Casting Info BB Chev topper

Big Block Chevy Cylinder Heads

En god måte å beskrive big-block topper på, er å kategorisere dem som "Open" eller "Closed Chamber". Closed Chamber topplokk har små forbrenningskammer for høyt kompresjons forhold , selv med lite domede stempler. Open Chamber er større forbrennings kammer og gir lavere kompresjonsforhold, samt krever en mer domed stempeltopp for å oppnå den samme kompresjon som Closed Chamber. Bruk av en av disse type topper krever at det blir brukt riktige stempler, ellers ...

Casting

Years

CID

Chamber

CC

HP/RPO/Comments

3904392

1967

427

Closed

106.8

430, 435 L-88/L-89, 1.72 ex

3919842

1968-69

396

   

375 L-89

   

427

Closed

106.8

430, 435 L-88/L-89, 1.84 ex

3946074

1969-71

396,402

   

375 L-89, 427 430 L-88/ZL-1

   

454

Open

118.0

425, 465 LS-6/LS-7, round ex

10051128

1990-94

454

Semi Open

 

72cc, IP 400cc, bowtie, sym port

14011077

1989-94

454

Open

 

118.0cc, IP 295cc, replacement, C port

14044861

1989-94

454

Open

 

425, 105.0cc, IP 380cc, bowtie, W port

3856208

1965

396

Closed

108.9

375, 425 Z-16/L-37, 1.72 ex

3873858

1966-67

396

   

375 L-78

   

427

Closed

108.9

425 L-72, 1.72 ex

3904391

1965-67

396

   

375 L-78

   

427

Closed

106.8

425, 435 L-71/L-72, 1.72 ex

3919840

1967-69

396

   

375 L-78, 1.72.ex

   

427

Closed

109.0

425, 435 L-71/L-72, 425 COPO

3964291

1969-70

396/402

   

375 L-78, Intake Port 325cc

   

427

   

425, 435 L-71/L-72

   

454

Closed

 

450 LS-6, 108.0cc

3964292

1970

454

Closed

 

450 LS-6, 109.0cc

3994025

1971

454

Open

 

425 LS-6, 118.0cc

3994026

1971

454

Closed

 

425 LS-6, 118.0cc

6258723

1971

454

Open

 

425

6272990

1971-94

454

Open

 

425, 118.0cc, IP 325cc

14096188

1987-94

454

Open

 

425, 118.0cc, IP 325cc, replacement

14097088

1989-94

502

Open

 

GEN V, 118.0cc, IP 325cc, replacement

OVAL PORT - Valve size 2.06 intake, 1.72 exhaust

Casting

Years

CID

Chamber

CC

HP/RPO/Comments

330864

1970-81

366/427/454

Open

   

330865

1970-84

366/427/454

Open

   

336765

1973-84

427/454

Open

   

336781

1973-85

454

Open

 

113.0cc

343771

1968-85

366/427/454

Open

   

343772

1976-84

366/427/454

Open

   

343783

1975-78

454

Open

 

car & truck

346236

1975-87

454

Open

 

113.0cc

346238

1975-87

454

Open

 

113.0cc

353049

1970-73

402/454

Open

 

113.0cc

473328

1968-85

366

Open

   

3856206

1965-66

396

Closed

 

325 97.2cc

3856213

1966-70

366

Closed

 

truck

3872702

1966

396

   

325, 360 L-34/L-35

   

427

Closed

 

390, L-36 98.4cc

3876875

1966-70

427

Closed

 

truck

3904390

1966-67

396

   

325, 350 L-34/L-35

   

427

Closed

 

390, 400, L-36/L-68 98.4cc

3904393

1966-68

366

Closed

 

truck

3909802

1966-67

396

   

325, 350 L-34/L-35

   

427

Closed

 

385, 390, 400, L-36/L-68 100.9cc

3917215

1967-69

396

   

325, 350 L-34/L-35

   

427

Closed

 

335, 385, 390, 400 100.9cc

3917219

1966-70

366/427

Closed

 

truck

3931063

1969-70

396

   

325, 350 L-34/L-35

   

427

Closed

 

335, 385, 390, 400 100.9cc

3933148

1969

366/396

Open

 

2V/427 265 122.1cc car & truck

3933149

1969-70

427

Open

 

122.1 cc truck

3964280

1966-70

427

   

335, 385, 390, 400

   

454

Closed

 

345, 360, 390 LS-5

3964290

1969-70

396/402

   

325, 330, 350

   

427

   

335, 385,390, 400

   

454

Closed

 

345, 360, 390 LS-5 100.9cc

3965198

1969

396

   

truck

3975950

1968-70

366/427

Closed

 

truck

3986133

1970-85

366/427

Closed

 

truck

3986136

1970-84

366/427

Closed

 

truck

3993820

1971

402

   

300, 330 LS-3

   

454

Open

 

365 LS-5 113.0cc

3999241

1972

402

   

240, 300, 330 LS-3

   

454

Open

 

365 LS-5 113.0cc

6272292

1971

402

   

240, LS-3

   

454

Open

 

270, LS-5

10101136

1991-94

454

Open

 

truck

10121033

1978-88

454

Open

 

truck

12352783

1979-93

454

Open

 

truck

14025175

1983-93

454

Open

 

truck

14081044

1986-90

454

Open

 

truck

14092359

1986-89

427

Open

 

truck

14092360

1985-89

454

Open

 

truck

14101398

1986-90

454

Open

 

truck

 

Vortech Topper

Vortec Heads

Many people are talking about Vortec heads these days. While the Vortec head is a very powerful and inexpensive production head there is some confusion as to exactly what makes a head the Vortec head. This article will explain the Vortec head and give you picture comparisons so the next swap meet you will know for sure your buying a set of 'Vortec' heads!

 A Little History

The Vortec name first appeared on 4.3L V-6 engines in 1986.These engines were the first to use a new "Vortex technology" designed to create a vortex (powerful swirl like a tornado) inside the combustion chamber. The Idea behind this is to create a more even and well mixed air/fuel charge that both generates more power and is more efficient. Over the years this Vortex technology has changed and improved to develop many new changes in the GM power train division. In today's world 'Vortec' Means power and here is where the confusion starts. There are literally thousands of cylinder heads that have been made with the vortex technology since 86 and many people refer to 87 and later small block heads as 'Vortec' heads. While this is a half truth the heads that GM sells under the Vortec name and the ones everybody is buzzing about did not exist until 1996.

 Outside Appearance 

From the exhaust side of the head you can't tell a vortec from any other head. They look nearly identical to all other chevy heads. The ends also look more or less the same. All the accessory holes on the outer edges look just like any other 87 and newer center bolt head.
The intake bolt pattern is different! It uses an 8 bolt attachment. This unique bolt pattern and the casting numbers are the quickest way to tell them apart from other heads. You also can tell by the casting mark on the end of the head since the vortec head has a 3 triangle or 'sawtooth' casting mark. They are available under 2 casting numbers 10239906 and 12558062. Both casting are good and performance wise they have no difference.

 

The Combustion Chamber

The vortec head as a smaller chamber much like the early 461's but the spark plug is more centrally located in the in the chamber. The kidney shaped chamber promotes better combustion thus making more power. While they are 'advertised' with a 64 CC chamber they can vary from 64-68 CC's in production.
These heads are all produced with 1.94/1.50 valves but they can be machined to accept 2.02/1.60 valves.

 

The Bolt Pattern 

The intake bolt angle for the vortec is different, 72 degrees vs. 90 degrees of earlier heads. It is also located in the upper 1/3 of the head and uses a 5/16 coarse thread instead of the usual 3/8 coarse thread of earlier heads. When the vortec heads are bolted on an engine all 8 attachment bolts are almost strait up.

The vortec head has only the outer bolts and the center bolts are no longer used. Also notice that there is no heat riser passage either but there is a indent where it would have been. Since the heat riser has been deleted form the vortec head if you choose to run these heads and have to retain the EGR valve for emissions you will have to change the exhast mainfolds, usually the drivers side at least, and obtain the EGR tube. This pipe feeds exhaust gasses from a port on the exhaust manifold to a port on the intake manifold that feeds the EGR valve.

With this new bolt pattern you will have to have a vortec style intake manifold, or you can drill and tap the cylinder head for the early style intake pattern. I have personally done this a few times but it takes very careful preperation and if not done correctly you can make the heads unusable. If you choose to try this you need to be aware of a few things, The old style intake and gasket may not cover the smaller bolt hole up top, The new bolt hole will intersect the smaller old one, drilling to deep on the outer bolt holes can punch through into the water passage, and the metal is kinda thin in the center where there are no existing bolt holes. I reccomend installing small 5/16 allen plugs in the old bolt holes with red locktite before you drill the new holes. Once drilled and tapped, clean with brake parts cleaner then cover the original holes and allen plugs with JB weld and smooth it down. This will prevent any leaks from sprouting from the old smaller bolt holes. When installing the bolts don't over torque the center 4 bolts or they will strip!!!! No more than 25 ft/lb on the center 4!


These are part numbers for new aftermarket intake manifolds that will directly bolt to the vortec heads. There are now several different varriations of the vortec intake and many brands, I only list the GM and Edelbrock brand vortec intakes because I have used them, I know these work!

GM Vortec intakes

Part # 12496820 is a low rise dual plane with EGR provision and dual carb bolt pattern.
Part # 12366573 is a high rise dual plane manifold with a holley carb flange.
Part # 12496822 is a high rise single plane manifold with a holley carb flange.
Part # 12496821 is a Throttle Body Injection manifold with EGR.
Part # 12498060 is the SDPC TPI vortec base manifold.

 

Edelbrock Vortec intakes

Part # 2116 Performer manifold non-EGR
Part # 7116 Performer RPM manifold
Part # 7516 Performer RPM Air Gap manifold
Part # 2912 Victor Reports 2-Barrel manifold
Part # 2913 Super Victor 4-barrel 4150 flange

 

A Word on Power

Valve Lift

Intake

Exhaust

.100

70

48

.200

139

101

.300

190

121

.400

227

140

.500

239

147

.600

229

151

As you can see in the table above, Vortec heads have excellent flow characteristics! In fact GM states that production vortec heads flow better than Bowtie Phase 2 Cast iron heads!!! Vortec heads have been used in many performance applications and by many performance magazines over the years and on average these heads, with standard off the shelf intake, exhaust and conservitive camshafts, make 400 + HP.

When GM designed the vortec head they basically took the intake and exhaust ports from the now infamous LT1 cast iron heads (the ones installed on SS Impalas) and packaged them in a standard water flow cast iron head with a new bolt pattern. GM uses a new 'Cast Port' head process that make for a very good port shape that is consistent from runner to runner and cylinder head to cylinder head. The only drawback to the vortec head is that the stock valve springs can only attain around .425" valve lift, mostly due to the oversized valve guide bosses and tall seal height. Machining the valve spring pockets for larger valve springs and reducing the seal height will allow for lifts into the .550 range. Adding screw in studs and guide plates makes these heads quite good performance pieces but it can set you back about $200 for machine work. Please note that Vortec, and all center bolt valve cover style heads, use a self aligning rocker arms! If you have the screw in studs and guide plates done, you will have to get new non self -aligning rockers!
Since vortec heads have been in production since 1996 you can find more than a few sets at swap meets and even salvage yards. GM sells them at the parts counter in 2 versions, a bare casting Part # 12529093 and fully assembled part # 12558060. The assembled version comes with 1.94/1.50 valves and stock valve springs. Both heads have 64 cc chambers, 170 cc Intake runners and 3/8" press in rocker studs.