So how good are the 305 vortec heads compared to the 350? would the 305 have a better CR? or do they have less flow?
thanks

Opinions on if the 305 heads had 1.5 rockers and 1.6 rockers and the difference it would make.

thanks

 

I wouldn't run a 305 head on a 350 yes better CR.....worse flow...

 

I have a question, I just got confirmation that on my 1985 Z25 with a 305...I have Vortec heads on them. But how do I identify if they are for 305 or 350?????

Thanks

 

If the heads on your '85 are the original heads, they aren't vortecs.

 

I am curious about 305 vortec heads myself, I believe that they share a 170cc runner size, and only the combustion chamber and valve size are different, but if that were so, i would think someone would have figured it out and people would run them, maybe someone else will chime in with some facts.

 

Hey GregsZ28, sorry to say, but you're dead wrong. My heads are not originals, but they are Vortecs. I've verified this through the casting number (12558062). And yes, my car is an 1985, I verified this through the VIN number.
Bart91406.....totally agree with you. Very hard to find any posts about Vortec users on a 305. I know fitment shouldn't be a prblem.....probably just the internal parts of the heads that have different characteristics

 

No, I'm right. Re-read what I wrote. You must have misunderstood me...

 

GregsZ28.......my bad!!!!! I miss-read

 

You can put 305 heads on a 350, but I don't think that there are any 305 vortec heads as good as the vortec 350 heads. I believe the sought after vortec heads are the 96+ ones, the earlier vortec heads, 305 and 350, aren't as good as the later ones, that made vortec heads so popular.

 

So can you tell by this casting number (12558062) wether my heads are 96+????? I've heard that the Vortec heads with my casting number are apparently sought after...do you agree?






quote=gregsz-28;4113196]You can put 305 heads on a 350, but I don't think that there are any 305 vortec heads as good as the vortec 350 heads. I believe the sought after vortec heads are the 96+ ones, the earlier vortec heads, 305 and 350, aren't as good as the later ones, that made vortec heads so popular.[/quote]

 

[quote=1985IrocZ;4113218]So can you tell by this casting number (12558062) wether my heads are 96+????? I've heard that the Vortec heads with my casting number are apparently sought after...do you agree?


12558062 is a 350 vortec head.

 

yes I know that, but can you tell from the casting number wether they are 1996 and up???? P.S. they are cast iron

 

You probably can tell from the casting number if it was one of the good ones, I think there are a couple more, other than what 10sec posted.
Could you post your casting # for us?

 

they are all the same up to 98. what does it matter what the year is?

 

I believe there were vortec heads made in the early '90's that only shared the name 'vortec' with the later heads, but that is all they have in common, there was nothing special about them like the later ones.

 

okay to clarify NOTHING pre 96 is a vortec head, it is a misconception that centerbolt =vortec, this is not true. real vortec heads have 8 intake bolts, as opposed to the older style 12 bolts. older centerbolt 350 heads out of trucks are useless for performance. this can be made to be a very good combo, there are a few articles around about putting the 062 vortecs on 305's with decent results. haven't heard of anyone doing the 305 vortec on a 350 tho with much success.

 

Hey, GregsZ28, here is the requested casting number: 12558062. Can you tell by my casting number if mine was designed for a truck thus making it obsolete for performance????.....or not??? Thanks

 

The truck heads, 96+, are the desirable vortec heads, and I believe the 062 heads, your heads, are the desirable ones that brando and 10sec mentioned, and are the good ones for performance.

 

I appreciate the help and info Gresz28. Have a good one