Thread: To Zero Deck Or Not?

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1. when the machine shop bores and hones the bores, they will leave a slight chamfer at the top of the bore anyway to help start the rings down into the bore when you assemble the motor. Check with the shop that's going to do your work and coordinate the finished o.d. at the top of the bore with the o.d. of the gasket you wish to use. Just don't allow them to chamfer too much so that you have a ledge of gasket overhanging the bore. That could be the source of a hot spot that would initiate preignition.

2. Mix and match gasket thickness with deck height to achieve the piston to head clearance you want. Check several sources for gaskets including GM parts. Take note though, that some GM gaskets such as 10105117, 12557236 and possibly others have a bore of 4.000", so you wouldn't want to use them in a bored 350.
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www.sallee-chevrolet.com
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confusion. Do not concern yourself with the gasket bore as long as you address it with the machine shop . The smallest gasket bore that would work is the Mr. Gasket 3130G at 4.060", 0.040" compressed. Fel-Pro makes several thicknesses in the 4.100" bore size....
0.015" #1094
0.016" #7733SH1
0.040" #1142

I'm sure you know how to proceed, but I'll outline it for the newbies...
The block goes to the shop to be magnafluxed so we can find out if it's cracked anywhere and also where all the meat is in the cylinder walls. In this case, we have determined that we will bore the motor 0.030" and use a 3.750" stroke crank to make a 383. We determine the pistons we're going to use along with the rings and we order them. The pistons will set the theme for the entire motor because they will determine the compression ratio and that will determine the cam used. We take the pistons to the machine shop and have them bore and hone the block to the pistons. Do not have the deck cut at this time. Pick up the block, one piston/rod assembly, all main bearings and one set of rod bearings. You won't need the rings. At home, assemble the crank in the block with all the oiled main bearings and assemble the one piston/rod assembly into #1 cylinder bore. Using a dial indicator, find TDC. Using a depth micrometer, measure the distance from the block deck to the piston crown at the 3 o'clock and 9 o'clock positions as you're standing at the side of the block. Record these measurements. Move the piston/rod and bearings to the #2 cylinder and do the same thing, then the #7 and #8 cylinders. When you are through, you'll know the deck height of the block at all four corners and you'll be able to communicate this info to your machinist so that he can cut the decks in accordance with the gaskets you're going to use in order to establish your piston to head clearance (squish). Of course, you can have the shop do this if you want, it just costs more money than doing it yourself.