1987 454 Magnum - What do I have?
12-14-2024 | 07:19 AM
#15
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Joined: Mar 2001
Posts: 1,239
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From: Oakville,ON
Below is some old info that I kept from Powerboat Magazine - Teagues on Tech. I don`t know if this is still valid info or not but perhaps it will be of use to you:
PROVEN 7.4 CARB UPGRADE
QUESTION: A few years ago you listed an intake, cam and head combination for upgrading a stock MerCruiser 454, 330-horsepower engine (mine is a 1987 model) that was good for up to 425 to 450 horsepower, if I remember correctly. Could I get that parts list? I looked through the archives, but have had no luck finding the article there.
Brad Anderson
Scottsdale, Ariz.
ANSWER: The article was in late 1998 or early 1999. By coincidence, one of the project boats that you are referring to was just in my shop for service and is still running strong with about 350 hours on it since the upgrade. There were actually a couple of stages to the upgrade. The simple one involved changing the heads, intake manifold, carburetor, ignition and the exhaust. The other expanded internally by installing a hydraulic roller cam setup, pistons and Manley H-beam rods. A few of the part numbers that were used at that time have changed. In order to make it easier for you, I have researched the parts and can provide their equivalent numbers.
The first stage of the upgrade included Edelbrock marine head assemblies (Part No. 61459), Dart oval port intake manifold (Part No. 6204), Holley 830 CFM carburetor, IMCO PowerFlow exhaust system, MSD complete marine ignition system, Manley push rods (Part Nos. 25795 and 25796), Crane rocker arms (Part No. 13750), and an upgraded flame arrestor and necessary accessory parts. The version of the Holley carburetor that was used is no longer available so I would recommend the Holley 9022 marine carburetor instead.
The second stage of the upgrade used all of the above parts plus some internal parts. The pistons were changed to a JE forged piston (Part No. 106904), the rods were upgraded to Manley H-beams (Part No. 14060), the cam was upgraded to a Crane hydraulic roller (Part No. 139731), the lifters were upgraded to Crane (Part No. 13532), the required push rods for the hydraulic roller setup are Manley (Part Nos. 25818 and 25855), the timing chain used is the Crane billet roller (Part No. 13977), and the oil pump was changed to a Mellings high-volume (Part No. HV-77). Obviously, there are many other small parts and gaskets required to do the job, but these are the main parts used with proven success.
PROVEN 7.4 CARB UPGRADE
QUESTION: A few years ago you listed an intake, cam and head combination for upgrading a stock MerCruiser 454, 330-horsepower engine (mine is a 1987 model) that was good for up to 425 to 450 horsepower, if I remember correctly. Could I get that parts list? I looked through the archives, but have had no luck finding the article there.
Brad Anderson
Scottsdale, Ariz.
ANSWER: The article was in late 1998 or early 1999. By coincidence, one of the project boats that you are referring to was just in my shop for service and is still running strong with about 350 hours on it since the upgrade. There were actually a couple of stages to the upgrade. The simple one involved changing the heads, intake manifold, carburetor, ignition and the exhaust. The other expanded internally by installing a hydraulic roller cam setup, pistons and Manley H-beam rods. A few of the part numbers that were used at that time have changed. In order to make it easier for you, I have researched the parts and can provide their equivalent numbers.
The first stage of the upgrade included Edelbrock marine head assemblies (Part No. 61459), Dart oval port intake manifold (Part No. 6204), Holley 830 CFM carburetor, IMCO PowerFlow exhaust system, MSD complete marine ignition system, Manley push rods (Part Nos. 25795 and 25796), Crane rocker arms (Part No. 13750), and an upgraded flame arrestor and necessary accessory parts. The version of the Holley carburetor that was used is no longer available so I would recommend the Holley 9022 marine carburetor instead.
The second stage of the upgrade used all of the above parts plus some internal parts. The pistons were changed to a JE forged piston (Part No. 106904), the rods were upgraded to Manley H-beams (Part No. 14060), the cam was upgraded to a Crane hydraulic roller (Part No. 139731), the lifters were upgraded to Crane (Part No. 13532), the required push rods for the hydraulic roller setup are Manley (Part Nos. 25818 and 25855), the timing chain used is the Crane billet roller (Part No. 13977), and the oil pump was changed to a Mellings high-volume (Part No. HV-77). Obviously, there are many other small parts and gaskets required to do the job, but these are the main parts used with proven success.
