i will start by saying that this will be my first engine build and my dad keeps telling me that the heads of my 305 will fit on the 350 because there both small blocks, but i dont think that is the case, anyone give me an answer?

 

Your dad is correct. They will bolt right up.

However, there are differences between the 2, that need to be explored in more detail.

305 heads have smaller chambers, which will boost the compression of a 350. Sometimes by ALOT depending on what 350 it is. Depending on what it is now, that might bring a low-compression smogger turd up into the reasonable range, or it might make a high-performance setup only able to run on race gas.

Like 350s, there is alot of variation in the heads that came on 305s. Some 305s have very restrictive ports and tiny valves, such as the ones on late 70s 305 2-barrel setups (my mighty 120 HP 78 El Camino is a good example). Ones in the mid 80s have much better ports, and although the valves are still too small to feed a 350, they will accept larger ones, and then with some port work, they can be decent performers. Late 80s ones are usually off of TBI motors, and have the swirl-port design; which has this giant obstruction in the intake port that's designed to improve fuel mileage but at the specific expense of high-RPM power.

Then there's the other minor issues; the intake bolt angle changed in 87, later ones have self-aligning rockers and center-bolt valve covers, etc.

So, yes, they will bolt on. Whether that's actually a good idea or not, needs further research. The Devil is in the details.

 

They will drop right on...

Depending what type of piston you have in there your going to get alot higher compression ratio though. You will have to calculate your compression before you use them or you may end up loosing your motor due to detonation.



Edit: damn, i type too slow... lol

 

Check your engine do you have flat tops.. where the piston is perfectly flat
is the piston flat with valve reliefs (only on one side, or are the reliefs on both sides) or are they dished pistons...?

First off get the year of your motor, get your casting number and go here...
MorTec, Inc. Home Page

thats will tell you your type of camshaft.

Now you want either 416's or 081's so you have to do less port work. 416's are non roller, standard valve cover heads, four bolts on the outer perimeter.

081's have 4 bolts in the center of the cover and are roller heads.

The others are more or less crap...

you need to have the intake valves opened up to 1.94" to make them work performance wise. You will want new valve seals as well.


Pistons

Flat top
http://www.kb-silvolite.com/images/piston/LKB223.gif

Flat top with single valve relief
http://www.campbellenterprises.com/i...ns/sbcllft.jpg

Dished

http://www.campbellenterprises.com/i...ns/sbcllft.jpg

 

good so that means i can get a short block and with some small work i can just put my heads on, and get more compression. thanks alot, i should have my engine in the next couple of weeks, i will let 'yall know how it goes.

 

yeah make sure you calculate the chamber size the static engine compression measured on... most piston sites have online calculators