[Gmecm] Chevy 350 Carburated to TBI / TPI?

[Jay Vessels]

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