Stupid stroker questions - using SBC rods & pistons
02-18-2011, 08:22 PM
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Stupid stroker questions - using SBC rods & pistons So i have this 383 SBC shortblock with nice pistons and rods in it and i have an LQ4 with a bad crankshaft....
The bore is easy and rod bearings are the same between SBC and LSx
The LS deck is 9.240"
My rods are 5.700"
My pistons have a compression height of 1.450"
with a 4.25" stroker LS Crank that makes 9.275", which puts the piston .035" out of the hole. The top ring land is pretty far down on the piston. I could chuck my pistons up in the lathe and take off .035" without even removing all the dish off the piston.
That all looks like it would work to me... tell me where i've messed up.
Let's move onto compression... 4.060" bore, 4.25" stroke, 72cc 317 heads, .056" head gasket. My pistons are currently 16cc dish, but let's stay on the safe side and pretend i turn off all of the dish when i take the .035" off....
that gives me 11.7:1 compression and 440ci.
So anyway.... somebody tell me why i can't do this. thanks in advance!
The bore is easy and rod bearings are the same between SBC and LSx
The LS deck is 9.240"
My rods are 5.700"
My pistons have a compression height of 1.450"
with a 4.25" stroker LS Crank that makes 9.275", which puts the piston .035" out of the hole. The top ring land is pretty far down on the piston. I could chuck my pistons up in the lathe and take off .035" without even removing all the dish off the piston.
That all looks like it would work to me... tell me where i've messed up.
Let's move onto compression... 4.060" bore, 4.25" stroke, 72cc 317 heads, .056" head gasket. My pistons are currently 16cc dish, but let's stay on the safe side and pretend i turn off all of the dish when i take the .035" off....
that gives me 11.7:1 compression and 440ci.
So anyway.... somebody tell me why i can't do this. thanks in advance!
02-19-2011, 09:03 PM
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SBC rod is "offset" a bit. LSX is not (or the other way round). This can probably be gotten around.
Biggest problem is will the piston skirt clear the crank counterweights at BDC?
I would bet against it clearing.
Finallly your rod/stroke ratio will be 1.34 which is not real good. Would tend to create an excess of thrust force in the pistons.
This was one of the problems with the 400 SBC.
Low rod length/stroke ratio wore pistons and bores out rapidly.
Biggest problem is will the piston skirt clear the crank counterweights at BDC?
I would bet against it clearing.
Finallly your rod/stroke ratio will be 1.34 which is not real good. Would tend to create an excess of thrust force in the pistons.
This was one of the problems with the 400 SBC.
Low rod length/stroke ratio wore pistons and bores out rapidly.
