TOP END REFINISHING

[orthodoct]

I used CPU heat sink paste, used a finger to coat thin film over entire surface, torqued down in three steps, cleaned excess at margins with a q tip. Idea is to transfer heat from heatsink surface on underside of ignition module to plenum. Covering entire heatsink surface is the goal; can put on too little with result of incomplete transfer of heat resulting in hotspots with potential to burn out IGM, but too much only squeezes out excess when torqued. I play around a lot with electronics and ham radio. KC4NWF

[mike100]

The secondary ports get dirty because they don't run all the time.

[mike100]

I will get the source of the thermal compound I used. It comes in jars that could do dozens of devices. Been running it for a couple years with no problems.

Pretty much the same stuff they give you for GM HEI ignition modules for the distributors. I learned a good lesson once- don't use the paste and the car will run for about 2 hours before failure.

[Dynomite]

Before you tighten down the Plenum (with Plenum tipped up in front) and ALL vacuum lines, and DIS module connections in place....check your vacuum systems.

With all vacuum lines connected, turn key on and listen for vacuum pump to shut off. If it does not shut off, start at the closest vacuum line to the vacuum pump disconnecting the line and holding your finger over the end. If the pump shuts off the leak is on other side of that. Go to next fitting and do the same until you are past the leak wherein the vacuum pump will NOT shut off. You have now located the leak.

Also check your HVAC and Cruize Control Vacuum System (check ALL connections). Also check your EVAP Purge system connections (charcoal canister which is under drivers side headlight on your 90'). That single small vacuum port under front of plenum facing rearward (90' only) is for the Evap Purge System. The second larger vacuum port on drivers side lower front of plenum is the main vacuum line for the Charcoal Canister. The second Vacuum port right next to that Charcoal Canister port is your PCV Vacuum port.

With the key on, ground the pink wire in the green connector (third from drivers side) on ECM. Use a small finishing nail stuck in alongside the wire connector with an alligator clip pigtail attached to the end for grounding. This will activate the Secondaries which you can watch with the plenum tipped up in front before you bolt it down. This after you are sure you have NO vacuum leaks in the Secondary System.

I promised GC I would not mention any modifications .....but you should eliminate TB coolant so you do not have to mess with coolant every time you remove the Plenum......DO NOT TELL GC I suggested this

Vacuum Systems 90' and 91' (Secondary and Cruize/HVAC)

[efnfast]

Dom, this is the thing bolted to the bottom of the plenum? I'm soon to change my plenum, this sounds important.

[XfireZ51]

Originally Posted by efnfast

Dom, this is the thing bolted to the bottom of the plenum? I'm soon to change my plenum, this sounds important.

Yep, that's the Ignition Module. Has 4 connectors around the periphery.

[efnfast]

Originally Posted by XfireZ51

Yep, that's the Ignition Module. Has 4 connectors around the periphery.

Where does one come by this stuff? It'll cook the IM without it huh? Thanks God for the forum.

[XfireZ51]

Originally Posted by efnfast

Where does one come by this stuff? It'll cook the IM without it huh? Thanks God for the forum.

It's "unobtainium" that can be found at Radio Shack. Just ask for heat sink compound.

[orthodoct]

I got a 20 grams container from Amazon for about 10 bucks. Will last me a lifetime.

[orthodoct]

Been using Bosch 4503 Platinum/Iridium with 4 prongs. Didn't think that that I would have to replace them until I got the PCV tube leak; fouled them.