kill4thril

if i get vortec heads on my 305 will it need to be tuned or will it run ok i already have headers back and an open element just wanted to knwo if it will run or not without tuning

kill4thril

these are the head im looking at http://www.summitracing.com/parts/NA...n/?prefilter=0

gmstrong

you'll need a vortec intake manifold too.save up for a 350

L98wit

iTrader: (2)

it wont run as greatas should and you would also need a new cam like the LT1 cam the stickies recommend to atleast get gain from the little cam the 305 tbi came with great. i would rather save up for a 350 unless ur set on your 305 and if you are squeeze a new cam in the budget. It will run but you will be dissapointed and u need an intake

alvanwie

Those are the 350 heads. Compression will be to low on a 305. Look for the 305 vortec heads. May run without a tune, but you will notice problem areas. Recommend a tune.

torque_is_good

what happened to the LS1 swap that you were starting?

kill4thril

car crash and the doner car sold befor i got to it

seanof30306

iTrader: (4)

305 Vortec heads are a completely different animal than the 350 Vortec heads; they don't flow nearly as well.

You can mill Vortecs up to 0.040 safely. With a thin head gasket, that will minimize compression loss. Probably means custom pushrods, though.

bluers91

The intake valve on those heads in the link is too big to run on a 305 with the small cylinders. They would probably cause clearance problems.

You can find 059 vortec heads meant for a 305 or mill the standard ones with the smaller 1.94 intake valves.

thomas1976

Looks expensive, for that money you can get aftermarked aluminium heads http://www.summitracing.com/parts/TFS-30300001/ direct fit. Less weight and easier to port.

seanof30306

iTrader: (4)

Here's an article about a carbed 305 using those heads:

http://www.superchevy.com/technical/...ild/index.html

Fast355

iTrader: (2)

The 059 305 vortecs flow within about 8-10 cfm of the 906/062 heads on the intake side and IDENTICAL on the exhaust, except they have 1.84 valves and a chamber that matches the 305s bore. THey are the logical choice to make power on a 305. I wouldn't even use a 350 head on the 305s bore after having used the 305 heads for a build. The result was over 350 RWHP.

seanof30306

iTrader: (4)

I'd sure like to see some documentation of that. The 305 Vortec head has a standard D-shaped combustion chamber, just like an L98, rather than the heart-shaped combustion chamber of the 350 Vortecs. It also has smaller intake valves, so to flow within 8-10 cfm of the 350 Vortecs on the intake side, it would actually have to move air more efficiently, kinda disproving the whole heart-shaped combustion chamber theory.

When I brought up 305 Vortec heads years ago, everyone told me to stay away from them, that they were crap. I'd need to see actual flow bench data before I changed my mind on that.

EDIT:

I'd want to talk to this guy:

https://www.thirdgen.org/forums/post...701-post6.html

In his post, he linked to a comparison between a set of 305 Vortecs and a set of 350 Vortecs flowed on the same bench. The link is dead, but from the text of his post, he clearly felt the 305 Vortecs flowed nowhere near what the 350 Vortecs did:

"Stay away from the 305 "vortec" heads, they do not compare at all to the regular 062 castings that everybody looks for. CChamber is totally different than the real vortecs so effeciency suffers, take a look at these flow numbers. I bought a pair of "vortec" heads from a shop in Arizona, but through our many conversations he never mentioned they came off a 305 pick-up and I never asked.

The numbers in larger print are what my 305 "vortec" heads flowed, the little numbers above them are from a set my buddy had flowed by the same shop on the same flow bench, his were the 062 castings. Numbers dont lie, so if your going to all this trouble, get the right heads the first time. You can always reuse them on a different motor when you have the cash to go that route.

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

thomas1976

Thanks for the link, I have never come across that one.

Looks like a decent no brainer option, I would just skipp the carb

Fast355

iTrader: (2)

I've done the research by flowing a set, porting a set, flowing them again, then building a 310 cid .030" over roller cammed 305 and installing them on it under a SLP's TPI unit with a siamesed base and ported edelbrock TPI Vortec base. The numbers for the 059 heads were quite healthy at 356 RWHP @ 6,000. The heads are definately "fast burn" too as I found peak HP with only 30* advance. The 520's are different castings and flow alot less.

STOCK 059 castings flow 221/163 @ .500" lift

seanof30306

iTrader: (4)

Chris, here's what puzzles me.

Chevy High Performance flowed a set of unported L-31 Vortecs when they did that Mission 305 project back in 2004 and got 215.1/152 @.500 lift. I spoke with the in-house engine builder at sdpc.com when I was looking at their upgraded Vortecs and he told me those numbers are accurate.

Here is the full breakdown of CHP's Vortec flow #s

Lift Int. Ex.
.050 30.9 24.1
.100 60.3 47.8
.150 92.1 76.2
.200 125.0 95.9
.250 155.9 115.0
.300 179.3 136.0
.350 199.5 143.8
.400 215.1 149.1
.450 227.0 152.0
.500 215.1 152.0

Years later, In Feb '09, CHP tested a set of the SDPC Upgraded Vortecs and got almost identical flow numbers.

SDPC Upgraded L-31 Vortec
216/155 @.500 (before porting)
231/170 @.500 (after porting)

Here's the full breakdown:

Lift Intake Exhaust
0.100 66 57
0.200 129 101
0.300 186 136
0.400 219 149
0.450 225 150
0.500 216 155


http://www.chevyhiperformance.com/te...est/index.html


So, what you are saying is, even with 1.84" intake valves, those 059 Vortecs flow better than L-31 Vortec heads @.500? I find that astonishing, especially when E-Tec 170s only flow 232/183 @.500

And, on that 221/163 @.500 number, is that from your own testing? Can you post the .100, .200, .300, and .400 numbers?


EDIT:

OK, I found the flow sheet from IHI's 305 Vortecs in another post of his:

https://www.thirdgen.org/forums/atta...flow-sheet.jpg

It's hard to read, but on the "Cyl. Head Type:" line, it says "2332520", and I think the word after it is "casting". That would appear to make it the 520 casting, and therefore not relevant to this conversation, if the 059 and 520 Vortecs are truly that different.



EDIT:

OK, there's been a lot of back and forth over the combustion chambers. In my search, I've found a few people saying the 520 casting has a D-shaped combustion chamber, while the 059 casting has a heart-shaped combustion chamber. Chris, in another post, you said your 059s have heart-shaped combustion chambers.

Yet, if you look at this post, with comparison pics between 059s, 906's and E-Tec 200s, the 059 head clearly has a D-shaped combustion chamber.

http://www.nastyz28.com/forum/showpo...&postcount=478

Fast355

iTrader: (2)

There are TWO different 059 castings floating around out there. It seems GM decided one way was correct, then changed the design and felt a different approach was better. Keep in mind that some blocks in this change also have metric threads in place of SAE. This includes accessory bolts, bellhousing bolts, and engine mount holes.

The 2000s that I used have a D-shape to them. The 2002s that I had floating around had a smaller D shape with a more kidney bean shaped design. I found the same heart shaped 059s on a 2007 Marine engine. The Marine version as shipped with the TINY 196/206 @ .050, "395" Marine camshaft in it makes 253 HP @ 4,800 and 301 TQ @ 3,800 through the restrictive marine wet manifolds and wet exhaust.

906 castings have repeatedly flowed in the 235-240 cfm @ .500" lift. My stock 97 906s off the Express were about 240 @ .500 and about 170 @ .500 on the exhaust. With 2.05/1.60s in it and lots of porting they are in the 265 @ .500" and 210 @ .500 range. I would have to dig out the actual numbers before and after, but those are close. I put them on a 18cc dished piston TBI short block, with a mild little 208/214ish reed custom roller cam, with tri-ys, and a single plane and pushed 5,500 lbs of G-Van to a 14.2x @ 98.xx mph with a 2.12s 60'. So I have no doubt in the potential of the heads. The 310 pushed the van to a 15.08 @ 93.xx on a 2.18s 60'

The 059s I ended up using did not have the little < on the backside of the chamber, but the 305 really doesn't seem to need it with peak power at a mere 30* advance.

seanof30306

iTrader: (4)

OK, I'm not sure I'm geting this .....

You're saying the 059 heads you got the 221/163 @.500 out of had the D-shaped combustion chambers?

Also, you first said there were two different 059 castings, but it appears you then went on to describe three different castings didn't you? ... the 2000s, the 2002s, and the Marine heads?

Fast355

iTrader: (2)

The heads that produced 221/163 were 059s with D-shaped chambers from a 2000 Express and they were flowing over 250 cfm through a 1.94" valve by the time I was done with them. I have had another set of 059 heart shaped chambers in my hands from a 2002 Express. I have also seen the same 059 casting on a marine 305 in a 2007 Mercruiser application. Marine blocks/Heads are IDENTICAL to the ones used in the Trucks.

seanof30306

iTrader: (4)

OK, then two things:

Can you post the complete stock flow numbers you got for the heads that produced the 221/163?

And do you have flow numbers for the set of 059s with the heart-shaped chambers?

Fast355

iTrader: (2)

I dug around and found the information stored in my old notebook. @ 28 in/h20

Lift......I.......E
.100...68.....47
.200..128...103
.300...179...138
.400...205...152
.500...221...163

The ports stalled at 221/163 even at .700" lift the same numbers were repeated.

Same heads, ported, 1.94/1.60 manley raceflow valves, and 5 angle valve job.

Lift-----Intake---Exhaust
.050------32------25
.100------65------60
.200-----130-----113
.300-----185-----157
.400-----218-----167
.500-----254-----175



I have never flowed the 520s or the 059 heart chambers.

odecca

Man this is good stuff!
But I am new to this, so can someone tell me how much better are these vortec heads (which I heard elsewhere need to be milled) than porting and rebuilding the stock 187s?

What would the cost/HP gain be.

And lastly, for everyone else... YES, I'M SAVING FOR A 350 TOO! So we don't need to revisit that one for the billionth time on this site.

thomas1976

Thats good numbers, almost identical to the direct replacement, lightweight (aluminium), TFS 175 out of the box http://static.summitracing.com/globa...175%203766.pdf
http://static.summitracing.com/globa...175%204000.pdf