vortec heads?

[ukregal]

I want to put vortec heads on my 305. I know I need a vortec manifold but what else do I need? is there any problems with doing this swap?

i have done some reading up on the net but there seems to be a lot of different infomation! Any help or advice would be great


P.s i know i should just get a 350! 😀

 

[DIYShifter]

Hey!

Nope, the swap is pretty straightforward. They made 305 and 350 Vortec heads; the 305 heads had bigger valves and bigger combustion chambers, IIRC. You might wanna look for the 305 ones, which still flow better than most stock 350 heads.

But yeah, you'll need a new intake, and if you're going hog-wild, you might wanna throw some roller rockers or roller-tip rockers on it...the stamped steel ones kinda suck.

They also only bolt in the front and back, so make sure you tighten them all down evenly and slowly with a torque wrench so you don't warp the intake. GMPP makes a real nice Vortec intake....I'm running a Weiand Action Plus on my Cutlass and I really like it; however, it's not set up to run a Quadrajet, so you'll have to get an adapter plate for it if you plan on running a q-jet.

Good luck! Any questions, I'm more than willing to help! 😀

 

[ukregal]

Thanks for the reply.

is there any problems with compression? or clearance?

can i use stock pistons?

Thanks again

Mark

 

[DIYShifter]

You should be fine...if you're really worried, you can put some plastiguage in there and turn the motor over by hand (keep the plugs out and unplug the ignition), and you can check your clearance. But, you should be just fine!

 

[megaladon6]

you do need to find out what the heads combustion area is on the stock heads and the vortecs. if the stock ones are 64cc and the vortecs are 76 you'll have no compression (about 7.5). reverse those numbers and you'll gain compression(about 10.0). piston to valve clearance is not a problem either way. you will need self aligning rockers and no more than .450 valve lift.

 

[ukregal]

Thanks guys im looking forward to this now 😀

 

[DIYShifter]

Actually, I know the Vortec 350 heads will take up to .480 lift before you have to modify them...but why you would want that kind of lift would be beyond me.

I always wanted to build a Vortec 305 with the Crane L79 blueprint cam (222/222* dur, .447/.447 lift)..thought it would make a fun lil' motor!

 

[ukregal]

Im go to run a 268 Comp cam 'H E', performer inlet, 600 holley, headers and dual exhausts. Should be ok hopefully! i would like to build a bit wilder but our petrol is over $2 a litre at the mo and I wouldn't be able to run anything to juicy! 😀

 

[bigdan]

there is two casting nos: 062 and 906

the 062 are preferable ...the 305 vortec heads have smaller intake valves then the 350 all 350 vortec heads have 1:94 intake valves
get the upper valve guide boss grinded down by about .125 to obtain more then .480 lift limit ( if ever you switch camshaft)

the vortec 350 heads have 64CC chambers .....dont worry about compression issue ...you probably have some stock 76CC heads ...you will get aprox: 9.4 to 1 CR with these ( perfect) nothing else you need to know....
dan

 

[ukregal]

there is two casting nos: 062 and 906

the 062 are preferable ...the 305 vortec heads have smaller intake valves then the 350 all 350 vortec heads have 1:94 intake valves
get the upper valve guide boss grinded down by about .125 to obtain more then .480 lift limit ( if ever you switch camshaft)

the vortec 350 heads have 64CC chambers .....dont worry about compression issue ...you probably have some stock 76CC heads ...you will get aprox: 9.4 to 1 CR with these ( perfect) nothing else you need to know....
dan

Thanks for the info dan.