off the LT4 cam at .050 lift but adds a little lift though still well under .5 inch and brings an even TBI friendlier LSA of 117 degrees.