mvvette97

My friend has a 97 firebird that the engine went bad. We know a local guy that has a rebuilt 94 LT1 that he is willing to sell. I know something with the opti is different but will I need to change the cam also? What needs to be changed for the 94 engine to work in the 97?

brianswimmer23

the computer may need to be as well as the wiring harness, different emissions on the 97 than on the 94 plus the trany. but you shouldnt have many more issues that i can think of.

mvvette97

I figured I would just swap all the parts over so I shouldn't have to worry about the sensors and pcm

sbs

Use the knock sensor from the 97 and have the computer tuned to ignore the CPS. No other changes required.

mvvette97

what is CPS??

chevyz4life

my guess.

mvvette97

Ohhh, so does the 97 have a crank sensor?? I guess I didn't know they did. I thought it was just the opti.

Injuneer

In OBD-II (96/97 LT1) they added a crank position (CKP) sensor to detect misfires, only. The Opti still provides the cam position signal for ingition and injection timing. There's a 4-pole reluctor wheel on the crank, just inside the timing cover, and a pickup mounted in the lower portion of the timing cover.

mvvette97

ok I see. Is it possible to just swap that wheel and cover over to the 94 engine? If not then what happens when the pcm doesn't see the readings from the crank sensor?

Injuneer

You need to swap the timing cover, the reluctor wheel, and the damper hub. The 96/97 damper hub is shorter, to allow space for the reluctor wheel. If you want to use the vented Opti from your 97 on the 94 engine, you need the 96/97 timing cover, the 95/97 timing set, and a cam with a deeper pilot hole and the longer dowel pin. If you leave the unvented Opti on the 94 engine, you will need a new short Opti harness, from the passenger side of the intake manifold to the Opti.

Your 97 engine also has a vacuum switch on the passenger side, that tells the PCM if the EVAP purge system is working correctly. 93-95 does not have that switch. You will also have to swap the exhaust manifolds, since the AIR connections on the 94 engine manifolds are larger than the 96/97 manifolds.

mvvette97

well I'm doing this for a local kid in town so I'm tryin to do it as cheap as possible. So I'll just need to use his cam and chain and all the parts on the front? I wasn't sure if his wheel for the crank sensor would fit the 94 crank but if it will then that's good. I'm sure his cam is probably ok also. I'm gunna pull the engine in the morning so I'll just yank the cam out also. I'll be honest here, I have always had LS engines so the LT1 is new to me on the inside. But if I'm able to swap all his parts over to the 94 then we should be set good.

ACE1252

Don't forget to swap over the key for the cam sprocket on the crank too. It is cut for the hub(I think its either cut more or less...can't remember...but it is different). I damaged mine removing it and had to get a new one. It can be tricky to install.