Original 1965 Early 1966 P/B,vacuum "T" fitting

[David L.]

Does the "T" fitting in the photo look like an original 3868858 power brake/vacuum fitting for 1965 and "early" 1966 models? I removed the fitting off an "early" 1966 C.I. 427 intake manifold (casting # "3868948" and casting date "I 24 5"). Refer to the 1965 AIM, UPC J50, sheet 3.

The 11/16" hex steel fitting has 3/8" NPT threads and is for a 3/8" hose and a 1/4" hose. The 1/4" hose end slopes down about 12 degrees and measures 0.75" along the top and 0.65" along the bottom.

The 3891525 "T" fitting is similar but the 1/4" hose end does not slope down and has a ridge for better sealing purposes.

Dave

[Rich P.]

Re: Original 1965 Early 1966 P/B,vacuum "T" fitting

Dave this fitting would bee for A/C or auto. Look at the top of the fitting sometimes you can see a small dimple in the center.

Rich

[David L.]

Re: Original 1965 Early 1966 P/B,vacuum "T" fitting

Rich,

The fitting on the intake manifold for 1966 models w/AC as well as 1966 models w/M35 is GM # 3891523 (3/8" NPT w/1/4" tube) as shown in the AIM (UPC C60, sheet C2 and UPC M35, sheet A8). The fitting in the 3 photos below is from a 1966 327 CI intake ("3872783" and "B 4 6"). The fitting has the Weatherhead logo stamped on it (the letter "W" with an arrow thru it inside a hexagon) and has 3/8" NPT w/1/4" tube.

Dave

[David L.]

Re: Original 1965 Early 1966 P/B,vacuum "T" fitting

If the model has all of the 3 options (P/B, AC, and A.T.) then the 3891526 fitting (3/8" NPT and two 1/4" tubes) is used.

Dave