Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Buying new heads. Suggestions???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by zach78k5, Nov 29, 2004.

  1. zach78k5

    zach78k5 1/2 ton status

    Joined:
    May 14, 2000
    Posts:
    406
    Likes Received:
    0
    I have 305 with holley projection, high rise dual plane intake, and headers. I am looking to buy new heads. I have heard that 350 heads will work and some say they wont. will they? I would love vortec's but would rather stay with the older bolt pattern. I am not looking to spend a ton but plan to upgrade to a 350 eventually and want some more ponies for the 305 until next summer when the rest of the engine gets replaced. Also, what compression would be optimal? I know if I get aluminum i can go with about a point higher on the compression ratio.
     
  2. bonanza

    bonanza Registered Member

    Joined:
    Oct 18, 2004
    Posts:
    55
    Likes Received:
    0
    Location:
    Sterling, IL
    There's no reason that 350 heads won't work on a 305. You will lose some torque because of the bigger intake ports, but you should be fine. Vortecs are great heads and can be had for about $520 out of jegs or jim pace. Also world products S/R and S/R Torquer heads are pretty nice pieces for about the same as the vortecs. I'd try to shoot for about 9.0:1-9.5:1 on pump gas.
     
  3. Thunder

    Thunder 3/4 ton status

    Joined:
    Jul 20, 2000
    Posts:
    8,946
    Likes Received:
    1
    Location:
    Northeast Nevada
    350 specific heads dont work well on 305s. 350 heads are made for 4" bores. The smaller bore of the 305 will shroud the valves and hurt performance.Also because the runners are larger you will prolly also lose lowend torque.
    305 heads are 58cc chambers so to keep your compression ratio the same you will need to find 350 heads with that small of a chamber. Not many around like that. I think the Vette L98 heads were 58cc

    If you really want to boost performance in your 305 get some heads off early 80s 305 IROC Camaros or Formula Birds.They are pretty easy and cheap to get.

    You can get performance aluiminum heads that will work on both engines like AFRs But they are pretty spendy.
     
  4. Adub

    Adub 1/2 ton status

    Joined:
    Aug 16, 2002
    Posts:
    106
    Likes Received:
    0
    Location:
    OK
    Didn't they make Vortec heads for the 305 as well or am I out of my mind?
     
  5. Thunder

    Thunder 3/4 ton status

    Joined:
    Jul 20, 2000
    Posts:
    8,946
    Likes Received:
    1
    Location:
    Northeast Nevada
    Yes GM made 305 Vortec heads for a couple of years in the 90s
     
  6. socalblazer

    socalblazer 1/2 ton status

    Joined:
    Mar 18, 2004
    Posts:
    110
    Likes Received:
    0
    Location:
    Redondo Beach, CA
    Like previously stated, 350 heads won't work well on a 305. Dont blow the money on aluminum for a motor that you're going to replace next summer. I'd rebuild the ones you have, while they're apart take a grinder to the ports and clean them up a little. Install bigger valves and a set of springs matched to a new cam that will optimize your combination. This should hold ya til next summer.
     

Share This Page