Smithelectric

does anyone have or know anyone with some good 454 heads? i found some 990s but heard the crack easy on a marine engine

pantera232

I have stock 781s I'm not impressed w them but I've read good things, I should've done some flow work to them and maybe increase valve size bc I can't get 454 over 5200 rpm

MILD THUNDER

iTrader: (3)

990 heads were used on about a millon stock mercury engines. They are no more prone to cracking than any other iron gm head.

My thoughts on heads are this.

By the time you buy a set of used heads, buy new inconel and severe duty valves, have the heads magged, machined, valve jobs, new springs seals and guides installed, many times you aren't that far away from a set of superior aftermarket bolt on castings.

Without knowing your combination, I can't suggest any heads, and if your running in salt, then youd prob wanna stick with iron heads. If so, the Dart 308 Iron Eagles would be a nice 454 head. If aluminum is a option, the dart 310 Pro 1 is a excellent choice, or the edelbrock marine rect ports. Price wise, its hard to beat the edelbrock marine aluminum heads.

I believe the Dart Iron Eagle 308, is comparable cost wise to the Edelbrock marine Aluminum. Both have some advantages.

The Darts have raised exhaust ports, cast iron is very durable, and in my opinion back to back would probably make a bit more power than the Edelbrocks due to the design. The dart 308 High velocity casting has been around a long time, and is a proven HP maker on a smaller big block like a 454.

The edelbrocks, will be lighter, allow for a bit more compression, can be repaired more easily if something happens.


One of the problems on a 454 bore size, is the compression. If you are running a flat top piston, or a dish, you will have less than optimal compression unless you plan to run a blower. With a 118CC chambered head, you are looking to be around 8.2-8.4, and with a GM dished, under 8:1. With small domes, like a 454 mag piston, you will be closer to 9:1.