How much will milling the heads .030 raise the comprssion ratio? On a stock 454 mag after milling heads, should I change to 89 octane instead of 87?

I can't remember where I saw the website that talked about notching the bore. That is done under the intake valve, right? Is it worth the time?

There was an article in Hotboat Oct 03 called "low maint powerhouse" which mentioned notching. it is done to help prevent detonation.

Mark

depends on the gaskets you decide to go back with. Get me the gaskets compressed volume in cc's, cc's of your heads piston type and cc's of valve reliefs.

Roby

Notching the bores allows more air to flow around the valve and bore. Be carfull not to grind below the top ring. Also if your comming up short on compression you may want to reconsider, it may not be worth the trade off.

Milling the heads .030 will raise the compression maybe about 1/2 pt, but your adjustment on your lifter preload may require push rod changes and manifold milling to realign and seal your intake manifold. Valve to piston clearance should also be rechecked and it just might not be worth the trouble. A set of good aftermarket heads with a smaller cc chamber will probably net you a lot more power (with a good cam) and you'll avoid all the problems above. Remember all engines are systems and just heads alone without a better breathing cam and exhaust are generally not going to net you the real power available. Just some thoughts.
Raylar

I was thinking about swapping to hyd roller cams and better rockers already. I switched to Gil manifolds last year. I was thinking I should keep everything apearing stock so my insurance wouldn't be an issue.

I've talked to a few people that have done this with very good results.


The Oct, 2003 HotBoat is about the only issue I can't find. I should forget about the bore notching anyway as it would be awefully hard to do it cleanly with out disassembling the engine.