rebuilding my 89 242's 454mag this winter. im trying to pick a cam. What I have is Dart iron eagle 308 heads, air gap intake, emi exhaust(wet) and scorpion 1.7 rockers. I want to avoid reversion at all cost. I am looking at a lunati hydraulic roller. 272/280 @.050 int 221/exh 229 lift .575/.575 112LSA. Anyone think this will cause me reversion. Ive heard some people say anything about exh .224 is too much and ive also heard don't go above .235 . Also anyone know the compression on a 89 454mag off the top of your head. Thanks

You need to post this in the General or boat on a budget section, you will get a lot more feed back

Found your compression its either 180 for Gen IV and 150 psi for Gen V with aluminum rocker covers and lack fuel pump block off mounting pad

http://boatinfo.no/lib/mercruiser/ma...ser15.html#/20

Thanks. Sorry I mean compression ratio 9.5:1?

The link in my post above takes you to the manual page. The page shows 454 at 8.5 with two different pressures, would guess this would be for the 150 psi number. If you cylinder head volume is less and results in the 180 psi then would figure in the 9.3 to 5 ratio. If you have a head casting number we could look it up, then use this calculator to determine

http://www.csgnetwork.com/compcalc.html

9.3:5??

Nope somewhere between 9.3 to 9.5 is my guess

454 mag is about 8.6:1

13.7cc dome
121cc chamber
9ish cc head gasket
5ish cc piston in the hole
930cc swept volume

Actual numbers may vary depending on deck height and actual chamber size.

Now I understand what you meant

That cam should be fine; only 52 degrees of overlap. Getting over 65 degrees tends to cause issues depending on the exhaust.

Should run nicely. What exhaust are you going to run?