[Gmecm] Chevy 350 Carburated to TBI / TPI?

[Jake Tucker]

Bob,
    If you are going to use a TH400 transmission, you will want to find
a wiring harness from a truck equipped with the TH400 and use a CAL from
a TH400.  If you can't find the CAL, let me know and I can tell you
which one I used that I uploaded to the server several years ago.  The
TH400 uses an electric solenoid for the kick-down on the transmission.
On a carb, this is activated by a simple switch that is below the gas
pedal and senses full throttle.  On a TBI system, it is controlled by
the computer, which allows you to change the set point.  You can
probably re-pin a harness that doesn't have this wire, but that's a
little more difficult.  Look for an orange wire that is by itself, near
the firewall on the drivers side.  The TH350 and manual trans versions
of the TBI system will not have this wire.  The TH350 uses a mechanical
cable for the kickdown, and obviously the manual trans doesn't do
anything.

Jake

-----Original Message-----
From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On
Behalf Of Aphelion79
Sent: Thursday, January 11, 2007 4:13 PM
To: gmecm at diy-efi.org
Subject: Re: [Gmecm] Chevy 350 Carburated to TBI / TPI?

Ok, so that means I will need the distributor from the truck that I pull

the TBI, harness, and ECM out of (and all accompanying sensors) as well 
right?

Also one more thing I've thought of...
How does the TH400 transmission work with the stock carburetor?  Does it

have anything to do with it? If so, how does this work with the TBI?  
I've only messed with manual transmissions in my lifetime, never worried

about autos! =)

Thanks for all the help, thats about all I can think of that I'd have 
problems/concerns about!

Jay Vessels wrote:
> Hi there!
>
>> I was wondering if the TBI systems used on the '87+ Truck 350s were 
>> fuel only, or did they control timing as well?
>
> They controlled the timing as well, through the distributor ignition 
> module.
>
>> On the GM 151 4cyls I've had experience with they used a computer 
>> controlled timing curve (basically the same idea as a vacuum advance,

>> I.E. the computer has NO idea where the timing is in relation to the 
>> crankshaft)
>
> The ECM doesn't have absolute position of the crank, but it does have 
> relative position in that it trusts that the distributor is set at a 
> particular static timing position, and it adjusts from that.  Since it

> is not doing individual cylinder timing adjustments and is not doing 
> sequential fuel injector firing it does not need to know exactly where

> the crank is.
>
>   I also know of other types of engines using complete timing
>> control where the use of a crankshaft positioning sensor / knock 
>> sensor is used...
>
> Many GM DIS systems don't provide crank position to the ECM.  The 
> ignition module has that data but doesn't pass it on since the ECM 
> doesn't need it.
>
>> Also, for an O2 sensor, do you need one for each "side" of the 
>> engine? (Where as my previous knowledge is I4 and I6's, I only have 
>> one exhaust manifold! =D )
>
> For this system (older TBI) there is only one sensor.
>
>> Also these systems are all OBDI, because to my knowledge OBDII didn't

>> start up until 1996?  (Dunno where I got that year from, but for some

>> reason it comes to mind, lol.)
>
> Right on both counts.
>
> Jay Vessels
> 1982 Chevrolet S-10 Sport, 2.8V6 TBI
> 1984 Chevrolet S-10 Blazer Sport, 2.8V6 (TBI pending)
>
>
>> Thanks for the support everyone!
>>
>> Jake Tucker wrote:
>>> Bob,
>>>     The Carter is a square bore, just like a Holley.  As a matter of
>>> fact, I believe the only stock spread bore carb was a quadrajet
>>> (although that was almost all GM 4 barrel carbs).  Holley, and
others,
>>> do make a spread bore replacement, but the OEM carbs that weren't
>>> quadrajets were all square bores.
>>>
>>> Jake
>>>
>>> -----Original Message-----
>>> From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org]
On
>>> Behalf Of BNRVL at aol.com
>>> Sent: Tuesday, January 09, 2007 11:45 AM
>>> To: gmecm at diy-efi.org
>>> Subject: Re: [Gmecm] Chevy 350 Carburated to TBI / TPI?
>>>
>>>
>>>
>>>  Hello , what is the bolt pattern for  69 Corvette Carter carb.  ??
>>>
>>>  thanks
>>>  Bob Norville
>
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