Mild 350 w 400 heads

I have a 350 bored .030 with flat top pistons, orginal torker intake and a edelbrock 600 cfm carb, and a cam not sure how big all I know is it has a nice lope, My question is I found a set of 400 heads cast num 3973493 with 2.02 and 1.60 valves the guy says they are 68 cc I am wanting to upgrade the stock heads to make some power but do not want to empty the wallet also don't want to worry about running 91 octane fuel due to 89 being the highest octane in the area, also worred about detonation with these heads since compression is raised with flat top pistons. Any help or suggestions are appreciated.

Sorry I didn't see this sooner...

400 heads were all 76 CC chambers, as far as anything I've ever seen. The 493 IS listed as a 400 head, but I would guess it's been milled down for compression. The only REAL difference (from 350 stuff) I've ever noticed were the "steam holes" drilled in the 400s. We've drilled them in many a 350 head for use on 400.

The 2.02 intakes are not "original". The 1.6" exhaust MAY be (I've seen some that were, some that weren't). We see them a lot, where the intakes have been "upgraded" to 2.02. There is no such thing as an "original Torker" on a GM car. Edelbrock intakes are strictly "aftermarket". Or maybe you mean "Torker 1" as in the first design?

8.8-9.0:1 compression is as high as you "dare" for 89 octane. According to my calculations, staic compression with those heads will be right at 9.54:1. Too high, IMO, for anything lower than 93.

Jim

Yes I knew the valves were not original, as to the intake I ment the Torker I, not the newer Torker II. Thanks for the help Jim

No sweat!

Jim