Would they work on a LO3 TBI motor? Are they worth the swap from stock heads if upgrading to a vortec intake? Might combine them with an LT1 cam swap. Any info on these heads would be appreciated. thanks.

 

The 305 Vortec heads are a lot different than their bigger brother found on the 350. Most notably is the chamber differences which help the 350 versions become one of the best bang for your buck heads out there. If you want to use vortec heads on your 305 you would be better with a 350 set milled (to decrease chamber volume to maintain 9.X:1 CR on stock 305 bore). I would not waste my time with the 305 Vortec head. A ported set of 187's (stock LO3 heads), 416's, 601's or 081's will go a long way on your 305 and you won't have to fork over additional green for a vortec specific intake.

 

I on the otherhand disagree. The 059s have a different chamber design, but flow ALOT better than any of the other heads listed. When ported they will blow just about anything off the flowbench so to speak.

 

When ported I agree, but for a novice LO3 builder this may not be the best route to go. Sticking with ported or stock cast Gen I heads may be the easier/cheaper route for the first time heads and cam swapper.

We all know that you can make cheap and incredible power with Gen I 305 castings, thanks to hot rod enthusiasts like yourself that have made our lives easier and have paved the way for us . A 305 ported vortec swap may be better in terms of potential but availability and cost may become an issue that outweigh the performance gains on a 305 compared to readily available gen I castings. I had trouble finding 059 castings anywhere within my area/state that didn't require a hefty price (back when I was on my 059 kick). Granted, this is likely not true for everyone but a real possibility none the less, and something maybe worth considering.

 

What types of prices do the 059s fetch?

 

See thread: https://www.thirdgen.org/forums/tech...ght=305+Vortec

noting that it shows the 305/5.0 Vortec L30 casting number 2332520 as ported and with bigger valves vs the 350/5.7 062 stock unported Vortec head. For each lift and cfm block in the table, the 350 flow data appears above, and the 305 data appear below. It also appears that the 305 heads were altered to have 2.02/1.60 inch valves (based on what's in the table). The valve didn't seem to help much -- the 305 heads can't keep up with the intake of the 350, but are about the same as the exhaust on the 350. The 350 heads, meanwhile, flow very well and on-par with other flow data elsewhere on the web.

and

http://img.villagephotos.com/p/2004-...cflowsheet.jpg

 

The 059s are a completely different casting with the 350 style raised ports.

 

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

12552520...97-up...305..........Vortec, truck
---
12558059...97........305..........Vortec, truck, 1.84"/1.5" valves

Interesting. I'm surprised that GM would make two different completely different head castings for the 305 truck model. I think I've seen pix of the 520 head but not the 059.

 

Well if they do exist and can be made to perform well *shrugs* it would mean one less reason for not keeping a 305 around. (Will see next week how badly damaged my stock LO3 is when I pull it)