Is there something better than the OEM TBI carb for my '95

[Darrell]

Hello all,

I finished a rebuild (top-bottom) of my '95 5.7 on my Silverado C1500 about 8k miles ago. Since I just have not been happy with the performance of the OEM TBI on it. I can't seem to get it dialed in right.

Is there a more preferred carb/intake set up ? Would a 4 barrel be to much?

I pretty much left everything stock as I needed a friendly daily driver as well.

I currently have the stock (rebuilt) TBI sitting atop

Intake: Edelbrock #3704
Cam: Edelbrock #3702
HEI Distrib: #1103952
External Ignition Coil: #48000 Street fire

All internal parts such as Lifters, Push rods, Rocker Arms, Heads ect are stock specs as well as the 4L60 E trans.

*note* the catalytic converter was removed

Engine runs strong once it's up and operating at normal temp. It's problematic getting there.

I'm open for suggestions/opinions

Thanks

 

[PlayingWithTBI]

Try this site, I went with the 46mm bored TB with an 18LB spring, and bored my 3704 intake to 48mm (I'm running bigger heads and cam though).

https://www.ebay.com/str/sprperformance

You'll need a vortec fuel pump (and new filter) for these pressures and volume

https://www.summitracing.com/parts/ado-ep381

Then you'll want to tune it, that will help both cold start up and performance.

 

[c1500deathtrap]

If the entire setup is stock other than the manifold, no tuning is necessary. Did you reuse all of the old sensors? Was this problem there before the rebuild? What defines rebuild? Bored? Did you do the work, if so what was the ring gap?

 

[Darrell]

If the entire setup is stock other than the manifold, no tuning is necessary. Did you reuse all of the old sensors? Was this problem there before the rebuild? What defines rebuild? Bored? Did you do the work, if so what was the ring gap?

The original eng and trans was tired and wore out with nearly 235k orig miles and ran like crap to be honest. I replaced with a stock short block replacement from this place via a recommendation. So I can only assume that it's at stock specs.

GM Chevrolet 5.7 350 Short Block 1987-1995 TBI 2-Bolt Main - NO CORE REQUIRED - 90 Day Limited Warranty

The heads are new (rebuilt) stock spec. All sensors are new and I've even replaced them all a second time with new ones.

Overall I'm very pleased with the actual performance once it's warmed up. I'm getting 11-12 psi on the fuel pressure gauge that's mounted at the rear of the TBI. The injectors appear to be working perfect and spray a nice even mist of fuel into the bowls.

If I adjust the timing at "0" TDC, I believe to be correct, then it's hard to start, spits and sputters. If I advance to like "20" then it starts easy but idles high near 1500 rpm.

Just seems to be a TBI issue and I can't dial it in.

 

[letitsnow]

Does it have an IAC, and if it does, maybe it is stuck open?

 

[smdk2500]

If I adjust the timing at "0" TDC, I believe to be correct, then it's hard to start, spits and sputters. If I advance to like "20" then it starts easy but idles high near 1500 rpm.

When you are setting the timing you are unplugging the tan/black wire under the dash before you set it correct.

 

[Schurkey]

I pretty much left everything stock as I needed a friendly daily driver as well.

I currently have the stock (rebuilt) TBI sitting atop

Intake: Edelbrock #3704
Cam: Edelbrock #3702

No opinion--haven't researched the cam specs.

HEI Distrib: #1103952
External Ignition Coil: #48000 Street fire

Is that a TBI-style small-diameter HEI?
IS THE PICKUP COIL in good condition?
I don't trust Street Fire products.

Engine runs strong once it's up and operating at normal temp. It's problematic getting there.

What does the scan tool tell you about coolant temperature, MAP voltage, IAC position, O2 sensor voltage and cross-counts when the vehicle is warming up?

If I adjust the timing at "0" TDC, I believe to be correct, then it's hard to start, spits and sputters. If I advance to like "20" then it starts easy but idles high near 1500 rpm.

Just seems to be a TBI issue and I can't dial it in.

Did you ever compare true TDC of #1 against the damper/timing pointer?
What is the cranking compression?

 

[L31MaxExpress]

Valves too tight perhaps?

 

[LikeARock94]

You say it's a TBI issue but you don't say why. You say you have to set the timing way off to get it to run right, by you don't think that's an issue? The TBI is generally extremely reliable. If you know you have a different problem fix that first before you suspect, with no evidence, that there is a TBI problem. There is basically nothing to "dial-in" on a TBI unless you need to tune the PROM, which judging by the parts on your build, you do not.

Sent from my Moto G (5) Plus using Tapatalk

 

[randomguy]

Put an AC Delco coil in it. Aftermarket coils can cause all kinds of weird issues.