So here are all the details...I'm building my Buick 364 Nailhead for my 364 LeSabre. Not a HP build. .020 over cast pistons, rebuilt heads with new stock SS valves, mild cam, 4bbl intake, and that's about it other than other goodies like bigger carb, dual exhaust, electric fan & pump. TA Performance did all the machine work and I'm assembling it.
So here is the deal with the compression. All nailheads were advertised with 10.25:1 compression, but from what I've seen they are not even close, especially the smaller motors. Here are the stock specs:
Bore: 4.125"
Stroke: 3.4"
Head gasket compressed: .015"
Piston dome: 45cc
Combustion chambers: 126cc
Piston to deck height: .050 or so.
If you do the math the stock compression is around 8.8:1 or so. Not even close to 10.25:1.
--This makes sense, right?
So now onto my specs with the new setup:
Bore: 4.1445"
Stroke: 3.4"
Head gasket compressed: .020" (assuming I get a modern steel shimmed gasket)
Piston dome: 53cc (Same exact dome, but there is a groove machined into the outer edge of the top of the piston that accounts for 8 cc)
Combustion chambers: 124cc (measured after the heads were rebuilt and resurfaced.)
Piston to deck height: .096
Compression here comes out to 8.77:1.
--This to me is really close.
Now, if I decide to use composite head gaskets instead of steel, my compressed thickness is now .040, resulting in 8.43:1 compression.
So my first question is, do my numbers make sense? I know there are a couple good Nailhead guys out there and they are on the V8 Buick board, however they are big on having custom pistons made to get close to advertised compression. All I care about is that I am in the ballpark on the TRUE stock compression of the motor.
Now to my final question...on a motor that will be putting out 300hp at the crank if I'm lucky, will the drop in compression from using composite head gaskets make much of a difference? Maybe 5ph?
So here is the deal with the compression. All nailheads were advertised with 10.25:1 compression, but from what I've seen they are not even close, especially the smaller motors. Here are the stock specs:
Bore: 4.125"
Stroke: 3.4"
Head gasket compressed: .015"
Piston dome: 45cc
Combustion chambers: 126cc
Piston to deck height: .050 or so.
If you do the math the stock compression is around 8.8:1 or so. Not even close to 10.25:1.
--This makes sense, right?
So now onto my specs with the new setup:
Bore: 4.1445"
Stroke: 3.4"
Head gasket compressed: .020" (assuming I get a modern steel shimmed gasket)
Piston dome: 53cc (Same exact dome, but there is a groove machined into the outer edge of the top of the piston that accounts for 8 cc)
Combustion chambers: 124cc (measured after the heads were rebuilt and resurfaced.)
Piston to deck height: .096
Compression here comes out to 8.77:1.
--This to me is really close.
Now, if I decide to use composite head gaskets instead of steel, my compressed thickness is now .040, resulting in 8.43:1 compression.
So my first question is, do my numbers make sense? I know there are a couple good Nailhead guys out there and they are on the V8 Buick board, however they are big on having custom pistons made to get close to advertised compression. All I care about is that I am in the ballpark on the TRUE stock compression of the motor.
Now to my final question...on a motor that will be putting out 300hp at the crank if I'm lucky, will the drop in compression from using composite head gaskets make much of a difference? Maybe 5ph?
