88_Import_Slaye

12558060 - Cast Iron Vortec Cylinder Head Assembly

How would these heads compare to my stock 416 heads as far as power / flow?

The specs say that the vortec heads have 1.94/1.50 valves, I have 1.92/1.60 valves. Would it be worth the $400 cost to swap my heads out for these heads?

Spectre

its either 062 or 996

vortec's are superior

88_Import_Slaye

In what way? Port flow capacity, port velocity? Complete design or what?

del91_305

Im sure that they will flow better than 416's. I have heard that they are very similar to LT1 heads

ME Leigh

LT1 heads only flow slightly more than 416 heads about 10cfm. Vortec out flow them all about 20cfm over even the vortecs.

LT1 heads and vortecs only have the fastburn combustion chamber design in common. Nothing else.

88_Import_Slaye

what is the difference between fast burn and other chambers?

F-BIRD'88

Stock vortec heads flow about 228 cfm intake and 150cfm ex. @.500" lift. They also have excelent swirl and a high tech fast burn combustion chamber that all contribute to their excelent power output.

Stock 416's flow about 185 and 110 respectivly with stock 1.84-1.50 valves. Quite a bit less.

I have ported and flow tested many sets of modified 416.
I have exceded the flow figures of stock vortec heads.
( 1.94x 1.50 or 1.60" valves) The highest was in the mid 240 range and 190 ex.
But I don't just lightly " pocket port these heads" I give them a good "hogging out" working specific areas that really kick up the flow. Finished port volume is 178 and 62 cc's respectivly. I take out a good bit of metal.

Even thou your heads have larger than stock valves you make no mention of any port work. ( makes all the difference.

I ran both vortecs and my ported 416's on the same 350 short block, in the same car and while I don;t have specific ET slips or dyno numbers, I can tell ya the ported 416's ( mine ) work real nice. ( No they don't make 500hp)
But how your heads compare to mine I can't say.
There is a big difference between a fully ported head and a stock head with larger vlaves thrown in.
A few friends have followed what I did with the 416's on a few other street performance motors and have gotten suprisingly good results.

* I have also fooled around with some porting and flow testing modified vortecs.
All in all the vortec head is superior to anything else GM has ever factory installed on a production motor. except maybe a LT-4 head.
Over all they are a better head and also respond to typical porting and larger valves. Because the head is much better to start with the gain seen with porting is not near a great as the gains seen on a 416, ported.

How much porting is done to your heads? Pictures? Flowtests?

88_Import_Slaye

I havent done an yporting yet. I've been researching which way I am going to go. I've only put bigger valves in the heads. I've trying to determine if I would be better off getting a new set of heads with bigger valves or porting my heads. I'm trying to determing money wise, power gain wise, if I can use my manifold with new heads, etc.

It looks like I might be better off getting a set of GM vortec heads for $400 and putting bigger valves in them for an added $100. BUT, I do like to be different, thus the fact i'm trying to push everything I can from this LG4.

five7kid

iTrader: (14)

I've never heard of any good done by putting larger valves in Vortecs. The $400 heads need better springs, guides cut for more lift capability, and better rocker studs. You're better off spending the money to get Vortecs that have had that done than to put larger valves in the $400 stockers.

del91_305

Wow, i didnt know that, i had always heard that LT1 and vortecs were about the same. im running ported 081's on mine

88_Import_Slaye

Which set do you recommend?

ME Leigh

Well i always thought stock 416's flowed 195cfm, but i guess F-Brid has actually flowed them at 185cfm.

LT1 heads flow around 210-215cfm.

While vortecs are around 230cfm

These are all stock numbers though.

kdrolt

Iron LT1 heads are the same basic casting as the (iron) L31 Vortec head (062 or 906 casting number suffix). The L31 head (which has conventional flow cooling) was based on the iron LT1 head (which has reverse-flow cooling).

The iron LT1 head was patterned after, and slightly improved from, the aluminum LT1 head. Alum LT1 came out in 1992 (Vette), then in the 1993 (Fcar) and then followed by the iron LT1 in 1994 (Caprice, Roadmaster, Impala SS). Slight improvements were made in the iron castings based on lessons-learned on the aluminum LT1 heads. So the iron outflow, slightly, the aluminum versions -- that's the 215 cfm vs 230 cfm difference mentioned (but not explained) above. The aluminum heads have smaller chambers than the iron ones so that raises the CR by approx half a point; this makes up for the heat transfer of the aluminum.

The flow tests on LT1 iron and L31 show the same basic flow #s, as you should expect given that the runners (raised at the intake manifold), chamber (heart shaped squish, compact volume for fast burn), and exh are the SAME. Web postings and magazine articles on LT1 aluminum, LT1 iron, and L31 Vortec prove the airflow and inspection of each shows the similarities.

Head cloning was also done to the LT4 head (some 1996 Vettes). The LT4 aluminum head is reverse-flow cooled, and it was also cloned into the conventional-flow cooled aluminum "Fastburn" head that GMPP sells. The flow numbers on the LT4/Fastburn are better than the LT1s but they are not good choices on a small-cammed 350 because the airflow (in most of the engine operating rpm range) isn't fast enough to keep the fuel well-mixed. They'll work on 350s with big cams, or on strokers, but not well on the usual 350 with LT1/ZZ3/845/LT4HOT cams or equivalent. HTH.

---

EDIT: 12558060 is probably the part number for the cast iron Vortec Cylinder Head Assembly; the 062 and 906 numbers are the last three digits (the suffix) in the casting number on the Vortec heads. The casting number, and the part number, are not the same thing so I wanted to clarify. HTH.

ME Leigh

Aluminum LT1 heads i know for a fact don't have raised runner. I successfully adapted a standard weiand stealth sbc intake to my AL LT1 heads. No grinding was necessary.

IHI

iTrader: (1)

Here's teh actual flow sheet from my 305 vortecs I bought with 2.02/1.60 valves. the big/bottom numbers are my heads. The little numbers above my numbers are 062 vortec casting in box stock form. Dont waste your money on installing bigger valves in the vortec, what they really like is ome minor touch up on the intake side and alot of hogging on the exhuast side.

F-BIRD'88

This flow test is not with a 350 vortec head with 2.02's and proper chamber preparation for the larger valves.

Do not take this as any indication of the potential of a 350 vortec head 062 casting with or without larger valves.

The 350 Vortec head 062 casting will flow more air with the larger 2.02 valve installed **** when you prepare the chamber to suite the larger valve.*****

With a head like the vortec with a radius chamber wall almost all the way around the valve it only makes sence that if you just install a large valve you are infact making the flow window around the valve smaller.
You have to openup the chamber around the larger valve
so it can flow.

If you read the popular published articles on vortec heads they all say exactly the same thing. There is flow to be had with larger valves in vortecs, BUT ya have to rework the chamber a little to get the flow. This is very typical of many many other high perf heads.

I have flow tested these heads with the stock valves and with the 2.02's stock port and chamber and after porting and releiving and they do flow more air with the larger valves ( after mods). My heads are not highly modified or heavy ported. (just general clean up and tweeking from stock.) Ya don't need to change the shape of the chamber just make the same concept a little larger around the new larger valves. Common sense.

I cannot imagine how you can F&^% up a 305 vortec head that bad. but even still that has nothing to do with a 350 vortec head.
Sorry IHI. Not trying to flame ya just want to get the truth out without confusion.

Vortec heads work great stock out of the box with stock valves. They can be mildly improved with porting and stock valves. Just adding large valves at this point will not improve flow UNTIL YOU PORT FURTHER AND RELIEVE THE CHAMBER RADIUS AROUND THE LARGER VALVES.> Then they flow more.

If you want a head that flow 270+ this is not the head to start with. Start with a simular larger head.
If you want a head that has 230(stock) to 250/ 260cfm (ported) and a small port and high velocity for a 350 or smaller motor this is a good head to start with.

midnyteeight1

Ok KDROLT, I'm getting this from you. The LT1 Aluminum heads are the inspiration for making the Vortec heads. The only difference in the two is the flow of the cooling system. If so, does this mean that you can use LT1 heads with a vortec manifold? Of course I know you have to get T-5 aluminum strips to fill/weld/ and surface the water jackets on the ends. Just would like to know.

IHI

iTrader: (1)

F-Bird, no flaming taken. You've been there done that with these heads and have first hand knowledge so it's safe to say you know wtf your talking about. I was just gonna freshen up my old 355 and bought those "vortec" advertised heads off e-bay, got the e-mail/phone call smoke screen and then those castings arrived Had them flowed and within an hour of picking them up I literally put the entire top end kit I had peiced together on ebay....for the record those 305 vortecs and lunatic solid flat tappet I picked out was put on a 9:1 compression 383 running 11.70's in a 2900lb 62 nova.

I talked with a few other guys at the track with street cars running vortecs into the low 12's and got some feedback-and one produced his flow sheet to compare my 305 vortecs too which is where I got the info on my sheet above. He said he tried one set with the 2.02/1.60 valves and minor clean up and did'nt pick up anything cfm wise, but I'm assuming the shrouding issue cam into play since the chambers are so tight as it is.

Vortecs are a great budget head, just not one I'd sink much money into when other casting out there flow as much but leave you alot more room to grow and allow larger cam installs without machining.

kdrolt

The basic difference is as you said, the direction of cooling flow.

There are subtle differences between the iron (LT1, L31) and aluminum LT1, but they are slight.

There is a very fine sticky post on the TPI section (at the top of the page) that details what people have done on using the alum LT1 heads in sbc config. ME Leigh (who posted here) is I believe one of them. Read the entire thread.

In re ME Leigh comment: LT1 heads did not have raised runners in the same sense that the LT4 and Fastburn heads do --- that's VERY raised in production sbc heads. I did think that GM raised the runner slightly on the LT1/L31 heads based on their description, but I haven't measured them side-to-side so you're probably right.... especially if you got the Weiand intake to mate with zero grinding on either manifold or head. Thx for correcting me.

EDIT: aha no correction needed, GM considers them a raised runner head. I thought I read that right...:

So (ME Leigh) the Weiand intake manifold you used must have been designed, deliberately or accidentally, to allow good runner-runner contact with no flange leaks.

The LT4 and the Fastburn heads have a inlet runner to the head that is raised even more than it is on the LT1/L31, when when those heads are used, you MUST use a compatible manifold otherwise you get big intake leaks. HTH.

midnyteeight1

Hey, the question I meant to ask is:
Will a Carbed Vortec intake, i.e. Edelbrock Air Gap, work on modded LT1 heads? They are virtually the same as Vortec heads, with the exception of the cooling.

kdrolt

IIRC GM sells, thru their GM Performance Parts line, a carb-capable intake manifold designed specifically to mate to the LT1 iron and LT1 alum heads. HRM used one when they did a mild build of a 1995 Buick Roadmaster LT1 engine (HRM, Oct 99 if I recall right).

They took the stock, but used, engine and added headers, carb intake, carb, LT4 HOT cam, 1.6 rockers and got 422 fwhp (engine dyno test). They did not port the heads, and they did use the GM intake. Look at Pace or Sallee's web sites and I'm sure you can find it. HTH.

EDIT: you'll have to ask the aftermakt mfgs themselves if their intakes will work with LT1-type head bolt pattern, or search here and see if someone has already done it.