1973 Trans Am Question

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TORONADOXS · #1 10-29-2011, 02:50 PM

I worked on a very nice '73 TA yesterday, did a rear main seal on it.. 455 auto, original engine. Anyway, the block was drilled and tapped (except one hole) for 4 bolt mains but it had 2 bolt caps. Was this normal? Why drill and tap them and then use 2 bolt caps, and why tap all the holes except one? I'm confused.

**njsteve** · #2 10-29-2011, 05:00 PM

That is normal. Dont know about the one untapped hole though.

Brewster · #3 11-04-2011, 02:48 AM

I dont know if anything GM does or did can be considered normal but yes the standard 455 should have two bolt caps. In 1973 the only 455 motor that had four bolt caps was the super duty motor.
Not sure about the one hole not being taped but it was probably produced on a Friday late afternoon?

**Keith Seymore** · #4 11-04-2011, 01:20 PM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TORONADOXS</div><div class="ubbcode-body">I worked on a very nice '73 TA yesterday, did a rear main seal on it.. 455 auto, original engine. Anyway, the block was drilled and tapped (except one hole) for 4 bolt mains but it had 2 bolt caps. Was this normal? Why drill and tap them and then use 2 bolt caps, and why tap all the holes except one? I'm confused. </div></div>

Re: one untapped hole: probably broke the tool in that location. The inspection station is usually a few operations downstream, so typically you build five or six units with a discrepancy before it gets caught.

Probably missed just that one (...or two...)

K

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