Hey, i have been looking on ebay for some vortec heads. they all say they are for a 350. will these still work for my 305. i was thinking they will but i wanted to be sure, and also is there any certain model i should look for. Let me know what you guys think.

Thanks

 

yes they will work, but the drawback will be you will lose compression due to the fact that they have 62-64 cc combustion chambers, where your 305 has 58 cc chambers. You could have them milled to the same cc tho. As far as which casting number is better i dont know.

Kevin

 

There are two different castings of the vortecs. One isn't as good as the other.
12558060 is the part number of the good ones, I'm not sure what the casting number is though. I had mine milled down .030 for about 60 bucks. Then used a thin head gasket.

 

http://www.mortec.com/castnum.htm

Either one is fine.

Avoid the next two at all costs. They're the 305 heads. They're not even good for an upgrade on your 305. :nono:

 

Alright, thanks guys.

 

there are differences in the vortec heads avoid the ones off an early (first 2 years i think) 3/4 or 1 ton truck they have a restriction and slightly diffrent shap in the intake port. which makes them not as good as the other ones for performance

just my 2 cents

Ryan

 

The eight-bolt intake bolt pattern is totally different than the early model V8 12-bolt design. Use new manifold P/N 12366573, 12496820, 12496822.

450 bucks a pair right now at most places, or you can find a set of good used ones in a yard off an L31 truck 96-up for less in which i am going to do

you have to use a special intake to run carb or any injection manifold other than what came on these


http://www.google.com/search?q=12558...hl=en&safe=off


http://www.macmaster.on.ca/sbgm.htm


http://gilbertautoparts.com/frame.ht...TOKEN=33173055



http://www.mortec.com/castnum.htm

 

That is just a rumor, congratulations on spreading the original magazines mistake. The 906 and 062 castings are IDENTICAL. The difference is the seat itself leaves a ridge in the throat of the bowl toward the valve. That reduces exhaust flow a few %, nothing drastic.

EDIT- Wow, just looked at when this post was originally posted.

 

Yep, a four year old post.

 

probably before that statement was retracted.

 

Also quotes the 059s as being "BAD" heads. They are very much like the 350 heads in everything, including flow.

 

Just a note, but I appreciate updates on old posts. I am researching head numbers to build my 355 TPI motor, so this is important information to me. Keep it up. Thanks.