primernrust98

Hey guys I found a set of cheap vortec heads and was gonna use them for a new motor build. The new motor won't be started for a while so I was gonna put the vortec heads on the 305 in it now. Can it be done fairly easily and kinda cheap? Can I put a carb on a vortec intake? And with the stock cam will any extra power be made?

primernrust98

Anyone?

fiveoformula

You can run vortecs on a 305, theres alot of info out there, people have done it.
two main things; you need a vortec specific intake manifold, and just bolting stock heads onto your 305 will lower compression. Need to usually have them milled to make the combustion chamber smaller which will raise compression back up.

billyhoss

iTrader: (1)

yep have to get them milled to keep the compression up and use a thin head gasket also to keep it up + the vortec intake

Fast355

iTrader: (2)

I would pickup a pair of 059 Vortec heads off a 305. No need to mill them and they flow every bit as well as the 062/906 heads.

BASSETT IROC 85

iTrader: (2)

Save your vortec heads for your 350 build.

jokerZ71

You'll need to mill .030 to .040 off the decks to get them back into the 58cc range which will then make them likely unusable on a 350 later.Like was said above,find a set L30/305 059 heads.They don't have the fastburn chamber of the 906/062,but they flow in the 220 cfm range.We've also used them on older 307 builds as well.Great heads for an iron OEM head.

Damon

I've used them on a 305 WITHOUT milling them. Stock 305 heads have chambers about 58cc. Vortecs are listed as having 64cc chambers, but if you take the time to cc them you'll find they're actually around 62cc plus change. Not enough of a difference I felt like milling them, so I threw them on as-is. They absolutely blew the stock heads into the weeds, performance-wise, despite the slightly lower compression.

Note, I was using them on a 305 with factory flattop pistons, so I was starting with 9.5:1 compression to begin with. Probably low 9s once the stock Vortecs were bolted up top. The engine didn't care about the slight loss of compression. The Vortecs still made more power everywhere in the RPM range and didn't nose-over on the top end like the stock heads.

Fast355

iTrader: (2)

^^^^ This also works....If you do not have the 12cc dished pistons that came in the first LG3/LG4 305 engines. With a rubbber embossed steel shim .016" thick head gasket a flat top piston 305 will be right at 9:1 compression. With a standard rebuilder .038" you are looking about 8.8:1.

Everybody gets caught up on static and dynamic compression ratio, when in reality its cylinder pressure that you want and cylinder pressure is highly dependent on head flow, cam timing, intake and exhaust dynamics and ignition timing.