I have a 95 that’s blown and purchased a 93 engine. I understand that the opti and intake are slightly different I plan to use the 95 intake on the 93 and swap the opti cover to vented one. My concern is will I need to swap exhaust manifolds as well or can I run the 93 manifolds on the 95 or could I just swap 02 sensors . I’ll be using 95 harness and pcm. Also any other tips would be greatly appreciated.

 

There are other differences between 93 and 95. Shoebox has a good chart:

http://shbox.com/1/4th_gen_f-body_ye...onversions.pdf

As far as the exhaust manifolds, keep your 95 exhaust manifolds, AIR plumbing, EGR plumbing, and 4-wire O2 sensors.

Keep your 95 intake manifold including the throttle body, fuel rails, and injectors - the 93 injectors flow less, and the 93 idle air control (IAC) has a different harness connector. You don't need the TV cable connection on the 93 throttle body.

Keep your MAF sensor and air ducting.

The Opti is a toss-up. While you can get a vented cap, that will not exactly duplicate the venting of the 95 Opti. The 95 has one of the vent connections on the body, rather than both on the cap. I would think it would "vent" slightly better. Connection for the harness on the 93 Opti requires a "short" harness connector. 95 wiring harness has a "long" connector. But you can just swap out the 93 harness extension replacing it with the 95 harness extension between the connector on the bracket on the side of the intake manifold and the Opti. And some replacement Opti's now come with a permanently attached harness extension, so who knows what's on the 93 engine at this point. The work to go to a true vented Opti is extensive - timing cover, timing set, cam dowel pin.... probably not worth the work.

The 93 oil pressure sensor is above the oil filter. 95 sensor is on top of the block behind the rear edge of the intake manifold. May require harness adjustment.

 

Thanks. So I’ll use the 95 intake and everything attached to it and swap over to the 93. Run 93 opti harness with 95 engine harness. But when doing that what will I do with the vaccum lines that go from the intake to the opti. Would that cause a leak or a miss. Could I move the oil pressure sensor to the location of the 95. Trying to do as less wiring as possible

 

A vented cap for a unvented Opti should have two hose connections. One hose comes from the blue plastic 90° fitting on the air inlet rubber elbow, existing on your 95. The other would connect to the hose with the blue/white plastic check valve and flow restrictor that runs from the 95 intake manifold to the 95 Opti.

http://shbox.com/1/opti_vacuum_hose.jpg

http://shbox.com/1/opti_vacuum_harness.jpg

All the vacuum lines on the 95 intake manifold should remain connected. The complete EGR vacuum parts stay on the 95 manifold. If your car had the AIR system recall, there's a vacuum line that goes down to a solenoid near the AIR pump.

http://shbox.com/1/air_pump_recall.jpg

This brings to mind two more issues.

The 95 has the AIR pump attached to the front of the engine, sharing one bolt with the water pump. The 93 mounted the AIR pump to the subframe. If you still have a functional AIR system on your 95 move the AIR pump and any connected parts to the 93 engine.

The PCV valve plumbing is different between 93 and 95. The PCV valve on both intakes is in the same location. But the 93 has a short “C” shaped hose that bends directly from the valve to a nearby vacuum nipple on the manifold. The 95 PCV vacuum connection is on the front of the manifold, below the throttle body. Keep that intact when transferring the 95 intake manifold to the 93 engine.

http://shbox.com/1/pcv_pipe.jpg

As far as the oil pressure sensor, if the 93 block has a threaded connection for it on top of the rear block wall like your 95, move the oil pressure sensor and 90° fittings. If no plugged hole in the block, you MAY have to extend the single wire for the 93 location above the oil filter. 95 harness might be long enough???

http://shbox.com/1/oil_pressure_sensor.jpg

http://shbox.com/1/op_sensor.jpg

http://shbox.com/1/harness.htm

 

If I use the 93 opti what do I do with the vacuum lines that we’re going to the 95 opti to intake
do I plug them?


With the 95 air pump I’m not sure if it works I bought the car not running.

im also not sure if the 93 have the hole for the oil pressure sensor. 93 is still in a running car. I’ll check it this weekend

 

You said you were using the 93 Opti, but buying and would “swap the Opti cover (cap) to vented one”.

Simple - you keep the 95 Opti vacuum line on the intake manifold and attach the other end to one of the Opti cap vents. You leave the Opti vent air supply on the blue plastic elbow on the rubber elbow in front of the throttle body, and connect the other end to the second vent connection on the Opti cap.

I explained that in the first paragraph of post #4. I even linked a photo of those line connections.

 

Right but wouldn’t swapping to a new cap give me one of the two vaccum hoses. I thought you said 2nd is on the body.

 

If you use an MSD cap/rotor kit for the non-vented opti, it has provisions for both hose connections on the cap, thereby making a vented opti out of a non-vented one.

 

Either the cap will have 2 connections, or will include a way to add a connector to the body. If there are not 2 connections, the Opti will not actually be vented. You need air flowing in one hose (from the rubber intake elbow) and out the other hose to the intake manifold. The vent is there primarily to remove the ozone generated by the high voltage jumping from the rotor tip to the spark plug wire contact buttons..

If you only apply vacuum to the Opti, it can suck in the cap, deform it and cause misfires. It may also suck in moisture through the joint between the cap and body, or through the harness tower (a known weak point in the unvented Opti). Might even suck some oil in from the timing cover..

Note also that you have to take the vent air supply from the rubber intake elbow (as done on your 95), because that air has been included in the MAF sensor flow measurement. That air eventually ends up in the intake manifold, then into the combustion chambers. The PCM needs to add the fuel required by the vent air to maintain the A/F ratio.

The Petris cap comes with a vent connector that plugs into the three holes already in the body of the unvented Opti.

https://petrisenterprises.com/collec...stallation-kit

The MSD appears to add the vent to the plastic divider plate that separates the cap/rotor from the optical sensor area.

https://www.corvettecentral.com/2745...UaAh_AEALw_wcB