[Singleton]

picture is of an original 66 tri-power intake that I picked up yesterday. Just goes to show that even the factory makes some boo boos every now an then. Easily fixed, but I have to wonder if it affected the performance. Probably not.

[pfilean]

I had one like that also. Just takes a little die grinder work but makes you wonder about quality control back in the day.

[Tom Vaught]

Guaranteed that a Pontiac Plant QC person is not going to stand around and personally inspect every Intake casting that Pontiac Foundry suppliers did on Tri-Power Intakes, especially a 1966 unit where there were about 100K of GTOs sold and a bunch were Tri-Power engines. Chit happens.

Tom V.

[Dick Boneske]

My '64 I'm using for my wife's car had a similar defect. The bottom of two ports out of the eight were 1/4" blocked at the bottom (next to the cyl. head). Die grinder-5 minutes--no problem.

[Ron Landis]

would be an excellent time to gasket-match it! Just sayin'...

[Ron Landis]

would be an excellent time to gasket-match it! Just sayin'...

[mgarblik]

Because it's at the top of the port. there would be a slight performance loss from that blockage. Typical thing to fix when blueprinting. If the defect was at the bottom of the port, I doubt it would ever be noticed.

[projectfolly]

For what its worth.

My Dad spent most of his GM career working at Pontiac Motors, in the foundry, starting in the late 50s.
I showed him the picture of the casting flaw. He said right away - broken core.

Back then, Pontiac used sand to make the cores used for casting. As such, cores were very brittle.
A crack or break in the core allowed metal to flow where it shouldn't have, leaving behind what we see here. Sometimes it was thin flashing, other times thicker.

My dad said there were people on the line who's only job it was to stand there and knock off casting flashing, using a hammer and sort of a simple pick/chisel tool.
Cant tell how thick the flashing is. If the defect we see here is beyond the normal flashing thickness, it might've been too thick for the operator to knock out or the operator just plain missed it. It happens.
As an aside, dad also said there is a pattern number cast in the part, which correlates back to the core. This is how they could track the defect backwards in the process, to the offending core.

Pontiac foundry cast parts in multiples at a time, over 3 shifts, sometimes running 7 days a week, especially during Pontiac's heyday. Expand that thought beyond intake manifolds to the other cast parts on our cars, as well as parts for other divisions, (yep Pontiac foundry cast parts for the sister divisions too like rear differential center sections for example) and that's lot of parts running down the lines!

No excuse, but like others have said, stuff happens.