Need Head(s),,,,,,, bad!!!!!!!
12-10-2005 | 05:17 PM
#1
Thread Starter
Registered
Joined: Aug 2002
Posts: 2,896
Likes: 3
From: Eastern Lake Ontario
Need Head(s),,,,,,, bad!!!!!!!
OK, got a buddy trying to assemble a complete, spare, stock, Mark VI 454 Mag. We don't have an available (to rebuild) engine, so we don't have block numbers/head numbers.
What we need is head casting numbers from a Mark VI (1987) 454 Mag. I did my engines last spring (1989 454 Mags) and could not find "new" original heads, no longer produced by GM. So, I bought 4 new aftermarket DART heads. But, my buddy is only intending on building ONE spare, so it needs to match the original.
What I did find out is that these heads were the same heads used on 1970 454 Chevelle SS and Corvette LS6/LS7 heads. Do you guys know this, is this correct? If so, or not, we should be able to find some used LS6/LS7 heads and rebuild them, that's the plan.
Any input on this will be helpful.
What we need is head casting numbers from a Mark VI (1987) 454 Mag. I did my engines last spring (1989 454 Mags) and could not find "new" original heads, no longer produced by GM. So, I bought 4 new aftermarket DART heads. But, my buddy is only intending on building ONE spare, so it needs to match the original.
What I did find out is that these heads were the same heads used on 1970 454 Chevelle SS and Corvette LS6/LS7 heads. Do you guys know this, is this correct? If so, or not, we should be able to find some used LS6/LS7 heads and rebuild them, that's the plan.
Any input on this will be helpful.
12-10-2005 | 05:31 PM
#2
~~~~
Joined: Oct 2000
Posts: 1,451
Likes: 3
From: Western New York
Re: Need Head(s),,,,,,, bad!!!!!!!
I think you mean Mark IV. 1987 454 Mag was used with an Alpha drive. This URL lists parts to that engine. Might be of help.
http://www.mercruiserparts.com/selec...doc_nbr=+14296
http://www.mercruiserparts.com/selec...doc_nbr=+14296
Last edited by RLW; 12-10-2005 at 05:40 PM.
12-10-2005 | 05:36 PM
#3
Registered
Joined: Jul 2004
Posts: 8,908
Likes: 9
From: Long Island,New York
Re: Need Head(s),,,,,,, bad!!!!!!!
Originally Posted by ThirdBird
OK, got a buddy trying to assemble a complete, spare, stock, Mark VI 454 Mag. We don't have an available (to rebuild) engine, so we don't have block numbers/head numbers.
What we need is head casting numbers from a Mark VI (1987) 454 Mag. I did my engines last spring (1989 454 Mags) and could not find "new" original heads, no longer produced by GM. So, I bought 4 new aftermarket DART heads. But, my buddy is only intending on building ONE spare, so it needs to match the original.
What I did find out is that these heads were the same heads used on 1970 454 Chevelle SS and Corvette LS6/LS7 heads. Do you guys know this, is this correct? If so, or not, we should be able to find some used LS6/LS7 heads and rebuild them, that's the plan.
Any input on this will be helpful.
What we need is head casting numbers from a Mark VI (1987) 454 Mag. I did my engines last spring (1989 454 Mags) and could not find "new" original heads, no longer produced by GM. So, I bought 4 new aftermarket DART heads. But, my buddy is only intending on building ONE spare, so it needs to match the original.
What I did find out is that these heads were the same heads used on 1970 454 Chevelle SS and Corvette LS6/LS7 heads. Do you guys know this, is this correct? If so, or not, we should be able to find some used LS6/LS7 heads and rebuild them, that's the plan.
Any input on this will be helpful.
12-10-2005 | 06:56 PM
#4
Thread Starter
Registered
Joined: Aug 2002
Posts: 2,896
Likes: 3
From: Eastern Lake Ontario
Re: Need Head(s),,,,,,, bad!!!!!!!
Yup, my Roman Numeraling is not good, oops. Anyway, we'll check out the site you offered.
JCPerf:
Open/Closed chamber,,,,,,,,,???????
You've just exceeded my knowledge level! I don't know what that refers to.
I like to think I know a litltle bit about motors, then you guys show me I don't.
Please expound!!!!
JCPerf:
Open/Closed chamber,,,,,,,,,???????
You've just exceeded my knowledge level! I don't know what that refers to.
I like to think I know a litltle bit about motors, then you guys show me I don't.
Please expound!!!!
12-10-2005 | 07:32 PM
#5
MarineKinetics
Joined: Oct 2002
Posts: 942
Likes: 4
From: Rochester, NY
Re: Need Head(s),,,,,,, bad!!!!!!!
Thirdbird,
The original 454 LS6 head was an open chamber,320 cc rectangle port, 118 cc combustion chamber. The casting # was 3994026. The service replacement for these heads is the 990/188 casting, which is the same head used by Merc in the HP motors.
Bob
The original 454 LS6 head was an open chamber,320 cc rectangle port, 118 cc combustion chamber. The casting # was 3994026. The service replacement for these heads is the 990/188 casting, which is the same head used by Merc in the HP motors.
Bob
12-29-2005 | 11:58 AM
#8
Registered
Joined: Jun 2001
Posts: 710
Likes: 1
From: Babylon N.Y.
Re: Need Head(s),,,,,,, bad!!!!!!!
1970 Ls 6 head was 3964291 closed chamber head 
. They are worth alot of money to car enthusiasts, I have them. 1971 and newer got the 026 open chamber castings that are open chamber Even rarer than the 291's. The 188 and 990 were replacements , and were on crate engines and many Marine 454 365,385 Mag, as well as 420 etc... they are getting hard to find because they are ending up on salt water marine engines, and also are prone to cracking due to coming in and out of the water shocking a hot head with cool water. If you can afford it buy the Dart's they have much thicker decks, flow better than a ported Gm right out of the box. Buy them bare and build them. Dart dosen't offer heads that are assembled with Inconnel exhaust valves. It really pays to go with the Dart heads, 2006 technology Vs. 1971 technology intended for production automotive use. BBB
. They are worth alot of money to car enthusiasts, I have them. 1971 and newer got the 026 open chamber castings that are open chamber Even rarer than the 291's. The 188 and 990 were replacements , and were on crate engines and many Marine 454 365,385 Mag, as well as 420 etc... they are getting hard to find because they are ending up on salt water marine engines, and also are prone to cracking due to coming in and out of the water shocking a hot head with cool water. If you can afford it buy the Dart's they have much thicker decks, flow better than a ported Gm right out of the box. Buy them bare and build them. Dart dosen't offer heads that are assembled with Inconnel exhaust valves. It really pays to go with the Dart heads, 2006 technology Vs. 1971 technology intended for production automotive use. BBB
Last edited by Big Block Billy; 12-29-2005 at 12:17 PM.
12-29-2005 | 12:16 PM
#9
Registered
Joined: Jun 2001
Posts: 710
Likes: 1
From: Babylon N.Y.
Re: Need Head(s),,,,,,, bad!!!!!!!
Oh ! 
I noticed that you need heads bad. Remember, You don't need BAD HEADS. So be careful, there is alot of junk out there on e-bay. I have been victimized ! So many people think they have gold, because what the part # is or what it is for. Many don't know the real condition, or maybe trying to sell something that belongs on the scrap pile. Also the shipping costs are quite high, It not worth it to send scrap for $40-$50 per head. Unless you are sure what you are buying. Also many heads have been wrecked by porting, and you don't want to find out when the motor hydro locks, and find out that that there is a pinhole in the exhaust port, from corrosion from the water jacket side and porting on the exhaust side. It could cost you a motor. Alot more money and headaches than a good set of heads would cost. I sent out a head last year that seemed good and put hard seats in it, guides, cut for bigger valves etc, only to find pinhole in an exh port, that the machine shop missed. A few hundred dollars and another head and a few hundred more dollars and all was well. Also when they suck water and sit, they rust from both sides. Be real leary of heavy rust in an exh. port. Also they rot where the water crosses over through the intake. Make sure there is plenty of good Iron left. Iron that is black is Impregnated with corrosion, and maybe salt. Chip them good. You should have at least 1/4"(but rather have more) bare minimum to hold the intake gasket. BBB
I noticed that you need heads bad. Remember, You don't need BAD HEADS. So be careful, there is alot of junk out there on e-bay. I have been victimized ! So many people think they have gold, because what the part # is or what it is for. Many don't know the real condition, or maybe trying to sell something that belongs on the scrap pile. Also the shipping costs are quite high, It not worth it to send scrap for $40-$50 per head. Unless you are sure what you are buying. Also many heads have been wrecked by porting, and you don't want to find out when the motor hydro locks, and find out that that there is a pinhole in the exhaust port, from corrosion from the water jacket side and porting on the exhaust side. It could cost you a motor. Alot more money and headaches than a good set of heads would cost. I sent out a head last year that seemed good and put hard seats in it, guides, cut for bigger valves etc, only to find pinhole in an exh port, that the machine shop missed. A few hundred dollars and another head and a few hundred more dollars and all was well. Also when they suck water and sit, they rust from both sides. Be real leary of heavy rust in an exh. port. Also they rot where the water crosses over through the intake. Make sure there is plenty of good Iron left. Iron that is black is Impregnated with corrosion, and maybe salt. Chip them good. You should have at least 1/4"(but rather have more) bare minimum to hold the intake gasket. BBB
