454 Intake Bolts

[Mark E.]

What's the proper bolt for a 454 LS5 intake manifold? Most of the bolts currently installed on my car look like the photo below- recessed hex head with a flange/shoulder and dark/black phosphate finish (this photo is from an eBay vendor claiming to sell NOS bolts).

But the JG shows a "flat" (not recessed) hex head with a flange/shoulder (Fig. M 7.10 on p 135, 6th edition). My car has one or two of these too (a mixed bag- it was overhauled by a PO).

Second question: Are all 16 bolts the same length, as this photo suggests? I ask because a couple of bolts go through the engine lift bracket... should these be longer?

I did a search on this forum but came up empty handed.

Thanks for your help.


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[Gary B.]

Re: 454 Intake Bolts

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Very low mileage 71 454.
Gary Bosselman

[Mark E.]

Re: 454 Intake Bolts

Thanks Gary. It's interesting the parts houses sell both flat and recessed head bolts for this application. Could use vary by year, or perhaps both were used for a given year?

Update: I found this photo on my PC of an original looking '70 454. Note the two flat head intake bolts on the lift bracket (the forward one can be seen when the photo is blown up), recessed heads elsewhere. Maybe the flat head bolts are also longer?

Original 70 LS5 from Forum t.jpg

[Gary B.]

Re: 454 Intake Bolts

Give me a few days, I'll run into the Library and look at several 68-72's.
I'll get back to you.
Gb

[Gary B.]

Re: 454 Intake Bolts

Went to the Library today. What can be seen:
My 68 435 has indented hex head bolts with a built in washer as part of the bolt. It has an aluminum intake.
The 69 390 hp, with aluminum intake has a hex head bolt (not indented), with an integral flanged washer bolt. See first photo below.
The1970 454, with cast-iron intake uses a indented hex head bolt with an integral flanged washer.
The 71 LS6, aluminum intake, uses hex head bolts (not indented), with a built in washer as part of the bolt.
A 72 454 cast iron intake, SN 219xx range, uses a indented hex head bolt with an integral flanged washer.
A 72 454 cast iron intake, SN 231xx range, uses a hex head bolt with an integral flanged washer.
All lifting brackets uses regular hex. head bolts, NO washers.
My gut instinct is it probably doesn't matter. On a sample of 6 cars anyways...
Gary Bosselman
70-72 TIM&JG Manual Coordinator.

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[Mark E.]

Re: 454 Intake Bolts

Gary,

Thank you so much for taking the time to research this.