GM Tech Info, cams, springs, etc.
#1
11-16-2007, 05:58 PM
GM Tech Info, cams, springs, etc.
General Motors Engine Technical Specs & Information
cam specs, spring info, and more...
GENERAL MOTORS TECHNICAL INFORMATION
PAGE ONE
Small Block and Big Block Chevrolet engines have become legendary since they were introduced over 50 years ago. The people at COMP Camsยฎ, along with a lot of top engine builders, have spent many years improving these and other Chevrolet powerplants. We know the basics, and the basics are important. We have also learned a few tricks along the way.
If youโre rebuilding an engine, it will be worth your while beforehand to either read our books or watch our videos on the subject. If you need more help or have any questions, call our CAM HELPยฎ line at 1-800-999-0853.
Engine Types
V6 90ยบ -uses โ18โ, โ09โ and โ56โ Prefixes
The 4.3L V6 90ยบ engines produced since 1985 are equipped with two types of camshafts and three types of cam drive systems. Early 1985 and 1986 engines (Prefix โ18โ) were produced with flat tappet cams. Hydraulic roller cams were first introduced in 1987 (Prefix โ09โ). These two cam types require different timing chain sets, because the hydraulic roller cams have a stepped nose like the LT1 engine as described later in this section. In 1992, a balance shaft was incorporated in this engine, which necessitated a third timing chain setup to drive both the cam and the balance shaft. The cam (Prefix โ56โ) in this balance shaft engine is also shorter than the earlier model and does not have a fuel pump lobe.
Small Block V8
There are several varieties of small block engines currently in use in the aftermarket. Although they mostly use the same block, the cylinder heads are very different and require totally different camshafts. The valve arrangement in the heads is different, and therefore the lobe placement on the camshafts must coincide with the head you are using. The โ54โ is the first cam to completely stray from the original design. It is .300โ larger in diameter.
The nose of the standard early model cam โ12โ is very different from the later model hydraulic roller โ08โ. The nose of the hydraulic roller โ08โ is necked down to accommodate the cam retention plate. The โ07โ is an LT1/LT4 shaft which has a longer dowel pin and a center hole for the distributor. Be sure to check the diameter and depth of the hole in the front, as well as the length of the dowel pin.[/align]
Standard Small Block Chevy -uses โ12โ Prefix
This is the basic engine configuration found on all small blocks from 1955 until 1987, when Chevrolet introduced the roller cam. Itโs important to note that the 1955-1957 versions require an oiling groove to be machined into the rear cam journal, but the camshafts are interchangeable.
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cam specs, spring info, and more...
GENERAL MOTORS TECHNICAL INFORMATION
PAGE ONE
Small Block and Big Block Chevrolet engines have become legendary since they were introduced over 50 years ago. The people at COMP Camsยฎ, along with a lot of top engine builders, have spent many years improving these and other Chevrolet powerplants. We know the basics, and the basics are important. We have also learned a few tricks along the way.
If youโre rebuilding an engine, it will be worth your while beforehand to either read our books or watch our videos on the subject. If you need more help or have any questions, call our CAM HELPยฎ line at 1-800-999-0853.
Engine Types
V6 90ยบ -uses โ18โ, โ09โ and โ56โ Prefixes
The 4.3L V6 90ยบ engines produced since 1985 are equipped with two types of camshafts and three types of cam drive systems. Early 1985 and 1986 engines (Prefix โ18โ) were produced with flat tappet cams. Hydraulic roller cams were first introduced in 1987 (Prefix โ09โ). These two cam types require different timing chain sets, because the hydraulic roller cams have a stepped nose like the LT1 engine as described later in this section. In 1992, a balance shaft was incorporated in this engine, which necessitated a third timing chain setup to drive both the cam and the balance shaft. The cam (Prefix โ56โ) in this balance shaft engine is also shorter than the earlier model and does not have a fuel pump lobe.
Small Block V8
There are several varieties of small block engines currently in use in the aftermarket. Although they mostly use the same block, the cylinder heads are very different and require totally different camshafts. The valve arrangement in the heads is different, and therefore the lobe placement on the camshafts must coincide with the head you are using. The โ54โ is the first cam to completely stray from the original design. It is .300โ larger in diameter.
The nose of the standard early model cam โ12โ is very different from the later model hydraulic roller โ08โ. The nose of the hydraulic roller โ08โ is necked down to accommodate the cam retention plate. The โ07โ is an LT1/LT4 shaft which has a longer dowel pin and a center hole for the distributor. Be sure to check the diameter and depth of the hole in the front, as well as the length of the dowel pin.[/align]
Standard Small Block Chevy -uses โ12โ Prefix
This is the basic engine configuration found on all small blocks from 1955 until 1987, when Chevrolet introduced the roller cam. Itโs important to note that the 1955-1957 versions require an oiling groove to be machined into the rear cam journal, but the camshafts are interchangeable.
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#2
01-06-2011, 11:23 PM
You can download some good info now from GM Heritage Center.
http://www.gmheritagecenter.com/gm-h...tion-kits.html
http://www.gmheritagecenter.com/gm-h...tion-kits.html
#3
01-06-2011, 11:27 PM
Here are other places for info
http://chevyinfo.net/parts_books/che...parts_book.pdf
http://www.chevytech.com/
http://chevyinfo.net/parts_books/che...parts_book.pdf
http://www.chevytech.com/
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