Cam choice - 94 z71

[sir_talk_alot]

Hey guys, been awhile. Ive been busy with work and my two side projects-a 75 yamaha rd and a 73 datsun. Anyways, I need to get my big girl finished. 94 z71, 6" lift, 35" 20x10. 4l60e has been built big with the toughest internals i could get, and also a 2k stall converter. The 350 in it runs pretty good. No smoke or noise. The did old school airfilter, and have shorty headers to 3" collectors. Ill run 2.5 two into 1 3" out. Went out to fire it up and its leaking coolant, its a greasy 350, And a few of the manifold bolts are broke. So im just gonna throw another set of heads on it. Ive got a set of tbi heads in good shapeI dont wanna swap vortec heads because finding them around here is 400+ a set plus an intake. I could get a set of old doublehumps to build for 120 for the castings. I dont have a ton of money to dump in it with having to regear the truck. Im already having to save for 4.88s. So with that being said just a stock strong running tbi 350, 2k stall what would be the best cam to toss in the truck to get the most tq out of it? Or best cam for my situation. Or shoot id also listen to best top end budget upgrades heads and cam combo wise. Not building a mud bogger, but i figured if im pulling heads off might as well throw a cam and set of lifters in it, make it a bit better toy hauler and mud slinger. Ive seen people say lt1 cam but open to suggestions. What could i expect from a good cam upgrade? Thanks guys.

[rickpilgrim]

TBI and Cams require computer mods at the very least, for no computer mods try 1.6 rockers, TBI spacer, Injector pod spacer, Edelbrock TBI intake, cold air from cowl area and good cap,rotor,wires and MSD coil with Summit Racing ignition box running iridium plugs gaped @ .045 . This will get you close to Vortec 5.7 power and will work with a Holley TBI on a 383 later.
LT1 cam needs a jet chip to work ok and if you want great more computer mods needed.
BTW- TBI swirl port heads are great for low end but don't really flow enough for good power.

[sir_talk_alot]

I plan on throwing a chip in it and maybe adjustable fuel pressure. Might port the heads since they are there. Wouldnt hurt. Just looking for a tq cam for my setup

[rickpilgrim]

The problem with the TBI engines is not fuel flow it's air flow. If you take the intake valves out of TBI heads there is a corkscrew cast in to promote swirl to better mix and tumble the air/fuel for a more complete burn. If you feel you must cam the motor use comp cams camquest program to pick out what you like.
1.6 rockers are the equivalent of 1 step up in cam in lift and duration. I've had them in my 86 350 for 58K mi now with no problem and it sounds and acts like it has a mild rv cam even though it's got the 929 truck cam.
If you don't want to step up to Vortec heads then you need heads with small cc chambers to keep your compression where it belongs.
Seeing the heads you have are limited try to improve everything above the port. Just doing what I posted will give you close to 45 flywheel hp but more importantly in the 50 ft lb of below 3600 torque. I've done that same build to 4 TBI trucks and everybody was happy with it.
Jet and other chips to performance tuning is like putting a bandaid on a gash that needs 10 stitches. Those chips are designed for stock engines, throw a cam and headers in the mix and yes they help but what should be done is strap that exact motor to the dyno and find the optimum fuel/timing/tempature for best power and burn chip off that data.
These days I'm lazy, out goes the mouse motor and in goes the big block.
Use camquest to find what you need if you must cam it.

[sir_talk_alot]

50ftlbs isnt bad at all for some small tricks like that. I think these trucks factory had like 300 ft lbs so 350 ft lbs is fine. I dont have to put a cam in, just figured someone out there found a good cam for decent price that helped a stock tbi out a bit. I appreciate the input. And just to clarify, this motor was kind of abused by the previous owner, so no sense in going out and buying heads and big cam and all that and risk tearing up the bottom end when this winter then ill build the motor and go vortec or performance iron heads. Ive fixed the smoked trans and front axles. Since it runs good i just want to give a bit more pep till i build a motor. Axles are next on the to do list with a 14blt rear swap and 4.88s. Then ill move to the motor. Thanks again.

[iluvmy72]

lope time

[sir_talk_alot]

Originally Posted by rickpilgrim

The problem with the TBI engines is not fuel flow it's air flow. If you take the intake valves out of TBI heads there is a corkscrew cast in to promote swirl to better mix and tumble the air/fuel for a more complete burn. If you feel you must cam the motor use comp cams camquest program to pick out what you like.
1.6 rockers are the equivalent of 1 step up in cam in lift and duration. I've had them in my 86 350 for 58K mi now with no problem and it sounds and acts like it has a mild rv cam even though it's got the 929 truck cam.
If you don't want to step up to Vortec heads then you need heads with small cc chambers to keep your compression where it belongs.
Seeing the heads you have are limited try to improve everything above the port. Just doing what I posted will give you close to 45 flywheel hp but more importantly in the 50 ft lb of below 3600 torque. I've done that same build to 4 TBI trucks and everybody was happy with it.
Jet and other chips to performance tuning is like putting a bandaid on a gash that needs 10 stitches. Those chips are designed for stock engines, throw a cam and headers in the mix and yes they help but what should be done is strap that exact motor to the dyno and find the optimum fuel/timing/tempature for best power and burn chip off that data.
These days I'm lazy, out goes the mouse motor and in goes the big block.
Use camquest to find what you need if you must cam it.

Did you change pushrods or leave the stock ones from the 1.5 when you went 1.6?

[rickpilgrim]

Originally Posted by sir_talk_alot

Did you change pushrods or leave the stock ones from the 1.5 when you went 1.6?

No, not for factory roller cams. Take a piece of cardboard about 2' x1' and put 2 side by side rows of 8 about 3/8" . Make one end front and when you take your pushrods out use that to mark their location so you get them back in the same order. Clean you pushrods making sure they are not plugged and let oil through.
When installing your new rockers put a bit of engine assembly lube on both ends of the pushrods and the rocker face for the valve tip. Set the pre load of the rocker at 1/2-3/4 turn down from initial contact , making sure each cylinder is at TDC while adjusting it .Other than that there's nothing else you need to do to install the 1.6 rockers.