1987 454 engine questions
#1
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1987 454 engine questions
Hi,
I have an 87 242 LS 454 with Alpha 1 outdrive. I’ve tried three different props ranging from a 14 x21 as 3 blade, 21 4 blade aluminum and a 19 x 4 aluminum with no measurable improvement in low end performance. Even with the 19 pitch the engine did no go over 43/4400 rpms. Any info, recommendations or suggestions would be appreciated.
Many thanks,
Tony S
I have an 87 242 LS 454 with Alpha 1 outdrive. I’ve tried three different props ranging from a 14 x21 as 3 blade, 21 4 blade aluminum and a 19 x 4 aluminum with no measurable improvement in low end performance. Even with the 19 pitch the engine did no go over 43/4400 rpms. Any info, recommendations or suggestions would be appreciated.
Many thanks,
Tony S
#4
I believe the info tag on the valve cover says 4,200 - 4,400 rpm max.
Most 242 owners prefer a Rev 4 prop. Your Alpha is most likely a 1:36 ratio. Try a 19 Rev 4, I bet you will like it.
Good Luck
Most 242 owners prefer a Rev 4 prop. Your Alpha is most likely a 1:36 ratio. Try a 19 Rev 4, I bet you will like it.
Good Luck
Last edited by GLENAMY 242SS; 07-03-2021 at 06:09 AM.
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masi242 (07-06-2021)
#6
They never put the real Mag in front of an Alpha. Trust me I have owned 2 of these.
For reference see the following I copied from another site:
For reference see the following I copied from another site:
GM Marine Engines
Based on the same 454-cubic-inch big block Chevy, General Motor's Marine Engine division set up the motor specifically for use in boats. Because General Motors was not a boat maker, but a motor and automobile maker, their marine engines division often sold parts to companies specializing in setting up marine engines such such as Mercruiser.Marine Applications
The 330-horsepower, marine 454 is different from the 454 automobile engine from which it was derived. Because boats have just one gear and very different power and torque requirements, everything that shapes power and torque characteristics are different: compression, valve-train, intake and headers. Water pumps for marine engines are specifically designed to withstand corrosion because the systems use open water for cooling and may contain salt, minerals and all kinds of chemicals. Marine carburetors are also designed so that fuel delivery is uninterrupted despite the extreme pitch of the boat during cornering. All electrical components must be able to withstand a hostile, wet environment.454 Marine Specs
The GM marine 454 had a bore of 4.25 inches and stroke of 4 inches with compression ratio of 8.1-to-1. The engine breathed through a four-barrel carburetor, and ignition was provided by a Delco Electric unit. The marine 454 weighs 980 lbs and makes 330 horsepower, at its maximum RPM of 4,400
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Okay...just to get past the maybe-uncomfortable-question...do you understand how to trim an outdrive? Meaning you start with it 'tucked in', full-down, whatever you want to call it, then gradually trim it up or 'out' after you get on plane?
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