ok guys I have a factory equipped intake on a 455 engine in the bottom of the intake there is a hole on each side of the intake about 7/16 wide.
It`s underneath where the carburetor sits,its inline with the exhaust riser part of the intake. Should these be plugged or left open? Can I close these off or should I . I think it would cause a leak of some kind , Please help I don`t know what to do .Thanks

 

ok guys I have a factory equipped intake on a 455 engine in the bottom of the intake there is a hole on each side of the intake about 7/16 wide.
It`s underneath where the carburetor sits,its inline with the exhaust riser part of the intake. Should these be plugged or left open? Can I close these off or should I . I think it would cause a leak of some kind , Please help I don`t know what to do .Thanks

 

Those holes are the EGR valve ports.All Olds V8s had them from '73 on. Does your car still have a working EGR valve on it(round metal valve located on the drivers side between the carb & valve-cover,held on with 2 bolts)? If the valve is disconnected(no vac. line hooked up)it should be closed so no exhaust gases would be going up through the valve & back down through the passage under the carb. If you're using an EGR block-off plate(like the ones Edelbrock supplies with some of their intakes)the holes are made non functional by the plate. Either way you can just leave it as is with the holes. If the EGR valve is hooked up & working just leave it ,it won't hurt anything, if the valve is leaking the car won't idle worth a crap. If your car has some performance mods(cam, exhaust,etc)I'd use a block-off plate. You can easily make one out of steel or aluminum, just use the EGR gasket for a template.

 

Those are EGR ports. If you have either an EGR valve in place or a block-off plate over the EGR valve location, those ports are effectively blocked. Don't worry about it.

 

Mine had a hole that was threaded . It's an after market intake . I had it welded shut . I never got a satisfactory answer for what it was for.
Railguy

 

"there is a hole on each side of the intake about 7/16 wide."

I take this to mean at the intake to head) gasket surface. The heat crossover which can serve EGR and/or Carb Heat functions. For an all-seaon car, I would leave the heat crossover open. You may run EGR or not as you see fit. If not, cap the ports with an EGR valve or your plate as set forth above.

 

Keep reading, Chris:

The later intakes like the 14, A4, and A5 have threads in these ports for the EGR nozzles under the carb primary bores:

 

oh yeah, THOSE holes
7/16" does not descibe the intake/head surface ports either.
Once again, JP is spot on.