marine heads?
Thread Starter
Drifting
Joined: May 2001
Posts: 1,329
Likes: 12
marine heads?
I'm always for the lookout for performance parts on ebay and I fell onto this
http://cgi.ebay.com/ebaymotors/aw-cg...item=599047448
And I was wondering, what makes a pair of heads "Marine" ? the angle? The flow?
http://cgi.ebay.com/ebaymotors/aw-cg...item=599047448
And I was wondering, what makes a pair of heads "Marine" ? the angle? The flow?
Le Mans Master
Joined: Feb 1999
Posts: 5,877
Likes: 1
From: Park Ridge IL
Re: marine heads? (Lohkay)
I'm not positive, but I beleive it has something to do with the cooling passages. I can't remember what's different, but I beleive it is related to the fact that marine engine typically have open cooling systems, circulating cooler lake/ocean water through the engine, rather than closed systems like in our car.
Drifting
Joined: Aug 2000
Posts: 1,805
Likes: 36
From: Annapolis MD
Re: marine heads? (Lohkay)
There is nothing different in the basic casting design. "Sometimes" a marine aluminum part will have brass water passages cast in (usually only in intakes), or may have some corrosion coating. "Usually" marine heads will include bronze valve stem guides, and if complete heads it "almost always" means they have Inconel exhast valves and severe duty stainles intakes. If complete heads they "may" also have different valve springs to take high RPM for long periods of time.
-Greg
[Modified by GregP, 8:48 AM 12/11/2001]
-Greg
[Modified by GregP, 8:48 AM 12/11/2001]
Le Mans Master
Joined: Mar 1999
Posts: 6,744
Likes: 1
From: delmont pa
Cruise-In I Veteran
Cruise-In II Veteran
Re: marine heads? (Lohkay)
GM supplies the casting and merc marine does its own machining,so there may be some difference in the parts needed for marine service.
Drifting
Joined: Aug 2000
Posts: 1,805
Likes: 36
From: Annapolis MD
Re: marine heads? (Lohkay)
"Well then, what would stop someone from building an engine with marine heads?"
They usually charge more for anything that says marine :D . Seriously, there should be no problem using "marine" parts on a car, there can be problems with going the other direction.
-Greg
They usually charge more for anything that says marine :D . Seriously, there should be no problem using "marine" parts on a car, there can be problems with going the other direction.
-Greg
Burning Brakes
Joined: May 1999
Posts: 760
Likes: 1
From: Greenwich, CT
Re: marine heads? (GregP)
"Marine" parts cost 3X as much as the same part for "auto" or "truck" engines!
If you think Corvettes mods aren't expensive enough, buy a boat. They are God's way of telling you you have too much money.
drj
[Modified by DOCTOR J, 11:34 PM 12/11/2001]
If you think Corvettes mods aren't expensive enough, buy a boat. They are God's way of telling you you have too much money.
drj
[Modified by DOCTOR J, 11:34 PM 12/11/2001]
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Thread Starter
Drifting
Joined: May 2001
Posts: 1,329
Likes: 12
Re: marine heads? (DOCTOR J)
"Marine" parts cost 3X as much as the same part for "auto" or "truck" engine!
If you think Corvettes mods aren't expensive enough, buy a boat. They are God's way of telling you you have too much money.
If you think Corvettes mods aren't expensive enough, buy a boat. They are God's way of telling you you have too much money.
Safety Car
Joined: Jun 2001
Posts: 4,004
Likes: 2
From: Severna Park Md
Re: marine heads? (Lohkay)
I think the difference is, as a standard, marine heads would always have stainless steel valves and hardened valve seats. Not really nessisary on a street engine. Marine engines when being used are always under load. There is no criuse on a marine engine. Even at part throttle its workin hard. Marine heads can handle extreem conditions better.
Burning Brakes
Joined: May 1999
Posts: 760
Likes: 1
From: Greenwich, CT
Re: marine heads? (Jvette73)
Just as a clarification:
"marine heads would always have stainless steel valves and hardened valve seats"
All engines use stainless valves (unless they are titanium). Standard valve alloy used to be 21% Cr - 4% Nitrided Ni - - Aftermarket valves have a higher alloy content, i believe. (I spent two summers in college as QC metallurgist in a stainless mill, melting tons of valve steel for Chrysler.)
And I thought hardened valve seats were required on anything running unleaded gas? I'll have to look that one up.
Not an argument - I just get very few chances to drop the phrase "QC metallurgist for valve steel" into a conversation.
drj
[Modified by DOCTOR J, 11:33 PM 12/11/2001]
"marine heads would always have stainless steel valves and hardened valve seats"
All engines use stainless valves (unless they are titanium). Standard valve alloy used to be 21% Cr - 4% Nitrided Ni - - Aftermarket valves have a higher alloy content, i believe. (I spent two summers in college as QC metallurgist in a stainless mill, melting tons of valve steel for Chrysler.)
And I thought hardened valve seats were required on anything running unleaded gas? I'll have to look that one up.
Not an argument - I just get very few chances to drop the phrase "QC metallurgist for valve steel" into a conversation.
drj
[Modified by DOCTOR J, 11:33 PM 12/11/2001]
Drifting
Joined: Jul 2001
Posts: 1,418
Likes: 1
Re: marine heads? (Lohkay)
There is nothing Marine about those heads on ebay.Unless they forgot to add the should be on top of a 540 + ci motor!
Seriously.Usually a off shore boat will get Iconel exhaust valves and a upgrade in valve springs but that is it.A guy does not want to use exhaust seat inserts in a Marine application cause if that thing goes lean after extended high speed runs"marine engines have a higher fuel demand" there goes the head and the Iron heads cannot be repaired.Go lean and tulip a valve and recess a seat it can be repaired with a seat insert but the other way kills em dead in the water"he he".
Seriously.Usually a off shore boat will get Iconel exhaust valves and a upgrade in valve springs but that is it.A guy does not want to use exhaust seat inserts in a Marine application cause if that thing goes lean after extended high speed runs"marine engines have a higher fuel demand" there goes the head and the Iron heads cannot be repaired.Go lean and tulip a valve and recess a seat it can be repaired with a seat insert but the other way kills em dead in the water"he he".
