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 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.
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!
GM Vortec intakes Part # 12496820 is a low rise dual plane with EGR provision and dual carb
bolt pattern.
Edelbrock Vortec intakes Part # 2116 Performer manifold non-EGR
A Word on Power
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! |
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