305 vortec intake and heads on tbi 350

[w.stevens]

I have a '96 gmc with a vortec 305. I was recently given a complete running tbi 350. I want to build up the 350 block and run my 305 heads and intake. Can anyone tell me if this will work? Will I be able to run a mild cam or even go .30 over without much trouble?

[jdoggat22]

well the parts will bolt up, but getting it to run right might be a bit of a problem. typically the 305s come with smaller combustion chamber heads than the 350s. however this website http://outintheshop.com/faq/casting/heads.html says that from 96 up 305/350 cast #10239906 heads are both 68cc chambers. before making any decisions on the subject you should first look up the cast number for the 305 heads and do some good research on them to find out for sure what size chambers they are and also to check what size the ports and runners are. as long as they are about the same as the 350 heads you shouldnt have much trouble, other than the computer tuning that will be required to make it run right. if the heads have a smaller combustion chamber (54cc was typical on 305s) then you might have a bit harder time tuning it and it could also raise the compression too much, and you might not be able run pump gas. i would definatly do the research on those heads to find out the specs first, you can look up the casting number on google and it will pop up with a couple sites with lists of cast numbers.

[grayblazer]

No, you can't go ".30 over"......but could probably go .030 over :thumbup:
You do realize that boring the cylinders that much is ONLY to clean them up if needed during a rebuild.

[w.stevens]

No, you can't go ".30 over"......but could probably go .030 over :thumbup:
You do realize that boring the cylinders that much is ONLY to clean them up if needed during a rebuild.

Haha yea I realize that. Just missed a 0 in there. I was curious because i plan on rebuilding it. It has 175k on it so it should probably be freshened up. I haven't got into the block yet. Im just looking for advice as to whether this is the best way to go about this swap to keep my fuel injection before I get too far into it.

[w.stevens]

Thank you. I will check into my heads and see what I'm working with. I appreciate the help

[w.stevens]

I checked my heads and the number is 12552520 which are the l-35 heads according to the website you gave me.

[GreaseDog]

(54cc was typical on 305s)
58cc was common on passenger car 305s, alot of truck 305s got 76cc heads. the only thing 54cc heads were common to is early power pack heads for 283s

[GreaseDog]

I checked my heads and the number is 12552520 which are the l-35 heads according to the website you gave me.
the site is wrong then. L35 heads would be 4.3 V6 heads. they are L30 heads.

[jdoggat22]

58cc was common on passenger car 305s, alot of truck 305s got 76cc heads. the only thing 54cc heads were common to is early power pack heads for 283s

my bad... you're right.

to the OP i would def check a couple different sites out cuz i have found conflicting info between some of them.

[Mitchell93]

i have 350 votrec heads, and i dont need them, and i am however in need of some 305 vortec heads... hummmmm...

[SUBURBIAN]

58cc was common on passenger car 305s, alot of truck 305s got 76cc heads. the only thing 54cc heads were common to is early power pack heads for 283s

Wrong. My 601's (305HO heads) cc'd at 54. Every other pair of them (even 416's) I've had my hands on cc'd between 52 and 58.