Re: TBI, was Re: Hornet status

[farna@xxxxxxx]

Scratch the booster pump idea. EFI needs a steady high pressure fuel stream for the injectors. IIRC TBI requires less pressure than MPI (due to fewer injectors?), but still requires a constant pressure. So you need a pressure regulator and return line or an in-tank fuel pump with pressure bleed. The only way to get the later is to use a 97 or later XJ/TJ pump and tank, or convert your tank to mount the pump (not sure how big the hole needs to be, might be doable without cutting the tank itself). 

There is no problem with using an HEI distributor or knock sensors. There is no crankshaft position sensor when you use the HEI distributor -- the position sensor is in the distributor itself. As I mentioned you can use the stock GM ECU without an HEI distributor. You just have no spark control and the "check engine" light will stay on. Fuel delivery will continue to work just fine though. If you can locate an in-line six coil in cap HEI distributor I'd use it for the spark control though. Switch guts from the V-6 distributor. Would mean you need to buy both, but should be worth it in the long run. The distributor could be a later project though. 

You may not need an adapter for the throttle body. You might be able to do a little port matching and drill/tap the intake. That you'll have to see. Since you're using a 2V carb now you'll need the small 2V throttle body from a 2.8L V-6 (Holley lists the replacement as 400 cfm for 1985.5-1989 S-10/T-10 Chevy/GMC 2.8L equipped trucks, I'm sure Camaro/Firebird and other cars used the same, but may have direct port injection). 


On June 10, 2005 Tom Jennings wrote:

> On Thu, 9 Jun 2005 farna@xxxxxxx wrote:
> 
> 
> If I can assemble a TBI system from junkyard parts (and strategic
> new) I will do it this year, and write up the process.
> 
> I want only a carburetor replacement; I'm not looking for maximum
> performance, I want reliability, simplicity, good fuel economy.
> Plus I'm very lazy.
> 
> I don't want to use knock sensors, crank-position sensors,
> multi-coil or HEI ignition. I know all those things make for a
> better system, but I don't have the time, money nor inclination.
> I just wanna get rid of the !@$$%! carburetor. I want to bolt it
> to my existing, installed, bracketed and hand-fitted, intake
> manifold. I assume I'll have to make an adapter.
> 
> I know this is technically possible.
> 
> 
> Here's what I've determined so far:
> 
> *** All-GM OEM parts are the way to go. Cheap reliable and
> plentiful!
> 
> *** Throttle bodies are the easiest component to select. I'll go
> to U-Pull-It.
> 
> *** A booster pump (9 - 12psi) following the existing mechanical
> pump should be just fine. No tank recirculation or tank-mounted
> pumps.  All that just seems silly to me. Mechanical pumps suck
> fine, you can filter between the two pumps cheaply and safely.
> 
> *** The hard part to me right now is picking the ECM to use. I
> know I want one that works with distributors -- but can I pick one
> that is capable of changing ignition timing, and simply not use
> those outputs? Can I ignore or terminate unused inputs like knock
> sensor?
> 
> I'm looking...
> 
> 
> 
> 
> 
> .


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