seanof30306

i was talking to a head remanufacturer about vortec heads for my 89 lo3. it currently has 187 castings. i told him my concern was how much to mill the vortecs to get from their 64ccs to the stock lo3 58cc chamber size. he insisted that pre-87 305 heads were 58ccs, but 87 and newer 305 081 and 187 castings were 64ccs. i'm sure everything i've read on this has all lo3 heads at 58ccs. help?

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1989 WS6 Formula Firebird T-Tops
L03 305 TBI 5 speed
SLP takeoff 3.42 posi rear (was 3:08 open)
Ultimate TBI mods
1/4" injector pod spacer
MSD 6A ignition (switched back to stock, AC/Delco distributor, coil and wires and picked up 3hp!)
'84 Trans Am functional cowl induction with K&N element
SLP 1 3/4" shorties w/air
Dual 2 1/2" converters
Custom 3" cat(s) back
Flowmaster 40 series muffler
Spohn weld-in subframe connectors
Lakewood control arms
Hotchkiss adjustable panhard bar
KYB shocks and struts
170 rwhp, 263lbs. ft. torque
best 1/4 mile: 15.62 @87 mph

vjo90RS8

youre right, 87+ 305 "187" and "081" cylinder heads are 58cc.

iroc22

The only two combustion chamber sizes that I've ever heard of coming on a 305 were 58cc and some early 305 heads had 60cc. 64cc is a standard 350 chamber size.