Stupid question but I have never worked on a Stock Manifolded LT1, Im putting headers on for a buddys, does he need that block off plates if hes not using the pump or anything anymore?

 

If his headers dont have AIR and EGR hook ups then yes he will need block offs. If it is 96-97 he will need to have the PCM reprogrammed because he will get an SES light for sure. He might not get one if he has OBD1.

 

I put the block off plates on my 95 Z when I deleted my EGR and got an SES light. The fans kept coming on every 30 seconds. So i put the egr back on the car until I get my longtubes, then I will just have it programmed out.

 

The only way to get rid of the SES light is when you get it tuned out of the computer... even if you have the plates.... BUT is it necessary to have the plates???? I have it tuned out of my computer, but I DO NOT have the plates...... is it doing any harm i.e(losing power... etc)

 

For removing EGR, as a minimum, you need to block off the hole on the back of the intake manifold where the corrugated tube from the #8 exhaust runner connects. Then, if you remove the EGR valve, you need to block that hole with a plate. If you don't do at least one of these, you run the risk of a large vacuum leak.

On the AIR system, there are no "blockoffs" required (if the headers don't have AIR connections). As a precaution, remove the rubber hose that connects from the air inlet ducting to the AIR pump, and cap the connection on the air inlet ducting with a 5/8" vacuum cap. That will prevent the intake system from pulling unfiltered air (and rust particles) through the AIR pump.

If the headers have AIR connections, you need to put plugs in the holes, size depending on the brand of headers.

 

What if you the EGR hooked up but nothing hooked up to the header (the egr pipe)? Would you still have a vacum leak?

 

You would need to block off the EGR tube. I have left my EGR valve on, have the tube blocked off and it's fine.

 

If you don't cap the header where the EGR tube went, you would then have an exhaust leak.

 

You would only have a vacuum leak if the EGR valve pintle was not seating fully - always a possibility, due to carbon buildup. You need to put the blocking plate on the back of the intake where the corrugated tube used to connect to eliminate this possibility. An easy way to do it is to cut a thin plate out of a metal soda can to match the dimensions of the flange on the corrugated tube, and sandwich the thin plate between the corrugated tube and the intake manifold.... gonna look a little sloppy with that tube all dangly and such....

 

Came up with a new cheap way to block off the corugated tube this week. Cut off the tube and save the intake manifold flange. Tap the plate with a 3/8 pipe tap and install a steel 3/8 pipe plug with locktite. The hole is the perfect size and does not require drilling. Use some RTV on the plate when you put it back in place and your done.