Merc 454 cam

[Cgrohe223]

Has anyone here had any experience putting a cam in a 454 mercruiser? Want to see if anyone has recommendations on what size cam they installed or what kit they used, also changing out valve springs lifters and seals while I’m in the top end.

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[Racey]

Probably not worth it on those small port iron heads, short intake manifold, and cast iron exhausts.

Those 454/330 motors will go 1500 hours if you just regularly change the oil and do basic service. Your's look super clean, meaning it's probably in really good shape, I wouldn't screw with it.

If you want more power start putting money away for a motor with a 4 bolt main, and Aluminum heads.

 

[Cgrohe223]

Probably not worth it on those small port iron heads, short intake manifold, and cast iron exhausts.

Those 454/330 motors will go 1500 hours if you just regularly change the oil and do basic service. Your's look super clean, meaning it's probably in really good shape, I wouldn't screw with it.

If you want more power start putting money away for a motor with a 4 bolt main, and Aluminum heads.

Thanks boat and motor are super clean I do have some headers I was going to throw on during winter

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[mash on it]

I went with a full roller from Howard's Cams.
Mostly stock bottom end. Forged trw's.
427 truck heads. Stock sized valves. 9:1.
.567"/.578", 225°/231°, cl 108.
Victor Jr airgap and a 750 Holley.
Logs and snails.
Idles low enough for a Mercruiser.
505 hp @ 5000 rpm.

Dan'l

 

[mjc]

That looks like a 365 how 454. They had better heads and 4 bolt mains
I had one in my first boat I ran good I only put imco exhaust on it. Had 870 hours when sold.

 

[ramos45]

you already have exhaust and instead of rebuilding stock heads look into aftermarket head cam combo. Those stock peanut port heads will kill any gains from a cam change. with exhaust, cam and heads your new limiting factor will be the bottom end of the stock motor.

 

[Cgrohe223]

I heard depending on years some came with the better heads that respond pretty well to a cam, haven’t had time to pull the numbers off the block to see.


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[mash on it]

I heard depending on years some came with the better heads that respond pretty well to a cam, haven’t had time to pull the numbers off the block to see.


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Get the casting numbers off of the heads.
Approximately what year?

Dan'l

 

[C-2]

I had the same motor, it's the 365 hp with lagr rectangular port heads. I changed my cam out per Dennis Moore" and his Big Block Bible book, and he was on OSO giving me advice. I also had Lightning headers built.

And then I flattened a cam lobe...so I never knew how it ran.

Edit: rectangular not oval port heads

 

[Carlson-jet]

I would pull a valve cover and see what numbers are cast in the heads. That will give you a good starting point. 2/4/ bolt doesn't really matter imo if you are not touching the bottom end. You need a cam/head combo that makes power in a specific range. I would also do a compression and leak down tests before pulling anything apart. Putting new or fresh heads and cam on a tired bottom end is a disaster.

I think I like raceys idea the more I think about it. Start saving money and let it ride as a dependable in one piece motor, lol

Aaaand, I took too long to write out that post. lol

 

[Carlson-jet]

I had the same motor, it's the 365 hp with lagr rectangular port heads. I changed my cam out per Dennis Moore" and his Big Block Bible book, and he was on OSO giving me advice. I also had Lightning headers built.

And then I flattened a cam lobe...so I never knew how it ran.

Edit: rectangular not oval port heads

That book has some decent info for sure.

 

[Cgrohe223]

Motor only has 70 something hours and it may be around the years of 90-92 right at that weird cut off on changes on those motors


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[mash on it]

I had the same motor, it's the 365 hp with lagr rectangular port heads. I changed my cam out per Dennis Moore" and his Big Block Bible book, and he was on OSO giving me advice. I also had Lightning headers built.

And then I flattened a cam lobe...so I never knew how it ran.

Edit: rectangular not oval port heads

The exact reason I went full roller.
You can't do a flat tappet twice for the price of a full roller.

Hopefully his combo has decent large ovals or rectangle ports.

Dan'l

 

[ramos45]

Yep, the magnum 365 are rectangle port. Like mentioned earlier, check the castings and you might have some heads worth keeping.

 

[UltraLucky]

Motor only has 70 something hours and it may be around the years of 90-92 right at that weird cut off on changes on those motors


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MY 1991 Hallett 210 came with what appears to be the same engine, 454 magnum ('90 or '91). The heads on mine were casting 14096188 which is listed as rectangular port open chamber and would work well with a cam exhaust and intake change. I was going to go this route on my 210 before I decided to switch to a different engine package.

 

[Cdog]

I have the 454 mag 365 hp in my 90 Howard. It's a stout 454 with all the good internals. 4 bolt mains.Forged crank, 7/16 rod bolts, forged pistons and rectangular port heads. I believe its the base blower long block for merc back then. If I were you and you for sure have the 365 engine I'd find a reasonable hydraulic roller cam for it, roller rockers and install the imco's you have.

The intake should be an aluminum dual plane similar to an edelbrock performer. You can probably get a little more out of it by installing the new air gap style edelbrock DP intake. An MSD Ignition distributer and Ignition system will help too.

Pop off a valve cover and take a look at the casting info. I think the heads should have 088 or 188 as the last 3 numbers for Rec port open chambers.

 

[Cdog]

MY 1991 Hallett 210 came with what appears to be the same engine, 454 magnum ('90 or '91). The heads on mine were casting 14096188 which is listed as rectangular port open chamber and would work well with a cam exhaust and intake change. I was going to go this route on my 210 before I decided to switch to a different engine package.

Same here.