C2-64 Lower Spark Plug Wire Supports mounting Bolts

[Larry M.]

The 64 AIM page D148, section 6, page B3.00 shows these two support which mount to the top of rear flange of the engine block. The mounting on the car appears to be mirror image identical but the the AIM calls out two different bolts, 274430 left and 423554 right. The right is the same number as the ignition shield top screw.

Is there an explanation as to why the two screws are different in the AIM?

I've searched the parts. They are mentioned for coil mounting for C3s and a discussion of shield bolts but nothing on plug wire brackets. For most cars these are tough to see but my car is non radio so they are right out there.

My bolts are SEMS but otherwise seem correct: 1/4-20X7/16 indented head external tooth captive washer, bright plating.

Could the SEMS even be right?

[Richard M.]

Re: C2-64 Lower Spark Plug Wire Supports mounting Bolts

Strange why a different bolt on each side.

The only reason I could think is the lengths of the bolts. Maybe the blind holes are different depths.

I did a quick search and even the Camaro had 2 different bolts also.....

http://www.gmpartswiki.com/getpage?pageid=102178