A friend of mine has some rebuilt vortec heads off a 305 i could get for cheap
Was wondering how well they would on a stock bottomend 400 small block
Has anybody tried this setup/combo

Looking to make cheap power with some junk i got laying around

 

It will work well, but if memory serves, they have a smaller valve than the 350 version.

 

slowbu! The first thing is what cc chamber size are the heads? Second what are the valve sizes? Third do these heads have the steam holes drilled in them?
If the chambers are the closed chamber 305 heads you will raise the compression to at least 11.1 or more depending on which pistons you have.
If these heads are true 305 heads they will have smaller valves than the 400 heads came with, this will lower the flow rate for the 400 and lose power.
You must have the steam holes drilled in the heads for a 400, if not it gets bad!!!!!!!
With raising the compression with any head on a 400 you will build alot more heat in the cylinder due to the fact the cylinders are what is called siamesed. THEY HAVE NO WATER JACKETS BETWEEN THE CYLINDERS.
If you plan on daily driving the vehicle that will not work very well. It will run hot on you and blow head gaskets no matter what you do it just dosen't work well. If you strickly drag race it, make your run and get back to the pits and gradually cool it down.

 

The 305 vortec are 58cc chambers
The valves are smaller but i was thinking that even tho they are smaller its still a better flowing head with better chambers
I know it will bump the compression by like 1.5 points
Its a stock rebuilt 400 so the piston are probably in the hole .04-.05
So from 8.5to1 with the big chamber heads id be lucky to see 10.1 compression with the 305 heads

 

My plan was to run one of the cheap jegs cam with 224/234 duration .465 .488 lift 114lsa
Maybe port an bowl work the heads
AN YES I KNOW TO DRILL THE STEAM HOLES LOL
So..

 

The 305 Vortec heads do not have the same chamber as the 350 heads. They do still flow close to the same air though, even with the smaller valve. Personally, I'd cut the guides down to clear the lift, and run them. It should run like hell through the midrange.

 

Don't know where the don't drive a 400 every day came from since I have seen it don't time and time again, I don't see a problem.