1994 4.3l refresh mods (wanna let her breathe).

[th838]

Original owner of a 94 c1500 single cab. Did an airaid intake and tb spacer bout 5 years ago. Has an old flowmaster since 1997 or so with an exhaust leak somewhere… 201k on the odo. 4/6 drop with 275 on 20” rear with 4.10 gears (used to be lifted with 33’s so gearing is low now but I like it).

Was going to put little headers and clean up the exhaust setup a bit don’t really know what would be best on this. Sound is secondary, not trying to make a v6 sound like something she’s not, just want her to breathe right. Flowmaster 50 maybe??? I was thinking dual in (from the shortys) and dual out using the muffler as the collector but I don’t know much..

Truck still has all the emissions equipment installed, but no longer gets inspected. Is there anything from the intake side I can do to allow her to breath a bit better? I’ve seen egr block off plates marketed? Cat delete?

Not expecting big power, just want a happy little v6 that run another 200k .

 

[th838]

So I’ve had some time to play this morning and think I’m on the right course. I’d like to swap the 94 tbi heads for a set of newer vortec heads (clean up and whatever the heads need too). If I’m going down to the block I might as well replace as many maintenance items as I can. Is there a little torque cam that would play nice with the vortec heads? Maybe a little mill on the heads for a slight compression bump? I’ll do the Edelbrock manifold with the tbi adapter and run some 350ci injectors (should I get a bigger tb)?. Are there a set of mid/long tube headers that work? Can I still use my tb spacer with the modified manifold?

 

[1998_K1500_Sub]

Back around 2002 I was keen on trying to make some power with the 4.3L TBI in my 1995 S10. I remember reading stories such as this in Motor Trend:

Chevy 4.3L 262ci V-6 - Engine Build - Overview - Tech - Hot Rod Magazine

We build a Chevy 4.3L 262ci V-6 using V8 parts and technologies. Find all the details inside Hot Rod Magazine.

www.motortrend.com

If you want to make that 4.3L more fun to drive, change the ECU tune to do at least the following:

- change it so power enrichment is enabled without delay (typically there's a delay built into the GM tune, it's a few seconds); this can be easily tweaked, e.g., by changing the RPM at which power enrichment is allowed to occur immediately (I think this value's typically 3200RPM).

- change the power enrichment enable so that, instead of being triggered by the TPS, it's triggered by manifold vacuum. Doing so provides a welcome, extra "umph" at low manifold vacuum akin to the power valve on a Holley

- disable EGR

- change the shift points and TCC lockup to suit your taste / tires / rear gear. Doing so will enable spirited driving if that's your thing, e.g., downshift with less throttle tip-in, upshift at higher speed, etc.

- I've likely forgotten a few tweaks; maybe someone will comment

If you want to make it drive better with a trailer / load, I would approach the tweaks a bit differently. I won't comment, here.

I used TunerCat to make changes to the base tune, with a plug-in adapter / circuit board and EEPROM from Moates in the ECU. If you need assistance, drop me a note, but others here can I'm sure help.

Eventually, on my S10 I pulled the 4.3L and shoehorned-in an L31 long block, then added an Edelbrock pn #3506 (#3505 is similar) EFI manifold with individual injectors in the runners. The whole thing runs off the OE 16197427 ECU w/ custom tuned $0D, which batch-fires the injectors (left bank / right bank). The original TBI unit is neutered in Edelbrock's design... the injectors are removed but the throttle body is retained and mounted atop the Edelbrock manifold. I deleted the EGR from the tune, thus sidestepping the need to install the EGR plumbing / hardware; that simplified matters.

Similar parts may be available today.

OP, you may not be interested in this type of conversion but someone else might. And there's always the LS swap option.

The Edelbrock kit's instructions are here, from Jeg's site:

350-3506.pdf

 

[1998_K1500_Sub]

I’ve seen egr block off plates marketed?

You'll need a tune to make any block-off work well... but one can just disable the EGR in the tune so a block-off is unnecessary.

Cat delete?

This was the subject of a recent, epic thread...

CAN I CUT MY EXHAUST OFF?

My exhaust on my truck is stock from the engine to the cat. Then cut off around the back of the cab with a flowmaster Super 10 short type muffler. It only has one o2 sensor and it's on the front of the cat. If I cut it off in front of the cat I would have around 1 inch to weld new pipe to and...

www.gmt400.com

I’d like to swap the 94 tbi heads for a set of newer vortec heads (clean up and whatever the heads need too).

I had once considered this for my S10 (see earlier post). I actually have the heads, still, from a 1996+ 4.3L Vortec L35. Yes, they're for sale.

Is there a little torque cam that would play nice with the vortec heads? Maybe a little mill on the heads for a slight compression bump? I’ll do the Edelbrock manifold with the tbi adapter and run some 350ci injectors (should I get a bigger tb)?. Are there a set of mid/long tube headers that work? Can I still use my tb spacer with the modified manifold?

Your objective seems to be improved volumetric efficiency, and possibly some fuel delivery changes. Once accomplished you'll need a tune to make the most of it. Factor it into your abilities / budget.

 

[Schurkey]

I instead pulled the 4.3L and shoehorned-in an L31 long block,

Winner.

Blowing time, money, effort, and enthusiasm on a 4.3L is even worse than doing it with a 305.

 

[Erik the Awful]

Was going to put little headers and clean up the exhaust setup a bit

I wouldn't bother with headers on a 4.3. Enjoy the V6 for what it is, cheap and reliable. Spending money for speed parts on a 4.3 is putting a diamond in a goat's butt. It's never going to be pretty.

 

[Ando069]

I'll start by saying i do agree that though a good engine its ot really worth it to me to invest "much" in the 4.3.. but in my case my exhaust manifolds on my 4.3 are bad.. someone buggered some jb weld over the holes and probably cracks as well. For the time being im wanting to drive it while i wait for a v8 swap... here is my question and i believe the answer is yes..

Do the 96 4.3 (sonoma/s10) and 1988 4.3's in these trucks have the same bolt and exhaust ports? I found a great deal on stainless shorty headers that say they bolt up to factory y-pipe and they are cheaper then the CI manifold replacents..

I just want to button up the exhaust and drive it as is for a little... it will get a v8 in the spring..

Thanks in advance for the kbowledge.

 

[Schurkey]

The only OEM variation in the small-block Chevy exhaust bolt pattern was when they added an additional hole at the far rear (and far-front, to make the head interchangeable left--right) to accommodate exhaust manifolds where the rear runner went more rearward before going "down" to fit some chassis.

You must be registered for see images attach

I suppose they did the same to the V6, although I have no direct experience.

Point is, if your heads use the far-rear hole for the manifolds, they may not when headers are installed.

But perhaps others have direct experience with V6 exhaust issues.

 

[Ando069]

Thanks Schurkey for taking the time to reply, i'm actually familiar with V8 versions...

i'm now dealing with the 4.3 in a 88 c1500 and from my research it seems from 88 to 96 the head "bolt Patterns" didnt change but GM did some squirlly stuff with twisting the intake runners for the "vortec"..

my question was on the 4.3.. or the 3/4 V8 as some come to call them.

 

[Ando069]

I ordered them i'll update on the fit.. I dont want to contitrube to another dead end thread... i read sooo many.