1993 5.7 TBI tinkering

Would love some practical advice. With 232,xxx miles , and a 2.xx geared rear end , I have a slug. I'm not trying to build a hot rod , just better. Have been doing A LOT of reading , and although this has been ours for 11 years , it wasn't my driver , and it's our only GM product we've owned. So I don't speak Bowtie fluently.

I have been over at a TBI site reading (link from here) and it seems the generation 350 my whale is pulled around by is one of the worse from a cam , and head standpoint. I live where I don't need emissions to drive (after 25 years.....) so I wanted to investigate building in stages. I have found a lot of post on build , build , build ($$$) the old 350 , but less on step by step building , as time and money allows. So here are a few questions:

If I wanted to buy some Vortec heads , and still run the TBI , do I need a specific intake for the heads , or will the stock TBI intake work? I don't mind modifying the TBI a bit to breathe more. Read upwards of 50 hp replacing these heads , seems worth it.

Is there a better head than another to source? I will bolt all my accessories back on (A/C , P/S , etc...) , are there heads to avoid because of that?

What , if any Emissions stuff needs to stay? All appears to still be working , just clutters up a lot of stuff.

I saw a few suggestions for a better air box , but seems like its digging through salvage yards to piece together. Is that the only reasonably priced solution for the TBI motors?

I've built (Like rebuilt) a few motors over the years , so I'm pretty familiar with keeping camshafts mild for good street manners and decent vacuum (for brakes , etc..). Is there something the TBI crowd likes better than most?

I'm aware I have given you eye rolling , here we go again material. Remember , I speak motor , just not GM. I am fluent in Isuzu and AMC , so the working knowledge is in there. I appreciate any advice (or links) , and I am not afraid to ask additional questions , or admit when something might be over my head , and I could use more explanation.

Thanks ,
Dan

Do yourself a favor and buy a crate motor everything is new ,comes with a warranty ,and depending on which version you chose base or fully dressed you will end up saving money in the long run . Chevrolet sells brand new motors and Summit Racing sells crate motors from various manufacturers my friend just installed one from Summit and it was $4500.00 complete .

Hi Dan. Welcome. What I'm doing is using a gm crate motor. 330 hp from the general. It has vortec heads but no roller cam. 350hp has the roller cam no vortec heads. For the tbi on a vortec motor you need a GM tbi intake from performance parts. You will have to machine out the distributor hole as the "B" bodies use a large diameter distributor. Other than that, everything should bolt right up

base version of this engine is about $3200. Complete long block, no intake

I have a 4 bolt main block punched .30 over that I will build as time and money allow. I'm aware I can buy a crate motor , but the advice I'm looking for here is giving this 180 (original)hp motor a little more pep in her step until that time comes.

Keep it coming.

DESCRIPTION
24502476 CAMSHAFT - HYDRAULIC FLAT TAPPET.
USED IN G.M.'S 350/330 H.P. CRATE ENGINE. THIS CAMSHAFT IS A MODERN VERSION OF THE OLD L79 327 CAMSHAFT. IT'S PROFILE HAS BEEN SLIGHTLY MODIFIED FOR EXTRA LOW END TORQUE AND DRIVEABILITY. THIS IS A NICE ALL AROUND STREET CAM, THAT PRODUCES BOTTOM END POWER AND HAS A NICE SOUND. WORKS VERY WELL WITH VORTEC HEADS. LIFTERS ARE NOT INCLUDED. NOT EMISSIONS LEGAL.
INTAKE LIFT-.435"
EXHAUST LIFT-.460
INTAKE DURATION @ .050"-212
EXHAUST DURATION @ .050"-222
LOBE CENTERLINE- 112.5

chevy man wrote:

DESCRIPTION
24502476 CAMSHAFT - HYDRAULIC FLAT TAPPET.
USED IN G.M.'S 350/330 H.P. CRATE ENGINE. THIS CAMSHAFT IS A MODERN VERSION OF THE OLD L79 327 CAMSHAFT. IT'S PROFILE HAS BEEN SLIGHTLY MODIFIED FOR EXTRA LOW END TORQUE AND DRIVEABILITY. THIS IS A NICE ALL AROUND STREET CAM, THAT PRODUCES BOTTOM END POWER AND HAS A NICE SOUND. WORKS VERY WELL WITH VORTEC HEADS. LIFTERS ARE NOT INCLUDED. NOT EMISSIONS LEGAL.
INTAKE LIFT-.435"
EXHAUST LIFT-.460
INTAKE DURATION @ .050"-212
EXHAUST DURATION @ .050"-222
LOBE CENTERLINE- 112.5

Nice. OK , I did a little snooping around. I found an intake like you mentioned but that puppy was nearly 6 bills. Sound right? Curious , can anything be done to these heads that would make them any better , or are they glorified paper weights?

I certainly see where guys come from when they say "Skip all of this and .......... , but cams , heads , etc , can be done in an afternoon. I'm a glutton for punishment.

The TBI engines use a roller cam. They are so tiny that an LT1 cam is an upgrade. As is an L98, etc... plenty of cheap used choices out there.

If you don't use Vortec heads you can use a Edelbrock TBI intake. Looks like about the same money

if you have a 256 rear get a set of gears. some tbi cars came with 323 gears that will wake it up

mtrhead79 wrote:

if you have a 256 rear get a set of gears. some tbi cars came with 323 gears that will wake it up

On the list. Thinking 3.55 or 3.73. This highway gear is brutal.

jayoldschool wrote:

The TBI engines use a roller cam.  They are so tiny that an LT1 cam is an upgrade.  As is an L98, etc... plenty of cheap used choices out there.

Jay , ok , again I'm learning the differences in motors. That said , is there a cam I could swap in that I would notice a bump in power with , without needing to change valve springs on the current heads? Without sounding too generic , I'm used "RV" cams in the past for better low to mid power in my 4x4's. Mild , but effective. Is there a good roller that is a drop in , and I could do heads , etc..down the road? This is the type of advice I need. Frankly (honestly) , I didn't know it was a roller motor until you mentioned it. Looked up lifters on RA , low and behold , you were spot on.
Thanks.

Before you go spending a lot on rebuilding an older SBC, look into grabbing a engine in the LS series. Good PNP junk yard engines with trans, wiring, and transmission can be bought for under $1000. You must pull it. Some of them came with a 4L60e, and will fit without modification of the tunnel. You need adapter mounts, but they are only about $50. You will also need a few minor mods to make it fit. The 5.3L is a good choice, and makes a lot of HP. A 6L is probably the easiest with the most HP. An LQ4 from a truck is a really good choice. You can add a cam, and get 400 HP with just some valve springs. You can get some of the LQ4s with a 6L80e, but you must clearance the tunnel a little to get it to fit. The 6L80e has an ultra low and double overdrive, so you can get the effect of a shorter final drive.

There are some install threads on impalassforum.com. If it fits in a 94-96, it will fit in a 91-93.

If you keep your cam lobe centerline at least 112 deg, you will have good vacuum and a smooth idle. If you do not care about vacuum, you can install a Hydroboost for the brakes. (The closer you get to 106 deg of lobe separation, the more choppy your idle will become.) The lines are available from Rock Auto from a mid 80s diesel. I would use the Hydroboost from a mid 2000 Tahoe or equivalent with a flat mounting plate available on ebay for about $25 (fits early 90s Astrovan). You should get a higher rpm stall converter if you up the HP.

If you use the donor wiring loom, you only need to hook up your gauges, and make a provision for O2 sensors in the exhaust if you are using headers. You can use the FEAD from the donor as well, although you will probably need some custom AC lines, and maybe coolant hoses. You need a walbro 255 fuel pump, and maybe reroute or make custom fuel lines. Some of the engines have throttle by wire, and you have the option of replacing the throttle body, or installing an electronic pedal. If it has throttle by wire, it may be easier to install the pedal.

The rear in the 93 is a 2.73, and is pretty much a slug. You can build a good rear with an Eaton Truetrac, and Moser axles for about $1000 if you use your housing. It is not all that hard to do. I did mine, and it is nice and quiet. I used a 3.42 Richmond gearset (they have two lines, one make in China, and on made in the US. The ones made in China are cheaper.) A lot of members like 3.73 gears, but I think they are just a little too much for highway driving. It takes a few specialty tools that I included in the cost. If you get the factory service manual for any 92-3 B body, the instructions are the same.

The springs need to come off to change the cam, so just change those, too. The stock ones were barely enough on the day it was built.

A cam, springs (and 1.6 rockers while you're at it), and 3.42s or 3.73s, and the car will feel like it picked up 100hp and lost 1000lbs.

As for Fred's idea of an LS swap... sure, it's doable. But by the time it's all done, it will cost you a few thousand, and it will be a lot of work.

jayoldschool wrote:

The springs need to come off to change the cam, so just change those, too.  The stock ones were barely enough on the day it was built.

A cam, springs (and 1.6 rockers while you're at it), and 3.42s or 3.73s, and the car will feel like it picked up 100hp and lost 1000lbs.

As for Fred's idea of an LS swap... sure, it's doable.  But by the time it's all done, it will cost you a few thousand, and it will be a lot of work.

Anything he does will cost a few thousand, and will be a lot of work. The LS style swap is no more expensive than his plan to upgrade an LO5. The LO5 will need a computer chip to function with different rockers, and a cam.

The springs do not have to come off to swap the cam. You only have to loosen the rockers, and remove the push rods, and lifters, then reinstall the pushrods, lifters, and reset the rockers. You should still change the springs if you put a more aggressive cam in the engine.

You can bolt an LS type 6.0 L engine in the car without opening it, and have the same HP as the built up LO5. I have an LO5 that has Vortec heads, new 30 over pistons, 4bbl manifold, and an L99 cam that I would trade for a decent LQ4 (less than 100K miles)with the wiring and computer. The heads have been checked and referbed, and the crank turned 10 under for the mains and rods. It is assembled, and ready to go. I was going to get a Fitec TBI, but would rather put in an LQ4 in place of it.

I appreciate all of the advice. Really. I think the most costly thing I will have done is a regear on the rear end. As I can’t do it myself. I’ve done cam swaps and head jobs , so that’s just parts and my labor. I’m not trying to build a missile , just a fun cruiser , and on a modest budget.

I did the rear in my car, and it was the first one I ever did. It turned out perfect. I just followed the instructions in the FSM. It is no harder than a cam swap and the heads. You need a few specialty tools, but the actual build is simple. The hardest part is picking the correct shim, and you have some leeway on that as well; 0.038-0,042 inches. You can get someone to press the bearings on, or even do it yourself if you use some science. It will save you about $500 and you can use that to do something else. You can use top of the line parts, and still be around $1500, even with the tools.

You need a magnetic tool stand, dial gauge, micrometer or caliper, torque wrench, rotary torque wrench, and a pinion holder. You can use a pipe to remove bearings/races, and loan-a-tool for a race/seal installation tool. According to you, you should have a torque wrench, a variety of sockets, maybe even a micrometer/caliper, magnetic stand, and dial gauge.

Moser axles $385, Eaton posi $605, Yukon gears 215, carrier bearing kit $90-120, wheel bearings $60, axle seals $10, fluids $25. Total $1420. You can get cheaper axles, and cheap bearings, gears, and maybe a cheaper posi, but the life span may be reduced. Prices have gone up a lot (about 30%) since I built mine, so I am a little surprised at the cost.