92_RS_305

Which would be the better/more power producing way to go on getting a set of Vortec heads or just getting the stock heads ported and polished......? If going with the stock heads what all should I have done to them.....?

tbuck46

If you get a set of vortec heads, then you will need to get a new intake manifold because the stock will not bolt up. Not sure who makes one for tbi, maybe Edelbrock. As far as stock heads you might be better off just getting a set of World Products S/R torquer 305 heads. They will flow better than stock. If porting the stock ones, fine, but don't try to increase the valve size because you will hurt the performance more than help it because of the smaller bore size of the 305.

Sitting Bull

Do the stock 305 heads yourself and save some serious coin. Follow the link at the end of my sig. Opening the intake valve to 1.94" from 1.84" is crucial for flow and power. They will flow as wel;l as Vortecs and cost a lot less

tbuck46

I was thinking 1.94" valves were the stock size in the 305 heads, but I was wrong. Going to 1.94" is fine, but like I said, don't go bigger than that because bigger valves will restrict flow because of the small bore size of the 305. The valves will sit too close to the edge of the cylinder wall.

GreaseMonkey83

the biggest i could go was 1.94" intake, i think you start cutting into the water jakets if you go any bigger than that. and unless your just cleaning up the chambers, i would fully port and polish them yourself. you should have a professional do it that has access to a flow bench.

Sitting Bull

I give good instructions at my link, he doesn't need a pro.

irocz8957

vortech heads are the only way to go!!!

irocz8957

oh yeah be prepared to spend a nice little chunk of change when you to buy them!

walrus108

Great info. I've always wondered what went in to that. Still seems impractical though. This would cost around $400 like you said but you can get a complete set of vortecs for under $500. Even if you do get these heads to flow slightly more on the bench than a stock vortec you still would be making 20-30hp less than the vortecs will make. There is alot more to making hp than flow numbers. And there's pretty much nothing you can do to make a 305 head flow anywhere near the vortec's at low lift. And no swirl or tumble like a vortec. So for the time and money the vortecs still win i.m.o. Something to keep in mind for all those considering.

Sitting Bull

A heads potential to make hp is ENTIRELY tied to its ability to flow air. Chamber design, etc., helps a little but certainly not to the 20 or 30 hp figure you believe.

On top of the cost of your Vortec heads ($500) are a suitable intake manifold ($200) and valve covers ($100). Suddenly the project's cost comes into sharper focus, eh?

$800 vs. $400 ... hmm, which one will I choose?

Chuck!

If you had LB9 or LG4 heads Id say 100% go ahead and port them, but you have L03 (187 castings) heads which might have been the worst cylinder heads to ever come on a small block chevy. Take them apart and look at the short side, and just the overall poor design, you'll want to vomit all over them.

You could score cheap LB9 heads though, a friend picked up a set for $75 ported them and had them back on, made good power with an LT1 cam. Neither of us are tuned, and the difference between his setup and mine is the Vortec heads vs ported LB9, and he has a projection manifold with a 2" tbi, where I have the Performer RPM with stock tbi and Im trapping 2 mph higher. But then again, both with stock tuning we have lots left in our cars.

Edit, I bought my vortecs used for $405 and they already had valve guide work along with the Z28 spring and were milled .020. After it was said and done he had about $320 (new seals, valve job, new springs) in his and woulda been more but my dad scored him a delux porting kit for free. So he saved in the long run and had fun porting them, but I went with the lazy route

The final price figures looked like this:
$585 ($405 (heads), $180 (manifold) stock valve covers work fine ) for me
$450 ($320 (heads), $130 (manifold) ) for him. So I was out $135 but Im more than content.

axoid

I just completed an upgrade on my L03. World Torquer 305 heads, Edelbrock Performer intake and a LT1 cam.

I like the Torquers, with old perimiter bolt valve covers it's a direct bolt on, no machining needed. To use center bolt covers a little machining is required.

irocz8957

shop around and try the find the best set i heard trick flow are damn good heads!

walrus108

Yes but the ability to flow more air and fuel from the point the valve leaves the seat to the time it closes. There is no way to get 305 heads to flow more at low lift (.100, .200) than the vortecs do. You may get the same at .5 or .6 and have the same peak flow but never the same mean flow. And the 305's won't keep the fuel mixed as well, will take more timing advance, use more fuel, and make less power. The spark plug is in a different location and the vortec's ports and combustion chambers are far superior to anything that can be done to 305. Even porting the old "camel backs" isn't too practical now days. My focus is clear, I wish to not put dollar one into p.o.s. 305 heads. Why really? There are so many better ways to go about it and i.m.o. better options. You and i are just looking at it from different angles. Head tech has jumped by leaps and bounds in the last 10 years. There are many advantages to using that tech on our older cars. For me I'm saving for some fast burn heads or possibly afr's. Any money spent on 305 heads, to me, would just a waste from my point of view. I'm not saying your wrong to port them. Just others may want more of what I do from their cars and should take note of the different options.

Sitting Bull

I respect your point of view. When I heard that 305 heads are an untapped gold mine, I was skeptical too! After all, they're giving them away at the junkyards, how can they be any good?

The guy I learned all this from, F-Bird'88, hangs out on the www.thirdgen.org forums and is a long time pro at this stuff. Let me quote you what he's informed me of.
_________________________
October 17, 2002

The latest set I did with 1.94 x1.60" valves flowed 238@28" in
and 189 ex.

Thats not too shabby for something that you'd throw in the garbage.
Even my friend with the flow bench was shocked. "This thing must be leaking or something!!"

We flowed a set of Brodix -8's and a set of 2.02 Vortecs
at the same time so we know the bench was operating right.
Outflowed the unported 2.02 vortecs and a set of mildly ported
041's.

If it ever stops raining here:
I will be getting them on the car (with a few other mods
single plane intake .550" lift solid cam, 12.65:1 cr)
and will report on their performance.
My vortecs (Set A) are coming off. Flow was 228@28" on these vortecs and it runs 13.05. Won't be a direct comparision but...

Looking for a 12.6? et at about 108mph
I'm curious to see what these 305 heads would do on the dyno
also.... maybe some day.

In my opinion these 305 heads have a little more potential
than the common open chamber smoggers if you're willing to
put the work and bigger valves into them. The combustion chamber size and shape is better especially after a lil reshaping (unshrouding). The ports are about the same.

Note: These 305 heads are not lightly ported. a lil pocket port
will not cut it. Plan on removing some metal. These numbers are from a set that I didn't take to the max.


lift cfm
.100 70.1
.150 105.2
.200 135.27
.250 158.6
.300 187.0
.350 205.41
.400 222.11
.450 225.45
.500 225.45
.550 218.77
__________________________
His name is Russel Patrick and he lives near Hamilton, Ontario. He flowed the heads at his buddy's shop. That guy does head work for CASCAR engines (Canadian equivelent of NASCAR) and knows his business.

These are the latest figures I've seen for L31 Vortec heads.

.100 59.000000
.200 118.000000
.300 177.000000
.400 217.000000
.500 226.000000

So, Vortecs ain't got nothing a good set of P and P'ed 305 heads can't match or surpass