73 L82 TH400 Frame Off Restoration

[JRNichols52]

I'm new here so bear with me as I have a lot of questions. I'll start with the motor it is the correct matching numbers L82 for my 73 coupe. I also have the correct TH400 transmission. The A.I.R. pump is of course long departed.
In restoring the motor my first question is what threads were used on the ram's horn exhaust manifolds for the smog pump injectors. They appear to be 1/2-20 but I would like to get that confirmed before I start with the helicoils. The second deals with the EGR valve, does any one have the correct GM part number for the EGR valve? Also there is a solenoid mounted on the intake manifold the the passenger side that looks like it controls vacuum some how. What is the purpose? Does any one know the correct GM part number for this item. And last but not least can any one point me in the right direction to find vacuum drawings as well as electrical drawings.

 

[6880 Mike]

...In restoring the motor my first question is what threads were used on the ram's horn exhaust manifolds for the smog pump injectors. They appear to be 1/2-20 but I would like to get that confirmed before I start with the helicoils...

Do you have the original injector tubes? Measure those. Otherwise, order the reproductions and measure those.

...The second deals with the EGR valve, does any one have the correct GM part number for the EGR valve?...

The 73 assembly instruction manual (AIM) will show the original EGR set up and list the original part number. The AIM will be a big help during your restoration.

 

[JohnZ]

Although the holes in the exhaust manifold appear to be 1/2"-20, they're not. They're actually a unique 1/4"-18 National Straight Pipe Thread.