348 intake manifold "secret passage"

[Joe Van Sickle]

Just starting rebuilding 348 w 4bbl, pwrglide in 1960 Impala.
Stock intake manifold has a 2 in diameter round hole cast in back edge, just to the drivers side of the distributor mounting hole.
Hole passes into the lifter valley under manifold.
What is this ????
Car has passed through several owners. Is a vent tube or plug supposed to go into this hole ??

Joe VanSickle
Sacramento, CA

 

[BRYAN FUGATE]

Road draft tube

 

[61BUBBLE348]

this can be plugged with a welch plug and a PCV added if you want.

 

[models916]

Or, put the draft tube back in. Show-Cars has the correct version for you.

 

[chuckl]

Joe, is the intake manifold off the car now? If so, is the baffle still in place? If it is not installed, you will get a lot oil coming out of the draft tube hole. The draft tube's job is to pull the oil mist/vapors out of the engine by the slight negative pressure generated by air passing over the end of the tube under the car. Without the baffle the oil flying around the upper engine spaces have an easy path to get out of the engine and into the tube. Your garage floor will thank you!

 

[Joe Van Sickle]

Thanks you guys, esp Chuck for detailed explaination.
Draft tube was probably lost several decades ago, car had been used as a farm vehicle in 1970's in Winters Ca. Maybe ran over some organic tomato vines and got ripped off.