Thread: 454 marine engine questions

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I opted for changing heads on my 350 marine engine instead of stroking to a 383. I put on the Dart Iron Eagle heads and was impressed. I only got about 30 horses or so though...

Should I stick with a good GM set of heads, or spend the money for after market cast iron. I need to stay cast iron...

Originally Posted by 76GMC1500

You'll make more horsepower putting a better set of heads on there and raising the compression ratio than you will with a stroker crank. 400-425 hp is reasonable to ask for with a change of heads and cam. You'll get better fuel economy if you pick the right cam.

Originally Posted by AdamB

I opted for changing heads on my 350 marine engine instead of stroking to a 383. I put on the Dart Iron Eagle heads and was impressed. I only got about 30 horses or so though...

Should I stick with a good GM set of heads, or spend the money for after market cast iron. I need to stay cast iron...

I would choose your heads after you figure out if you are going low deck or tall deck.
In other words a tall deck would be larger and require more head.

some day I'll crawl into the engine bay and take some pics LOL. I did look for the engine numbers but didn't see anything. Will look again in better light.

they did not use 454 tall decks in the low power mercs that i ever work on they did use 427tall decks and they did make hi hp tall decks but alot more CID a540 short deck would not use a smaller head than a 540 tall deck

Originally Posted by pat mccarthy

they did not use 454 tall decks in the low power mercs that i ever work on they did use 427tall decks and they did make hi hp tall decks but alot more CID a540 short deck would not use a smaller head than a 540 tall deck

I was refering to a 489/496 low deck when I talked about a smaller head meaning if it is a tall deck I would assume he would go 530+ cubes.

Originally Posted by erik erikson

I was refering to a 489/496 when I talked about a smaller head.

well ok tell mehe as making what ? a tall deck or short ? i have not seen a 454 tall deck? what head to use it is top RPM with the prop he will run and build from there

Originally Posted by pat mccarthy

well ok tell mehe as making what ? a tall deck or short ? i have not seen a 454 tall deck? what head to use it is top RPM with the prop he will run and build from there

Pat,I don't know what he is trying to build.
I have not seen a tall deck 454 but I have seen a tall deck 427.
Pat,are you messing with me??

Originally Posted by erik erikson

Pat,I don't know what he is trying to build.
I have not seen a tall deck 454 but I have seen a tall deck 427.
Pat,are you messing with me??

maybe he did say 454 tall deck ? or am i having flash backsneed to lay down room is spining

Originally Posted by pat mccarthy

maybe he did say 454 tall deck ? or am i having flash backsneed to lay down room is spining

Pat,does your stress seem to get worse when you are on the forum??

Originally Posted by erik erikson

Pat,does your stress seem to get worse when you are on the forum??

no i take good drugs i just did not time them right to kick in i hate it when my timing is off

Originally Posted by pat mccarthy

no i take good drugs i just did not time them right to kick in i hate it when my timing is off

Ignition timing or cam timing???

Originally Posted by erik erikson

Ignition timing or cam timing???

must be valve timing intake valve yup that is it or just to much over lap

There are no tall deck marine engines, the 330 hp 454 is the same engine found in the 70's-80's Chevy pickups.

yes i think i did say that

Okay, I must have heard or read wrong some where about the tall deck thing. I will make a point of uncovering the boat today (wednesday) and crawling in there to see if I can see some engine #'s. Like I said, this boat originally had a 502 in it, but the owner replaced it with whatever is in there now. It says 454 on the valve covers but......

Sorry to all you guys if I caused the room to spin LOL.