this may be a stupid question but here goes can i put a set of 305 vortec heads on a 400 small block i know you have to drill holes for water passeges heads are 58cc off of a 1996 chevy truck

 

Im not sure but I would also like to know.
From the 400 that I took apart I noticed that the pistons are very similar to LG4 type "DISHED, from 74 GMC PU" so it shouldent through out super high compression with 58cc heads unless you replaced the pistons.
SSC?

 

technically it will work. Your going to have compression problems unless you have a cam with a whole lot of duration. To keep compression in the 10 to 1 range, you need at least 86cc above the piston (head gasket, deck height, valve reliefs and chamber volume) for a 400. You can figure about 9cc for head gasket, at least 3cc for valve reliefs, and from 3 to 5 cc on deckheight. That means you need close to 70cc of chamber volume or your going to have a lot of compression.

 

Are the Vortec heads on the 305 different (58cc vs "64cc") than the 350? I mean most of the Vortecs I've actually checked are 62cc (off 350s),, although Chevy markets them as 64cc heads. Your compression will depend on the piston type. Do you know what kind they are? Brand / dished, flat-top, dome? The chamber design on the heads and 400 engines both "like" less timing than on a 350,, so it's possible to run a little more compression with this combination than most would think. Let us know what pistons you have. If they are "stock" 62cc heads, even with -4cc flat top pistons, and you have a stock deck height,, you can run a thick .051 head gasket and have around 10.4:1. With the right cam grind,, you could get away with that. Even if the heads are 58cc and the pistons are -8cc or more,, then you still could be around 10.4:1 with stock deck height and the .051" head gaskets,, so,,, you could be in luck - depending on the pistons and deck height.

[This message has been edited by BadSS (edited July 28, 2001).]