when instaling carb on an 85 vette does the ecm still control the guages and transmision was told the 85 did not have a lockout but dont know about the digital guages is there a kit that converts the system

Why?

I really hate it when people ditch EFI for carb. Even the most crude EFI is better than the best carb. The only advantage is that people still seem to understand the carb better, but in reality, understand neither.

That's my opinion... and it's worth no more than anyone elses. Just had to share.

With a bit if education, EFI is the way to go. Now, with the mid-80s EFI... that's a problem. It was crude, but there are ways of improving it without going away from EFI.

Ways of improving that will help performance, reliability and MPG.

First off, you can upgrade to a later EFI system, in fact, the entire LS1 system is available for early C4s. Check out www.eficonnection.com

I agree with Andy that converting to a carb on a stock or mild motor is a waste of time and money, and will cost you fuel economy and performance in the long run.

However, the ECM will still control most gauges, if not all, but you may get some SES lights. The trans is not computer controlled for any shifting, but will control TCC lockup. That function can be activated with a simple ground switch.

Matthew

Funny, wish I could find the picture.. someone blocked off the throttle body, cut a hole in the top of the plenum and bolted a carb on to their TPI car...


It's like a step backwards.. if carb's were better they'd use them today... now saying that.. they are cheaper..
-=Rick

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Gauges work independent from the ECM ; wires run direct from sensors to gauges.
All you loose is the range / MPG readout

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[IMG]http://i171.photobucket.com/albums/u309/vetteoz/Engine/carbonTPI-1.jpg[/IMG]

$3,000

And I hate it when people tell the asker of the question that his idea is bad, stupid, or not cost effective. There are plenty of reasons to go carb'd, the most obvious is for a race motor.

I agree with the points above, it's a step back in time for no reason in most cases. But let's be clear - it is simpler and most likely cheaper, and it is a helluva lot less to troubleshoot at the track when something goes wrong. Some people don't need closed loop operation, they run in specific situations with a specific set of requirements, they don't need emissions and fuel mileage and diagnostic capability, etc etc.

The question was regarding ECM controls, not "should I carb my '85?"

Answer the question first, then help get to the bottom of "why would you want to do that?" Because in a lot of cases it may not be the right way to go.

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The other reason? Ity kills whatever value was left. How many of us have seen folks try to sell carb'd C4's only to be nearly unsellable or sold at such a discount to make them real money pits? For example, the car would be 100% illegal in CA and no one would want to go near it. CA is stuck with emissions on cars until pre-1976; it is not the sliding scale other states enjoy.

Doing a carb conversion is valid for race conditions. I meant to add that to my original response. For the street, carbs are really a step backwards. Carbs are at their best when wide open. They dump fuel so much faster than EFI can ever dream of.

Even NASCAR is finally ditching the carb and going EFI! I will be curious how it works out for them.

Is your goal a race car or an attempt to improve reliability? The early C4 has a very lame wiring harness, they are prone to insulation failures, which lead to dead shorts and crossed circuits. Many of the troubling issues with an early C4 can be attributed to age of the sensors and condition of the harness. If you see wiring shrinkage around connectors, it's time to consider repairs. Check the big bundles, and anything that might get near the block. Chaffing, heat, chemicals, all conspire to eat the wiring up, or, dry it to the point of being brittle.

If do you a carb conversion, you will need the carb. On a stock L98, a 550 CFM to 650 CFM is ok, but you will need to jet it rather lean. Intake, tons to chose from, but stick lowrise, there isn't a lot of hood space. You will need a lower pressure fuel pump, somewhere down in the 10-15 PSI range. You will also need brackets to accept not only the throttle cable, but the cruise control and TV cable (trans kick down).

I am sure someone can burn your chip to disable the injectors from firing, and use as many of the sensors, and perhaps even the TCC lockup. The TCC lockup is very important to MPGs and performance, otherwise, the torque converter will not fully lock, meaning there is always lost power in the transmission. The invention of the locking torque converter has let the automatic become as efficient as a manual at highway cruising speeds. They only lose 1 mpg, on average, on the highway over a manual! Before then, it was a huge loss.

Ultimately, it is your car, and we will help you do whatever you want. I just wanted you to be aware that it may not be the best idea around.

Done right, there's nothing wrong with a carb setup

The biggwst issue you're going to have is hood clearance

Just keep all the original parts in a box

In some cases, it brings value to the table

Some people new to C4's don't want to learn the ridiculous complexity of the stock L98 or LTx EFI systems. I'm sure that on the car I was asking about last week a carb conversion would make it saleable.

But yes, we are talking about the exception, not the rule.

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Not required
I have a Vic E intake with 4bbl Accufab TB that I can swap a carb on to for testing purposes
When running the carb , the still connected ECM ('165 ECM ) primes the pump as stock then does nothing .Injectors are not going to pulse because the ECM is not seeing any ref pulses .
Dash fully functions except as noted above

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Pete K will confirm but IIRC lockup is required on the early T700's because they only had full fluid flow to the trans cooler when in lockup mode.
This was changed to give full flow at all times with the revisions done in '89?