TBIThrottle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.
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Does anyone have any idea what cam specs the stock cam had?
For that matter, I’m guessing that it came with a roller block but a flat tappet cam, is that right, or is there some chance that it will have a roller cam?
The LO5 in question is out of a ’92 ½ ton truck (I know that there are slight differences, but info about any of them would be helpful)
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Huh, no one? There is some stuff here on the board but it only appears to be conclusive about the passenger car stuff, the info on the truck LO5 is sketchy at best, and I figured with Fast355 and a few others you guys would know what was there.
Even if cam timing numbers don’t exist even just if it has a roller cam in it and if not if all the provisions/machining is would save me a lot of down time when I take it apart…
I do know that there are 2 versions of the truck LO5 that haven’t been mentioned anywhere on the board, the 9.1:1 compression one used in the ½ ton trucks and the 8.9:1 version used in the ¾ and 1 ton trucks, but I don’t know what the differences are otherwise…
The only one that I have have any experience with was a 1995. It was a flat tappet. It had the spider boss's in the lifter valley but they were untapped. The same for the cam retainer ring on the front.
Here are the specs for the 3 L05 350 truck engines. Roller compatibility is hit and miss. To tell, pull the intake and look in the lifter valley. You will have 4 possibilities. No roller boses, untapped roller boses, tapped roller boses, or a roller cam.
Some specs I found published and others (such as cam specs) were measured in stock engines.
A.) Was used in 1/2 ton trucks, vans, and suburbans under 8,600 lbs GVW.
It had 9.3:1 compression ratio, 193 head castings(1.94/1.50 valves 64 cc chambers), a cam that measures 248/252* @ .008, .382/.401 lift, 109* lobe seperation, installed on a 112* intake centerline. The stock TBI is 400 cfm @ 1.5 in/hg and they typically have a better flowing intake than L03 cars do. There are 4 different casting numbers on the intake that I know of. These typically use 61 lb/hr injectors with 68 lb/hr units showing up ocassionally. The air cleaner and exhaust vary between lines, but they are typically much better than a stock L03. For 1987-1994 these are rated 210 FWHP @ 4,000 and 300 ft/lbs @ 2,800. For 1995 it is rated 200 FWHP @ 4,000 and 310 ft/lbs @ 2,800. Strangely, there were no mechanical differences, just programing.
B.) Was used in 3/4 and 1 ton trucks, vans, suburbans over 8,600 lbs GVW. It had 8.75:1 compression, dished pistons, 191/810 head castings (1.94/1.50 valves 76 cc chambers, typically a L03 peanut roller cam (could also be the old "929" cam as well depending on the year/application) The L03s roller specs at 244/258 @ .008, .350/.385" lift, 109* lobe seperation angle, installed at a 110* intake centerline. The "929" specs at 260/271 @ .008, .390/.410, 112* lobe center, installed at a 108* intake centerline. It shares the same TBI, 68 lb/hr injectors, and typically the highest flowing intake. The exhaust is typically shared with the lighter duty L05. For all years the engine was rated 180 FWHP @ 3,800 and 300 ft/lbs @ 2,400. Note that some of these engines have forged cranks and beefy rods. All have sodium filled valves.
C.) The third L05 was in a class of its own. It was used in the C60 series of medium duty trucks. It is a completely different animal than the lighter duty engines. It is also 8.75:1, forged crankshaft, forged beefy rods, dished hyper pistons, 810 head castings (1.94/1.50 valves(sodium filled exhaust), 76 cc chambers, and water cooling of the exhaust valve guides. The intake is typically the best appearing unit. The TBI contains a weird looking governor unit and a totally different pod than a car/light truck TBI. The injectors in this unit flow around 70 lb/hr at 12 psi. The TBI injector pod is fitted with an AFPR with an adjuster screw right up top in the open. The TBI flows closer to 550 CFM @ 1.5 in/hg in stock form. The exhaust is odd in itself. The catalytic converter is placed rear of the muffler, shortly before the exhaust exits the truck. The engine uses a roller cam almost exclusively with the following specs (I haven't measured it installed in an engine with a degree wheel and indicator, but GM list it as 196/206* @ .050, .431/.451 lift/ 109* lobe seperation installed at a 112* intake centerline. The engine is factory rated at 215 FWHP @ 3,800(its TOP goverened RPM it makes more at higher RPMs but is restricted in a heavy truck by the governor) and 325 ft/lbs @ 2,600. With an edelbrock 3704 intake bored to 2", open center 454 style TBI spacer, 75 lb/hr worth of injector, 1.6:1 roller rockers, JBA shorty headers, electric fans, an underdrive crank pulley, and DIY prom tuning, it has pushed out over 248 RWHP @ 4,800 and 317 ft/lbs @ 2,700. It has pulled a 5,300 lbs G-Van with 3.73 gears, a 700r4 with a 2,000 stall, and P295/50/R17s to the following times.
Plus it has NO difficulty pulling a 4,100 lbs boat behind my 5,300 lbs van(well over 10,000 lbs when loaded), up a 1+ mile long 6% grade, while maintaining 70+ MPH in 3rd gear with pedal left. Unloaded semi's would be eating my back bumper otherwise as there is NO climbing lane.
Medium duty TBI unit.
PS- the pod fits our TBIs as well and injectors are available to 125 lb/hr.
Here are the specs for the 3 L05 350 truck engines. Roller compatibility is hit and miss.
B.) Was used in 3/4 and 1 ton trucks, vans, suburbans over 8,600 lbs GVW. It had 8.75:1 compression, dished pistons, 191/810 head castings (1.94/1.50 valves 76 cc chambers, typically a L03 peanut roller cam (could also be the old "929" cam as well depending on the year/application) The L03s roller specs at 244/258 @ .008, .350/.385" lift, 109* lobe seperation angle, installed at a 110* intake centerline. The "929" specs at 260/271 @ .008, .390/.410, 112* lobe center, installed at a 108* intake centerline. It shares the same TBI, 68 lb/hr injectors, and typically the highest flowing intake. The exhaust is typically shared with the lighter duty L05. For all years the engine was rated 180 FWHP @ 3,800 and 300 ft/lbs @ 2,400. Note that some of these engines have forged cranks and beefy rods. All have sodium filled valves.
Fast355, ^^^^ this motor should have a roller cam correct? Meaning I can swap in my L98 cam and Lb9 heads and be fine? The motor I am interested in is from an '88 3/4 ton Chevy Van. I made another post, but I just found this post.
Sorry, for the hijacked thread 83crossfireTA. I am having one hell of a couple months with my car and I think there is light at the end of the tunnel.
Any more info on 83's question? Ive got the exact same scenario... Ive got a 92 K1500 that I want to put a spare Lt1 cam and roller lifters in, but its my main mode of transportation so Im not tearing it down until I know exactly what I need.
IIRC and according to posts by Fast355, only later model trucks (late 94 and 95 timeframe) got roller cams with TBI, prior to the switchover from TBI to Vortec with Central (poppet valve fed) FI. I think 92 models are much too early for that, so IMO if you have a 92 you have a flat tappet cam.
I realize I have a tappet cam, but what Id like to know is if the bosses are drilled and tapped. I can swap the cam and springs in a day with my eyes closed... but if Ive gotta go drilling and tapping out these holes, I may not even bother.
The only truck block (TBI) that I've done was a 1995 350 and it was a flat tappet. The boss's were there but not tapped......so to be sure you are going to have to take a peek......
Here are the specs for the 3 L05 350 truck engines. Roller compatibility is hit and miss. To tell, pull the intake and look in the lifter valley. You will have 4 possibilities. No roller boses, untapped roller boses, tapped roller boses, or a roller cam.
Some specs I found published and others (such as cam specs) were measured in stock engines.
A.) Was used in 1/2 ton trucks, vans, and suburbans under 8,600 lbs GVW.
It had 9.3:1 compression ratio, 193 head castings(1.94/1.50 valves 64 cc chambers), a cam that measures 248/252* @ .008, .382/.401 lift, 109* lobe seperation, installed on a 112* intake centerline. The stock TBI is 400 cfm @ 1.5 in/hg and they typically have a better flowing intake than L03 cars do. There are 4 different casting numbers on the intake that I know of. These typically use 61 lb/hr injectors with 68 lb/hr units showing up ocassionally. The air cleaner and exhaust vary between lines, but they are typically much better than a stock L03. For 1987-1994 these are rated 210 FWHP @ 4,000 and 300 ft/lbs @ 2,800. For 1995 it is rated 200 FWHP @ 4,000 and 310 ft/lbs @ 2,800. Strangely, there were no mechanical differences, just programing.
B.) Was used in 3/4 and 1 ton trucks, vans, suburbans over 8,600 lbs GVW. It had 8.75:1 compression, dished pistons, 191/810 head castings (1.94/1.50 valves 76 cc chambers, typically a L03 peanut roller cam (could also be the old "929" cam as well depending on the year/application) The L03s roller specs at 244/258 @ .008, .350/.385" lift, 109* lobe seperation angle, installed at a 110* intake centerline. The "929" specs at 260/271 @ .008, .390/.410, 112* lobe center, installed at a 108* intake centerline. It shares the same TBI, 68 lb/hr injectors, and typically the highest flowing intake. The exhaust is typically shared with the lighter duty L05. For all years the engine was rated 180 FWHP @ 3,800 and 300 ft/lbs @ 2,400. Note that some of these engines have forged cranks and beefy rods. All have sodium filled valves.
C.) The third L05 was in a class of its own. It was used in the C60 series of medium duty trucks. It is a completely different animal than the lighter duty engines. It is also 8.75:1, forged crankshaft, forged beefy rods, dished hyper pistons, 810 head castings (1.94/1.50 valves(sodium filled exhaust), 76 cc chambers, and water cooling of the exhaust valve guides. The intake is typically the best appearing unit. The TBI contains a weird looking governor unit and a totally different pod than a car/light truck TBI. The injectors in this unit flow around 70 lb/hr at 12 psi. The TBI injector pod is fitted with an AFPR with an adjuster screw right up top in the open. The TBI flows closer to 550 CFM @ 1.5 in/hg in stock form. The exhaust is odd in itself. The catalytic converter is placed rear of the muffler, shortly before the exhaust exits the truck. The engine uses a roller cam almost exclusively with the following specs (I haven't measured it installed in an engine with a degree wheel and indicator, but GM list it as 196/206* @ .050, .431/.451 lift/ 109* lobe seperation installed at a 112* intake centerline. The engine is factory rated at 215 FWHP @ 3,800(its TOP goverened RPM it makes more at higher RPMs but is restricted in a heavy truck by the governor) and 325 ft/lbs @ 2,600. With an edelbrock 3704 intake bored to 2", open center 454 style TBI spacer, 75 lb/hr worth of injector, 1.6:1 roller rockers, JBA shorty headers, electric fans, an underdrive crank pulley, and DIY prom tuning, it has pushed out over 248 RWHP @ 4,800 and 317 ft/lbs @ 2,700. It has pulled a 5,300 lbs G-Van with 3.73 gears, a 700r4 with a 2,000 stall, and P295/50/R17s to the following times.
Plus it has NO difficulty pulling a 4,100 lbs boat behind my 5,300 lbs van(well over 10,000 lbs when loaded), up a 1+ mile long 6% grade, while maintaining 70+ MPH in 3rd gear with pedal left. Unloaded semi's would be eating my back bumper otherwise as there is NO climbing lane.
Medium duty TBI unit.
PS- the pod fits our TBIs as well and injectors are available to 125 lb/hr.
i see this thread is old. but fast where did you get your hands on that TBI unit. im seeing a bunch in the scrap yard lately (cash for clunkers) but not like that. im running the lo5 in jeep wrangler for offroad and mud bogs.. and looking to pick your brain some. im new to forums so im not sure how else to communicate with you. im in process of rebuild now. i added mild comp cams cam xe249 series cam and looking to port the 193 castings.. any idea's.. thanks!!
