380 cu SBC in vortec head build


The Grumpy Grease Monkey mechanical engineer.
Staff member
380 cu in vortec head build
heres a mild high torque build using a set of mildly reworked vortec heads and a chevy hot cam.

Recently I built a 380 inch small block with 906 Vortec heads for Pat Mcneil. The build: 4.020 X 3.750, 10.1 compression, hyd roller on a steel billet 218/228/112/109/.525, Crane/GM LT 4 1.6 roller rocker arms, very mild, Ferrea 1.940/1.50 stainless valves, GM titanium retainers, GM locators, GM valve springs, the 906 Vortec heads featured honed bronze valve guides, race valve job, spring pockets cut, machined for screw in studs, fully ported, 65 CCs, Performer RPM intake, 850 Holley, 31 degrees total timing, 5 quarts 10/30 Valvoline oil.


If your going to run vortec heads, you either check you have clearance on current heads, with accurate precision tools and/or if you find you don,t have the required clearance,your going to be forced to modify current heads or you could buy heads with the correct clearance

keep in mind theres no real replacement for added displacement
the increase from 350-383 in a sbc generally benefits you in two ways, it obviously adds the 33 extra cubic inches of displacement
and youll generally find your N/A engine makes about 1-1.3 hp and ft lb of torque per cubic inch, it also tends to effectively increase compression if the similar piston design is used simply because you compressing an increased volume per cylinder into the same size combustion chamber.
one other factor often over looked is the longer stroke of the 383 increase's mid and lower rpm port speeds this generally increases cylinder fill efficiency, in the lower and mid rpm ranges.
obviously if your going to supercharge or use turbos the piston and rods and crank assembly should be made to withstand the stress levels so a 4340 forged steel crank, forged pistons and after market forged connecting rods with the significantly stronger 7/16" ARP rod bolts are strongly suggested as is dropping the static compression to the 8:1 range to increase the potential volume of compressed fuel/air mix to be stuffed into and burnt above the piston
Id point out that most transmissions are designed to shift at well under 6000 rpm and most hydraulic valve trains won,t retain best stability above about 6300 rpm, so going the 383 or the 406 SBC stroker route tends to maximize the SBC potential on a mild or mid range performance build

reading the related info will be helpful














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