I have a 93 merc 502/440HP motor with low hours on it im looking to put in my 67 chevelle. I was told that the marine heads have special heavy duty "IMCO" stainless valves. I partially disaasembled the motor for inspection/cam change. I pulled 2 of the valves out of one head and found they had EATON and a part# on them. I was told by a friend that the marine valves are very heavy and I should change them while the heads are off to lighten up the valvetrain. The heads are in great shape and can be just bolted on and run. I have a spare set of speed-pro stainless 2.19/1.88 valves I could drop in. Tommorrow im going to wiegh the valves compared to the speed-pro's to see if theres much of a difference. Just thought I'd ask to if any experience with marine stuff...............THANX

Horses&^t, who do you think builds ALL the GM H/P stuff. Mercury has been doing all the 454, 502, 540 stuff for years. The blocks have different nickle content and the head gaskets are different, other than that they are very similiar. I'd run a marine engine on the street any day.

read this: http://www.chevelles.com/forum/ultimatebb.php?ubb=get_topic;f=4;t=018864

THANX for the reply 4 speed......I did wiegh the eaton valves compared to the speed-pro valve and them seemed to be on average 5 grams heavier(was using a questionable scale). The 502 will not be spun more than 5600-6000max. The whole point of buying and running the 502 was less compression /RPM's and would still make as much or more than the 468 I was going to build and in the long run cheaper to build. Bought the 502 running, low hours with bad cam for $2000

THANX for the reply 4 speed......I did wiegh the eaton valves compared to the speed-pro valve and them seemed to be on average 5 grams heavier(was using a questionable scale). The 502 will not be spun more than 5600-6000max. The whole point of buying and running the 502 was less compression /RPM's and would still make as much or more than the 468 I was going to build and in the long run cheaper to build. Bought the 502 running, low hours with bad cam for $2000