I ran across a great deal for a pair of Mercruiser 305 marine engine heads. From what I've read they have about the equivalent of 20-30K on them (400 hours). Will these bolt on to my engine to give me a cheap power boost? Seller told me they are the old style non-Vortec heads. The marine engines were rated at ~220hp in their 4bbl configurations.
Marine heads
- Thread starter Bludacious
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Make sure it’s not a raw water cooled system engine especially a salt water cooled one. The water jackets will be corroded.
There's really nothing special about those heads. You won't likely notice any performance gain. If your current heads are shot and the marine heads aren't super rusty then feel free to use them. Just don't pay "marine" prices or any extra power.
I thought I read somewhere that marine-spec heads had hardened valve seats and guides or something like that.
Like others have said, I have found nothing special about a marine head. Low hours YES more power NO. If you have a 350 motor then just get a set of real Vortec heads 906 or 062 castings. These will make the power.
Hardened valve seats have been pretty standard fare ever since unleaded fuel.
Marine longblocks are typically very similar to their automotive counterparts. The main differences being cam specs and brass freeze plugs. Basically just crate motors dropped in boats with marine peripherals. Occasionally they might be reverse rotation but aside from the cam and oil pump, all the reverse stuff is external.
I'm referring mainly to pleasure boat, ski boats, etc. Obviously the guys with a V-drive picklefork or offshore racer would probably not be running a 305
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Marine longblocks are typically very similar to their automotive counterparts. The main differences being cam specs and brass freeze plugs. Basically just crate motors dropped in boats with marine peripherals. Occasionally they might be reverse rotation but aside from the cam and oil pump, all the reverse stuff is external.
I'm referring mainly to pleasure boat, ski boats, etc. Obviously the guys with a V-drive picklefork or offshore racer would probably not be running a 305
.My car currently has a bone stock 2002 goodwrench 305 crate motor with the LG4 low output specs. From what I'm seeing the marine 081 cast heads have the same larger valves as the 416 and 601 heads so I thought they could be good for a couple ponies and possibly a higher CR if they have the smaller combustion chambers. The main reason they even caught my attention is because they're the cheapest set of heads I've found on CL in my area!
If I use these heads it will be as-is. I have neither the skills or the facilities to do any sort of head work.
If I were in your position and going through the trouble of a head swap, I'd go just a bit deeper and add a cam to the mix. That will likely net you more power gain than a head swap. Goodwrench replacement engines have pretty lame cams.
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