Correct Intake Manifold bolts

[Patrick H.]

Re: Correct Intake Manifold bolts

Not an answer to the OP's mid-year question, but an example of the fastener diversity common to all engine assemblies. There are seven different styles (including headmarks) on the intake manifold of my 1970 LT1. One is a stud, and one a washer-head bolt for the lifting bracket. Neither of those would be on a mid-year though. The two fasteners that hold the distributor shield supports have different headmarks than any other intake manifold fasteners.

When I judge, I make a minor deduction if all the intake manifold fasteners are the same headmark. The odds of that happening in production are greater than those of you winning the lottery; but the odds of that happening if you buy an intake manifold fastener kit from one of the Corvette supply houses is about 100%.

Agreed.
I have 4 or 5 different ones on my 71 and 72 cars.

[Terry M.]

Re: Correct Intake Manifold bolts

Labor was cheap in the mid-years. Maybe Chevrolet had a couple of entry level workers sorting the intake manifold bolts at the engine plants. In late 1967 calendar year they got laid off in a cost reduction move.

[Loren L.]

Re: Correct Intake Manifold bolts

FWIW, the 1971 Standard Parts Guide calls out #435611 as a 3/8 X 16 X1 1/8" bolt and, as Joe indicated, also calls it out as a Grade 8 (300M) bolt.