Building my first engine and need to figure out what these holes are for and if i need to plug them or what to do.


1. ??
2. ??
3. This goes to the area behind the engine where the clutch will be.


4. Oil pressure sensor? Plug this since I have Oil pressure sensor elsewhere?


5.Think this will get sealed by the intake gasket, one on each head, wondered what they are for though?


6. There is one of these on each head - no idea?
7. ??
8. ??

 

#1 - If this hole is the same size as #7 & #8, see explanation below, otherwise, I don't know.

#4 - Don't quote me on this but I think on my car, hole #4 is for the oil pressure sending unit for the gauge because the one by the oil filter is just the fuel pump relay switch.

#6 - For my car, the one on the drivers side has the coolant temp sending unit for the gauge, and the one on the passenger side has the switch which turns my fans on.

#7 & #8 - These are for bolting up a spark plug wire loom kit or something like that. If they are left as is, the engine will not explode or anything, they're just there for your convenience

 

They are:

1. For spark plug heat shield
2. Early (about 66 back) clutch pivot ball mount
3. Late (about 67 up) clutch pivot ball mount
4. Oil pressure sending unit port; MUST be plugged, if not used; 1/8" pipe (NPT)
5. Exhaust crossover port; for intake manifold pre-heat, and EGR; intake gasket will take care of it
6. Coolant temp gauge sending unit on one side, or fan switch on the other; MUST be plugged if not used; 3/8" pipe (NPT)
7. More spark plug heat shield mounts
8. More spark plug heat shield mounts

 

Thanks guys, so do you know what was in 6 on a 92 TPI wiring harness? I kind of thought that the CTS was on the front of the intake manifold, and one of the head holes had the fan switch, so the other was plugged?

thanks,
Richard.

Edit: And 2 & 3 dont need to be plugged?

 

#6 was explained already - on driver head is for the coolant temp sender for the guage, and on pass head it's for the fan switch. Makes no difference what wiring harness - they all had both. They both need plugged if not being used - coolant runs though there.

 

B/c GM never switched the placement of sensors between years.. Thanks...