Big block head bolt(s) question

rrent · Jun 24, 2019

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I’m putting together a 454 ‘85 short block / 1976 781 factory heads and need head bolts.
Quick question are there only two lengths?
Seems the bolt holes on the outsides (still under the valve covers) should be shorter?

QBuff02 · Jun 24, 2019

There are 3 different lengths of bolts for the head bolts. Because you are correct, the outer head bolts are shorter. And also if you're going to order new head bolts, make sure that you get the right lengths because numerous kits have head bolts that are shorter than the factory bolts by like .250-.300 and you risk pulling the threads on the block when torqueing them on a Mark IV block with factory cast irons heads. And I'd recommend running a tap through all the head bolt holes in the block. Some of the bolt kits come with the thread sealer already on them. As a side note, most of the aftermarket bolt kits have a smaller diameter head on them that as a bonus avoids interference with the push rod guide plates as well and that's kind of a nice thing.

shiftpro · Jun 24, 2019

After tapping out all holes, and don't forget the valve cover bolt holes, use liberal brake cleaner in the holes to get any sealant or whatever out. Blow them out with your eyes protected.

Wumbo · Jun 24, 2019

2 lengths on iron heads. 8 short bolts, the rest are long bolts.

10 short bolts. Duh moment.

Big block head bolt(s) question

rrent

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QBuff02

I like Big Blocks and I cannot lie

shiftpro

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Wumbo

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