Swapping motors

[Kenny734]

I have a bad 350 fuel injected engine in the car and I cant really afford a 350 right, so can i put in a 305 in it without any probs?

[JWhite8055]

You can put a 305 in it but you'll need to change ECM or run the engine in open loop mode.

[Kenny734]

I am swapping a 350 for a 305 in a 89 Chevy caprice and How do I change the ECM or run engine in open loop mode?...Which is the best way and easier?

[JWhite8055]

The wiring harness should be the same, the ecm is located on the passenger side behind a plastic kick panel just ahead of the door. Just remove the panel unbolt the ecm unplug the connector and swap it. Thats the best and easiest way

[hakogen]

what kind of tranny? turbo 400, something along those lines?

[quaddriver]

you can put in the 305 no problem, you dont have to run any 'open loop' modes either. the 305 shouldnt run behind a 350 ecm because the spark table is a little agressive for a 305. You can offset this a bit by running higher octane fuel always (ouch) or retarding base timing a degree or two until you get a proper ecm (all years the 350 was avail the 305 was avail)

[JWhite8055]

Disconnecting the distributor from the emc sets the system into open loop mode, the spark timing is then controled by the distributor. It negates the need to retard timing. NOTE this is also a TEMPORARY fix, change the ecm if you expect any kind of performance.

You could of course completely de-computerize the engine as well. Change the distributor to a vaccuum controlled model and replace the intake and toss on a good ol' Rochester.

[JWhite8055]

a 400 tranny will work

[quaddriver]

Originally Posted by JWhite8055

Disconnecting the distributor from the emc sets the system into open loop mode, the spark timing is then controled by the distributor. It negates the need to retard timing. NOTE this is also a TEMPORARY fix, change the ecm if you expect any kind of performance.

You could of course completely de-computerize the engine as well. Change the distributor to a vaccuum controlled model and replace the intake and toss on a good ol' Rochester.

Whoa nelly...

disconnecting 2nd dist cable (the 4 prong not 2/3) only disables the EST and sets the EST code, it DOES NOT negate closed loop operation. IT is no different than an est failure. And without the return value from the ECM, the gizmos will only select small timing advances, not enuf to develop full power.

Closed loop is triggered by ECT reading 100* or more. In the event of ECT out of range, the TBI ECMs use run time to guess that the car is heated up. In the event of an O2S failure the ecm will STILL use the last BLM settings to make a stab at closed loop. Note, this is to be considered limp home mode with the thinking that the owner will seek help quickly and does not mind the resulting loss of power and non-overfuled condition.

(true closed loop also negates lockup of the torque converter, which for a prolonged period of time is fatal to a 700R4/4L60/E)

[JWhite8055]

..well maybe I had to do something else I dont recall at the moment, but I've run engines in this open loop mode before. I _do_ remember cooking the 4L60 tho!

At any rate, an new or used ECM is in order for this job.