Any adverse effects if I disconnected the two lines going to the throttle body spacer and still have the EGR connected? I'm planning on using one of the ports on the lower intake for a temp sensor for my electric fan set up.
The coolant lines are used to reduce the temperature of the returning exhaust gas back into the intake. Exhaust temps reach in excess of 600 degrees. So every time the EGR opens, close to 600 degree air is being diverted into the intake manifold. You would likely begin to see drivability issues.
Revised 24 July 2011 to add better temp sender location description and the necessity to loop the fluid flow through the heater circuit.
How it works:
If you want any kind of operation similar to stock, the ECT/heater feed line is the best place for a temp sender or fan thermo sensor. After all, the computer uses the ECT to pick up data on how warm the engine is. Putting the temp sender in the same line as the ECT is a simple way to get the best possible accuracy at minimum cost and complication.
Some things to keep in mind:
Just be sure that you haven’t blocked the coolant return because of a leaky heater core. For this to work correctly, the coolant needs to flow from the ECT sensor tubing back to the water pump. That means a leaky heater circuit gets looped rather than just plugged up. Join the rubber hoses together with a hose splice from Home Depot rather than plug them up.
Where to put it:
Use the heater feed that comes off the intake manifold that has the ECT sensor in it. Cut the rubber hose that connects the manifold water feed to the heater and splice in a tee adapter for the temp gauge sender. That way you will get the most accurate temp readings since the coolant is always flowing through the heater circuit in a stock car. Remember to include a ground wire if you use an electrical sender.
Tee adapter info:
Make a pilgrimage to your local hardware or home supply center and get some copper pipe and a tee that fits the temp gauge sender. Solder two pieces of copper pipe onto a copper pipe tee with threads in the tee part. Find the correct brass fitting to match the temp sender threads to the tee fitting.
If your emission system is not working and the egr valve has been deleted then eliminate the coolant lines to the throttle body. If that is not the case then look for an alternate location
The lines also keep the throttle body from icing in the winter. It was a bigger problem on GM's of the era, but the TB would Choke from ice on cool, very humid days.
There is another spare 3/8" NPT boss that can be used on the driver's side of the intake. EXACT same as the one the coolant line is in.
Thing is, the back of the intake tends to run 10-15 degrees cooler.
What i'd do is relocate the factory temp sender from the front driver's side of the intake to this boss and extend the wiring. Then install your aftermarket temp sender in this spot up front