i've been researching heads for my 305 for awhile.

the ideal heads would:

* have 58 cc chambers to keep compression up

* have egr compatability

* use a pre-87 intake (so i can use a weiand 7525 intake)

* use center bolt valvecovers (so i can use my wires and looms).

i looked long and hard at vortecs, but the only intake available with egr for vortecs is the gmpp aluminum intake, and it doesn't flow that well. it doesn't make sense to put a good set of heads on the engine, then choke them down with that intake.

i looked at upgrading and porting a set of tpi heads, but it'd be too expensive for the airflow you'd get.

i settled on a set of world products s/r torquer 305s after i found a set on ebay for 300 (with springs, retainers, etc., but no valves.) i bought them, planning on putting in a set of manley stainless valves and spending 5-700 on porting. i'm having second thoughts now that i've seen the flow numbers on a set of them done like i planned to do mine. don't get me wrong, they flow better than any non-vortec factory head, but i'd have over a grand in them by the time i got there, and i believe i can do better for the money.

earlier this week, i came across a set of aluminum zz4 heads for $1,100. they have 58cc chambers, use the pre-87 intake and center bolt heads. better than that, they've been professionally ported and flow a lot of air.

.300" intake: 175 exhaust: 128
.400" intake: 206 exhaust: 154
.450" intake: 212 exhaust: 167
.500" intake: 215 exhaust: 172
.600" intake: 215 exhaust: 177

i know the heads don't have egr passages, but as long as i can use an intake with an egr port, i can use an external egr valve, just as the corvette these heads cam off of did.

the only concern i have is the zz4 "orange" springs on the heads. I'm pretty sure they're only good to .510" lift, and i'm thinking i want to use an lt4 hot cam, which i believe has 5.25 lift.

does anyone have any thoughts on this?

 

I know a guy that is running the L98 aluminum vette heads (almost the same as the ZZ4) on a .030" over 305. He makes quite a bit of power with it. He is running the same cam I am. It is in an S10 backed to a 700r4 and 4.10:1 gears where it runs low 14s.

 

If I were going to drop $1,100 on a set of heads I would not go with zz4's. Look into some AFR's or save some money and get some Pro Lightnings for less than that 1100 and I'm sure both of those options will flow much better.

 

both of those heads have 2.02 intake valves and will not work on a 305. i've spent a lot of time researching this, and the only 1.94 intake aftermarket heads i've been able to find are the pro topline vortecs, gm fast burns and edelbrock e-tecs. all of those have 64cc chambers and use vortec-style intakes.

these zz4s have been ported by racing head service. if you look at the flow numbers, they're in the neighborhood of vortecs and etecs, though not quite as good past .500". the mid-lift numbers, though, are very, very close.

 

Yeah I looked at those heads after I posted and did notice the valve size, so that's a problem. But honestly to get heads that are close to the flow of stock vortecs for 1100 dollars is just not sitting well with me. Why not go for the Pro Topline vortecs and use a Performer RPM intake? I think in the long run you'd regret going with those zz4 heads. r90camarors is running those pro toplines and he's laying down great numbers and if you ever want to port those later on you stand to gain quite a bit. I think with those heads and the hot cam that'd be a real nice combo. Look at Jon Prevosts setup too, he's running the Performer RPM on top of vortec heads and it works well.

 

you're right, i love that combination, but i have one hangup ... egr.

the only intake for vortecs with egr that i know of is the gmpp, and it doesn't flow well. it also cost around 300 bucks. so, a set of pro topline vortecs would run around 700. 300 for the intake puts me at a grand and that intakes poor flow would choke down the heads.

if weiand made a 7525 for vortecs, i'd be on it in a second!

i've looked at this from every angle, and this is the best way i can find.

 

Yeah, that's kind of a tough call, I know what ya mean. What about doing something similar to what Swerve-Driver did to route the EGR into the intake? He's running vortecs too.

 

i was the one who asked him for details. he's running the gmpp intake.

the ideal solution to running egr with vortecs would be to simply plumb the output of the egr valve into the plenum. i don't know whether you can just do that, though. it obviously wouldn't be carb legal, but my version of legal is to have all emissions equipment installed and operating and the car being able to pass visual and sniffer test.

i've asked the question about the egr functioning properly if it's simply plumbed into the intake, but have never gotten an answer.

 

2.02 intake valves will work on a 305

 

I might be able to get you a set of the 113 casting (zz4, d-port exhaust) L98 aluminum heads, complete with vlaves and springs (should be replaced, as will all heads), used, for $500. Guaranteed to be crack free! Email me RPPerformance@comast.net if your interested!

 

thanks, dude, but it's not just the heads, it's the porting. these have been professionally done. look at the flow numbers. i have the "before" numbers, too, but they're at work. i'll post them tomorrow. the difference is huge.

 

2.02 valves will fit on a 305. I saw an engine built by RHS. A 290 horse smog legal 305 that was running AFR 190 heads and an RV cam. Still had the computer carb too.

http://www.goingfaster.com/spo/290hp305.html

Add a bigger cam and drop the smog legal part and you should have more power than this engine.

http://www.goingfaster.com/spo/343hp305.html

or this one

http://www.hioutput.com/tech/400hp/400hp.html

 

I saw your posted flow numbers. Stock, the 113's do 199 @.500 on the intake, forget the exhaust off the top of my head. Seems like those heads were VERY mildly ported. 15 CFM could come from a simple 3 angle valve job.

 

the manley intake valve on the 400 hp engine (#11560) measures 1.937".

the 345 hp engine used 1.94 intake valves.

on the rhs 290 hp engine, it doesn't say what the valve sizes are. as far as i know, all afr heads have 2.02" intake valves. there's a lot of information about that buildup we don't have, though. for example, they used a stroker crank. changing the stroke may have had an effect on valve clearance. i've also heard of people clearancing the block to run 2.02 heads on a 305.

i spoke with tech support at afr about using a set of 180s. the first thing he brought up was valve clearance. when i told him i'd heard of people clearancing the block for the valves, he said that wasn't the only issue, that shrouding still existed and hurt performance.

personally, i'm not too impressed with that 290hp 305. when you look at the parts on that engine, it should make more. those afr heads are about the best you can buy for under $2,000, and that's a pretty healthy cam, too.

 

according to chevy high performance magazine's flow bench database, the 113 l-98 head flows:

.300" intake: 160 exhaust: 123

.400" intake: 186 exhaust: 140

.500" intake: 196 exhaust: 155

.600" intake: 199 exhaust: 159

comparing that to the numbers on the ported one's i'm looking at:


.300" intake: 175 (+15) exhaust: 128 (+5)

.400" intake: 206 (+20) exhaust: 154 (+15)

.450" intake: 212 (N/A) exhaust: 167 (N/A)

.500" intake: 215 (+19) exhaust: 172 (+17)

.600" intake: 215 (+16) exhaust: 177 (+18)

essentially, a 10% improvement in flow. now, look at vortecs:


.300" intake: 176 exhaust: 133

.400" intake: 212 exhaust: 151

.500" intake: 211 exhaust: 159

.600" intake: 211 exhaust: 157

the ported zz4s have virtually the same .300" and .400" (mid-flow) numbers, and breathe much better at .500" and up. on top of that, the zz4s have 163cc intake runners while the vortec's are 170ccs. so, these heads should not only breathe better up top, they should have a bit more torque, too.


the really amazing head, to me, is edelbrock's e-tec:

.300" intake: 177 exhaust: 138

.400" intake: 215 exhaust: 169

.500" intake: 240 exhaust: 180

.600" intake: 240 exhaust: 190

that's better than even fast burns! i'd go with those in a second if i could just figure out a way to plumb egr into a non-egr intake.

i was talking to a guy who sells refurbished vortecs awhile back. he said he was going to start drilling the heads for old-style intakes. if that could be done on an iron head, i wonder if it could be done on an aluminum one? if it could, the problem would be solved ... i'd just use my weiand 7525. the only other challenge would be to port match the intake to the vortec heads' taller intake runners.

 

There's two problems with making a standard intake fit vortec heads.

1. Not enough metal to redrill bolt holes in head on intake mating surface.( Very little as far as amount of threads to hold down intake, heads have thin metal in this area)

2. Stanard intakes leave at least a .050" to .100" gap above the manifold so welding, machining and porting would be required.

Unless you are trying to build a 350+hp engine then the fully ported zz4 heads would be overkill IMO. A set of stock aluminum L98 heads with some bowl work would be a great head for the money.

Steve

 

i've decided to go with the ported zz4 heads. thanks for the advice.

now, i'm on a cam search

 

The $1,100 heads?

 

for $1100 bones, why not go with something that is a proven performer, like the fastburns, pro-topline, TFS 23*, brodix, AFR, or the like.

the ZZ4 heads, as far as i can remeber are nothing more than alum. L98 heads.

 

dewey.. read the above, it's all discussed. tfs, afr, brodix are all 2.02" heads. will not work.

these heads have been ported by rhs. look at the flow numbers i posted above and compare them to the vortecs .... virtually identical mid lift numbers and the vortecs fall on their face at .450" while the ported zz4s flow all the way up to .600"

fast burns, pro topline vortecs, etc require 300.00 intake to make egr work that flows like crap. fast burns are 1,300 a set and have 200cc intake runners ... way too much head for a 305. pro topline vortecs are 700 with shipping, 300 for the intake. so, a grand to go with vortecs (not including what it costs to have the heads disassembled and milled to address the compression issue).

no one has suggested anything else that meets all the criteria:

* vortec or better flow numbers

* 1.94 intake valves

* 58cc chambers

* 170cc or smaller intake runners

* egr compatible

* able to use weiand 7525 intake


these heads will bolt right on, flow better than vortecs, allow me to simply plumb exhaust gas from the passenger air tube into a corvette external egr valve in the intake i already have and like.

 

ok, i guess my view on it is this.

you are paying 1100 for basicly a ported stock head. the other thing that hasn't' been brought into play here is your compresion ratio. even though those have 58cc chambers, they are alum. the reason they have that is to up the compression on a 350 to the proper place with alum. due to the head disapation properties of alum. vs iron, you typicaly run 1 point more static compresion with alum. vs what you would run with iron. you are also going to a cam with more overlap than the factory has, that will lower you dynimic compresion ratio. that factored with the pretty low compresion for an alum. head. you really are not making the most of the combination.

please don't let me discourage you, i am trying to help you make a descesion that will get you the most for you money. i really suggest that you take some factors like the dynamic compresion ratio into play, and since you tend to want a high compresion with alum. you might want to look into having them mill the heads down for compresions sake. check out a dynamic compresion calculator, run diffrent cams specs through it, and find the static compresion ratio that is optimal with alum heads and the cam you want. i am willing to bet money you end up in the 10.0-10.5 range with the cams that you mentioned in your other post. to hit that number, you will need to have those heads milled. most aftermarket heads take milling into account, and they tend to have a very think deck surface for that reason, most of can very easily go down to 54cc or 52cc chambers. but you are right, you get stuck on the valve size. you might consider making some phone calls to some of the head companies, and see what they offer in a 1.94/1.5 valve combo that will fit on a 305, you might just find something that will be a better fit for you than those heads.

 

dewey,

trust me, you're not discouraging me. the reason i started this thread was to see if anyone could offer a better solution. i've literally researched this for months. i've talked to afr, brodix, edelbrock, holley, trick flow, pro topline, scroggins-dickey, at least half a dozen head porters/machine shops, etc. none had a solution. several suggested either the s/r torquer 305s or the corvette aluminum heads. the rub is the 305's bore. when you rule out a 2.02" intake valve, you eliminate a ton of choices. the other rub is egr/vortec intake. the only egr intake currently available for vortec-style heads is made by gmpp, and the tech rep at scroggins-dickey said it flows like crap. with those two outside barriers, the only head i've been able to find "between them" that flows the kind of numbers i want is the ported zz4.

you're right, it is just a ported stock head, but the bottom line is the flow numbers. i have a set of world products s/r torquer 305 heads i picked up used for 300 bucks (with springs, no valves). by the time i put valves in them and have them ported, i'll have over a grand in them and they'll flow nowhere near what those ported zz4s flow now. i can get a set of pro topline vortecs for right at 700 (with shipping). same for the upgraded gm vortecs from sdpc2000.com. 50 bucks to have them milled and 300 for the intake puts me at 1,050, and i don't know what kind of valve geometry problems i'll have from the milling.

i've said it before, for 1,100 bucks, i believe the best head available is the edelbrock e-tec 170. look at the flow numbers on those heads! but why put 1,100 into a set of heads, then spend 300 on an intake that will just choke them down. the guy at scroggins-dickey said an edelbrock performer rpm airgap was woth 60 hp over that gmpp intake on a vortec-headed 350! unfortunately, the performer rpm air gap doesn't have a provision for egr.

your point about compression is valid. do you know where i can get access to a dynamic compression calculator?

 

http://members.uia.net/pkelley2/DynamicCR.html