sorry to be a bother, but does anyone know off of the top of their head what the size of the combustion chamber is on the stock L03 tbi cylinder heads (I ask because i need to do a rebuild and i'm contemplating a head swap so i can have a half decent spare bullet, but don't want to mess with the compression too much). all of the signs seem to point to 58cc i think, but i've been wrong before.
thanx

 

The stock heads have a 58cc combustion chamber.

The problem with these heads is they provide next to no flow.

If you are buildnig up a 305, look for a set of engine quest vortec heads, if you were going to use these on a 350. dont bother.

With a little porting you can free them up a bit, but these heads are awful.

 

ya, i figured as much. i just need some cheap performance heads and a good cam to allow the motor to make the bare minimum (according to moi)of 230hp and 280ft-lbs. where can i aquire a set of these quest vortec heads?

 

Not sure what the problem is using the Engine Quest brand vortec head on a 350 is but.....

if you want to build a better 305 With stock heads then get a set of common 305 HO heads and port them and add bigger 1.94" intake valves. The casting number of these heads ends in 416. many carbed 305's had them and some early 305 TPi motors had them. They are nominally 58cc's. they will not be 58cc when your done modding them but can be flat milled to bring them down to 58cc or less if you need that.
If you prefer the center bolt covers use the heads off a 305 TPI after 86. these casting numbers end in 081. Again home porting and 1.94" valves.

GM 305 Vortec heads work good too. Again you can upgrade to a 1.94" intake valve. casting number ends in 059.
Needs a vortec manifold.

 

I think i'll go with the newer vortec heads. theres something to be said for being a little newer and i need a new manifold anyways seeings how its gonna be a carbed motor. Perfect, all i gotta do now is shop.

 

To use 350 vortec heads on a 305 i would bore .030 over, use a 350 shim style head gasket .015" thick and flat top pistons. Stock 350 vortec heads are 62 to 64 cc's i wuld flat mill them to a 60cc spec. You'll have to cc your heads to determine the chamber volume of your heads. they do vary a little. Build it like this and your cr will be 9.72:1

You'll be very impressed with the performance of a vortec
headed 305. Remember if you go over .450" valve lift, the stock vortec heads will need to be modified. (shorten valve guides)