454 Mag had a aluminum intake, 7.4L LX should be a 330HP with a iron intake. If you have the 330HP version, i'd consider selling them complete. They are great engines, but nothing in them other than the block is suitable for making decent power. The heads suck, cast cranks, weak rods, etc. The 365HP versions had better internals, and better heads.

If you in fact have 365HP mags, then you can do carb, intake, cam, exhaust, roller rockers, and they will wake up a bit. If you wanna get silly, you can even add a blower. Without the blower, 450HP is realistic. With the blower, 550-600 is realistic, using the GM Rect heads and above mods.

Yeah ditto.

First you need to determine what you have in the boat. 365hp motors will have an aluminum GM dual plane intake. 330hp motors will have a cast iron intake. See if a magnet will stick to it. If you have an iron intake, you have 330's. If you have an aluminum intake you have 365's. As stated above, the 330's do not have the guts to support over 450hp or revs over 5,000. The 330's have cast pistons and won't support supercharger boost over 3.5psi.

188 heads are on the 365 already and the valve sizes are already 2.19/1.88 - aside from bowl blending or porting work, they don't need anything done to them to make power. "Good" after market heads are better than 088's so if you currently have peanut port heads and are wanting better heads, there are a lot to choose from.

990, 188, 088 are essentially the same head from GM. There are some who claim the 188 has a smaller chamber, but it's only a 2cc difference and that is out the window if they have ever been resurfaced anyhow. Essentially the same ports, same valve sizes, and similar flow characteristics. The 088's have some cooling passages slightly different so be sure to use the correct head gasket if you plan to run them on a MkIV block.

MC

IF they are designated as 7.4 they are the 330 hp with the peanut heads. 7.4 wasnt used on any motor until 1988. 454 mag with forged internals and 088 heads didnt come out until 1988 and would be called a 454 mag.

They made a 454"mag" in 1987 that was a 330 in front of an alpha

i guess they called it a mag cause you needed a magnet to get all the pieces of gear out of the lower housing...

had an '87 24 Baja with that combo...

Yup. 1987 454 mag was really a 330hp. 1988 it was 365hp and entirely different engine setup

Not true dereknkathy...I had one in a 27 Baja that I never had a problem with, and I wasn't really to easy on it.. I was easy out of the hole but once on plane I beat it pretty good for 9 yrs all I did was put a water pump impellor in it 1 time..

actually, i am planning on running a 454 in front of an alpha gen 1 as soon as i get 350 boat and get my spare 454 together. BUT, i snapped a shaft on one with a 400 small block just with engine torque. (i think it was pre-alpha with the o-ring groove and spring pin. and it was a early sundancer with a big dia prop. and i firewalled it racing a friend.) but you can break an alpha with a big block...and 454 magnet sounded funny....454-alpha was the standard set-up in 87. TRS was done-at least for production boats, and bravo was still being developed. they only did it one year. i wonder why?